Author Topic: 20 cc Horizontal 2 Stroke Diesel  (Read 64480 times)

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #120 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #121 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #122 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.
Best regards

Roger

Offline zeeprogrammer

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #123 on: April 02, 2017, 01:34:47 PM »
Just saw the video. Thanks. That helped a lot.

 :popcorn:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #124 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.
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #125 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.

<a href="https://www.youtube.com/watch?v=nizTJNc4xnU" target="_blank">http://www.youtube.com/watch?v=nizTJNc4xnU</a>
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #126 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. 
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #127 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.
Best regards

Roger

Offline fumopuc

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #128 on: April 12, 2017, 07:33:00 PM »
Hi Roger, I do like your CAD (cardboard aided design).
« Last Edit: April 13, 2017, 04:56:53 AM by fumopuc »
Kind Regards
Achim

Offline 90LX_Notch

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #129 on: April 13, 2017, 01:54:07 AM »
I'm still following along Roger.  I like your C.A.D. system, very effective.

 -Bob
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Offline Dave Otto

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #130 on: April 14, 2017, 12:57:42 AM »
Lots of progress there Roger, everything is looking great!

Dave

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #131 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  ::) 
Best regards

Roger

Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #132 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  ::) )
Best regards

Roger

Offline zeeprogrammer

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #133 on: April 18, 2017, 10:42:08 PM »
It's getting more and more interesting.  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline Roger B

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Re: 20 cc Horizontal 2 Stroke Diesel
« Reply #134 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. 
Best regards

Roger