1994 cinci 500 vmc, wont mill circle round

[chaz6966]

when i circle mill a diameter of 1.125 on the mill the circle is large by .002 at a 45* angle to x-y travel.
anyone have any suggestions. not sure but i think the faster you feed the worse the elipse is.
thanks, chuck

[andyb4]

That usually indicates that your axis are not square to each other. I would check the gibs. It may be moving one of the axis off square when moving

[scudzuki]

1994 Cincy 500 is a linear rail machine. No gibs.

Joe

[holbieone]

check for backlash in the screws in both "+" and "-" directions

if there's a few tenths of back lash you can adj. it out (you'll have to find out how to do it on your machine)

if there is no backlash you may need to tune your drives

[andyb4]

Oops my bad. I don't know the machine in particular, just machines. I still believe if you are cutting an eliptical shape the geometry of the machine is off. Backlash setting usually help with steps at the 4 axis direction changes. Have you had any crashes or the like that may have moved the trucks or the rails on the machine? It is surprising how small of a "bump" will do this. Is the .002" only across one 45, say 45 - 225, or is it out at 135 and 315 as well or is it smaller? High spots at 45's usually points to the drives, while high spot at one 45 usually indicates geometry

[Boots]

This is backlash and can be tipically removed or fixed with a backlash adjustment by adjusting your backlash parameters. Please consult your machine manufacture or your manual to remedy the situation.

[laka]

What is the finish like on the circle? Our Arrow 750 had bad chatter in one quadrant, turned out to be the x,y axis thrust bearings. There is no way to grease them, not too bad to change out