circle routine cutting "ovals"

[pyrodenis]

My problem:
I used a 1/4" super O bit to cut (using circle centerpoint routine) .5" dia circles in corian. They are coming out long in Y axis. Also, there seems to be little "bumps" at the 3 and 6 o'clock positions.
I'm running at 15,000rpm, xy 1ips, z .5ips in a spiral plunge.
Both x and y values are equal in my settings.
Anyone?
THNX

[bruce_taylor]

I would try .5 ips at 12000 rpm cut .46 diameter first then cut it at .5. Of course I'm assuming you have check your machine is normally cutting pretty dead on and don't have any other issues.I cut alot of corian and normally do three passes. It cuts pretty easy. Hope this helps. How much off is it in the "Y"?

[Brady Watson]

Check for a loose pinion grub screw. You'll need to pull the motor to check properly.

-B

[pyrodenis]

thnx Brady. that makes sense. and now I know what a grub screw is.

[steve_g]

When I was contracting...I was always surprised at the different nomenclature in various parts of the country. The term Grub screw is etymologically from the UK and folks with ties to the old country will use that term for what the rest of us call a set screw. In my part of the country... tightening the set screw will often have no effect as they are typically stacked in twos, you have to remove the first one tighten the deeper one and then replace the backup one/s.

Steve

[Brady Watson]

In my part of the country... tightening the set screw will often have no effect as they are typically stacked in twos, you have to remove the first one tighten the deeper one and then replace the backup one/s.

Steve

Know what ya mean there Stevie...It'll drive you nuts if you didn't know to check for a 2nd one!

-B

[beacon14]

Yeah, I wish I had known that before I used a gear puller to force the pulley off the main shaft of my wide-belt sander. Could not for the life of me figure out what was holding that pulley on so tight - I had already loosened the (first) set screws!

[michael_schwartz]

I guess you learn something new every day. I have never encountered "stacked" set screws yet.

[pyrodenis]

I had 2 screws, but at 90 deg to each other. And, there was a key involved. I was surprised that the key would allow any play; maybe it was gradually "hammered" smaller, by the constant tapping during the change in direction. Anyway, I guess I'll go back in, to see if there's a 'buried' grub in there somewhere. ...replace the key too?