Brian Builds the Kerzel Hit and Miss I.C.

[mklotz]

I'll look forward to reading how you go about setting it relative to the workpiece. I have my own procedure for doing this but I always like to hear how others approach a new-to-them subtle job. Often there is great wisdom in such revelations.

 

[kcmillin]

I too am interested in how you are going to register the corner rounding cutter.

I have a set and thus far I have only Eyeballed them to "Close Enough" I would imagine that measuring the cutter would help out quite a bit.

Kel

 

[Brian Rupnow]

Well---Let me see---the cutter is listed as being a 5/32" radius cutter. So--If I bring the end of the tool down to touch the top of my part, set the vertical travel dial indicator to "0", then advance the quill 5/64" that should put the center of the curved cutting face in line with the top surface of the part. Then I move the part in untill it just "kisses" the edge of the cutter, and feed in 0.010 increments untill the resulting radius is where it "Looks good". Take note of the total amount that I fed the part into the cutter, and use that figure to set up cuts on the other 3 sides.---am I close????

 

[Jasonb]

Well---Let me see---the cutter is listed as being a 5/32" radius cutter. So--If I bring the end of the tool down to touch the top of my part, set the vertical travel dial indicator to "0", then advance the quill 5/64" that should put the center of the curved cutting face in line with the top surface of the part. Then I move the part in untill it just "kisses" the edge of the cutter, and feed in 0.010 increments untill the resulting radius is where it "Looks good". Take note of the total amount that I fed the part into the cutter, and use that figure to set up cuts on the other 3 sides.---am I close????

If its 5/32 radius you need to drop it 5/32 not 5/64, same with the sides, touch an edge and feed in 5/32. In reality you may find that something like 0.090 is whats needed.



Jason

 

[Brian Rupnow]

Jason---I just started modelling a cutter and a part to show you why you were wrong. Then part way through I realized you were right!!! Egg on face!!! Eating crow now!!!

 

[mklotz]

Ok, Brian, that's essentially how I do it. Scratch on the inside surface of your eyeglasses - radius = diameter/2.

 

[Brian Rupnow]

Not a whole lot of exciting stuff happening on Kerzel right now. I managed to get in some real work and have to do my 8 hour stint designing whilygigs for paying customers, then play model machinist between days end and when Jeaprody comes on at 7:30. I picked up a peice of 2 1/2 x 1 1/4" aluminum bar yesterday at one of my suppliers ($10 for half a foot) and got all the holes drilled and c'bored last night. Tonight I flipped the part over and milled the clearance slot for the con rod big end. I don't know why I torture myself by making something like this base from one solid chunk of aluminum, but I like the finished results---so tomorrow night I will mill out the two sides to finish the shape. I guess a little bit of progress each day is better than no progress at all!!

 

[Brian Rupnow]

I was thinking last night about the cylinder liner for this engine. It press fits into the water jacket, and the piston runs inside it. Normally I build cylinders from 1018-1020 mild steel and use aluminum pistons with Viton o-rings for piston rings (They stand up to the heat and wear just fine). However, with this hit and miss engine, the outside of the cylinder liner sets in the coolant water in the waterjacket, and I'm sure it will rust to some extent, and this rust will be visible through the hole in the top of the waterjacket. What are the pitfalls of using a peice of 316 stainles steel for the cylinder?

 

[Brian Rupnow]

Well now---Isn't that just Ducky!!! I finished up the base after dinner today. The four "windows" that appeared in the base were a complete surprise to me. When I modelled the base, I just put in a standard depth counterbore for a #10-24 shcs., and no windows showed up in the model. Then when I was making the base, I measured my stock of cap screws and found that they were only 3/4" long. No problem, thought I---I'll just make the c'bores extra deep and avoid buying longer capscrews. I hate it when surprises show up in my machining, but at least this time it doesn't hurt anything. I haven't used my radius cutter on the top of the water jacket yet---I'm rather torn.---I kind of like it the way it is with square corners. I think the next thing I tackle will be the bearing stands.

