Model Engine Maker

Engines => Your Own Design => Topic started by: Roger B on November 26, 2015, 08:38:49 PM

Title: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 26, 2015, 08:38:49 PM
You can never have too many projects on the go  :)

As I am slowly progressing with my fuel injection system I need an engine to try it on. This one has popped up in a couple of threads already and now it's time to make a start. The design is (very) loosely based on the Field Marshall tractor engine. If it works I will then build the tractor to go round it. Some basic details:
Bore 25mm
Stroke 40mm
Theoretical compression ratio 25-1
Cylindrical open combustion chamber
Reed inlet valve(s)
Water cooled

I have a piece of 120mm diameter aluminium for the crankcase and some 50mm cast iron for the cylinder block and head. The 120mm bar will be a challenge with my lathe but I have some ideas.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: b.lindsey on November 26, 2015, 09:17:41 PM
That's a sizeable chunk of aluminum Roger, but you will figure it out. Do you have a rough sketch of it yet?

Bill
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Jo on November 27, 2015, 07:28:15 AM
You can never have too many projects on the go  :)

Or casting sets  ;D

Jo
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 27, 2015, 07:52:11 AM
This is the current state of the design. There are a lot of details to work out but as long as I can get started on the big aluminium piece I think that it is buildable (whether it will ever work is another question  ::) )

The yellow circle is the 120mm dia. piece of aluminium.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Niels Abildgaard on November 27, 2015, 08:48:27 AM
Hello Roger

This one does not interest me anylonger so You can have the crankcase with inside crank if You can use it for experiments.
Stroke is 44 m and a piston of 28mm dia will be possible
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 27, 2015, 11:43:36 AM
Thank you for the offer Niels  :ThumbsUp:  :ThumbsUp: 
It is certainly tempting, but I think that the changes I would need to make will be too difficult. The main problem being lubrication, this engine will induct just air not a fuel/oil mix, so I would need to add an oil feed for the bearings, especially the big end.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 28, 2015, 05:50:16 PM
One side of the aluminium blank is fairly flat, the other side has quite a large step so I need to get the faces flat and parallel before I can start milling it into a square.

I drew the planned 90mm square (will just fit the 4 jaw chuck  :) )on the good side and rested my faceplate on top, there was room for a couple of threaded holes so looks ok. I had nothing to fix it to the bench drill, but by removing the soft jaws it would just fit in the bench vice. Two M6 threads later I could fix it to the faceplate  :cartwheel:  Swarf time  ;)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Jo on November 28, 2015, 06:03:01 PM
 :o I thought it was going to look big on the faceplate.

Carefully does it  ;)

Jo
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 29, 2015, 03:56:19 PM
That went well  :cartwheel: I ran at 250 rpm and by keeping the cut down to 0.1mm I got a good finish on the outside  :) . It finished at 119mm but that's not critical. I was able to clean the ends up to give a length of 55mm which will make the bearing design a little easier.
Taking the middle out with a hole saw is much quicker than boring and also gives a useful 30mm dia. blank. The hole will allow me to clamp it to the angle plate for milling the sides.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on November 29, 2015, 04:22:53 PM
I am following along. Nice stretching of you machining capability.

Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 06, 2015, 06:48:50 PM
Thanks Achim  :ThumbsUp:

Having been playing with fiddly injection parts I decided to see how far I could stretch my mill  ::) The crankcase blank was bolted to the angle plate ready to be squared up. I am using a 20mm roughing cutter at  width of 9mm and a cutting depth of 2mm (I tried 3mm but it was too much). I am getting much less vibration and a better finish running the cutter at 1120rpm that I was at the start running at 560rpm.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 09, 2015, 08:55:07 PM
Still carving out the crankcase. With hindsight it may have been better the square the block up to the end of the angle plate rather than using a square.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 13, 2015, 06:18:26 PM
I finished milling the block square and then needed to set it up in the lathe to bore the center to near finished size. It was set true using the radiuses (radii ?) on the corners and also checked for flatness.

The square block and the protruding jaws seemed a bit scary   ::) so I tried to fit the chuck guard but there was not enough clearance. Luckily the one from  my Minilathe could be used  :)

I could take 1mm deep cuts at 500 rpm so it didn't take long to reach 58 mm diameter. I will now put this aside to relax until after Xmas.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 13, 2015, 06:21:33 PM
A short more physical interlude cutting of the piece of 50mm dia. cast iron for the cylinder and head. It's at times like this I get out the catalogues and look for small bandsaws and power hacksaws although I don't really have space for one.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 13, 2015, 06:31:29 PM
One end of the bar already had a central hole which I was able to clean up and use to turn most of the bar to 45 mm dia. It was then turned round and held with the fixed steady whilst the end was faced and centre drilled. The remains of the ring on the end are visible but barely detectable with a finger nail.

The final action was to part the cylinder head piece from the cylinder. I kept it supported with the center until the last few mm. I should have lowered the speed from 250 rpm at the start but lived with the chatter instead  ::) (lower speeds are possible but a bit of a fiddle). Finally I cut a centering groove on each end so I can take out the middle with a hole saw.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on December 13, 2015, 07:24:55 PM
A short more physical interlude cutting of the piece of 50mm dia. cast iron for the cylinder and head. It's at times like this I get out the catalogues and look for small bandsaws and power hacksaws although I don't really have space for one.
Hi Roger, nice progress. My little band saw found its place under the table. I have to go on my knees to cut something, but I enjoy it.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 14, 2015, 07:05:39 PM
Thanks Achim, unfortunately the space under my table is already occupied by my tapping guide and arc welder  :headscratch:

I core drilled out the center of the cylinder and as with the block will put it away until after Xmas to relax.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 06, 2016, 11:05:25 AM
Another member has asked for some details of this engine and as I can't attach anything to a message here is the current drawing.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brian Rupnow on February 06, 2016, 12:33:19 PM
Wow Roger--You don't mess around, do you. I will be following this thread with great interest.--Brian
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 07, 2016, 09:58:51 AM
Thank you Brian  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 21, 2016, 07:25:00 PM
I've started to look at the ports/timing in more detail. I put the dimensions from my first sketch into the calculator on the MEN website. These seemed a little soft compared to the recommendations in ETW's book so I moved the top of the ports up and recalculated. This second set appears to be reasonable so I will base the design on these dimensions.
Would it be more sensible to start with the port heights 0.5mm lower and then raise them if required? It's much easier to remove metal that to add it  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 22, 2016, 08:01:59 PM
Moving on with this I made the baseplate for the cylinder from a piece of 10mm thick aluminium plate. I drilled the start of the hole rather than using a hole saw so I could keep the centre.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 22, 2016, 08:10:01 PM
I then set up the cylinder on the Keats angle plate for boring. This was on the limit of the length of my lathe, but the compound slide just cleared the tailstock. As my 25mm barrel lap is 25mm diameter I took the bore to 25.1mm to give a little clearance. Both ends were within 0.01mm according to my callipers (I don't have any internal mikes). The finish is quite good, but at the end I realised I was still using the aluminium insert from cutting the baseplate  ::) I then turned the stub to fit the baseplate before turning it around to face to length and machine the water passages.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on February 22, 2016, 10:18:16 PM
Following along Roger.
I'm learning a lot. I hope to do something like this someday.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 25, 2016, 07:27:04 PM
Thanks Carl, I'm learning a lot as well  ::)

I turned the water space on the other end of the cylinder. I will make a cast iron sleeve to fit over it which will be Loctited in place. As expected the radius turning tool chattered a bit.

The next stage will be to cut the ports and as these are a fairly complex 3D exercise I decided to make a trial aluminium piece to see if I get the angles correct.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brian Rupnow on February 25, 2016, 07:43:15 PM
Nice work Roger. There is a big similarity between what I am building and what you are building right now. I learn from your continued updates.---Brian
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on February 27, 2016, 06:40:48 AM
 Hi Roger, good to see more swarf at this project.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 28, 2016, 07:12:09 PM
Thank you both for your interest  :ThumbsUp:

I was intending to try cutting some ports in my trial block but unfortunately I had a dig in whilst milling the flat for the exhaust port and broke the drive belt on the mill  :( I've ordered a couple of spares but they will take a few days so I decided to continue with the crankcase.

I set it up in the 4 jaw chuck, bored through at 60mm and then cut the clearance groove for the big end. I started with the boring bar set at an angle and finished of with my homemade grooving tool.

I then started turning the crankcase sideplates from a barely wide enough piece of 75mm diameter aluminium.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 28, 2016, 07:16:06 PM
Parting off the sideplates was a little tense as the swarf tended to jam, but it worked. I ended up with around 1mm clearance between the parting tool holder for the second one. Enough but not much to spare  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on February 28, 2016, 08:26:15 PM
Hi Roger, looking good. What's the diameter of your chuck, 80 or 100 mm ?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 28, 2016, 08:36:32 PM
It's 80mm. This engine is on the limit for my lathe  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 13, 2016, 04:51:30 PM
I got a new belt for the mill and had a go at milling the ports in a piece of scrap aluminium. The exhaust ports are at 45° to the bore and are machined from a flat area where the exhaust pipe flange will sit. The top of the ports need to be on  a curve the same radius as the cylinder so that they will be level. I centre drilled and then drilled 3mm hole in each port to start. The end mill was fed in using the quill and due to the angles I was having to lower the quill and move the X axis together  ::)

I'm fairly happy with the results and can see how to improve the real thing.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brian Rupnow on March 13, 2016, 05:27:35 PM
Roger--very nice work.---Brian
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 13, 2016, 06:46:36 PM
Thank you Brian, the geometry of angled ports takes a little thought  :headscratch: The originals would have been cored in the casting as below.

I then had a go at the transfer ports. These are angled at 60° which made clearances more of a problem. The centre port was not flat so I need to go and recheck my calculations (something to do in the evenings in China next week  ::) ) Access with the full length cylinder will be harder. I may need to get a longer milling cutter but then the deflections will also be greater  :headscratch: plenty to think about and there is still enough of this trial piece for another couple of goes before I wreck the real thing  :toilet_claw:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 25, 2016, 06:30:13 PM
Back from my travels and in the workshop again  :) I've got a lot of catching up to do on the forum, I could get the words in China but the pictures took for ever  :(

I sorted out my geometry problem, rather than reducing the circles radius by the Tan of the port angle I needed to make it an ellipse with the longer axis extended by the Tan of the port angle  :insane:

To aid the clearance problem I found a 3mm straight shank end mill, not very stiff but reaches the parts other end mills cannot. I tried cutting the two outer ports but the left hand one ended up much to high. I wasn't sure if I had made a mistake or the cutter had deflected so I milled another transfer passage and tried again (one more go left  ::) ).

When I am cutting these ports I initially plunge the end mill straight in and then widen the port keeping to the line of the ellipse. Looking at the results it suggests that the initial plunge is relatively true (as the forces are balanced) but when I widen the port there is significant deflection. The centre port was started in the middle and the two side ports were started closest to the centre port. I need to think about this some more  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 26, 2016, 04:32:47 PM
I had another, more successful attempt an the transfer ports. To reduce the deflection problems I started by plunging on the right hand side of the ports (looking from outside from the crankshaft end) and then reduced the depth of the following cuts to around 0.5mm instead of 1.2 - 1.5mm. This was significantly better than before  :) Now I have to consider if I will get more cutter deflection in cast iron  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 29, 2016, 04:42:34 PM
I decided to start on the real cylinder. First I needed an angular reference so I decided to drill and ream the fixing screw hole to 3mm to give me a 90° reference series. I only have a four jaw independent chuck that fits on my RT so I mounted it on a MT2 adaptor in the lathe to centre the cylinder.

I didn't have enough Y travel for the exhaust port initially and had to move the setup. I am using the angle block from my quick set Keats as it is the largest I have.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 29, 2016, 04:47:34 PM
With the exhaust port cut I had to turn the cylinder 180° to do the transfer passage. I checked the angle against the mounting holes and the exhaust port. To get enough clearance I had to clamp onto the reduced diameter for the water jacket which gave a significant overhang. Luckily this didn't cause any problems  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on March 29, 2016, 07:41:42 PM
Hi Roger, some interesting set ups on your machine.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Kim on March 30, 2016, 05:51:43 AM
Yes, certainly some inventive setups you used to fit in your limited Z-height.
Well done!
Kim
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 30, 2016, 07:34:08 AM
Thank you both  :ThumbsUp: Holding the complete cylinder at 45° and 60° for milling the ports is the next challenge. It is too long to fit my tilting vice (used for the trial piece). I think that I can clamp the Keats V block to an angle plate.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on March 30, 2016, 09:34:02 PM
Hi Roger

Quote
Holding the complete cylinder at 45° and 60° for milling the ports is the next challenge.

Why those angles - the optimum angle for the transfer to enter the cylinder is very close to 15 degrees and zero will work just fine - admittedly with a Schnürle porting (and that requires at least two transfer ports) .... hmm - perhaps I should just  :-X

Best wishes

Per
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 31, 2016, 05:54:32 PM
Hi Per, a valid question. This engine is based on two prototypes, the Field Marshall diesel tractor and the Petter Atomic diesel. These were developed before Schnürle porting and had simple opposed transfer and exhaust ports with reed valve induction. The high compression ratios and requirement for a compact combustion chamber meant that a deflector piston was not practical. Both engines used slightly coned pistons with a steeply angled transfer port and in the case of the Field Marshall an angled exhaust port (there is a picture of this further up this page).
I have attached a section of the Petter engine taken from my father's 1947 copy of 'Heat Engines' by A.C. Walshaw.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 02, 2016, 06:20:39 PM
On with the ports. When I went to mark out the exhaust ports I found that I had not cut the flat wide enough so back onto the mill  ::)
I was able to mount the V block from the Keats on my angle plate with enough clearance under the mill.
The milling went quite well. I started each port with a centre drill followed by a 3 mm drill and then opened up with a 3mm end mill. The flat sides were cut with a combination of X travel and quill movement due to the angle. The curves were cut with a series of plunges.
I am glad I made the test piece first rather than starting on the 'real thing'   :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 02, 2016, 06:36:00 PM
The transfer ports were not so easy  :( The long 3mm endmill wouldn't cut the CI and just deflected. In the end I used a combination of a short centre cutting 2 flute end mill (the centre drill was not happy with the compound angles), a 3mm drill and a 3mm endmill. As the ports go right to the side of the transfer passage the wider part of the endmill limited the depth I could cut to.
Unfortunately one of the transfer ports had a bit too much deflection and ended up a bit to high  :( I was already expecting an amount of hand fettling and had bought a cheap set of diamond rifler files (10 Francs (or Dollars or Pounds or Euros they're all much the same)) It looks like I will be able to fix it, but both ports will be around 0.5mm higher than planned so I can make the piston slightly longer and recess the cylinder head to compensate  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on April 02, 2016, 11:00:31 PM
Roger,
I think that I missed your 2 stroke Diesel build, due to my own focus on my own engine build. I have read through the whole build today. My first mill was a Rusnok, great machine high quality but only about 4 inches of Z travel. I quickly took things to work to use the Chinese Bridgeport clone. You have come up with some ingenious ways to make your equipment do what you need. My hat's off to you! A question about the fuel system. Are you going to use injection & if so doesn't that use a rather microscopic hole for the injector? I must admit to knowing very little about 2stroke Diesel's and hope that this runs like a champ so I can see the follow up tractor build. :ROFL:
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on April 03, 2016, 06:02:32 AM
Roger, I am still with you, following along quitely.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 03, 2016, 08:16:17 AM
Thank you both  :ThumbsUp:

Art, the development of the fuel injection system is in another thread:

http://www.modelenginemaker.com/index.php/topic,4906.0.html
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on April 03, 2016, 12:10:49 PM
Catching up here Roger.
You say the parting op was tense? Downright scary to me.

