ESAB Ultrarex UXD-P 2500 retrofit with Linuxcnc and Proma THC

Hi, i have the same esab plasmacutter to retrofit. I ask you why do you change the z servo motor with a stepper?

Z axis has a DC motor with simple feedback, not a usable servo motor.

In this case you use the computer paralel port to command the z stepper driver and 6i25 to command the mesa 7i77? The control panel from esab is working now or is just for design? You assign all the key?

Can I use a doughter card from mesa to comand the z stepper motor?

alexandrub wrote: In this case you use the computer paralel port to command the z stepper driver and 6i25 to command the mesa 7i77?

Yes.

alexandrub wrote: The control panel from esab is working now or is just for design? You assign all the key?

The client was not interested in using the control panel at all, i was since i already have 2 of 7i73 boards. He won !

alexandrub wrote: Can I use a doughter card from mesa to comand the z stepper motor?

You can use the other port on the 6i25 to drive the stepper, but you would need to flash the 6i25 with different firmware. You should use a BOB to protect the 6i25, just in case.

alexandrub wrote: Can I use a doughter card from mesa to comand the z stepper motor?

You can use the other port on the 6i25 to drive the stepper, but you would need to flash the 6i25 with different firmware. You should use a BOB to protect the 6i25, just in case.[/quote]

What is a bob? Can you give me an model?

BOB = break out board
They cost from 7 to 40$.

If it was possible to add an encoder to the Lifter mechanism, you might be able to use the 7i77 or a Linuxcnc PID component to control the lifter. You need position feedback so you can set pierce height and starting cut height positions.

From your experience, if i use a stepper, what is the minim torq i need to use for lift z axis? I need closed loop ?
Can you tell me what breakoutboard do you use for retrofit the esab plasmacuter?

thefabricator03 shared a spreadsheet that could work this out for you recently. I used a very unscientific approach and used a 269 oz/inch NEMA 23 stepper on a 5mm pitch ball screw becasue I had one on hand. I think Tommy uses NEMA 17 motors.

You don't need a closed loop stepper motor. Any error from missed steps will be corrected on the next touch off.
Because you are using a 7i77 which supports 6 servo drives, you might also look at using a small servo motor which is probably going to give you better velocities and accelerations which is desirable for plasma....

Regarding breakout boards, thats not my forte, so I'll let someone else answer but there are heaps on ebay.

As Rod said, you can add an encoder to the existing DC motor and use a servo drive for Z axis.
On that machine i just piggy-backed a Nema23 stpper on top of the existing DC motor, so they are both mounted there.