I was trying to bore some holes to a sliding fit tolerance. During my testing though, I found all my holes were 3.5 thousandths bigger that than what was programmed!
I did find some runout when indicating the base of my tool, but not on the outside of the spindle. It seems like there is potentially some runout somewhere.
Has anyone else encountered inaccuracy or runout ?
That machine should be capable of holding something like ±.0005” depending on tolerance stackup. The probe will usually repeat closer to .0002” which includes spindle runout. .0035 is enough that you should be able to slide a 1-2-3 block up against the tool and clamp it down and rotate it by hand and feel it bind up if that’s where your problem is.
yah the collet/toolholder is the first place to check runout as you did. they are not the best quality and have been abused. Second is the gibs, the x/y have been adjusted recently but could use another look over. I can send the video on how to check and adjust. Lastly how you programmed should be looked at. typically, on precision holes I will bore or drill under size and then come in with a stepped finish contour to dial in the tolerance.
I drilled undersized, then bored with .004 stock to leave, and then did 2 bore finish passes. Tolerance was set to .0001.
Maybe I will get my own toolholder. For accuracy, is it better to get an ER holder or a set screw holder?
I would recommend trying just a multiple depth 2d contour. (less machine vibration and resonance than spiraling)
Also you can turn on compensation in control with 2d contour so you can just adjust the diameter in path pilot to dial in the tolerance instead of reposting the code.
As for set screw vs er. I don’t have a strong opinion. just measure it and see.
I have a new 3/8" set screw holder and maybe a 1/2" you can try if that’s the size you need