 :ThumbsUp: and  :popcorn:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 03, 2016, 04:51:03 PM
Catching up here Roger.
You say the parting op was tense? Downright scary to me.

 :ThumbsUp: and  :popcorn:

There is an advantage in having low powered belt driven machines, if I am not too comfortable I leave the drive belt slack so if anything goes wrong I get a smell of burning rubber rather than shrapnel everywhere  :)   
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on April 03, 2016, 06:45:57 PM
Hi Roger

Thank you for your reply - I had not realized (or remembered  :noidea: ) that it's a kind of historical engine.

Quote
There is an advantage in having low powered belt driven machines, if I am not too comfortable I leave the drive belt slack so if anything goes wrong I get a smell of burning rubber rather than shrapnel everywhere  :) 

 :ThumbsUp: - yes the rubber ting is just kind of unpleasant, where as the alternative is downright scary  :help:

Per
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 10, 2016, 04:56:53 PM
I tapped the cylinder fixing holes for the mounting plate M4. Unfortunately the holes in the mounting plate did not line up so I will have to remake it  :(  The holes were originally marked out with a protractor. I will need to devise a way to divide them in the lathe  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 24, 2016, 06:52:55 PM
Back in the workshop after some travelling. As the R&D department was closed due to snow I did a bit more on this one.

I decided that it would be better to set out the holes in the cylinder mounting plate on the rotary table and so machined a new blank with a 6mm hole to match the hole in the RT.

This all went without problems and I used the tailstock centre to align the plate on the faceplate for boring. I fitted the chuck guard from my mini lathe again to stop the swarf being thrown right across the cellar  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 24, 2016, 07:07:00 PM
After chamfering the cylinder side I could try it on the cylinder, success  :cartwheel:

I then made a start on the crankshaft. This is the other half of the 15x60mm Ck45 flat used for the gas engine crankshaft. I squared up the ends with a rather dubious milling set up. I was using a 14mm endmill at 365rpm  in two passes. At 0.5mm depth everything was happy but increasing the depth to 0.8mm produces squeals and chatter. Reducing the feed from 40mm/min to 20mm/min didn't help  :headscratch:

I marked it out, centre drilled for the shaft and crankpin and then hacksawed and chain drilled out ready to turn the crankpin.

The setup for the initial turning is a little tight but should work  ::) I will rough the journals to 13mm and then leave it for a few weeks to relax/bend as it wishes.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 29, 2016, 08:15:56 PM
On with the crankshaft. So far I have used 5 different tools, 8mm left and right for facing the webs, 8mm straight for the middle of the crankpin and 6mm left and right for the ends. The final finishing cuts will be done with a blade type parting tool.
The tailstock was used as the carriage stop in one direction with a normal stop in the other direction.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on April 30, 2016, 04:17:39 AM
Hello Roger, I am following your build with great interest - I hope to build a scale replica of an Electro-Motive Division 567 engine a long (loooong) time into the future, and I can learn a lot from your pioneering work :)

Will you harden the crankshaft after the machining is done?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 30, 2016, 06:53:50 PM
I won't harden the crankshaft. I think that even with a good electric furnace (which I don't have) the chance of distortion would be too high.
It is a .45% carbon steel so in it's normal cold rolled state it will be more than adequate for the likely running time of this engine (if it ever runs  ::) )
Heat treatment, like gear cutting, is another skill I need to learn and is another set of equipment to acquire  :headscratch:   
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on April 30, 2016, 07:54:58 PM
(if it ever runs  ::) )

Of course it will. You have all the necessary ingredients.

And we're here to watch it run.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on May 01, 2016, 07:24:56 AM
Hi Roger, I am following along with much interest. I have never made a crankshaft this way until today,but I think it is time to do it soon. Thanks for showing it.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 13, 2016, 07:00:47 PM
A bit more crankshaft. I cut out the first shaft and used one of the offcuts to make a bridging piece to take the end thrust from the centres. The M5 threads will be require to hold the balance weights on.

This shaft will be rough turned to 13 mm. When I do the other end it will be held in a collet. I have set a carriage stop just before the webs to reduce the risk of a crash due to lack of attention.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 15, 2016, 08:25:08 PM
As I had problems getting a good finish on the crankshaft for my horizontal engine (from the same material) I decided to experiment a little on this one. Following a suggestion from Jason B I tried an aluminium tip in the tool. This gave a good finish with cuts from 0.05 mm to 0.2 mm depth, the only issue being long curly swarf.
With the first shaft turned to 13 mm I hacksawed out the other shaft ready to turn. I was having some problems keeping the cuts straight and at the end noted that my hacksaw frame had started to crack  :( Time to spend some more money  ::) this time on a Swiss frame.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 16, 2016, 07:19:40 PM
I finished roughing out the 2nd shaft and then noticed I had lost count/concentration somewhere and had gone down to 12mm instead of 13  :facepalm:  :facepalm:  :toilet_claw:

Not a complete disaster as I can either reduce the size of the bearing that side or turn the shaft down further and sleeve it for the bearing. I will continue with this crankshaft as I also need to drill oil passages along the shafts, nearly 60mm deep 2.5mm holes, another chance to scrap the shaft  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Bertie_Bassett on May 16, 2016, 09:07:30 PM
you'll have to call that 12mm shaft a 'design feature' maybe to ensure that's things don't get assembled the wrong way round??
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: cfellows on May 28, 2016, 05:16:16 PM
That happened to me on my latest build, the 2 cylinder horizontal IC engine.  I had designed it for a 3/8" main journal and went a few thou too far when finishing it.  So, I took it on down to 9mm.  Wasn't a problem other than I had to buy a 9mm reamer and some 9mm bearings that I hadn't had on hand.

Chuck
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on May 28, 2016, 08:31:28 PM
Hi Roger, that will give your engine some special character. I would not worry about the function.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 18, 2016, 06:46:55 PM
I decided to try and drill the oilways in the crankshaft. I had bought a couple of new standard length split point drills as well as couple of long 2.5mm drills.

I started with a standard drill which I took down to 40mm (also the maximum stroke of the tailstock). I then moved to the long drill which I fitted with a depth stop. Every 5mm I moved the tailstock back to clear the swarf. This went, luckily, without  problems  :whoohoo:

The webs were then cautiously drilled as I was expecting problems when I broke into the crankshaft holes, but again no problems  :cartwheel:

Finally I used the long drill again to drill through the crankpin. The holes in the crankshaft and crankpin will be closed with M3 grubscrews.

I still need to drill through the crankpin itself, but am not sure whether to go on the outside (max pressure at TDC), on the compression side or on the firing side  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Steamer5 on June 18, 2016, 10:12:57 PM
Hi Roger,
 Nice skills! Bet you were happy that the deep drilling went well. Have you decided whether its a keeper or a test piece yet? Looking like a keeper to me!

Cheers Kerrin
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 19, 2016, 04:06:56 PM
Thank you Kerrin, yes it's a keeper :cartwheel:

I bought a 11.5mm reamer for the 'feature' side. Both crankshaft halves and the outside of the webs were finished without problems, the rest of the feature side was reduced to 10mm.

The crankpin and crankshaft borings were then tapped M3 for the grubscrews. The holes through the webs will be closed by the balance weight fixing screws.

The crankpin was then centred in the Hemingway Keats and the inside of the webs were finished. Once again the chuck guard from my minilathe was pressed into service.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 19, 2016, 04:16:12 PM
The 14mm wide crankpin meant I could just finish it with my 6mm LH and RH tools. To start with I took the centre to just above size with an 8mm straight tool.

The final tasks were to mill the end of the webs to length and drill the oil hole in the crankpin. This was started with a 1.6 mm centre drill and finished with a 1.6mm drill. Is this too small or too big  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on June 20, 2016, 02:39:56 PM
Looks good, well done :)

Drilling the oil holes would make me so nervous. Seems like if something goes wrong you'd need to start again from square 1. Or is it not as bad as I think?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 20, 2016, 03:11:34 PM
Thank you  :ThumbsUp:

As I see it if the drill breaks you start again  :(  Maybe the remains of the drill could be removed with some sort of spark erosion, but not many people have that available  ::) .

For that reason I decided to try this on a shaft I had already made a mistake on. Even so the cost of another piece of C45k and a tip would still have been less than the cost of the 11.5mm reamer but I couldn't face all the hacksawing again.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 26, 2016, 05:25:55 PM
I turned a pair of top hat bushes for the main bearings from piece of 19mm bronze rod. These were pressed into the side plates and reamed again. It all fits together although I need to increase the end float a little (currently zero). Another crankshaft I can twiddle  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 09, 2016, 08:02:45 AM
Next step the connecting rod. There are always a number of different machining sequences depending on the details of the rod. This one is too long to mount on the faceplate so any boring has to be done on the mill.

As I wanted to radius the big end cap it was easiest (I think, suggestions welcome) to do this before the cap was cut off. To keep everything aligned I set up the angle plate with a V block as a fence so The centers for turning and for the bearings were all referenced to the same surface. The little end was reamed out to the final 10mm dia. and the big end was reamed to 6mm to match the pilot on my RT. I thought about adjusting the centers to compensate for the 0.8mm slitting saw but in the end decided that this was not really necessary (0.4mm in 80mm).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 09, 2016, 08:45:14 AM
While the rod was on the angle plate two flats were milled for the big end bolts then it was moved to the RT to round the end.

The cap was cut off with a slitting saw in the lathe and the holes were opened up to 3.1mm and counterbored. The holes in the rod were then tapped M3 and the cap was fitted back on.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 10, 2016, 05:44:26 PM
The basic shape was turned between centers, using a 3mm radius tool to blend the rod to the ends.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 10, 2016, 05:51:40 PM
I then went back to milling mode to bore out the big end and round the little end. After centering the rod to the scribed lines I opened out the hole with a 10mm endmill and finished with the boring head. Both were fed using the quill rather than the Z axis feed screw.

The little end was rounded using the RT and then cleaned up by filing. Once again I went a little too far round with the RT and ended up with a couple of marks that were too deep to remove. I need to check my geometry on this  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on October 10, 2016, 09:08:20 PM
Nice to see you back on track  :)    :popcorn:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 16, 2016, 06:03:43 PM
The next step was to machine the cylinder mounting face on the crankcase as well as an access hole on the opposite side to allow the big end to be assembled. This hole has a recess for a cover plate which I may also use as a mounting point for the initial reed type inlet valve.

The fixing holes were drilled to the appropriate tapping size and the main hole was opened out with a 15.5mm drill before being bored to size. It may have been quicker to have removed the bulk of the metal with a hole saw as I have done with some cylinders an liners.

The cover plate recess was cut using a 10mm endmill in 1mm steps. As it was centered over the fixing holes center cutting was not a problem.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 16, 2016, 06:11:17 PM
The fixing holes for the crankcase sideplates were drilled next. I have a small 4 jaw chuck with an M14 x 1 thread which will fit my RT as well as the lathe. The RT was fixed to the table, centered and then offset 34mm. The chuck was mounted on the lathe and the first sideplate was centered and the transferred to the RT for a round of center drilling at 60° intervals and then drilling through 3mm. The first plate has an additional center hole due to me thinking that 240 + 60 = 320  :facepalm: . The second plate doesn't have any unique features (yet).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 16, 2016, 06:16:08 PM
Finally for today I drilled the fixing holes in the cylinder mounting plate and milled the transfer passage in it.

The next step will be to mill the clearance for the connecting rod in the crankcase and the cylinder/cylinder mounting plate.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 19, 2016, 06:56:53 PM
The crankcase and the cylinder were clamped to the angle plate at the appropriate angle (14°) and the clearance slots were cut with a 12mm end mill. I plunged the end mill using the quill feed, moved another 0.3mm and plunged again. As the finish was not so important it was quicker than using the Z feed screw.

A quick check with the conrod looks ok. The little end is below the center of the cylinder.

Back to lathe mode to make the big and little end bearings and to lap the cylinder. I have an 80mm offcut of stainless steel that will be suitable for a flywheel if I can turn it (I had problems with a piece of P20 mould steel that I used to make my ER25 collet chuck ::) ), scrap bin stuff can be good but you sometimes need to know more than is it magnetic or not  :headscratch:

Luckily it seems ok, I faced it at 500 rpm (as the lathe was set to this) with SS insert and got a good finish without bright blue swarf  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 23, 2016, 07:02:57 PM
On with the flywheel. I turned away part of the center to reduce the weight a bit. This required three different tools, a straight tool to start and to finally face the inside, a RH tool to turn the boss and a boring tool to turn the inside of the rim. I had planned some radiuses inside, but my TC radius tools were not happy to cut this SS. The normal inserts that come with the tools were also not happy, the only tips that would not break and gave a good finish were some Mitsubishi ones I got from CTC.

