Er Collet angle question

Couldn't get that BB code to work but if you can't figure it out let me know.

Aaron
 
Following the collet instead of the math was the proper thing to do. I now have a collet block suitable for holding small diameter round stock in my micro mill. Still need to figure out why the math didn't work. I'm beginning to suspect that my spindle is not exactly parallel to the ways.

p-170771514-3435.jpg
 
AGCB97 said:
There's a youtube vid
[/url=https://www.bing.com/videos/search?...C1079183060921C14C28C1079&fsscr=0&FORM=VDFSRV] Haligan[/url]
Click to expand...

That's not a good video to follow. The result was quite a bit of run out.
I believe when you make tooling, your tool must be better than .0005 runnout, when using tools that measure .001 you can't be there. Why do you have to be better than .0005 because .0005 means your still talking .001 on what you are making with that tool. If you start off with .001 or the videos case much worse. So using a .0001 test indicator to set values becomes necessary, in his case he tested without a rod in the collet, so the bluing was inconclusive.. So my feeling is this is how to machine, but not how to make it. How to make it would come out with a usable unit.
 
marchyman said:
Following the collet instead of the math was the proper thing to do. I now have a collet block suitable for holding small diameter round stock in my micro mill. Still need to figure out why the math didn't work. I'm beginning to suspect that my spindle is not exactly parallel to the ways.

View attachment 229088
Click to expand...
I believe the easiest way to test for that is with a precision ground test bar sized for your spindle's taper. I rolled the dice on a cheap Indian-made one on eBay from AtoZ Tools. $42 or so for an MT3 test bar. I have been unable to detect any error in its form. It has, of course, also been center drilled on each end so it also allows me to test tailstock alignment with it held between centers, and to set an accurate tailstock offset, should I ever feel so inclined.
 
sine vs tangent?
If you're cutting a taper with the topslide the slide movement is along the hypotenuse of the triangle not the adjacent, at small angles sine and tangent are close (tangent slightly larger), but no cigar...

So... if you have the indicator in the toolpost (on centre height!) against a centred and parallel test bar and move the topslide 1" the indicator needs to read SINE of the angle, not tangent. Enough of a difference to give the wrong angle, definitely.

Dave H. (the other one)
 
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