Can't carve a circle?

I have a feeling something on my machine is jacked up… I used easel to draw out a simple 6 inch circle to cut into 1/2 birch plywood.

Absolutely nothing special what so ever –

At first it seemed to be doing OK on the first circle, but once it started into the tabs portion, and going clockwise in cuts it starting making weird new paths. and it was each pass that it followed this new path, not just a single time, like a belt skip or something. I used the factory settings for plywood 30 in/min, 0.028 in DPP

I ended up having to cut the profile, popping out the center hole, then running the cut path again this time selecting it as “outside” and no tabs" to even come close to a normalish circle. even on this 2nd cut, it still wasn’t close to a perfect circle.

Any thoughts on something obvious I am missing?

I probably have some scrap that I can try much lower feed rates, but 30 seems sufficiently low

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Try reducing your depth of cut, that will reduce the load on the bit. It may help. :confused:
Cutting slower but faster (to make up for the extra passes) sometimes helps.

Is easel reversing cut direction when it gets to the tabs?
If so this is probably part of the problem. Changing direction changed the forces on the bit, causing it to flex differently. This shoves it against the edges of the channel it has already cut, causing problems.

Is this a new machine that you are setting up or a problem that has popped up?

Check you pulleys, maybe one of those tiny grub screws are loose.

I’ve had the machine for a while now - however I haven’t touched it in 9+ months because I was working on my Kitchen and winter came, then a baby, etc. This weekend was my 1st time back out in the shop. I cleared all the dust, checked all teh connections etc before starting. I can double check pulleys again, but it seemed to be a consistent issue no matter where on the gantry it was (started all 3 holes in different locations)

Yes, when it got to the tabs, it started going clockwise for a full rotation, then counterclockwise for the next pass, back and forth.

You might want to try one without tabs as a test. Try “onion skin” instead. That is don’t cut all the way through, leave a thin layer on the bottom that can bet cut or sanded away after.

Do you have a stiffening mod of some kind? That will help.

No mods to the original 1000x1000 set up.

I’ll double check all pulleys, belts etc and then do an onion test. I am cautiously optimistic as the follow up"outside path" also seemed to not follow a circle perfectly, but much better than the “inside path” with tabs.

This is very likely a pulley, belt, v wheel, etc issue

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This is a similar issue as described here. Unfortunately, the user didn’t report back if he had checked the recommended things and if it fixed his problem.