With the first side completed I turned the tapered bush from a piece of (not so) mild steel. I got the best finish with an aluminium tip. The taper is 6° inclusive. The compound will stay at this setting so I can bore the flywheel to the same angle and by making the bush first I can check the fit/depth of the hole in the flywheel.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 23, 2016, 07:17:02 PM
The flywheel was put back in the lathe and faced. A quick skim on the rim showed that it was almost concentric with the first side. The final finish on the rim will be done with the flywheel mounted on a mandrel.

A 12mm hole was drill through the center and the taper was bored with frequent trial fittings of the bush. With this shallow angle it is very easy to go too deep  ::) This side will then be recessed to match the other one.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on October 24, 2016, 07:56:17 AM
Hello Roger, I am still following along.  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 29, 2016, 07:54:56 PM
Thank you Brendomn  :ThumbsUp:

I finished machining the recess in the flywheel and then inserted the tapered bush with a couple of light taps with a plastic hammer so I could index the holes for the clamping/removal system. I still haven't made any form of indexer for the headstock, but the center height above the base is 120mm, the chuck jaws are 10mm thick so a depth gauge set to 125mm allowed me to index 6 holes at 60° using the chuck jaws.

This engine requires a reed valve inlet and as this is new to me (other than a brief mention in Malcolm Stride's book) I started searching the Internet for more information. I rapidly came across a UK firm (Petrol Scooters) selling complete unused reed valve assemblies for £1.99 that looked like they would fit  :)  :) I splashed out and ordered 2 sets as well as a set of carbon fibre reeds (might be better, might not  :headscratch:  ::) ) These arrived today and look hopeful  :)  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on October 29, 2016, 09:35:29 PM
Nice to see that you're still on this project.

Looks like you got the orientation of the reeds right in the last picture - you should remove enough material so you get a straight flow from the reed to the transfer port  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on October 31, 2016, 07:51:34 AM
Thank you Per. I am also selecting the direction of rotation (anticlockwise in that picture) so the rotation aids the flow.

The next step on the flywheel was to finish the holes for the taper bush alterately M3 10mm deep and 3mm diameter 5mm deep. When the tapered bush is turned 60° this allows alternate hole sets to clamp the bush onto the shaft or to push the flywheel off the bush. The bush was then slit along one of the threaded holes with a 1mm wide slitting saw.

After some deburring the flywheel was mounted an a 12mm silver steel mandrel to allow the final skim of the rim. Finally I tried it on the crankshaft to check for any visible run out. Looked ok  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on October 31, 2016, 09:48:55 AM
Hi Roger good to see some more bits and pieces. I think your country also has a bank holiday tomorrow, which may be gives some extra shop time.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 08, 2016, 08:55:39 PM
Thank you Achim  :ThumbsUp: , unfortunately our day is the 1st August.

The next step was to make the big end bearing using the split and soldered bronze offcut from my horizontal engine. This already had a reamed 12mm bore so I mounted it on a 12mm mandrel and turned the outside to 16mm. It then went into a 16mm collet to be faced to length. Next it went back on the mandrel to machine the center down to 14mm. When it was almost 14mm (~14.2) it split along the soldered joint   :facepalm:  I tried to resolder it but couldn't get a good enough alignment to allow me to turn down the last 0.2mm and keep it concentric  :(

I will start again using the same technique as on the horizontal engine so that the two halves are held together by the 4 jaw chuck as well as the solder until the final parting off.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 13, 2016, 06:51:28 PM
I had to go to milling mode to split another piece of bronze for the big end and while it was cooling after being sweated together I decided to fit the reed valve assembly. This time I decided to remove the bulk of the material with a 29mm hole saw. The recess for the valve was cut with an 8mm end mill.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 13, 2016, 06:59:48 PM
The next step was to mill a recess for the valve mounting plate 2.5mm deep. As the radius of the 'ears' was 6mm I used a 12mm endmill, adding a little clearance. This left the valve opening against an blank surface so I then milled a 30° lead into the crankcase bore. Even with a12mm endmill hanging as far as I dared out of the chuck I still ended up with a step which I removed with a ball mill in my Proxxon followed by some rifler files.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 13, 2016, 07:06:28 PM
As the big end blank had cooled I centered the cut line in the 4 jaw independent chuck and trued it up to 16mm diameter. The bore was opened out in stages ending up with a 12mm reamer. The recess was cut as before with a parting tool and the bush was then parted off to length. This time it stayed together so I melted it apart with a large electric soldering iron. After cleaning up the joint it all assembled on the crankpin, although it is a little tight. I will check the chamfers on the end of the bush and probably ream it again when clamped up in the big end.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on November 13, 2016, 07:59:06 PM
Hi Roger, another big step forwards.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 27, 2016, 07:37:33 PM
A couple more steps forward. I turned and pressed in the little end bush and then turned the water jacket out of a length of rather too thick walled tube. Next I lapped out the bore ready to start on the piston. This was done as usual with an Acro lap and diamond paste.
Finally I drilled and tapped the remaining hole in the crankcase and smoothed the transfer passage.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 27, 2016, 07:43:13 PM
Next I tried to assemble the crankshaft and con rod in the crankcase. Unfortunately there was not quite enough clearance for the big end  :( I mounted the crankcase in my new 4 jaw chuck and opened the bore out a couple of mm with my home made slotting tool. This time it all went together and turned fairly freely  :whoohoo: . Finally I checked the height of the conrod and got 18.8 mm instead of the planned 18mm. Not to far out and can be compensated for in several ways  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 13, 2016, 09:08:22 PM
The piston is next. A 6mm centring rod was held in an MT collet and the Keats angle plate was then clamped to the faceplate. This allows me to centre the Keats on the RT for drilling/reaming the gudgeon pin hole and then bring it back to the faceplate for finishing to size and parting off. When I have made some backplates I will be able to do this the more conventional way with a 3or 4 jaw chuck.

A piece of 30mm diameter cast iron was turned down to 25.5mm, drilled out to 12mm and the skirt was bored to 22mm. The Keats was then moved to the RT and the gudgeon pin hole was centred on both sides, drilled halfway 3mm from both side and then drilled through 7.9mm. Finally it was reamed 8mm. The next step will be to mount the Keats directly on the milling table and to mill out the pocket for the little end.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: MJM460 on December 14, 2016, 06:09:10 AM
Thanks so much Roger, for taking the time to post the photos of your setups, particularly the simpler ones, as a beginner like me still has so much to learn in that area.  It is truly appreciated.  I will mostly be one of those observing in the background, particularly while I work through back to the start, but every post is worth studying.  Thank you.

MJM
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 07, 2017, 01:55:40 PM
Back in the workshop  :) The clearance for the conrod was milled out with a 6mm end mill and the two holes for the gudgeon pin clamping screws were drilled 2.5mm.

As I was in milling mode the next step was to fit the balance weights to the crankshaft. The two pieces were temporarily stuck together with Loctite.  These were not as easy to set up as the ones for my horizontal engine as I increased the angle from 90° to 150° to compensate for the additional weight of the cast iron piston. The fixing slot was initially cut with a 12mm end mill which gave a slot width of around 13mm and then each face was finished with the same end mill to give the required 15mm width.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 07, 2017, 10:25:56 PM
Hi Roger

I don't know if it's only me - but I can't see your pictures in the last post ....

Best wishes

Per
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: /// on January 08, 2017, 03:15:32 AM
I think it's just the forum being funky.. I can see the pictures, but there are other threads with no images for me, and there are whole threads that refuse to load. MEM needs a new host.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 08, 2017, 08:20:23 AM
Hi Per, can you see them and the new ones below?

The next step was to drill and counterbore the weights for the fixing bolts and then back to lathe mode.

The piston blank was mounted back on the faceplate (the 6mm dowel kept it concentric) and was turned down to 0.05mm over bore size. The final finishing was done with emery cloth backed by a steel rule until the piston was a smooth fit in the bore. I am hoping that a cast iron piston in a cast iron bore should not have a significant thermal expansion problem. Two 1.5mm wide ring grooves were cut with a parting tool and the blank was parted off.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 08, 2017, 08:33:08 AM
The piston was them mounted in the 4 jaw independent chuck with a couple of thicknesses of paper to protect the surface. The compound slide on the Hobbymat wont work at steep angles as the handle fouls the crossslide so I used an Emco type compound slide that I got many years ago. It's a lightweight construction but is ok with shallow cuts ~0.2mm.

With the piston completed I fixed the balance weights to the crankshaft and turned the outside radiuses (radii?  :headscratch: ). This is intended to be quite a close fit in the crankcase. I had to turn a small relief on the outside of the weights to clear the thrust surfaces on the main bearings.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 20, 2017, 07:54:13 PM
Next I needed a gudgeon pin. This was made from 8mm Silver Steel (with a careful check to make sure that it wasn't 5/16")  ::) The core was drilled out 4mm and two 4mm wide 0.5mm deep flats were milled for the grub screws. It was hardened and polished and then a trial assembly. It all fitted and turned  :cartwheel: the piston is a little low but that can be compensated for.

The next piece was a cover for the transfer passage. This was made from a piece of 4mm thick black bar with a rebate to fit in the passage. The internal corners were filed rather than making a complicated milling set up. This is held in place with two M2 screws (which will probably become studs and nuts).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 20, 2017, 08:03:30 PM
Then comes a cover plate for the big end access hole. This was made by hand, sawn from a piece of 3mm aluminium flat, filed square, and then the corners were rounded with 10mm filing buttons.

The parts so far were assembled, without gaskets, and turning by hand the inlet reeds can be seen to open slightly and there is a sort of chuff from in the cylinder so I guess crankcase compression is taking place  :) As there are no piston rings fitted yet the transfer port will be connected to the exhaust before the ports open into the cylinder.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 21, 2017, 03:00:17 PM
Nice to see that you are moving in the right direction again Roger  :ThumbsUp: and confirmation on crankcase compression and transfer is always welcome on a two-stroke  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 25, 2017, 05:45:24 PM
Thank you Per, I'm getting there if somewhat slowly  ::)

The next piece was a saddle to go on top of the water jacket for initially a hopper (Lanz Bulldog style) and then possibly two radiator banks (Field Marshall style). This was made from a piece of BMS. I left it over length to give me something to hold and also to, hopefully, control distortion when I silver solder it to the water jacket. The radius was cut using my boring head and a cheap brazed carbide bit. I set the radius at the start and with a speed of 365rpm and a 0.5mm depth of cut slowly bought it to size. I initially tried feeding with the quill but it was a bit too snatchy so I used the Z axis feed (not to comfortable as the handle is on top of the column  :( ).
When the temperatures become positive again I will solder the parts together.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 25, 2017, 08:56:05 PM
Quote
I'm getting there if somewhat slowly  ::)

Well I'm not going to point any fingers for that reason - I haven't had time to go to the workshop since last summer .... too busy trying to keep my job / income  :'(
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 28, 2017, 06:40:28 PM
As I said on the fuel injection thread the weather was good today, 20C + on the balcony, so I was able to silver solder up the water cooling saddle. I laid a layer of powdered flux in the joint and then directed most of the heat onto the holding piece until the flux melted. The silver solder was fed in from that end until it appeared at the sides and the other end.

I then hacksawed the extra piece off and cleaned up both ends in the lathe.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 07, 2017, 08:28:26 PM
Next I drilled the fixing holes for the hopper/radiators and milled out the water passages. Unfortunately I was thinking M3 and drilled the first hole 3mm instead of 2.5mm  :facepalm:  You can see the odd hole in the pictures. The water passages were milled out 6mm wide.
I worked out that I could make a sleeve M4 x 0.5 outside and M3 inside to salvage the piece. Normally I would have silver soldered a plug in and redrilled. The sleeve is held in place with Loctite 648. I will use the same to fix the water jacket to the cylinder.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: 90LX_Notch on February 07, 2017, 09:55:57 PM
Nice save Roger.

-Bob
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Kim on February 08, 2017, 05:44:31 AM
Nice recovery on that one Roger.  I know that sinking feeling you get as it starts to dawn on you that you did something wrong...  Not fun.  But you've got it figured now!
Kim
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 03, 2017, 04:59:55 PM
Than you both  :ThumbsUp:

As I was back in milling mode I finished of the cylinder head mounting face. I used a centering plug on the RT and was able to mount the cylinder using its of fixing holes. This resulted in a 30° offset so I had to keep careful track of the angles. The fixings are M4 and there are two milled slots for the water ways. There  was a bit of deflection of the mill, but not enough to cause a problem.

The next step was to flycut ~1mm off the block and 0.2mm off the fixing plate to correct the piston height and improve the surface finish.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 03, 2017, 08:37:52 PM
There was then a series of holes to drill and tap. Fixings for the exhaust, an oil feed to the cylinder and oil feed to the main bearings. The 2mm dia. cylinder oil feed is aligned with the centre of the gudgeon pin and just behind the ports. The 2mm dia. main bearing feeds start in the crankcase and then go into the side plates. As it is a drip feed rather than full pressure I don't expect significant leakage. All the oil feeds are tapped M5x0.5 for 3mm unions. Finally I drilled the two oil feed holes from the main bearings to the crankshaft oil passages to feed the big end.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on March 03, 2017, 09:47:01 PM
Looks like you're moving right along.  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 04, 2017, 07:32:57 AM
Thank you Carl, I'm getting there  ::)

Next I cut a keyway in the smaller end of the crankshaft to drive the oil pump and the injection pump. I decided to use a slot cutter rather than a slot drill as any deflection will affect the depth rather than the width which is less of a problem.

Finally I made a start on the oil pump which is a modified version of the ETW one used on the Atom engines. It has a variable output which is useful as this will be a total loss system. The cavity for the drive gears was milled out leaving a web at the back which will hopefully reduce distortion. The top bearing bush/adjuster hole was reamed 10mm and I then used a transfer punch lightly held in the mill to mark the center for the pump bore, hopefully keeping everything concentric.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 15, 2017, 07:43:20 PM
The next step was to drill the various oil passages, this will have three outputs, two for the main bearings and one for the cylinder. I then turned up a bronze bush to act as the top bearing and cam. The pinion and the cam then had to have the angled face cut. The pinion was held via it's grubscrew on a stub shaft held in an angle vice using the little V block from my Keats angle plate. The top bearing was held in place using a couple of clamps.

