Another thread about circle troubles, but this is a little different

Hi and thanks for looking to see if you can help. My machine is setup and seems to be doing a good job. Trouble is I keep getting a very unusual blip in my circles.

Pictures say a 1000 words.

That’s with Vcarve and UGS.

This is with Easel.

I get a strange redirection at 2:00 and 8:00 on the circle everytime. And it’s the same ~3mm every time. Shouldn’t be software since easel and vcarve both do it. All my v wheels are time. It’s not loosing steps. That easel photo was a deep (1mm) pass followed by a skim pass (<0.1mm) and the router followed exactly the same path both times. It keeps doing the same trick every time no matter what.

So in short, something is causing a hiccup at 2 and 8 on all my circles and it isn’t the software or steps. What else could it be? Thanks.

Ryan

Update. After posting I thought I should try an ellipse. Same issue on a couple different sized ellipses.

Squares come out right :slight_smile:

The first thing I’d suggest is checking your pulley screws. If they’re missing or loose (i.e. not tight and dead-center on the flat), that can allow the shaft to rotate before the pulley does. That will normally cause a blip. Other causes could be low (or high) pots or high (or low) belt tension. The blip itself is an indication of lost steps, you may want to check out this thread if you don’t find loose pulley screws: [Guide] Offset cutting, Lost steps, Positioning errors, etc

Are the two circles on the picture separate cuts?

I agree with Robert, most likely the pulley screw is loose.

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Thank you, you guys rock. When I read your comment I thought that made a lot of sense. Went and checked it out and found them all in place and seemed right. Removed and replaced them all to be sure and it worked. Thank you thank you thank you!!!

My xcarve is now rocking!

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Excellent! You may want to put a little bit of low- or medium-strength loctite or thread locker on the pulley screws when you get a chance, just to keep them from coming loose in the future.