Author Topic: 20 cc Horizontal 2 Stroke Diesel  (Read 49124 times)

Offline Roger B

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20 cc Horizontal 2 Stroke Diesel
« 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.
Best regards

Roger

Online b.lindsey

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #1 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

Online Jo

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #2 on: November 27, 2015, 07:28:15 AM »
You can never have too many projects on the go  :)

Or casting sets  ;D

Jo
Usus est optimum magister

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #3 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.
Best regards

Roger

Offline Niels Abildgaard

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #4 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

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #5 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #6 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  ;)
Best regards

Roger

Online Jo

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #7 on: November 28, 2015, 06:03:01 PM »
 :o I thought it was going to look big on the faceplate.

Carefully does it  ;)

Jo
Usus est optimum magister

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #8 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.
Best regards

Roger

Offline fumopuc

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #9 on: November 29, 2015, 04:22:53 PM »
I am following along. Nice stretching of you machining capability.

Kind Regards
Achim

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #10 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #11 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.
« Last Edit: December 10, 2015, 07:39:38 AM by Roger B »
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #12 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.
« Last Edit: December 13, 2015, 08:34:01 PM by Roger B »
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #13 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #14 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.
Best regards

Roger