Imperfect cutout

Hi all,
Been cutting a few shapes lately and am having issues.
First cut.

But I forgot to set the depth of cut to 3mm instead of 1. So I re did the file.
Second cut…

I have re done the gcode a few times and get the same result. SVG is fine and looks fine in Estlcam.
Any ideas what the problem is?

May as well check the tightness of the ever popular grub screws.

Which ones?

I’d check them all, especially if they weren’t Loctited during assembly, seems to be a somewhat common issue.

Just pinched them about 1/8th of a turn.
It’s following the same path every time. and cuts it exactly the same each time.

Is it following the path you expect or still going off course?

It’s not cutting the path it should be.

Just restored the original file and it cuts a perfect shape. Problem in I had forgot to set the depth and hold tabs.

As is often said: All’s well that ends well. :+1:

But I need to change the file. This one takes about 10mins to cut instead of 2 mins.
But when I change it I get the imperfect shape

Possible you’re pushing it hard enough to get flex in the bit?

I wondered that, but I would have thought the results would be inconsistent. It’s making exactly the same imperfect cut every time.

If it it cuts fine at 10 minutes and goes off course at 2 minutes, everything else being equal?, it would seem something is loose/and/or flexing. Maybe try a few other shapes requiring similar movements using the same speeds and DOC just to see what happens? Machine have a good history with few issues?

Ok, just tried the 2 min cut in different material and am betting the same result. Problem with my 10 min cut is I didn’t save it as a project. But i can open the gcode file, what line or code is speed rate? If I can find this out I can copy it.

Should be an F followed by a number which is (I believe) mm/min.

Check the tightness of the bolts holding the spindle on. Looking at your picture, it looks like you’re getting a ‘rounding’ when the bit changes direction. I’m thinking it’s still flexing somewhere in the machine.

Slow your feed rate down and see if it still does it.

Ignore all of this… you said a bit higher up it does it in a different material. What was the other material you tried in? Pink foam?

I tried it in pane and mdf, I will try it in foam.

It definitely sounds like there is an issue in the second gcode file. Try opening it in ncviewer.

MDF is harder to cut than pine due to all the glue in it. I’d expect MDF to produce a worse finish than the pine did.

Looking at the outline on the stock, I’m also leaning towards what Jeff said… gcode error. Looks to me like it’s running the inside of the contour, not the outside… or some issue with the CAM not using the correct bit radius or sumpn.

Post the gcode here if you want folks to help rule that out.

(Edit… well after reading the whole thread, I now wonder if it is just machine flex. Removing material 5x faster can increase loading substantially depending how it is done. You may have to change your method of speeding up the cut. Just using a deeper cut alone only goes so far. You might try using smaller step downs and increasing feed rate instead.)

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So I changed it to 2mm doc and 10mm fr.
Cut in foam and MDF.

Which says it’s deflection.
Any tips on stopping it? Or just lighter cut faster?
I did a heart at 3mm doc and 15mm fr and it’s perfect.