My plan to keep things concentric did not work too well and I had to open out the hole for the top bush to 10.5mm to allow the pump shaft to turn freely. This is not a big problem as the top bush will be held in place with a clamp to allow it to be turned to adjust the output.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 15, 2017, 07:55:24 PM
Next I milled a 4mm hexagon on the end of the pump shaft using my newly made chuck adaptor for the RT. This will allow me to prime the oil system using an electric drill (tilting the pump out of engagement with the worm first). I then cut the valve thing on the other end of the pump rod. Problem  ::) The pump bore had drifted such that it was around 0.5mm off axis and the valve would not work  :( I need to make a new body in a different way. There are two possibilities:
1) Drill the hole in the lathe with the body held in a four jaw chuck. This should keep the bore closer to the axis.
2) Drill through from the pump end and make a threaded plug to fill the hole. It looks like ETW used this method, but as the pump body was a bronze/brass casting he could sweat the plug in place.

Whilst thinking over this problem I realised that it would be better to put the web on the other side of the pump so I could mount the cam for the fuel injection pump next to the main bearing and then fit the worm to drive the oil pump. Quick redesign  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on March 15, 2017, 09:19:29 PM
I just noticed the post about milling the angle for the cam face.
I'd not seen something like that.

I do need to catch up on this thread and engine.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on March 19, 2017, 10:24:38 AM
Hello Roger

In this oil pump design, does that little cog get turned, which in turn causes it to move back and forth (making it a plunger pump)? Just trying to understand what I am looking at :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 19, 2017, 04:13:08 PM
Thank you both for your interest  :ThumbsUp: This video should show how it works. The stroke is constant and the phasing is varied by turning the top bush (cam) to reduce the amount of the stroke that it pumps.

The cavity in the body was milled out as before and then mounted in the 4 jaw SC chuck with packing pieces. As the packing pieces were calculated to put the centre in the right place this luckily showed up a marking out error before I made another 'trial piece'   :facepalm:  The bore was drilled 4.7mm and reamed out to 5mm. I then to tap the end M6 x 0.5 for a blanking plug (I hoped to avoid this plug on the first attempt).
The hole for the top bush was drilled 9.8mm and reamed 10mm in the drill press. The various oil passages were drilled next and this time it all lined up  :)
As the top bush is also the adjuster I knurled a finger grip. Due to the size of my knurls I had to mount the top bush on a tapered mandrel which luckily held  ::)
I then put my trial worm in the lathe to see if would all function.

http://www.youtube.com/watch?v=Sy4DoT07B_o

As the return spring tended to wander I made a couple of bronze top hat bushes to keep it central.

Next I need to make a retaining clamp for the top bush.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 26, 2017, 06:53:07 PM
Some parts are moving towards final assembly  :) I found some giant fluffy pipe cleaners in the local DIY store to clean out the oil ways. The three M3 grubscrews were Locticted into the holes in the crank shaft.
The rest of the engine pieces went in the ultrasonic bath (best solution after using diamond lapping paste).
I applied the local WD40 equivalent to the CI parts except around the water jacket joints and then used Loctite 648 to bond the water jacket to the cylinder. A suitably sized piece of aluminium was cable tied to the water jacket so I could keep the alignment with the cylinder mounting flange. The assembly was rested on the piece of low friction plastic I normally use to mix Araldite on, it doesn't stick.
The next morning it came away from the plastic without problems. There was a bit of overspill that cleaned up ok with a wood chisel.
Finally I cut some sealing groove in the oil pump plunger and hardened both ends.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on March 26, 2017, 07:04:12 PM
Before I can finalise the oil pump mounting I need to finish the ignition/injection cam. I plan to run this initially as a petrol engine with a temporary low compression cylinder head to confirm that the crankcase and ports are ok before I move on to fuel injection. The cam will be initially profiled to work with a contact breaker but can be later reprofiled to work with the fuel injection pump.
It was turned from a piece of 30mm free(ish) cutting steel. The basic shape was turned and then offset in the 4 jaw independent chuck to give the same profile I have used on the gas engine.
Next I need to make the oil pump drive worm that will be keyed to the crankshaft. The cam will be clamped to this so I can adjust the timing.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 02, 2017, 08:38:40 AM
Next up was the oil pump driving worm. This also has two radial slots to adjust the relative position of the ignition/fuel pump cam to set the timing.

The slots were milled with the RT, the 4mm clearance for the heads first and then 2mm for the bolts, as my 2mm endmill was only just long enough. These slots allow 30° movement so using the same set up I drilled three pairs of holes in the cam 30° apart to give a total of 90° adjustment.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on April 02, 2017, 01:34:47 PM
Just saw the video. Thanks. That helped a lot.

 :popcorn:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 02, 2017, 06:12:36 PM
Thank you Carl.

While I was in milling mode I cut a small recess in the pump body to clear the crankshaft. The worm was then pressed onto a taper mandrel to be screwcut 0.5MOD. I used the bench drill to broach the keyway (I have a little cup that fits in the chuck). Then came some drilling and tapping in various parts.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 02, 2017, 06:15:45 PM
Next I turned three 8mm long spacers for the oil pump body and a pivot pin for the contact breaker and put it all together for a trial.

http://www.youtube.com/watch?v=nizTJNc4xnU
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 12, 2017, 05:09:21 PM
The next step was an adaptor plate to fit above the reed valve so I could fit a carburettor for the first trials. This was cut from an 11mm slab of aluminium (because that is what I had). I roughed out the tapered bit with a 4mm ball nose mill and then finished of with a 10mm cutter in the Proxxon hand tool. Certainly not elegant, but as I'm not sure if the shape is right it will do for a start. 
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 12, 2017, 05:17:57 PM
Then I started on the exhaust flange/system. The flange was milled and filled from 2mm thick brass. The center was milled out first with a 5mm endmill and them with a 6mm endmill to create a step. All done with CNC (count number of cranks). The corners were rounded using filing buttons.
The tapered section was developed with CAD (cardboard aided design) and then cut out of 0.5mm brass sheet and silver soldered in place.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on April 12, 2017, 07:33:00 PM
Hi Roger, I do like your CAD (cardboard aided design).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: 90LX_Notch on April 13, 2017, 01:54:07 AM
I'm still following along Roger.  I like your C.A.D. system, very effective.

 -Bob
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Dave Otto on April 14, 2017, 12:57:42 AM
Lots of progress there Roger, everything is looking great!

Dave
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 18, 2017, 07:45:16 PM
Thank you all for your interest and support  :ThumbsUp:  :ThumbsUp:

When making a trial assembly I noticed that the water jacket was not quite square to the cylinder flange  :( something must have moved while the Loctite was setting. I could either bake the assembly, break the Loctite joint and redo or machine the water connection true again. The error was 1 or 2 degrees so I decided to re machine. The cylinder was mounted in the angle block from my Keats angle plate and a couple of passes with an end mill put everything true again.

I then moved back to lathe mode to make the petrol cylinder head, but first I made a plug gauge for the cylinder bore ready to make some piston rings. This was a close fit in the cylinder as turned and polished, but would not fit after parting off until it cooled down, a good sign  :)

The cylinder head was turned from a random piece of aluminium which produced some fine stringy swarf  ::) 
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 18, 2017, 07:54:53 PM
The compound slide on the Hobbymat  doesn't go easily beyond 45° so I used my little Unimat slide to turn the cone to fit the piston. I then went back to milling mode to set out the fixing holes and finished them off on the bench drill.

I now have a number of gaskets to make, some oil pipes to form and the exhaust to finish (plus an oil tank and a water hopper  ::) )
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on April 18, 2017, 10:42:08 PM
It's getting more and more interesting.  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 20, 2017, 08:13:24 PM
Thank you Carl, I'm now on the last 20% that also takes 80% of the time  ::)

I received a couple of UK pattern 10mm microbore central heating elbows for the next stage of the exhaust system which were duly silver soldered in place. I now need a length of thin wall 10mm tube for the final stage. I may make a clamp for this to allow the length to be adjusted (2 strokes are funny things).

I then cut a number of gaskets and finally started on the oil pipes. 
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on April 21, 2017, 12:56:58 AM
Hello Roger, you sure have been busy!

...All done with CNC (count number of cranks).

I am glad to discover that I have actually been doing CNC this entire time :D
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 25, 2017, 07:52:36 PM
Thank you Brendon  :ThumbsUp:

Next up was an oil tank. This was made from a length of 20mm dia 2mm wall brass tube (a 'trial' cylinder liner from my vertical engine). This is rather thick walled but allowed the connection union to be screwed in.
The base was a piece of 2mm thick brass strip silver soldered in place and then turned to match the tube. The bracket was from the same material this time soft soldered on. A hole for the union was tapped M5x0.5.
The cover was turned from a length of 20mm diameter aluminium. There is a 1.5mm breather hole and the O ring was one from the experiments with an O ring as a piston ring on my vertical engine.
The turning was done using the 4 jaw SC chuck as it is on the lathe for my injection/floating reamer holder experiments.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: 90LX_Notch on April 26, 2017, 12:14:00 AM
Roger-

Regarding Pic 470, did you plunge cut with an endmill in your drillpress?   My drillpress would self destruct if I did that.  Your's must be a very rigid machine.

-Bob
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 26, 2017, 11:27:50 AM
Hi Bob,

I have a Chinese 16mm capacity bench drill with the normal amount of play in the quill system. I find that it is generally ok for spotfacing. As this time I had to deal with a step it was done in several stages.

Drill 4.2mm
Spotface with an M4 counterbore (~9mm diameter)
Finish with a 10mm endmill
Open out to 4.5mm
Tap M5x0.5
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: 90LX_Notch on April 26, 2017, 06:30:14 PM
I see, most of the material was already removed.

-Bob
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: freefuel on May 14, 2017, 02:53:46 AM
Roger why did you go with spark ignition, when glow ignition seems closer to your eventual goal of a diesel engine?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 15, 2017, 09:24:58 AM
I chose spark ignition as I am familiar with it and have all the pieces. Glow ignition would add more uncertainties. I know that the ignition system and carburettors that I have work with petrol on my 25cc horizontal engine so I just have to sort out the two stoke induction/porting system on this engine. There is already a cam available for the fuel injection pump so I am using that for the contact breaker.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 18, 2017, 05:46:28 PM
A bit more done. I soldered the nipples on the oil pipes and then moved on to the piston rings. These were made as before, turn from a piece of CI bar, split, heat treat and then skim to size.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 18, 2017, 05:51:56 PM
With the rings complete I could start the final assembly. For the side plates, cylinder mounting and transfer cover I used Blue Hymolar as a sealant the rest used normal gaskets. Finally I turned it over with the battery screwdriver. There appears to be crankcase compression and normal compression  :cartwheel:

http://www.youtube.com/watch?v=P7nhqI6YPTE
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on May 18, 2017, 07:05:46 PM
Hi Roger, I am still following along. This kind of piston ring making, I have to try it soon.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on May 18, 2017, 09:31:48 PM
You can't be far from the first pop now  :cartwheel:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 20, 2017, 06:00:02 PM
Thank you both  :ThumbsUp: Achim, the piston ring making is shown better in my horizontal engine thread.

I connected the oil pipes and then primed the system. If I just fit the bottom bolt to the pump I can tilt it away from the worm and prime it with a 4mm socket in the cordless screwdriver. As this will reach 500 rpm it is the same as running the engine at 10 000rpm. I set the crankshaft to BDC so the main bearing ports aligned, blanked off one main bearing feed pipe and pumped oil through the crankshaft until it came out of the union.

As a two stoke novice I have read that the transfer ports should open with a pop or crack. I have tried to record what this one sounds like, is it reasonable?. The intake will suck on my finger and if I block it the pop goes away. Hopefully enough crankcase compression  :headscratch:

http://www.youtube.com/watch?v=HHDFFuaeVJs

I was not happy with the initial head gasket and as I suspect in diesel form I will be playing with compression ratios and bumping clearances I decided to make a proper punch system as I did for my vertical engine.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: yogi on May 21, 2017, 12:48:08 AM
A very cool project Rodger!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
I'm still following along, getting exited for the first pop...
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 21, 2017, 07:32:23 AM
Thank you Yogi  :)

I punched out a new head gasket, put the cylinder head on and then contemplated the size of the cooling hopper and length of the exhaust pipe. I am undecided as to going for the full height of the screw box or stopping at the bottom of the white table  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 16, 2017, 02:56:32 PM
A few more bits. I made a set of M3 brass nuts for the carb, exhaust pipe and cooling water tank studs from 5mm hex bar. The length for the exhaust pipe was guessed and silver soldered in place. I also started on the base plate in my usual way by gluing a thin metal plate onto piece of plywood. Next up is the cooling water tank. The base is made from 1mm thick brass with a 1mm reinforcing plate around the fixing/water passage area. The sides are folded from 0.8mm brass sheet. The seams on this part of the tank will be silver soldered so I can later soft solder a cover/splash protector on top if required.
Finally I made the M3 studs for the inlet, exhaust and water tank from free cutting SS.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 16, 2017, 04:14:25 PM
The studs were finished, I silver soldered the tank sides to the base, made a gasket and fitted it.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Ye-Ole Steam Dude on June 16, 2017, 05:44:26 PM
really nice looking engine.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on June 16, 2017, 07:19:18 PM
Hi Roger, nice to see the progress. It is comming together.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 17, 2017, 06:36:31 PM
Thank you both  :ThumbsUp:

I finished putting it together on its base and gave it a trial run. It sort of ran but I think it was four or possibly eight stroking. My cordless drill didn't have the torque required, but my 1kw corded drill got it going  :)

http://www.youtube.com/watch?v=4rAfjEW9BsU

I think I may make an adaptor to use a smaller carb  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on June 17, 2017, 07:32:08 PM
Hi Roger, congratulations for that first run.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: 90LX_Notch on June 17, 2017, 08:55:04 PM
Congratulations Roger.

-Bob
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: yogi on June 18, 2017, 01:12:48 PM
Congratulation on the first run Roger!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on June 18, 2017, 09:56:46 PM
Nice to see that you has successfully run the engine for the first time  :ThumbsUp:

This is always very gratifying  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 27, 2017, 08:48:04 PM
Thank you for your interest  :ThumbsUp:  :ThumbsUp:

I made a new adaptor for the smaller carb, the previous one having been converted into a fuel injection manifold for another set of trials. This ran well enough to allow me to adjust the oil pump for just a little blue smoke. Halfway through the trials it suddenly stopped and refused to fire at all  :( The battery was ok, the points were making contact but no spark at the plug  :headscratch: Solution, the water splashing out of the cooling tank had got into the plug cap  ::) I removed the plug cap and connected the resistor directly to the plug, all was well again.

