Need Help!- Paxton/Patterson w/G251's and Mach3

[jonboyusmc]

I just recently picked up a P/P lathe and a mill. Microkinetics was no help, so I decided to gut the lathe. I've put a pair of g251's in, and kept the original 40v power supply. I've got it up and running with Mach3, but it's dog slow (about 1 1/2 minutes to move 1/4") and you could fry an egg on the motors. I can't seem to find any part numbers on the motors. They are Oriental Motor brand. Does anyone know what these motors are, or where to find a part # on them? I'm running the g251's without any resistor, so I am sure that's where the heat is coming from. Can anyone shed some light on this, or at least point me in the right direction. Thanks in advance.

[Pplug]

Originally Posted by jonboyusmc I just recently picked up a P/P lathe and a mill. Microkinetics was no help, so I decided to gut the lathe. I've put a pair of g251's in, and kept the original 40v power supply. I've got it up and running with Mach3, but it's dog slow (about 1 1/2 minutes to move 1/4") and you could fry an egg on the motors. I can't seem to find any part numbers on the motors. They are Oriental Motor brand. Does anyone know what these motors are, or where to find a part # on them? I'm running the g251's without any resistor, so I am sure that's where the heat is coming from. Can anyone shed some light on this, or at least point me in the right direction. Thanks in advance.

Those sound like vexta stepper motors. I would replace them with motors you know the specs on. Also, they might be miswired unipolar motors that are being run with too much current. You better get some current limiting resistors on those babies, pronto! You don't need the most powerful motors for that machine. I would check out eBay for replacements.

Can you send a picture of the machine, I think I might have used one like it when I taught at my old school.

[762x51]

As Pplug said, they are probably the old round case Oriental Motor Vexta series PH268 NEMA23 size motors with a double ended shaft.

There were several models rated 83.3 or 125 Oz In torque and "normally" you'll find a decal on the end of the motor listing the actual part number as PH268-xx or PH268-xx.xx. If you Google that part number you'll find reference data for the one you have.

I've attached a sheet for the newer style motor but the wiring diagrams and wire colors should be the same as the older motors.

[jonboyusmc]

Thanks for the replies. It looks like these are rated at 1.5 amp/phase. I put some 1.8k ohm resistors in the g251's and it ran alot better. going to stop and get some 1.5k resistors today, and I should be all set. I will definitely be looking for a faster stepper in the future. I can only get 10 IPM in the X axis, before it starts losing steps from trying to move to fast. I can't figure out why I can jog in Mach3 just fine, but when I try to run a program in auto, it goes deathly slow. I can hear it ticking off every step. I verified with a dial indicator that it's movement was correct. .100 on the DRO was .100 on the indicator, so I am assuming that I have the motors set up right.

[Pplug]

Check the acceleration settings in the motor tuning and put in a lower number try 10 and see what happens when you run a program.

[jonboyusmc]

Pplug, it's still doing the same thing. I ended up trying it on my daughter's laptop that has a parallel port. I got it up and running programs in about 20 minutes. I did a complete re-install on the PC, and it didn't change. If I give it a G0 z-.5 in MDI, it will make a rapid move for about .050, then go back to the creep feed. I'm going to fdisk the damn thing and do a re-install of windows. I'm taking the sound card, ethernet card and modem out. It's going to strictly run AutoCAD, MasterCAM, and MACH3. My kids had this thing on the internet for years, hard telling what all is running in the background.

[Pplug]

Sounds like a good last resort. What type and speed does your computer have? Does Mach hold a steady frequency when you run a program?

[jonboyusmc]

I got it!!!! I pulled the ethernet card and sound card, and was just getting ready to format the hard drive. I thought I'd give it another shot, and she took off and ran like a champ!!! I was tickled beyond words. I wrote 4 different programs and it worked perfect. Damn legacy sound cards have always been a source of conflict. They're not really a concern now since most sound is built into the motherboard. This one had a Creative Sound blaster 16 in an ISA slot. I bet it was sharing an IRQ with the parallel port or something like that. Now to get my home switches set up and the spindle sensor reading right and I'll be golden.

[Pplug]

Nice! Can't wait to se a video of it moving! Congrats! Make sure you follow the Mach optimization sheet to keep the comp rock solid.