Webster eze .056 diesel.

[aircraftmech]

This is my first engine build and I am looking foward to getting some feedback from more experienced machinists. I expect a lot of mistakes and remaking parts...
This is my second try at making the cylinder/crankcase, the last one I cut to deep of a bevel on.
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Hoping to drill and finish boring out the crank and cylinder this evening.

 

[gus]

Just watch the cylinder bore and piston fit which is very unforgiving. Must provide enough meat to hone.Honing is another black art skill which takes time and patience to acquire and master.You have to DIY Honing tool.
Good Luck and All Success.My Bolero and FireFly are both paper weights. Will find time to rework or rebuild.
Meanwhile I am working on the Howell V-2 ,four stroke Gas Engine which take at least three more months to complete. I fair better with four stroke engines with two running very well. The Webster and Rupnow H&M are four strokes.

 

[Jasonb]

With a small diesel like that the fit will need to be lapped not honed. First with a homemade lap to get the liner bore to a good finish, lap the piston to a similar finish again with a homemade ecternal lap and then finally lap the piston into the bore with 1000grit.

J

 

[aircraftmech]

Thanks guys, the plans came with some drawings for the laps. Gonna have to play with them some to see how it works.

 

[werowance]

Thanks guys, the plans came with some drawings for the laps. Gonna have to play with them some to see how it works.

I would very much like to see the laps when you make them, and also the process you used to make them.

 

[aircraftmech]

So four cylinders after my last post I finally settled on a technique that allowed me to locate it on the faceplate accurately.
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After center drilling in the four jaw I transitioned to the faceplate. Then firmly pushed my live center into it to hold it in position before clamping, drilling, and boring.
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Finally this evening bored the hole for the cylinder liner.
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The paper is to prevent marring.
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[GailInNM]

That's looking very good. Just take it slow and easy and eventually you will have a good runner.

As others have mentioned the fit between the piston and cylinder are very critical on compression ignition engines. Even more critical is the fit of the contra piston to the cylinder.

Over the years I have built a flock of engines in this general size of displacement including half a dozen compression ignition engines, two of them twins. This size of engines are my favorite size to build.

If I can help in any way with any questions, just holler.
Gail in NM

 

[werowance]

Even more critical is the fit of the contra piston to the cylinder.

curious on the contra piston fit, should it move as freely as the piston or be snug that it doesn't move unless pushed with the compression screw or the compression of the engine? not quite a press fit, but one that it will stay put in an open cylinder without falling out if slung around and gravity or centrifigal force pushing it out. sort of like shaking the ketchup bottle upside down to get the ketchup to come out on your French fries.....;D
I am fighting a diesel trying to get it to start as well.

 

[GailInNM]

curious on the contra piston fit, should it move as freely as the piston or be snug that it doesn't move unless pushed with the compression screw or the compression of the engine?

I fit my Contra pistons so they are much tighter than the piston. My rule of thumb for fitting contra pistons in this size engines is that if I can push the contra piston in the place with my thumb without it feeling uncomfortable on my thumb then it is to loose. My contra pistons have a skirt on them normally about three quarters of a millimeter thick that I am pushing on.

When starting an engine that has been broken in I put a small prime in the exhaust. For starting I back the compression screw off about half a turn, about 15 thousandths of an inch (0.4mm), from the last running position and turn the engine over by hand (not flipping it) and as I approach top dead center I can hear a click as the contra piston breaks loose and moves up go and contacts the compression screw.

Most of the small commercial compression ignition engines that I have used react in the same way.

Gail in NM

 

[aircraftmech]

The plans call for a fit that is just loose enough for the compression to move it back... If that makes sense.

 

[GailInNM]

That's the same thing as I was trying to describe. You just want it to be tight enough that you are well up on the compression stroke before the contra piston moves.
Gail in NM

 

[aircraftmech]

I started turning the front housing down this evening. Didn't get very far, but far enough to make me wonder about what the plans call a "close sliding fit". Do you guys think the turned part that goes in the crank should be almost a press fit? Ultimately the housing will have four screws holding it on the crankcase...
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[Swifty]

A close sliding fit will allow you to push it in the bore with your fingers, but not rock excessively, looking at the size of the bore, .001" undersize would probably work.

Paul.

 

[Jasonb]

It should go in with hand pressure but if you pick one piece up the other should stay in place and not slip out. These three bits - head, liner and cylinder - all fit like that

 

[aircraftmech]

Thanks guys! Just didn't want to make it then later have it be a problem.

 

[aircraftmech]

Another update. Machined the head, front and rear housing. Just a couple holes to drill and tap on them. View attachment ImageUploadedByModel Engines1427337751.134130.jpg
Also need to drill and ream the .250 crank journal in the front housing.
I'm not going to make much more progress till I get some of the steel parts made... I am going to have to order the 12L14 for cylinder and crank. The piston is made of class 40 cast iron, where would you guys get the cast iron from?

 

[aircraftmech]

I managed to get some time in the shop this week and started on the crankshaft.
First I turned the front part that slides in the journal to .251 then finished it with 1500 grit sandpaper to .250 on an aluminum block to get it to turn freely but not have any slop. I used the block to help prevent introducing a taper.View attachment ImageUploadedByModel Engines1429250405.341061.jpg after that I cut the prop driver taper and drilled the prop driver stud hole.
Then I turned it around and started making the crank pin using a shop built offset jig. The jig was made by chucking the aluminum up .188 off center and drilling/reaming then cut with a bandsaw.View attachment ImageUploadedByModel Engines1429250611.294500.jpg
Just a picture of turning the pin down in the jig, I used sharpie marks on the side as slippage marks.View attachment ImageUploadedByModel Engines1429250685.389592.jpg
When finished I drilled a #31 hole in the center of the crank that will function as the intake. Next I will have to cross drill to this hole... It's going to take some good thought on how to do this as the angle before TDC sets the timing and must also line up with the hole in the front journal.

 

[aircraftmech]

Finished the crankshaft today. Cross drilled the intake and tapped the prop stud.
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I made sure the dial indicator touched on the center of the v block and was square with the table before using it to set TDC.
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Then I set the head to 28 degrees and center drilled then drilled it out.
I'm thinking the cylinder liner will be made next or maybe finish the milling on the front journal.

 

[aircraftmech]

Got a little time in the shop last night... Finished all the milling on the front housing.
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Milled out this little jig to hold it, the hole is a snug fit on the journal. A nut is pressed into the back of the smaller hole, which was also used to center it on the rotary table.
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Pretty happy with the way it came out. This the first real milling job I've done...

 

[aircraftmech]

Finally finished the connecting rod! I was having difficulty getting the large radius to straight section to look nice... Using the plans it didn't tell me where the straight stops and radius begins, also because your cutter is round and your stopping at a tangent off of radius I was having a rough time of it.
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The original plans...
After making about 7 that didn't work using different techniques, I realized I could draw it in CAD then locate a 1/4" circle (representing the end mill) where I want it. Then by measuring from the center of the radius to center of my end mill, determine where to stop the linear travel and begin rotating the table.
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My drawing with all the measurements... I drew this in "On Shape" on my iPad, it's actually a pretty easy program once you get used to it.
As you can see Y .211 and X .102 are the numbers I was after.
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