I can get a fairly stable low speed run, but when I try to accelerate it goes into loud four or eight stroking. This may be due to the porting or scavenging, but I think it runs well enough for some diesel trials  :)

http://www.youtube.com/watch?v=fRgmscG2wOY
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Ye-Ole Steam Dude on June 27, 2017, 09:14:20 PM
Looks and sounds great, now you can take your time to do the fine tuning.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on June 27, 2017, 09:49:27 PM
More Progress  :ThumbsUp:

Normally I would associate "four-stroking on a two-stroke" with too much fuel - but in this case I can't help thinking that you got a too restrictive exhaust, that prevents it from scavenging as well as could be wished for ....  :noidea:

Best wishes

Per
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 28, 2017, 03:16:49 PM
Thank you  :ThumbsUp:

I will attempt to check the port timing when I take the petrol head off to see if it is anywhere near what I planned. What's the best way to do this, measurement or blowing down the inlet/exhaust and seeing when the flow starts/stops? I guess that late exhaust opening would also cause poor scavenging  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on June 28, 2017, 09:09:03 PM
It's mostly down to a few factors in a simple two-stroke - blow-down and port area are the main ones along with the size and shape of the exhaust pipe.
Blow-down is the time from opening the exhaust to the transfer opens - this needs not be long if you got enough area in the port above the transfer port height compared to the bore diameter.
All this also relates to the rpm range - so low ports are for slow running and high ports are for fast running and high power if I should be very simplistic. Exhaust port with on 50cc mopeds in my youth ranged, from 45-70% of piston diameter. The pipe should have the same area as the port where it starts.

Transfer port duration between 100 and 120 degrees and exhaust port duration some 20 to 25 degrees longer for work engines. If the shape of your exhaust port is round (I can't remember) - I would make it D shaped in the cylinder wall with the round part down and the flat part as the roof of the exhaust port and the port around 50% of piston diameter wide - smoothly morphing to round where it meets the pipe.

If you want it to be slow running start with 100 for transfer and 120 for the exhaust port - you can always remover more metal to make it run faster ....
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on June 29, 2017, 03:20:24 PM
Per, thank you for your comprehensive reply  :wine1:

I took the head off and made a few measurements. The port timing was based on a recommendation from ETW in one of his books.

Transfer 110°
Exhaust 130°

I then used to design programme on the MEN website to come up with port heights.

Transfer 107°   91.5mm from crankshaft
Exhaust 130°    94.5mm from crankshaft

The engine is 25mm bore, 40mm stroke. The conrod is 80mm between centers and the piston crown is 25 mm above the gudgeon pin center.

First I blew down the inlet and exhaust noting the point where the port opened. This gave the following angles.

Exhaust  126°
Transfer  108°
So Blowdown 9°

Next I measured the port positions from the head joint face and calculated the positions based on 125mm from the crankshaft centerline to the head face.

Exhaust 31.5 from head face  = 93.5 from crankshaft
Transfer 33.2 from head face = 91.8 from crankshaft

Putting these numbers back into the MEN program gave

Exhaust 123°
Transfer 110°
So Blowdown 6.5°

I think that the transfer port is ok but I may need to move the top of the exhaust port up by around 1mm  :headscratch:  :headscratch:

The ports are in three 25° segments as I am using unpinned piston rings. The width of each segment is about 5.4mm so the total port width is 16.2mm which is around 65% of the piston diameter. Breaking the port into 3 will reduce it's efficiency. The ports are rectangular with radiused corners.

The exhaust port height with the piston at BDC is 8.5mm which gives a total area of 137 mm2. The exhaust pipe bore is 8mm giving an area of about 50mm2. This as you said may also be a problem  ::)

I've got lots to learn about 2 strokes  :headscratch:  ::)



Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on June 29, 2017, 10:09:45 PM
OK - armed with your data I would suggest to start with a bigger pipe as am almost 3:1 reduction in area is a dramatic "choke" - around 14mm diameter gives you 153mm2. and a bit of space if you need to increase the height of the port a bit.

If you by any chance are going for power - consider an expansion chamber exhaust system, since it can easily boost power more than 50% if you get the dimension close enough at the same RPM.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on July 01, 2017, 10:17:39 AM
Thank you again Per.

I made a cover for the cooling tank to reduce the splashing. The large hole was made with a Conecut which luckily also ended up with a nice profile, possibly due to the piece of wood I was using as a backing.

I than made a larger bore exhaust using 14mm bore plumbing fittings. One elbow was annealed and shaped to match the existing exhaust flange. It seems to run better than before but is still mostly four stroking. If I lean off the mixture any more it just stops. I also tried an extension on the exhaust pipe but I don't think that it made any real difference.

http://www.youtube.com/watch?v=xRUs5ny1NRg
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on July 01, 2017, 09:08:19 PM
It sound more "natural" to me now - but we can agree that it is not a fast runner in it's current state.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on July 11, 2017, 09:04:12 AM
Roger, I've been away from the forum for a while, and I see you've got your engine running. Congratulations!

For what it's worth, the second video sounded like a small petrol 2 stroke engine.... Albeit using mechanical injection :D
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on July 20, 2017, 05:42:22 PM
 Hi Brendon, This is just running as a two stroke petrol engine to check the crankcase compression and porting. I still need to make the diesel cylinder head and finish the injection system before the real diesel trials begin  ::)  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on July 23, 2017, 02:50:14 PM
The next step is to make the diesel cylinder head. This is another piece of cast iron from the bar used to make the cylinder. The combustion chamber was cut to depth with a 10mm endmill using my depth gauge held to the side of the tailstock.
When I removed the petrol cylinder head from the engine to check the fit of the new head I was surprised to find oil in the combustion chamber  ::) My lubrication system is obviously adequate.
The gap between the head and the cylinder at TDC was around 0.3 mm so I should be able to set a suitable bumping clearance with a 1mm thick gasket.
I then turned the boss where the injector will fit on the top of the head and checked that the injector would just reach into the combustion chamber.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on July 23, 2017, 02:56:03 PM
The cylinder head cover was made from a slice of 50mm bar out of the goodie box. This was turned down to 3mm thick using some spacers on the jaws and drilled 10mm for the injector mounting boss. I had to move to the next set of steps on the jaws to allow clearance for the drill. The piece was then mounted on a slitting saw arbour to turn the outside down to 45mm. The shaft of the arbour doesn't quite fit through the chuck but by taking light cuts the overhang was not a problem.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Stuart on July 23, 2017, 03:48:04 PM
Roger

I don’t post very often but be very careful if you get lube oil on top of the piston , it just could start to diesel on the lube oil not the fuel

I have once seen it on a full size engine and I don’t what to see it again ,they shut off the fuel but it just kept going full blown runaway

Followed trials and tribulations in getting this far best of luck with the outcome
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on July 24, 2017, 11:33:00 AM
Thank you for the thoughts Stuart. I am aware of the risks with, especially two stroke, diesels. The air intake on this one is a 10mm hole that is conveniently placed to be blocked with a thumb if nothing else will stop it. The exhaust port is also at the bottom of the cylinder to allow excess fuel and oil to drain out (originally as a precaution against hydraulic locking).
The deposit in the cylinder head was more like grease and had to wiped out. I guess that it is some form of degraded oil (I use cheap supermarket multigrade).

Back in the early 80s I had a hired Mercury Capri in the States that was hard to stop. In drive it would 'diesel' for 30secs - 1 minute. If I put it in neutral it would probably have still been running in the morning  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on August 01, 2017, 09:12:51 PM
A circular water cooling passage was milled in the head using a 3mm 3 flute mill down to 6mm depth and finishing with ball end cutter. I wanted to drill the holes in the cover together with the head and the easiest way was to start with one of the injector fixing stud holes so I could put a screw in and fix the two parts together.
Due to lack of clearance between the head and the chuck the holes were not drilled completely through. I wanted to drill out most of the water passages, but unfortunately the second hole broke through into the first one. The passage were milled 10 mm deep with a 3 flute mill and then cut through into the circular passage.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on August 01, 2017, 09:18:24 PM
The cylinder head was then taken over to the bench drill for the hole to be drilled right through. It was then put the other way up in the mill and re indexed at the 0° hole. The rest of the water passages were then milled out. The transition between the water passages was smoothed with a ball cutter in the Proxxon and some riffler files. I need to make some studs and then back to the injection system.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on August 05, 2017, 04:15:10 PM
I found that the injector fixing holes didn't quite line up with the head  :( The bracket may have moved slightly during silver soldering as both holes were offset the same way from the center. I moved them ~0.3 mm across with and end mill and then counterbored again.
Back in lathe mode I radiused the cylinder head cover using a 2mm radiusing milling cutter as a lathe tool. The flat was luckily (or maybe by design) at the right angle to the cutting edges  :)
I then countersunk the injector nozzle hole for a sealing O ring. The O ring is 5mm id, 1.5mm section so I choose a large end diameter of 8mm. The injector studs are from all thread and I made a few M3 5mm AF brass nuts then put it together.

The 0.35mm nozzle hole in the injector is enough to destroy the compression at hand turning speed and whistles quite well. With the needle in the injector I can't turn it over compression by gripping the flywheel  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Jo on August 05, 2017, 06:04:28 PM
You are doing well Roger  :ThumbsUp:

I am equally pleased that my old Hobbymat is still performing for you  :)

Jo
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on August 05, 2017, 08:47:27 PM
Quote
The 0.35mm nozzle hole in the injector is enough to destroy the compression at hand turning speed and whistles quite well. With the needle in the injector I can't turn it over compression by gripping the flywheel  :)

It sounds like you got this part solved to running quality - another tick on the list  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 19, 2017, 09:12:08 AM
Thank you both  :) The Hobbymat is doing fine  :ThumbsUp:

When I tried the fuel injection system in place it clashed with the cylinder oil feed so I made a right angle fitting to give more clearance. I made a holding block out of hexagonal steel bar to allow me to turn the head on the bolt part and then to index the hexagon.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 19, 2017, 09:15:42 AM
I am also working on reduce the size of the injection pump (over on the fuel injection thread) but even so clearance was still limited so I thinned the head on the bolt by 1mm and counterbored the block by 1mm to give a little more space around the delivery valve.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on November 19, 2017, 09:46:21 AM
Good to see you back in your cellar.
Out side the window the first fine snow is dancing around.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 19, 2017, 10:30:53 AM
Thank you  :) We have around 3cm of snow outside so I think the R&D department will be closed now.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 26, 2017, 04:15:22 PM
I then needed to modify the cam I used to operate the contact breaker to operate the injection pump. As it will have roller follower the flanks can be flat. My first thought was to use my cam jig as with precious camshafts but in the end it was easier to use the rotary table. The RT was centred and then offset 19mm (half the base circle 24mm + half the milling cutter 14mm). The two flanks were cut at the planned angles and then the RT was recentred to cut the base circle. This worked well, when installed the base circle was concentric with the crankshaft to around 0.08mm TIR  :)

Next step mount the injection pump on the engine  :wine1:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 28, 2017, 08:41:22 PM
I tapped two holes in the side of the crankcase to mount the pump and cut down the mounting plate to give access to the unions. I left the piece along the bottom so I can refit it to the horizontal engine for further trials with petrol if required. Two 12mm diameter 12mm high spacers keep it in place.

As expected/hoped the cam gives a short injection time.

KaU6CJTsWZs
On the horizontal engine with the excentric drive the injection period is nearly 180° (crankshaft). I need to fit the pump union to the injector pipe and arrange a fuel tank then it is smelly diesel time  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on November 28, 2017, 09:24:38 PM
So next test run is just around the corner, so to speak ....  :popcorn:

Hope that you get closer to a constant runner soon.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 04, 2017, 06:20:21 PM
As diesels at generally hard to start trying this one in sub zero (°C) temps is not sensible  ::) I silver soldered the nipple onto the injection pipe and then moved onto the governor. The 40mm diameter blank means I have to use the outside jaws on the chuck and am working inside a risky space  :(
Using a variety of tools I cut the cone and the central stub. The bearing bush was turned from bearing bronze. As I don't have 14mm reamer I bored the bush to 14.1 mm and the pressed it into the cone unit which bought it down to 14.02 mm. The finishing work was done on a taper mandrel.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on December 08, 2017, 01:46:14 AM
Hello Roger, I have finally caught up again. You are making great progress.

I noted in this post (http://www.modelenginemaker.com/index.php/topic,5545.msg153718.html#msg153718) your use a rotary table. Have you explained how you attach the three jaw chuck to it elsewhere on this forum?

Thank you
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 08, 2017, 07:37:54 AM
Thank you Brendon  :ThumbsUp:
This thread (hopefully) explains how the chuck fits:

http://www.modelenginemaker.com/index.php/topic,6646.0.html

Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on December 11, 2017, 09:26:07 PM
Thank you Roger, that thread was very informative.

