Jagged edges on portions of cut?

[kazlx]

I'm having an issue lately with my table and I can't figure it out. I thought I had a pic to post, but I guess I'll have to post later. It's really frustrating because it's not constant. I am using CandCNC electronics with the Mach3 controller. The torch head almost seems to stutter or vibrate in sections creating saw-like teeth. I'm not sure if it has something to do with the THC (using the Ohmic touch) or something else. I haven't changed the settings beyond voltages and feeds for different materials, yet, this just started happening. I have tried new consumables and it doesn't help. No idea what else it could be.

I can take a pic of 14g CRS I was cutting the other day when I get home.

[Stout]

Rack and pinion drives?

[kazlx]

Yes, its the Precision Plasma LCD kit.

[grindergary]

I just had the same thing. One of the pinion gears was not meshing properly in the rack.

I loosened the drive assembly and re tightened. Solved my problem .

Gary

[Gamelord]

Yup, had that problem as well but on my Torchmate table. One of the gears was actually a little loose on the shaft. The "saw cut" was only when the gantry was running fast and changing directions, the gantry would shake just enough to jiggle the torch for about 3/4" and give the "saw cut" edge you are talking about.

Double and triple check all the gears on your system and make sure they are seating properly and everything is tight.

The only other thing that could be causing it is "Slat Shake" where the slats in your table are shaking when your gantry moves.

[kazlx]

It's definitely not the slats shaking, because it was happening when I was cutting a half sheet of 3/8", so there was a good amount of weight on the table. I'll double check the gears when I get a chance. It looks to me as if it's almost the torch height control cycling up and down too fast. I noticed that if I put a little downward pressure on the torch carriage, it would stop.

[abmagrum]

RUNNING too fast will cause that also, check youre tension. and slow speed should fix the problem.
but if I remember right its not torch height. but travel speed. I think they suggest cutting back 20-30%

[jimcolt]

Program a 4" rectangle, cut it at the plasma's book specs. Inspect the 4 sides carefully, if you notice the jaggedness on opposite sides then look for a motion control issue (loose gears, binding, loose motor mount, loose belt, etc.) on the axis that coincides with the cut issues. If the cut looks good on all 4 sides, cut the same rectangle with a 45 degree rotation on it. If you see jagged edges on the rotated rectangle it could very well be drive tuning issues.....adjusting accelerations and gain settings may be necessary. Do these cut tests with the height control "off" at a fixed height.

Jim Colt

[I Lean]

I've had my torch height control "bounce" when cutting 3/8" before. I solved it by reducing the THC rate...you won't need very fast response anyway, with slower feed speeds. The varying height causes weird edge angles, but it's not a very pronounced "saw tooth", at least not on the top surface.

[kazlx]

I got it figured out. When every suggested the gears, I double checked everything. Turns out the drive gear was ever so slightly loose on the motor, so the X and the A weren't syncing up and and the carriage was wobbling a bit.

Thanks!