Judder when cutting large curves

I have an X-Carve 1000 and a X-Controller.
As a test I am cutting air in a large curve. When the motor is travelling in the XY plane the motion stutters and doesn’t cut the curve smoothly. It’s smooth in the X plane and smooth in the Y plane but not when it’s travelling in XY.

Is your work flow Easel - Circle - Carve or different?
Wheels too tight / belts too tight?

What Haldor said…check your hardware. Something’s too tight.

I’m using Candle 1.7
I’ve checked the wheels and belts and adjusted slightly but I don’t think it’s a physical thing that’s causing the stutter. It’s more like a data problem.
I’ve also tried two laptops. One Lubuntu on an i5 and another Windows 10 on an i7 - both exhibit the same problem.
I produce the gcode with Fusion360.
It’s as though gcode is not instructing the steppers to produce a smooth curve. If you amplified what it’s doing I reckon it would be like a zig-zag round the curve.

Due to workflow you may have hundreds/thousands of nodes, each require a ramp up/down in speed causing the behaviour you describe.
Gcode-file long?

If behaviour is different with plain circle in Easel you have ruled out the mechanical aspect.

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I’ve slowed down the feed rate and that seems to have calmed it down a bit. I think it’s now acceptable.
Thanks all for your comments.

IMHO - if it is a node thing, it is not acceptable and a setup for increased tool wear and precision issues.
If it is a work flow issue (like above) then sorting it out will be easy.

Have you tested a plain circle designed/carved directly from Easel?

Thanks for prompting me to carry out the test. The circle movement of the X-Carve was as expected, i.e. smooth.
Having carried out the test it has dawned on me what the problem is. The curve in my drawing that makes the X-Carve stutter is not a circle or an arc but a spline so that’s why it’s got lots of gcode to do and why it struggles a bit. I’ll amend my drawing to use an arc rather than a spline.
Cheers. Good to have input into a problem.

Exactly, a circle is broken into hundreds or thousands of “points” the bit is asked to touch => the bit speed up feed rate and decelerate for each point. It also is data transfer heavy.