Jerky motion

[Matty Zee]

Hi,

I have just got my diy router build finished and have been trying it out with Mach3 and some toolpaths created by the demo version of Vectrics VCarvePro.
When cutting an oval shape, the movement seems jerky with a lot of accelerating and decelerating for each line of g-code. I haven't tried cutting anything yet so i'm not sure how smooth the cut will be but it seems that it will take a lot longer than it should because of all the decelerating.
Is this being caused by the Grex or Mach 3 or the GCode file? What can i do to improve it?

Cheers
matt

[Clockwork]

I'm not sure how Vcarve generates G-Code.

Most programs generate elipses with a ton of tiny arcs - all different. Since velocity is actually a angular function it will tend to produce a perceivable difference in speed as it moves from one arc to the next.

Your code is probably OK

Give it a shot on some scrap wood.

[ger21]

Trying using CV mode. It's in general config, or program G64.

[Matty Zee]

Thanks Clockwork, i'll have a look at the G-code, it seemed to me at the time it was more like short (5-10mm) straight segments.

ger21, i did have CV mode set which i guess is why i'm a bit disappointed at the motion... What is your motion like? Do you have any links to a video of your machine cutting?

Cheers
matt

[Matty Zee]

This is how the cut came out. Where each line is is the short movements it makes. I had CV on and the g-code seems to be short line segments. Is this normal? has anyone else cut this same demo from VCarvePro??

[LeeWay]

I know in Turbocad, I can adjust settings for quality on things like this. I can tell it how many facets or short lines such an arc should have. The higher the settings, the more ram is needed. V-carve may have such a feature.

[ger21]

Make sure that all the CV options are turned off when using CV mode, both on the settings page and in the config screen. I don't have a G100 or even a running machine right now, so not sure exactly what the problem is.

[Monte]

Originally Posted by Matty Zee Thanks Clockwork, i'll have a look at the G-code, it seemed to me at the time it was more like short (5-10mm) straight segments. ger21, i did have CV mode set which i guess is why i'm a bit disappointed at the motion... What is your motion like? Do you have any links to a video of your machine cutting? Cheers matt

Can you post a bit of the code? If it looks like 5-10mm straight segments then it doesn't seem like it's going to get any better than you got.

Monte

[Oxyd]

I'd like to revive this old post. The problem is the same: when engraving a relief, which results in many Z axis movement, i get jerky motions as if the mach would stop on each code line. But here's the funny part, i can't understand: i know WHEN it happens, but don't know WHY and WHAT causes it. I have CV motion mode and all other options set properly. PC passes the driver test and so on...

Here's how it happens: when i run program it runs smoothly, no jerking or other weird behavior - Z changes smoothly while X moves at almost constant speed. When i stop the program and resume it with "run from here" option, thats when it starts making all those jerky motions. Anyone had anything mysterious?

Haven't tried to restart the mach and run program straight from that last line or reinstall mach yet, gonna do it next time to see what happens.

[Matty Zee]

I probably should have posted an update on my problem back in 2008 but it turned ut to be the fault of the Grex G100, or more probably the plugin controlling the G100. I ditched the G100 and used the good ol' parallel port and everything was sweet from then on.
Sorry, Oxyd, I can't shed any light on your problem. I haven't experienced anything like that.