Really weird improper toolpath following.. even seems to show in mach3!

So i cut some parts, quickly, and the inside of the letter "B" didn't properly follow the contour. The weird part is that it was consistent to the point that it seemed like it was designed that way.


I went back to aspire to check it out, and everything looks normal, and the aspire simulation looks great.


When I pull it into mach3 though, look at the path it takes. One weird thing is that if I run through the toolpath slowly, it doesn't do this. Notice when I run in reverse (second half of this short video), the same problem occurs but in a different spot:


2016-10-19_1251 - Volte6's library


Any idea why this is occuring? It shows up in the part as well (attached):


Note - you can see the proper toolpath right next to the flaw, because later I did a pass with a v-bit to bevel the edge without issue.

EDIT: Here is another short video of it running at a slow speed - no strange behavior! 2016-10-19_1305 - Volte6's library

Hi Dylan,

This is almost certainly an issue caused by the CV settings in Mach3, which basically tell the machine how much it's allowed to "blend" vector moves to achieve fluid motion. It's an old post, but here is some good information about CV, why it exists, and how to tweak it:

New CV features

For what you are doing, I would set the CV distance tolerance lower, set the "stop CV on angles" to a lower number, or both (this is under the config->general config menu). Since Mach calculates the toolpaths upon loading your G-code, you should be able to see the effects by re-loading your G-code with the new settings.

If you need additional support, feel free to give us a call and we can talk through it.

Best regards,

Ahren
CNCRouterParts

Thanks ahren, AAA support as usual!

It is possible that the motor speed and acceleration parameter setting could also be improved. This would need some experiment.

Cheers
Roger

Yes, acceleration and CV settings are very much related to each other.