 

[Brian Rupnow]

Since I truly an "making it up as I go along" I had to put a bit of thought into how to best make the bearing support plates. They have a diameter turned on them, but there is no good way to hold them, without resorting to the 4 jaw chuck. You can't make one and then split it in half, because you lose the material from the sawcut. I don't want to waste the material to make two. I have resurected an old fixture and modified it a bit to suit this application. I will show you what I plan on doing as I go along. Basically, I start with a 1" wide peice of material, drill and ream a 3/8" hole in it to fit over the center register on the fixture, and the 3/16" pin on the fixture fits into a hole in the 1" wide material to act as a drive key. Then after I have turned the diameter I complete cutting out the profile of the plate and the 3/16" hole gets cut away.

 

[Brian Rupnow]

This is what the bearing supports start out like---I've just got enough info on there to shape the profile and to drill and ream the 3/8" and 3/16" holes. This drawing is giving me fits!! There is a mistake on Kerzels drawing, which I willingly copied when I was making my models, and only noticed it tonight. Kerzels dimension of 0.608" has to be 0.615 to make all of the other dimensions work out correctly, to satisfy the 1.221" and 0.75" and the 1.00" and the 0.415" dimensions. I'm not sure what results this would have had on the finished engine, probably none. But Damn, it makes me crazy when my drawings don't make sense.

 

[Brian Rupnow]

This is where I ultimately want to end up. You can see the 0.615" dimension on this drawing.

 

[lathe nut]

looking great Brian, thanks again for the how to photo's and the drawing, you make it look so easy to do, Lathe Nut

 

[Brian Rupnow]

Well, so far, so good. My fixture to turn the bearing support stands seems to be working well. A lot of breath holding and multiple stops for measureing, but one down and one to go----

 

[Brian Rupnow]

I don't have a sine bar set up to determine angles accurately, and although my vice will tilt, I don't really trust its protractor to anything other than an approximation. Failing anyother way to do it, I scribed my intended cut line on the side of the bearing stands, set a 1/8" thick parallel on top of my vice, and eyeballed it to a point where the scribed line was parallel with the top of the parallel and tightened the vice there. I must mention here that I had the two bearing stands dowelled together with short peices of 3/8" diameter and 3/16" diameter stl. dowels in the reamed holes I had used on my turning fixture.

 

[Brian Rupnow]

And it was a good solid set-up. (for you sharp eyed guys, that 3/8" dowel was actually brass). I went ahead and "milled to the line". (That bit of brass and the black shim were put between the two frame halves as I tightened the vice to keep everything "true" under the power of the vice jaws.)

 

[Brian Rupnow]

Here I am picking up the center of the 3/8" diameter "Half hole" in order to position the drill head to drill the holes which will be threaded to hold on the bearing caps.

 

[Brian Rupnow]

And here we have the finished results. Everything worked out----If I were doing it again I would have used #5-40 screws to hold the bearing caps on. As it was, I used #10-24, and consequently ended up with another small "window' opening up in the side of the bearing support frame. This will not effect the operation of the engine, and will be mostly hidden by all of the other bits and peices which bolt to the sides of the engine. I simply file this information under the "watch for that the next time" category and keep moving foreward.

 

[Jasonb]

Brian, is there also a clash with the bearing cap screws and the ones comming up from below, I noticed this on your drawing but assumed you had just used a standard image for the threaded holes and would actually stop short on the build but it looks like you have drilled the tapping holes a lot longer than the threads?

Jason

 

[Brian Rupnow]

Yes Jason, there is a clash exactly as you show. In reality it doesn't cause a problem as the bolts can be shortened up a bit if I have to---remember, they only go in as deep as the threads show. I drilled and tapped the mounting holes in the underside of the bearing supports first. When I flipped them over to drill and tap the top surface where the bearing caps go on, I first ran a 1/8" end mill down full depth where the new hole had to go to keep my drill from trying to wander off into the already existing hole. Then I drilled the required hole, and as I expected the drill followed the hole created by the end mill. Then I mounted the tap in the drill chuck on the mill and rotated it by hand, depending on the quill to hold the tap "true" so it wouldn't try to run off. It all worked out fine.