I do have one more question. Part of the reason I asked was I reckon I have the same rotary table. How do you find it's accuracy? Good enough to just bolt the adapter on, or do you do some sort of adjustment to true it up?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 12, 2017, 07:46:38 AM
Hello Brendon,

The adaptor plate (from RC Machines) has a stub that fits fairly closely into the larger hole in the table top. It is sufficiently accurate for my current use. I have carried out some improvements on my rotary table:

http://www.modelenginemaker.com/index.php/topic,5444.0.html

Good quality small RTs are difficult to find, the Sherline one is a possibility or the maybe the Proxxon offerings  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 17, 2017, 07:36:34 AM
The centre piece also had to be held in the outside jaws so most of the metal removal was by facing cuts. The keyway was cut in the lathe, a bit of a push with a lever tailstock  ::) It was then held in a collet to face to thickness. This would have been much easier with a larger lathe, but you use what you have (or what will fit the space you have).
I then made a couple of trials with the assembly held on a tapered mandrel in the bench drill. I rapidly found that I required a spacer to stop the cone rising too far and allowing the balls to escape  :facepalm:
It sought of works, but there is a fundamental problem that the balls turn at half speed so that the force is reduced  :headscratch: The 6mm balls were better than the 5mm ones. I may try a new cone with a 30° angel instead of 45°.
Once again I have embedded the video and just pasted in the link. I can only see the link.

http://www.youtube.com/watch?v=TQuso5qq2xA

TQuso5qq2xA
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 27, 2017, 07:33:12 AM
I had used up my slices of 40mm free cutting steel and had to start using a length of bar. I had hoped that I could cut the 30° cone directly on the end but there wasn't enough space so I parted off a slice. It's difficult to swivel the Hobbymat topslide to get the required angle but I was able to hold it in place with a toolmakers clamp.
The test results were not much different to the 45° cone. It tends to stick in the closed condition and then suddenly spring open  ::) It seemed to work better if it all rotated together so time for a rethink  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 27, 2017, 07:39:24 AM
I found a picture of a Junkers governor which appeared to have a similar ball and cone arrangement and used a small ball race running on the face as a thrust bearing. I decided to try this arrangement. By increasing the thickness of the bronze bush I could make space for a 2mm keyway to keep the parts rotating together. The cone was made in the same way as before and I had to make a 14mm bush for the keyway broach.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 28, 2017, 10:55:47 AM
I made a trial shaft and a couple of collars for the next tests rather than using the tapered mandrel. The governor disk has a reduced height keyway which required a stepped 3mm key and I filed the rounded ends on the 2mm key for the cone. I was able to put together with only few donations of 5mm SS balls to the swarf gnomes  ::) and gave it a try using a 6mm diameter ball race held on an M3 bolt.
This seemed to work quite well but I will need to make a bell crank and a spring support to test it properly.

XDrqM_TDsXI
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brian Rupnow on December 28, 2017, 02:56:09 PM
That is interesting, Roger. I have never seen a governor like that before. I have made and experimented a bit with the old "fly ball style" steam engine governors, but that style is a new one on me.---Brian
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 28, 2017, 04:08:08 PM
Thank you Brian  :ThumbsUp:

I improved the test setup with a stand and a swinging arm for the follower bearing. The test weights are M16 nuts suspended on a bit of wire coat hanger. This seemed to operate at a bit under 1000rpm which is at the lower end of the expected (hoped for) speed range of the engine. I won't be able to develop this much more until I know what the running speed, required travel and force will be, in other words when and if the engine runs  ::)

I need to look a bit more at possible linkages. I originally planned for the cone to move inwards towards the crankcase but it may be easier if it moves outwards :headscratch: There will still be space to mount a drive gear if it ever runs well enough to become part of a tractor  :)

Xw76yqUuhrM
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brian Rupnow on December 28, 2017, 05:42:00 PM
Tell me more Roger, please. I see that you machined a 30 degree cone and a 45 degree cone. Why?--Did one work better than the other?---Brian
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Kim on December 28, 2017, 05:45:48 PM
This is just fascinating, Roger. I'm with Brian - I've never seen a governor like this...
Kim
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 29, 2017, 07:55:09 AM
Ok, as with everything I do on here I am learning as I go along so there may be errors  ::)

The initial concept for this governor was taken from an illustration of an American Bosch distributor injection pump. I think that it works with one fixed part and one moving part, the balls being there own thrust race. I made a trial assembly for this with a 45° cone as that is what it looked to be in the picture. I made an initial trial just holding the fixed part in my fingers (there is a video clip of this). The force didn't seem to be much so I tried using 6mm balls instead of 5mm ones. This was better. I then thought that a shallower angle would increase the force so I made A 30° cone. I didn't feel much difference.
The problem with this design is that the balls are rotating at half shaft speed and as the force is proportional to the square of the speed the force is reduced to 1/4. Some quick experiments showed that allowing the whole assembly to rotate did increase the force so I made the current test piece based on the Junkers illustration.
Having made the test stand I will go back and make some quantative tests with the 30° and 45° fixed cones.

I hope that this helps but feel free to ask more questions.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 29, 2017, 04:04:27 PM
I have also attached below a PDF of the section of the drawing and the complete drawing of the engine so far (it makes a good 'off site' backup).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 02, 2018, 11:25:29 AM
I did some more testing of the different types of governor and learnt a few things  :headscratch:

For the fixed cone system there needs to be enough clearance when the cone is closed so the balls only have two point contact.
The hysteresis can be quite high. This is partially due to friction and partially due to the r term in the force equation. As the balls move out r and hence the force increases giving a positive feedback.
The drag on the fixed cone system is quite high. For the first tests I just let the screw rest against the support. This was partially why the first test with 6mm balls would not rise. For the later tests I restrained the screw with my finger. Some of the drag may be due to the surface finish as these parts were made as quick trials.
The difference in speeds between the fixed and rotating cones was a factor of 0.6, less than I would have thought.
The difference between 5mm and 6mm balls was only a factor of 0.9 whereas the difference in mass was a factor of 0.7.

I have summarised the test results in a spreadsheet below.

rxU6Xi4FAEw
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Brendon M on January 08, 2018, 10:39:03 AM
Keep up the good work Roger, this is very interesting to watch

Also, thank you for taking the time to explain your rotary table improvements :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on April 30, 2018, 05:42:46 PM
As this engine uses a lot of unions I tried Regner as an alternative supplier to Holzapfel who I have used up to now. The Regner unions have a smaller spanner size and offer nipples for 2mm and 3mm pipe. They are also cheaper if bought in 10s.

After an unsuccessful start attempt (in the fuel injection thread) I decided to confirm that the compression was what I though it was. The design is aiming at a 20-1 compression. I made an adaptor to fit in place of the injector with a ball valve right at the tip. This was tapped 1/8" BSP and I then had a fitting to go to 1/4" BSP although this has a large dead volume.
The first trial with a 1/8" BSP 10 Bar gauge went straight off scale. With a 16 bar gauge from an old pressure regulator I was seeing 18 - 20 Bar. I'm not sure how much the spring behind the ball valve will affect the reading  :headscratch: Obviously if it is too strong it will not open and I will not see any pressure at the gauge  ::)

yAgO_amBfKw
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on April 30, 2018, 08:37:03 PM
Hi Roger

Are you sure that the ball valve Works as it should ...?... I ask because my compression tester has to be reset to lower the reading.

Other than that I think you are doing great and will continue to follow  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 02, 2018, 05:55:13 PM
Hi Per,

I paid a bit more attention to the sealing of the joints on the 1/8" - 1/4" BSP adaptor and the leak off rate improved somewhat and I rapidly came against the end stop of the gauge  ::) The next step I have is the 300 Bar gauge from the other side of the pressure regulator. This seemed to settle down at around 25 Bar which for a 20-1 compression ratio with some heat loss due to the small size of the engine is not too bad.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Craig DeShong on May 04, 2018, 02:28:40 PM
I'm following along Roger  :popcorn:  I LOVE the governor  8)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 06, 2018, 05:09:45 PM
Thank you Craig  :ThumbsUp:  :ThumbsUp: , I hope the engine runs so I get a chance to try the governor design  ::)

I had another start attempt. I adjusted the injection timing, tried with the weaker injection spring that I use on the petrol engine, tried with no spring at all  :headscratch: The results were all much the same. As I raised the fuel rack I got increasing amounts of blue smoke for the first couple of millimetres. If I raised it further there was no more blue smoke but oil being ejected from the exhaust. I think that this means my injection pressure/penetration is too high and most of the fuel is ending up on the piston crown. The bench tests have all been just rocking the engine over TDC by hand which gives a fuel jet of 10-20 cm. If this is being cranked at ~1000 rpm with drill the jet may be much stronger. When the smell of diesel has reduced I will make some more trials with alcohol in the cellar. If the jet is too strong, I have several options: Increase the size of the hole in the nozzle (easy, a new nozzle is an evenings work but will need cleaning in the ultrasonic bath after lapping). Increase the injection period to reduce the pressure (not so easy, a new cam with curved flanks will require much more design that the current flat flanked one). Get the mushroom injector working (unknown).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 26, 2018, 04:44:33 PM
I had another try with the needle injector opened out to 0.5 mm and with the mushroom injector. The results were similar, blue smoke as I started to raise the fuel rack followed by a spray of unburnt diesel from the exhaust as I raised it more  ::) When the smell has gone I think that I will remove the cylinder head and see if I can get any clues as to where the spray is going  :headscratch:

GRmWe5r2c10
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Tennessee Whiskey on May 26, 2018, 07:28:13 PM
Roger, still quietly following along. If I may: back in the early days of true diesel fueled farm and construction equipment here in the states, it was quite common to start the engine on gas (petrol) and once running, the diesel fuel took over. Might be a way to judge things in the “running state” :shrug:

Cletus
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: zeeprogrammer on May 26, 2018, 11:00:01 PM
I've also been watching.

I have to admit...a lot going on here that I don't understand...which is fine! Always learning.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 28, 2018, 02:34:05 PM
Thank you both  :ThumbsUp:

Eric/Cletus, I initially tried the engine on petrol with a different cylinder head with a carb and spark ignition. I know that the crankcase compression and porting were ok for that although after some advice from Per (Admiral DK) I modified the exhaust pipe. I am moving into somewhat uncharted waters here. I have seen pictures and videos of working engines but the constructors give very little detail. Reviewing Find Hansens website it appears that his injector, of the mushroom type, is much smaller than mine being based on a 1mm shaft instead of 2mm. I could make one that small but I hope I don't have to  ::) M1 threads are a bit scarey (as is the cost of the taps and dies) :(

Carl, don't worry I don't understand it all either  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on May 28, 2018, 06:33:04 PM
Hi Roger, I am still watching quietly. A great experiment you have started there.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on May 31, 2018, 07:22:29 PM
After it's quarantine period in the garage I bought the engine back into the cellar and removed the cylinder head. Unfortunately there are no real clues, just a film of diesel oil over everything  ::) Maybe I need to try some more settings for the start of injection  :headscratch: Once I can get some form of combustion it is easy to see what makes improvements but until then it is difficult to know what to change next. The joys of experimentation  :wine1:  :wine1:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on August 01, 2018, 11:15:35 AM
As a next step I bought a small bottle of Diethyl Ether from the local chemist and tried a few drops in the air intake. This certainly produced combustion and a cloud of smoke but it wouldn't sustain. It was also very 'kicky' due to the ether. Luckily my drill is heavy enough and powerful enough to absorb the shocks. I still tend to think that the problem is poor atomisation so I will order some 0.2mm drills and make a smaller nozzle as well as some stronger springs for the mushroom injector.

WGJdHk97Pnc
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on September 01, 2018, 06:54:37 PM
Another attempt  ::) I tried a stronger spring for the injector which gives a theoretical opening pressure of around 120 Bar. This is still using a 0.5 mm nozzle, I haven't lapped the 0.2 mm nozzle yet.  With 0.2-0.3 ml of ether dropped onto the reed valve there were short runs  :)  :)

ZgzHUR-hyJU
Getting there  :wine1:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on September 03, 2018, 04:58:11 PM
Nice progression! 120 bar theoretical pressure looks like a lot!  :ThumbsUp:

May I ask how much heavier the injector spring is now, compared to the old one? In terms of spring constant (N/m). And suspended length of the spring (pre load)/ surface of opening?

I do not know if you've been involved, but I'm thinking.
It would be nice to measure the 'practical' injection pressure. But I think that it would be difficult (or expensive), seen that the pressure increases / decreases rapidly. A simple reading of an arduino + printing or something similar would not be accurate enough.
But how about to measure the amount of injected fuel of a multiply test cycle?

The amount of fuel injected is partly dependent on pressure. Pressure, opening size, and injection time. Of course opening size and pressure changed during the injection.
Or is it an idea to measure the height of the injected fuel? Based on Bernoulli's law, an idea could be given about the injection pressure. Link: https://www.natuurkunde.nl/vraagbaak/7724 (Dutch site).
The same principle is used to calculate, for example, the maximum of a water pump (Hydraulic power” means an expression of the arithmetic product of the flow (Q), Head (H)) . Of course there is a somewhat more constant flow of liquid here.

This ideas could give an idea of what the average injection pressure is. More as a method to 'measure' the differences of injector adjustments.
But I understand that you want to improve the to evaporate of the injection. It is more of an idea.

Alex
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on September 03, 2018, 05:52:42 PM
Hi Alex,

The previous spring had a rate of 2.35 N/mm and was compressed to 6 mm giving approx. 14N. The new spring has a rate of 6.7 N/mm and is compressed to about 5mm giving approx. 30N. The needle is 1.5mm diameter and I am ignoring the nozzle diameter to calculate the opening pressure. I am expecting to inject less than 2mm3 per stroke at full output.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on September 04, 2018, 11:19:12 AM
Thank you for the information Roger
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on September 30, 2018, 08:03:37 AM
The previous trial runs resulted in a fountain of dirty oil from the exhaust so I decided to drill a 1.5mm drain hole in the bottom of the exhaust bend.

Having lapped the 0.2mm nozzle I fitted it for another trial. Several problems  :( The flywheel had worked loose in the previous trials but luckily just tightening the grubs screws on the taperloc was enough. I may need to increase the screw size from M3 to M4. The second problem was fuel leak from the injector union which I couldn't fix. I need to study the design again (in the fuel injection thread). The runs I did get were no better than before, but the fuel leak may have been responsible. The drain in the exhaust did work  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 03, 2018, 03:06:38 PM
I had another attempt today having fixed the injector union but with no significant improvement. I adjusted the timing in stages from so retarded that nothing happened to so advanced that the kicking shook the starter dog loose in the drill chuck but the best results were where I had been trying.
Trying the normal spring, stronger spring and no spring in the injector generally made things worse. Finally I got no smoke at all and found that the cam follower for the injection pump had fallen off  ::) More thinking required  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 18, 2018, 03:56:15 PM
After some thought I decided to make a new higher compression head, reducing the length of the chamber from 10mm to 7mm. As this is to be an experiment I won't be making any water cooling passages. If it works I can shorten the original head.

