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Your Own Design / Re: A new attempt at making piston rings
« Last post by Brian Rupnow on Today at 01:54:59 AM »
Third times a charm!!!--We're setting at 10 degrees angle and diamond is at or just below spindle centerline. And the moral to this story is Research-Research-Research. I spent two minutes on Google and found all kinds of information about what I am doing here, even drawings. Luckily, I didn't have to make any new fixtures---Just relocated the hole for the shaft which holds the diamond. Anything from 5 degrees to 15 degrees is suitable, so I'm good with this. Arrrrggghhh!!--Let that be a lesson to me.

Your Own Design / Re: A new attempt at making piston rings
« Last post by john mills on Today at 01:34:13 AM »
referring to my grinding book mc phersons  they where an austrailan manufactor and agent of machine tools
years ago when things wear made hear  it says it is good practice set the diamond at or just below centre at an angle of about 15 degrees  the drawing shows it angled downwards at 10 to 15 degrees.  the diamond should be rotated after every few dressings  which has the effect of keeping the diamond sharp. the company has long gone
but i have had the book from when i was an apprentice  .i know that work after mar than 50 years in machine shops .   John
Your Own Design / Re: A new attempt at making piston rings
« Last post by Brian Rupnow on May 13, 2021, 10:44:19 PM »
It is tilted up 15 degrees. If it was tilted down, the wheel would pull the diamond out of it's holder. Ahhhh Jeez---Now I'm being told that the diamond tool should be 15 degrees opposite to what I made it.---that it should be angled down at the front where it contacts the wheel.
Your Own Design / Re: A new attempt at making piston rings
« Last post by Laurentic on May 13, 2021, 09:49:18 PM »
I thought it was suposed to be tilted down 15 degrees - Brian yours look like it is tilted up 15 degrees!
Your Own Design / Re: A new attempt at making piston rings
« Last post by Brian Rupnow on May 13, 2021, 09:11:33 PM »
One more time with feeling---This time the diamond support is set at an angle of 15 degrees with the center of the diamond on centerline of grinder spindle and chuck all in the horizontal plane. It isn't quite as pretty as the first time around, but form follows function.

Nice work Craig!

Introduce Yourself / Re: New member from Lancashire
« Last post by scc on May 13, 2021, 07:06:56 PM »
Welcome Stuart.. :cheers:          Terry   (also in Lancashire)
Your Own Design / Re: Ringbom 1: Tim's Ringbom Stirling Engine Build
« Last post by tvoght on May 13, 2021, 05:18:47 PM »
Next up is an overhung crank consisting of a web, a shaft, and a pin.
The web comes first. A drawing is attached.

1.25" 303 stainless stock is put in the 4-jaw and drilled .015" or so less than
the .25 inch intended shaft bore, and deeper than the final length of the part. The hole is then reamed to .25" for the shaft. A shoulder is turned to space the web off of the ball bearing it will butt against.

The part was cut off with extra length and taken to the mill. The center hole was accurately located and a hole drilled at the crankpin offset.

The web was milled to thickness, and then the crankpin hole was drilled and reamed.

At the CNC mill, a tooling plate was clamped down and drilled and tapped for
shoulder screws to clamp the part. A program cut the web outline a little
oversize in progressively deeper cuts.

Then another program cut to final outline at full depth. Notice that there was no margin of error for that smaller shoulder screw. I don't recall how I managed to prevent it from being unscrewed by the cutter. It's possible I used loctite on the threads.

The shaft is purchased 1/4" stainless ground rod. The only machining necessary was to cut it to length. A drawing is attached.

The crankpin is made of stainless and unfortunately there are no photos of the
build. A fairly straightforward collet job. See the drawing.

I don't seem to have any photos of the parts first asesmbled, but they were put together with loctite 609.
Your Own Design / Re: A new attempt at making piston rings
« Last post by swarfjunky on May 13, 2021, 04:56:55 PM »
Are we agreed that the diamond itself should still be on the same centerline as the grinder shaft?

Yes, the optimum set-up would be the grinder shaft centerline, lathe spindle centerline and diamond should all be on the same plane.

From Plans / Re: Elmer's Oscillating Cylinder Engine #42
« Last post by crueby on May 13, 2021, 04:35:15 PM »
Only thing I've found that works well in aluminum (and it does vary with the alloy, some are worse than others) is to back out the tap every turn or so, sometimes it means working the tap back/forth just in that small advance, since the chips jam so much. Especially with small taps like 2-56, they fill the flutes very quickly. Need to back it up every half turn to break the chips small, then back out completely every full turn or so.
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