Edge finding a vertical bar?

[CraigH62]

Hi there

I've CNC converted a Sieg X1 and have been finding my way around it for 4 months.

Recently I've been machining some small parts for model helicopters and needed to mill a circular pocket in the end of an aluminium bar to accept a bearing at each end.


I've been scratching my head about the best way of edge finding this as
wigglers don't seem to be reliable on a curved surface.

I've found 1 axis by edge finding the V block with a wiggler and doing the maths (edge + (v-block-width /2 - bar diameter/2) offset into the DRO to give the Y edge of the bar. However X axis is a little harder and resorted to using a bit of paper between the mill and edge with Y axis aligned to bar centre axis.


Then test machining a circular pocket and measuring the distance of pocket to edge of the bar in 4 directions and offseting the error to get a very acurate reference for the bar I have got radial to within .02 mm with this technique.

Is there an easier way to do this?


Seems like hard work

Cheers

[Willbird]

You cannot just indicate the center of the bar with a test indicator ??

Bill

[InspirationTool]

Try a test indicator or a coaxial indicator.

-Jeff

[Willbird]

and I understand now and then for some reason an edgefinder is easier to use, you can find both sides of a shaft or a hole with the X axis, and note the DRO position at each side, subtract one number from another and add half the differance...move to that position and then do Y, set Xo Yo and then double check and be very close. Tram errors in your machine will translate into errors between indicated center and true center...so your cut and measure method detects that and compensates for it.

Bill

[CraigH62]

Hi Bill

The method you describe is what I was trying to do with an edge finder but not very repeatably.


Of course the obvious answer is always the one so simple and doh I missed it!

Dial indicating the peripehery of the rod is much less hastle to get centre.

The test cut as you said just removes any errors.

Thanks

Craig