Thc 300 Jerks Or Does Not Work?

[pointcloud]

Anybody got a thc 300 working CONSISTANTLY?
If so how did you adjust the volts?

Attempted to adjust by following the directions with pots in the middle range, not happening for me.

Mine does this >If you turn the pots the maximum counter clockwise it will dive into the table. If I start out that way it will jump up off the table about 2 inches and stop.

If I ever get it close to set it will jerk up and down as if it were trying to settle in, but never does...

It either jerks and makes a horriable cut or dives or raises to high to cut.

Really need some questions answered.

machine is a miller 2050.. tips are 35 amp, extended electrode machine torch with floating head. best speed with this problem is 60 but have tried as low as 50 and as high as 90. I am cutting 1/8" cold roll. Air is filtered by a 2 stage dryer at the tank and another just before the torch, it's 15 hp so plenty dry clean of air.

Also did you get your screen set for mach 3 thc 300 to work? I have not gotten mine to work. It's missing backgrounds and buttons on a few screens...

Help get this running please.

[kylemp]

Turn your Z acceleration way down..

[pointcloud]

bout 3 years and some months late, but I suppose that would have slowed the jerking down. But not stop it.

Thanks for your insight. have a great day..

[kylemp]

i know, i just figured in case someone else has issues.. that should stop the jerking because its reacting too fast.. unless you figured out what it was and it was something else..

[pointcloud]

Well there were a few issues.

angle velosity slowed
a miller torch noisy
Z max speed set slow but still have G0 moves
put 2 risistors on my drives and a cap on my encoder
After that it worked great

[Torchhead]

Turn your Z acceleration way down..

Actually acceleration in motor tuning has no effect for THC moves. It is not used during THC moves, only during normal moves like the lift at the end (anything called from G-code).

The setting that will effect that is the THC RATE. It sets the percentage of THC velocity based on the max velocity set in motor tuning for the Z axis. Depending on the courseness of the Z drive (resolution) settings too aggressive in THC Rate can cause "head bounce" and other effects from a condition called "overshoot" where the torch cannot move in small enough increments to balance out the target volts (set by the knobs) with the actual torch volts.

If the THC rate is too high for the motor and drive type, it can force the motor to stall. The THC will see that the voltage is wrong and try again and the motor will stall again , (etc, etc). The telltale sign is the DRO for Z gets out of sync with where the torch really is. It obvious at the end of a cut and the lift is the wrong distance off the metal.

TOM Caudle
www.CandCNC.com

[Pandinus]

It would be nice if the THC rate had its own tunable acceleration to prevent motor stall, and overshoot... because it "should" only be small movements anyways UNLESS you are CUTTING CORRUGATED materials... the acceleration can be higher than for a longer rapid move, while the deceleration could be almost instant for THC moves... even the ability to accelerate via motor tuning while decelerating instantly would be better than stalling.

[Torchhead]

It would be nice if the THC rate had its own tunable acceleration to prevent motor stall, and overshoot... because it "should" only be small movements anyways UNLESS you are CUTTING CORRUGATED materials... the acceleration can be higher than for a longer rapid move, while the deceleration could be almost instant for THC moves... even the ability to accelerate via motor tuning while decelerating instantly would be better than stalling.

That assumes motor acceleration and velocity have little or no interaction. Truth is you mess with one and you effect the other. The stall point is a combination of the two. The results with acceleration turned down and velocity high would be the same: The lift would not be fast enough to prevent the collision with the rapidly changing height. It's largely up to the dynamics of the Z drive to allow faster motion. You might be able to push the velocity up after the torch reaches speed in one direction but even cutting a sharp incline does not mean the torch is alway moving in one direction only and each move is a discreet start and stop. You would still have some down moves depending on the arc gap voltage so you have to stop and start in the other direction.

In our DTHC controls there are other tunable parameters that effect the THC response curve (actually a form of servo). The Span Voltage (voltage window where the THC does not adjust until it exceeds the set points) and the Analog sample rate are a couple.

You can cut corrugated if you slow down XY. The cut won't be as pretty and you may need to run with a higher target (preset) voltage but it beats doing it by hand (maybe). We ways cut the thinner stuff with a hand held electric nibbler. To me it's like cutting drywall with a CNC router. Perhaps if you had a product that used corrugated mateial the cutting out shapes with CNC plasma makes sense.

TOM caudle
www.candcnc/com

[Khalid]

TOM i have sent you email for quotation and help...