The blank was made from a rather stringy piece of 50mm diameter aluminium out of the bits box. It was drilled through 5mm, the combustion chamber was opened out to 10mm and then finished off with a 10mm end mill to the correct depth. The cone was turned using my rather dubious spare compound slide. I set out the fixing holes using the small Proxxon RT and drilled and tapped the injector clamping holes M3. The 4.2mm dia. fixing holes were drilled with the bench drill. The Proxxon is not much good above 3mm.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on November 18, 2018, 04:01:10 PM
I then bought the engine in from quarantine in the garage and removed the existing head. There has certainly been some combustion. With the new head fitted I was getting a compression pressure of over 30 Bar rather than 25 Bar with the original head. Maybe it will be enough  :headscratch:
Finally I refitted the injector cam follower that fell off last time ready for the next trials. Outside temperature 1°C so not today.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on November 18, 2018, 10:08:29 PM
We can only hope for more success this time  :ThumbsUp:

 :popcorn:   :cheers:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on November 19, 2018, 03:15:44 AM
Roger,
Hopefully you will have a warm day soon and can try it out. :)
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on November 19, 2018, 11:57:13 PM
Good to see you on this project.  Hopefully this gives an improvement!

Is it an idea to insert a glow plug of an rc engine into the cylinder head? To pre-heat cylinder or to initiate ignition? I do not know if this would fit in your cylinder head.

https://www.mecoa.biz/shopdisplayproducts.asp?id=81

Alex
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 01, 2018, 02:38:29 PM
Thank you all  :ThumbsUp:  :ThumbsUp:  Alex, I hope to get this to start without aids as others appears to have done. I had thought about glow plugs (there is a model Lanz Bulldog that uses an automotive one in place of the hot bulb) but I will keep trying without for the moment.

We had some reasonable weather today, up to 9°C, so I gave the engine another try. The first problem was that the injector tappet kept sticking, probably due to some slight damage when it fell apart last time  ::) I smoothed around the fork end with a diamond file and got it working although I need to dismantle it all again to check.
I was getting weak firing without any ether which was improving as I advanced the injection timing a little at a time. Then a problem, the starting dog slipped on the crankshaft gouging both  :(  :(

The dog will need to be redesigned to clamp better, I don't want to key it as something has to give. I can hopefully skim and sleeve the end of the crankshaft and may increase the grubscrew size in the flywheel when everything is dismantled.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on December 01, 2018, 05:28:32 PM
Roger,
Have you considered a one way bearing as the starter drive. I copied Steve's starter drive to use on VAL. Works great plus it allows the engine to take off when it starts. http://www.modelenginemaker.com/index.php/topic,3653.345.html (http://www.modelenginemaker.com/index.php/topic,3653.345.html) Here is the link to my VAL build, I had clearance issues and needed to make a spacer to give me the room on the end of the crank. Just a thought.
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 03, 2018, 08:27:34 PM
Thank you Art. I have used such a system on my vertical engine as at 3cc it had problems pushing the dog out. This engine is rather more violent and I need something that will give if something goes wrong. I had hoped that the pin would break but instead the clamp slipped and damaged the crankshaft.
I have modified the design, moving the cut round 90° and increasing the clamp bolt from M3 to M4. The new dog is made from a piece of fairly high grade steel from the bits box. It gives a nice finish with highish speeds and a carbide tip. When I started to mill a seat for the clamping bolt it migrated in the vise so I added a G clamp to keep it in place. The damage is just cosmetic.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 03, 2018, 08:31:21 PM
As I needed to use a slitting saw for the clamp screw slot I used it to cut the other two pieces.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 03, 2018, 08:34:56 PM
I could have made a complicated milling set up to cut the dogs but instead spent 15 minutes with a selection of files  :) Next step strip down the engine and hopefully salvage the crankshaft  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Ye-Ole Steam Dude on December 03, 2018, 08:54:38 PM
Hello Roger,

That is a lot of filing but it looks good.

Have a great day,
Thomas
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on December 05, 2018, 03:37:37 PM
Hi Roger,
at my last version of this dog  the soft edges were damaged very quick.
This was much better after a simple heat treatment, for this a CK45 Steel or similar is helpful.

Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 05, 2018, 07:41:44 PM
Thank you both  :ThumbsUp: The dog part of the current version survived the horizonal engine and this one, its the connection to the crankshaft that is the problem at the moment  ::)

After it's quarantine period I bought the engine in from the garage to strip it down. Even with the taper bush fully released I had to use a puller to get the flywheel off. The end of the shaft doesn't look very nice  :(  I had to file down a lot of burrs to get the side plate off.  The flywheel has obviously been slipping as well. The piston, bore and big end look fine  :)

I can't increase the flywheel clamping bolts to M4 without a redesigning/remaking the center but I will slightly deepen the clamping holes and use an end mill to give a flat bottom. I hope I can clean up the flywheel portion of the crankshaft but will have to turn down and sleeve the starting dog part.

Next challenge, get the oilway grub screw out of the end so I can get a center in. ( I note that the last picture of the damaged crankshaft is number 666  :mischief: )
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 06, 2018, 07:00:31 PM
On with the salvage. I worked out the original position for the taper bush and fitted all the screws. I could then carefully run a 12mm reamer through to clean up the worst of the damage.

I was able to release the crankshaft oilway grub screw as I had only used a threadlocker not a retainer grade of Loctite. The damage could be removed by skimming down to 11.45mm, just right for the 11.5 mm reamer I had to buy due to the unique feature on the other end of the crankshaft  ::) The sleeve was made from  a piece of 12mm ground ST50. Due to other experiences supported by Rich's (Firebirds) fun with the bushes on his Conway I needed to bore out the sleeve to ensure it was concentric. Drilling is not good enough.

A bit of Loctite, twist it into place to ensure good distribution and see what it looks like tomorrow.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 08, 2018, 04:53:55 PM
I faced off the end of the sleeve and then decided to reduce the OD of the dog to 18mm and radius the fillet to the clamping part. The flywheel was set up on the Proxxon RT and the three plain holes were deepened to 5.5mm with a 3mm end mill to give a flat bottom.
It was easiest to remove the cylinder block to refit the piston as there is a tapered lead. It will go from the cylinder head end but I would need to make some form of ring compressor. The rest was put together with a thin smear of Hymolar in the appropriate places. I then primed the oil system using the electric drill to confirm I was still getting oil to the main bearings and cylinder.
A little bit of work with a diamond file on the fuel pump tappet resolved the sticking problem. I now need to refit the fuel system, time it and bleed it.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on December 08, 2018, 06:27:21 PM
Looks like you are discovering how much heavier load there are on most of the working parts of a diesel compared to a gasoline engine the hard way Roger - but at least you seems to find the solutions too  :ThumbsUp:

 :cheers:      :popcorn:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on December 08, 2018, 06:43:23 PM
Hi Roger, perfect salvage.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 09, 2018, 08:16:29 AM
Thank you both  :ThumbsUp:  :ThumbsUp:

Per, the parts I have actually designed have been ok, it's the bits that have just 'happened' like borrowing the starter dog from the horizontal engine for the first trials and not updating it that cause problems  ::) Find Hansen bent the connecting rod on his first diesel  :toilet_claw:
I will put the injection system back together today and will then have to wait for better weather to try it again.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on December 09, 2018, 06:28:08 PM
Roger,
Looks like a good save.
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 10, 2018, 07:49:08 PM
Thank you Art  :ThumbsUp:

I refitted the injection system and then set it up with some cooking alcohol to prime and test it. I could not get any injection so I wondered if the 0.2mm nozzle hole had got blocked  :headscratch: I released the spring and got spurts from the nozzle, as soon as there was any spring pressure nothing  ::) Maybe there was still some air in the system so I span it up with the drill. Fuel sprayed from the back of the injector but none through the jet  :toilet_claw:  I dismantled the injector and checked the needle, still 1.480 +-0.001mm. I tried the other needle still no success  :( The 1.48mm pin gauge felt loose in the nozzle and a 1.5mm drill with a 1.455-1.458 shank would go in  :facepalm2:
I think that the problem was/is the holder for the 0.2mm drill which is made from silver steel rather than brass and has a sharp edge somewhere that cut a/some grooves in the nozzle guide resulting in rapid wear although the fit was originally good. I will lap the outside of the drill holder to remove any possible cutting edges and make a new nozzle (in the fuel injection thread).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 22, 2018, 04:13:55 PM
Some success :)  :) The weather was not so bad so I had another try. I was getting some combustion without ether and was able to optimise the timing, which was quite sensitive. I then played with the injector spring pressure. Interestingly the results improved as I lowered the pressure  :headscratch: Finally with  the adjusting screw on it's last threads I got a run  :D

yjbhKltmOos
If you look closely as it stops you can see the injector adjuster, spring and needle shooting out  ::)
Luckily all the parts could be found but I did not get much success when I put it back together, problem, the injection pump roller had failed again  :( A redesign is needed.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Ye-Ole Steam Dude on December 22, 2018, 04:20:12 PM
Hello Roger,

That is great news, boy that is an angry little thing when it does fire up. Just a matter of time now and it will be running as expected. Great job on your part  :praise2:

Have a great day,
Thomas
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: fumopuc on December 22, 2018, 07:29:59 PM
Hi Roger, really impressive. I admire your patience.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on December 22, 2018, 10:33:18 PM
Even if only for a very short run - I would consider it a great success  :whoohoo:  as it shows that you are on the right track :praise2:

Yes it is a bit of a pain to have to remake some parts, but you do know for sure that some worked exactly as planed => improved confidence - and that goes from the rest of us following too  :cheers:   :popcorn:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Dave Otto on December 22, 2018, 10:34:32 PM
That's really cool Roger, congrats!

Dave
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on December 22, 2018, 11:27:12 PM
Roger,
This is great, even for  short run. One more revision should about do it. :cartwheel: happy dance time :)
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Graham Meek on December 23, 2018, 01:08:19 PM
Hi Roger,

It has been a long journey, you are a whisker away from a reliable miniature true diesel. I bet old Rudolf had his set backs too. I too have often wondered about the injector spring pressure.

I am in awe of your achievement.

My best regards
Gray,   
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 24, 2018, 08:36:12 AM
Thank you all for your support and optimism  :ThumbsUp:  :ThumbsUp:  :wine1: 

I have started modifying/repairing the various bits that failed. When the injector tappet roller pin fell out the end of the fork scored the cam. Luckily this is outside the normal working surface so I polished it and then case hardened the lobe. Next up was a locknut for the injector spring adjuster from a piece of 10mm hex brass followed by milling some 6mm spanner flats on the end of the adjuster. I made a new silver steel pin for the roller which is held in place with M2 nuts rather than E clips. Due to a momentary lack of concentration the head has four flats instead of six  :facepalm: but it will work. This was then hardened.

I will measure the compression/load on the injector spring in the 'running' condition and see if I have a spring that can give this mid range rather than at the limit. I think further trials with the different nozzle sizes will be useful as well as a further increase in compression ratio. The amount of unburnt diesel that comes out of the exhaust suggests that the spray is hitting the walls or piston  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: cnr6400 on December 24, 2018, 04:23:25 PM
The new parts look great Roger! Hope this results in a great runner. Couple of questions re the design of the plunger:

1. Is the small slot in the plunger a keyway to control rotation of the plunger, and keep the bearing square to the cam? If so how close a fit is the key or pin in the slot?

2. How far is the plunger engaged in the block it runs in when the engine is assembled? Could play in the plunger to block fit allow the plunger to move too far sideways?

I'm asking about these things in view of what caused the mark on the cam in the last run. It almost looks like either the roller got angled to the cam and dived off sideways, or roller was still square to it but plunger and roller wandered off cam centre to the side, and jammed.

Great effort so far on this engine!  :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 25, 2018, 08:11:17 AM
Thank you for your interest  :ThumbsUp:

1. That is correct. The clearance is less than 0.1mm.

2. The plunger passes through a 10mm long block and is a close fit.

The score on the cam was caused when the pivot pin for the roller came out followed by the roller. One side of the fork on the plunger then dug into the cam. Due to the width of the cam the other side just missed. The pivot pin was retained by a couple of E clips which have failed before but just at cranking speed so there was no real damage. I am guessing that there is a slight difference in angle between the cam and the roller which is causing a side force on the pivot, but both times both E clips came off  :headscratch: Just one would be understandable.
This pin was another item copied from my petrol injection version where the forces are much less (same as the starting dog  :facepalm: )

I checked the compression of the injector spring in the final run which was about 1.5mm giving a theoretical opening pressure of ~15 Bar. This is the top end for the petrol injection spring so I can use that in the next trials. I imagine that with the short injection period, ~10-15°, and the 0.2mm hole the actual pressures are somewhat higher.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: cnr6400 on December 25, 2018, 04:07:44 PM
Merry Christmas Roger!

Thanks for explaining re the questions. Your experience with e clips is similar to mine with them in industry. They were very much in fashion at one firm I worked for but eventually they were placed on the "restricted use" list in design reviews. In applications where the side loads are small and evenly distributed on the clip they work great, but where side loads are higher or unevenly distributed, not so much. We had a lot of spring loaded mechanisms with e clips jumping off and causing major product malfunctions. We did a lengthy investigation and found that variations in clip heat treatment, and in groove geometry (top and bottom rads and side wall angles), could seriously reduce the side load the clips could handle, and where mechanisms were spring loaded, there were unforeseen side loads from spring buckling during compression. Everyone had the mind set that springs exert their force straight along the axis of the spring- not so in real life at all, there can be forces in many axes at the spring end! If these uneven or angled forces act on an e clip its' side load carrying capability drops dramatically and it is only a matter of time til it jumps out. One rough fix which was effective in some cases was to use the next OD size down clip for a given shaft diameter, and an extra deep groove. This gave more side wall to clip engagement. The clip manufacturers used to publish a fair bit of info on groove geometry and permissible loads. Not sure if they still do. The loads are not so easy to estimate or measure in model engine work though.  I think your bolt and nut approach for roller holding on the engine plunger is a good one since it will carry lots more side load than e clips.

Regarding control of the roller angle to cam - not sure exactly what dia your plunger is, but if the plunger is say 6 mm dia / 3 mm radius and the keyway to pin has 0.1 mm clearance, doing the trig, the roller could be angled at 1.91 degrees to the cam by the slot to pin clearance alone. (inv tan (0.1/3)) I think this may be a significant angle. An idea that occurred to me for a way to control it better would be to add a dowel pin at 90 degrees to the plunger just behind the roller, if there is room. This dowel could extend up or down to fit in a slot in the base or the cylinder assy to keep the roller as close to 90 deg to the cam as possible. The longer the pin is, the smaller the angle of rotation. For example if the pin was 10 mm from end to plunger centre the angle goes to 0.57 degrees with same 0.1 mm clearance pin to slot.

