Plasma/Mesa Guru's

John,

I wonder if the version of THC that you sent was maybe an incomplete version or in the beginning stages.

I finally got everything hooked up to my table last night. It seems that none of the Tolerance adjustments on the right side of the screen do anything. I was figuring that the volts tolerance would give me some dead band area, and it doesn't. The Z axis is constantly fluttering. I have a double shaft stepper on my Z and I put a piece of tape on it like a flag so I could watch the Z move. As it is cutting the Z motor is sweeping that flag just a tiny amount back and forth constantly.

So, my question now is, How can I fix it so the adjustments work?

I had some time to play with the plasma table again this weekend. I really wanted to get the controls on the right side of the screen working, but I couldn't seem to get that figured out... But, I was able to add some dead band by adding "setp thc.voltage-tol 1" to the plasma.hal file. Once I did that I could turn the correction-vel up to a level where the thc was actually doing a useful job. Before if I turned that up a little it was like the plasma torch thought it was a sewing machine. Just going up and down. I bent a piece of scrap twelve gauge so I had about an inch of rise over five inches and cut that out and the torch followed perfectly.

Another thing I am noticing, I had never been able to run my machine so fast off the parallel port. The drives must really be getting a much more refined signal from the mesa cards, this machine can really fly now. I still haven't tried to retune the table to see what I can get for rapids, but I wouldn't be suprised if it is 30% faster.

I will keep learning as time permits me. Does anyone know if there has already been a code written for an auto coordinate system rotate? If not I will be writing that. So If I throw a piece of heavy plate on the table I can just do an edge check in a couple of locations and have the gcode rotate to match it. My friend uses this feature quite often on his burny controller and it is pretty handy.

John,

I was just re reading your last post about the voltage tolerance pin int he comp. If I put that it there would that make it so that i could change that value from the spinbox on the screen.
"pin in float voltage_tol"

Then remove the voltage_tol 1 that I had just added to the plasma.hal

Well I still haven't taken the time to figure out how to add an automatic coordinate rotate... I have been too busy playing. I added a torch on/off to my joypad. Then I decided to have a little fun seeing how fast the machine can get. I was really, really surprised. It just kept going faster... I finally decided to just quit when I hit 1800ipm on both the x and y.

Before I added the Mesa cards, I was considering buying a complete servo setup for the machine. It is a 6' X 10' table and all though it didn't take all day to go from end to end at 450ipm it still seemed extra slow. Any faster than 500 with the parallel port and it was unreliable.

Anywho, just thought I was share the information about the performance increase. I was just amazed.

I was shocked it would go that fast myself. I think it will even go faster, I just stopped trying as it was way over my expectations.

I am running Compumotor S6 drives @ 3amps/phase to 640oz Nema 34's running a 3:1 gear reduction to the rack and pinion. I don't recall pinion count or rack pitch, but it around a 1" pinion.

I had originally planned to add air cylinders to tighten the pinion to the rack. The benefit would be that when the machine is off I would have the cylinders retracted so I could just push the gantry out of the way. But I am not sure when I will get to doing that upgrade. I really only get to play with the table a couple of days a month at the moment. Next on the list will be an air scribe attachment for making center marks for drilling.

what do I need to do to get the touch down speed increased a little bit? At the moment it is really slow and takes about 7 seconds to touch off the part. Doesn't sound like much, but it seems like an eternity when you are watching it.