Good luck with the next run!
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 27, 2018, 04:02:16 PM
Thank you  :) I think the problem with the E clips may have been that they were being pushed by a cylinder rather than a flat surface  :headscratch: I have used them as valve retainers without problems but there they are supported by a flat surface.

I had another try Today. I did run but adjusting the fuel rack had no noticeable effect  :headscratch:  :headscratch: As planned it stopped when I put my finger over the (very accessible) air intake which was the back up in case of a runaway. May be I have got the phasing of the helix with the rack incorrect  ::) It is definitely firing on the injected fuel as when the tappet started stick again it would stop instantly ( I did wonder at one point if it was running on the lubricating oil).

_vksgF1psPI
Apologies for the poor handheld video.

Next step: a weeks quarantine in the garage and then into the cellar to dismantle the injection pump and see what is happening.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: cnr6400 on December 27, 2018, 08:48:47 PM
Hi Roger, the latest run was great!  :ThumbsUp: :ThumbsUp: I think you are very close to having a reliable runner now. Standing by with the  :popcorn: for the next run!

The attached picture is of a Goold, Shapley and Muir 22 hp twin engine built around 1910 in Brantford Ontario Canada. They used a unique guide fork to keep the cam follower and end of pushrod lined up to the intake cam.  A fork on either side of the cam rode on a wheel with a close fit. This kept the follower on the straight and narrow. Simple but elegant solution. Just a thought in case it turns out the plunger is cocking and jamming in its' bore. Maybe you could do something like the GSM fork on the diameters beside the cam lobe? It would a) keep the plunger square and guide its' back end, b) would keep the roller dead square to the cam. Only food for thought.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on December 29, 2018, 08:48:48 AM
Thank you Jeff  :ThumbsUp:

I think that I have a clue to the cause of the problem. When the engine is turned by hand there is clearance between the locknut on the roller pivot and the aluminium mounting plate. Having made the last test runs there is a definite impact mark between the two so the follower must be rising above the cam. This unbalanced force could then slightly distort the fork  ::)

Thinking about it the lack of response to the fuel rack was probably due to moving from 'too much fuel' to 'even more fuel' which was just being sprayed everywhere from the exhaust. Although I tried to maintain the relationship between the helix and the rack after the first sticking plunger problem it must have moved  :facepalm: The engine revs are being limited by the porting, which I noticed when it rans as a petrol engine.

When I can bring it back into the cellar I need to make some measurements of the output of the fuel injection and lubricating pumps. I have ordered some 10ml measuring cylinders and have a smaller Veeder counter I can attach to the end of the crankshaft to allow me to measure output per 100 revolutions (or more?).
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 03, 2019, 07:20:44 PM
The diesel that came in from the cold.

I bought it back into the cellar and was able to take some measurements. The Veeder counter could not keep up with my battery drill at 550 rpm and died so I just worked on time. Zero fuel was certainly not zero fuel and max fuel was definitely more than I needed  ::)

As I dismantled the system there were obvious overshoot and impact marks in several areas. The actual cause of the jamming was impact from the end of the injector plunger on the tappet body. A quick twist with a 5mm reamer got everything moving properly again but I need to sort out the various strokes and clearances as well as rephasing the helix.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 03, 2019, 10:01:29 PM
Just thinking out loud. How many things (should) prevent overshoot here ?
I'm guessing a spring and the injector nozzle  :thinking:  and if I remember right, you loosened the spring on the injector to get a good run. I would guess that this also has an influence on the marks shown.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 04, 2019, 02:51:15 PM
Thank you Per  :ThumbsUp:

After I had written this I went back downstairs for another look and think  :headscratch: I think that the overshoot is happening when the inlet port is exposed again for the end of injection and the pressure in the system suddenly drops from 10s of Bar to zero. I could increase the size of the return spring but that would also increase the total load on what is already a fairly stressed cam follower. Chamfering the ends of the bronze bush in the tappet guide and thinning the two pivot nuts down from 2mm to 1.5mm will resolve most of the actual problems.

The next problem I found was that the plunger had come loose in the rectangular tappet that fits inside the rack gear. This is the reason for the change in phasing between the rack and the helix  ::) The M2 thread was originaly locked with a medium strength screwlock as I thought I would probably have to dismantle it again. I don't know if this failed due to the shock loads or due to the various fluids (petrol, diesel, alcohol, lubricating oil) that it has been surronded with. I will try some Loctite 648 next and if that fails I will have to work out a mechanical solution.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 04, 2019, 06:43:34 PM
I suppose that there is no space for a second short spring - might be at the end of the first one - with a much higher force factor to absorb the shock and prevent the damage ?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 05, 2019, 02:17:36 PM
I have thinned the nuts down which greatly increases the available clearance for overshoot. I think that this overshoot could have been responsible for pushing the original E clips off  :headscratch: To minimise the impact damage at the pump end of the tappet I have adjusted the clearances so that the roller is always in contact with the cam. This makes the little ball race work harder but it should cope as the load is minimal for most of a revolution.
After reassembly and priming I took some more volume measurements:

Stop was zero

In the previous 'working position' about 0.2mm3 per rev.

Full open about 0.4mm3 per rev.

The theoretical max volume required for a full charge of air (which won't be the case on a two stroke) is 2mm3 per rev. As you can't expect to use all the air and with the likely reduced air charge these figures seem reasonable.

The R and D dept. is currently closed due to snow so the next trials will have to wait.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 05, 2019, 08:12:02 PM
Glad to hear that you got yet another step forwards  :ThumbsUp:

As for the R&D department .... You could argue that It looks pretty and cold ... Brrr .... Her we had close to 10C and a nice sunshine almost all day  :cartwheel: .... But do see delays in the Test Report  8)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Art K on January 05, 2019, 09:15:01 PM
Have to admit that it's abnormally warm here in Wisconsin. The thermometer says 50 degrees F outside
Art
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Dave Otto on January 05, 2019, 10:52:23 PM
R&D Department Closed!
I see a little spot next to that yellow watering can where you could work.  :lolb:

Dave
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 06, 2019, 03:04:51 PM
Thank you all  :ThumbsUp:

Following on from Per's suggestion for a second spring I think I can fit an O ring in the space between the end of the rack pinion and the injector body. The theoretical gap is 1mm and a 5x1mm O ring should fit inside the spring. I only have a 5x1.5mm at present so will have to order some.

I then went on to measure the output of the oil pump. According to ETW the design was suitable for engines up to 30cc. The system is set up so that I can tilt the pump away from the worm and turn it with a 4mm hex socket on the end of the shaft. A it was set it would empty my 5ml oil tank in a couple of hundred revolutions  ::) Not only too much fuel but too much oil as well  :facepalm:

I found some reasonable settings with direct drive and will then try again via the normal worm drive (20-1) in case there is a speed effect. 550rpm with the battery drill is equivalent to the engine running at 11 000 rpm  ::)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on January 07, 2019, 08:36:02 PM
Good to read that you have made good progress in this project.
Hopefully the engine will soon run a stable speed.

Can I ask why you add oil to the fuel?

Alex
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 08, 2019, 11:10:22 AM
Thank you Alex  :ThumbsUp:

The lubrication on this is based on the Field Marshall tractor system as is the rest of the engine. There is a separate oil reservoir and pump feeding the crankshaft and the cylinder. Initially I am running it as a total loss system although I plan to add a return system from the bottom of the crankcase. The pump has a variable output, the initial setting was just a guess, resulting in much too much oil which was then ejected via the exhaust.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on January 08, 2019, 08:47:15 PM
Ah right! Thanks for your explaining.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 08, 2019, 09:38:34 PM
Old Suzuki (197x) two-stroke multi cylinder motorcycles had one way valves and small diameter pipes running from the bottom of the crankcase to the inlet of the neighbouring cylinder - this "flushed" the crankcase from excess oil earlier than waiting for full throttle and a big smoke back out .....
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: AlexS on January 13, 2019, 01:22:18 PM
I like that oil system on the Suzuki GT models.
Coincidentally my father has a GT 380. Especially when the engine has been stationary for a while, it produces a lot of smoking when it starts. I drive a Yamaha RD myself, where the oil is only sucked in at the carburetor. With this engine the smoke is a bit less. Also at full load. But I use a different oil. And use it in the summer as a daily transport.
I do not have that much experience with two-stroke systems for diesel engines.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on January 13, 2019, 04:41:45 PM
Quote
I drive a Yamaha RD myself

OK, now I'm almost back to my youth, as my first (official) road bike was an Yamaha R5F (the last model before the RD350).
I LOVED two-strokes, but that bike cured me from that  :noidea:  Had it been one of the later water cooled models, things might have been very different - but then again, I prefer to ride more than to repair them  :shrug:

Don't get me wrong - if money was no object, I would love to have a big two-stroke bike with great steering + braking to take for a short spin from time to time. Oh and like wise - I would get one of the new fantastic eBikes to run to a from work and other daily errands - driving + environment  :)
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on January 13, 2019, 05:23:19 PM
The Field Marshall had a similar oil return system with a one way valve in the bottom of the crankcase and a small bore pipe back to the oil tank. When I have some idea of sensible oil flows I will have to make some experiments.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 02, 2019, 03:15:57 PM
The temperatures eased a little today so I had a play  :)

In the first video I slowly raised the fuel rack until it started and then gradually lowered it until the engine stopped. In the second clip I tried the same but the fuel didn't shut off and I had to choke it. I also did a quick speed check and it seems to settle down around 4 000rpm  ::)

62P78-tVuHs
YVdG4UUF8LU
So it will have to sit in quarantine in the garage for the next week before I can investigate the fuel pump again  :headscratch:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Kim on February 02, 2019, 08:43:56 PM
So, what's the quarantine for?  Is your shop inside, and the engines smell too bad after they've been run?

Just curious,
Kim
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: yogi on February 02, 2019, 09:50:39 PM
Progress!!! It's fun to watch how that project came along.  :popcorn: :popcorn: :popcorn:
Looking forward to the next step... Thanks for sharing Roger.  :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 03, 2019, 10:19:44 AM
Thank you both  :ThumbsUp:

Kim, my workshop is in a communal cellar so I have to be very careful not to upset the neighbours, checking my shoes for swarf before going out etc. The diesel does smell quite strongly at the moment after running but hopefully that will improve as I improve the combustion.

Looking back at yesterdays runs I think I will make another cylinder head with a further reduction in volume. The theoretical compression ratio is already high, around 28-1, but being a two stroke the cylinder filling is probably not that good  :headscratch: I will also go back a try the larger injector nozzles again. It seems that the original lack of combustion was due to insufficient compression temperature rather than poor atomisation  :thinking: I may also need to think about limiting the lift of the injector needle as the needle opening increases the fuel volume in the injector.

However after a couple of Fohn days the snow has come back so the R+D department is closed again.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 10, 2019, 07:38:21 AM
I bought the engine into the cellar and dismantled the injection system. The cam follower bearing had failed, possibly as I had continuous contact for the last trials  :headscratch: The helix plunger was still ok  :thinking: I then removed the cylinder head, everything was black and oily but otherwise ok. I turned it over a couple of times and got a fine mass of black gunge that can only have come from the transfer port. That's probably why it wouldn't stop the last time  :facepalm:

Next steps:

Make an oil return line from the crankcase.

Skim another 1 - 1.5mm from the cylinder head.

Check the 0.5mm nozzle and make a new 0.35mm nozzle
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: bent on February 11, 2019, 06:12:27 PM
Roger - did the bearing fail by losing a couple of balls, or did it gall/seize?
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 11, 2019, 07:06:34 PM
It looks like it failed due to side pressure, I think one ball is missing and the cage looks distorted. Needs more investigation  :thinking:

I drained most of the gunge out of the crankcase and the started on the drain fixing. I could have completely dismantled the engine and clamped the crankcase to an angle plate or used a slightly risky setup  ::) With the engine held in my largest vise I started off, planning to minimise the amount of swarf in the crankcase. First a flat with my largest center cutting end mill, than center drill and drill 4mm, but not right through. Next a counterbore as it is guided/supported and finally right through with a 4.5mm drill.
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 11, 2019, 08:16:47 PM
The last step was to tap M5x0.5 for a union, followed by carefully cleaning any bits of swarf from the crankcase. I made up short connecting pipe and started re assembling. It's interesting that a 2mm hole is sufficient to destroy the crankcase compression at low speeds in the same way that a 0.35mm hole in the injector was enough to destroy the compression in the cylinder  :thinking:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 16, 2019, 08:09:15 AM
The non return valve was made from 6mm hex rod with a 2mm bore and 3mm ball. The cage was a cross cut in the union with a junior hacksaw. I put a length of clear tube on the outlet and spun the engine will the drill for a few minutes and was rewarded with some gunge  :) There also seemed to be a lot of air so I may need to add some restriction after the valve :thinking:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Admiral_dk on February 16, 2019, 04:50:21 PM
So what we see in the last picture is from the bottom of the crankcase then .... if so, quite a bit more than I would have expected .... but it certainly explains the extra smoke when you run it + to some extent its unwillingness to stop when you cut the fuel.

I hope this helps you back on track with the next run  :cheers:
Title: Re: 20 cc Horizontal 2 Stroke Diesel
Post by: Roger B on February 17, 2019, 05:02:48 PM
Thank you Per  :ThumbsUp: As ever more to learn  :headscratch:

When I drew the thinned down version of the current head the combustion  chamber was looking rather pancake like so I decided on a 8mm bore 8mm deep version. The bumping clearance was a little large, I have been aiming for ~0.5mm, so I had to skim 0.2 mm off the face. I then stared thinking about the clearance volume between the piston and the head  :thinking: 0.5 mm is not much but it is a reasonable area. A quick calculation gave a volume of 0.25cc, a significant amount compared to the combustion chamber  :facepalm:
Recalculating gave the (using the swept volume after the exhaust port closes, 15cc) original compression ratio as 16-1, the next step as 20-1 and the new head as 24-1. This is more in line with the measured compression pressures. With the new head and cranking at around 2000rpm I was getting nearly 40 bar  :)
I now need to make a new 0.35mm nozzle and wait for the R+D department to be open for the next trials.