Build Thread- Run of 120VDC 20 amp stepper motor drivers for Bridgeport series I and 2 mills

[leop]

Hi everyone.

Well after lots of looking I can’t seam to find decent and affordable stepper drivers for my Bridgeport series I and II mill retrofits.

Gecko’s are just short of the voltage and current requirements for the stock Bridgeport motors and Larkin is not currently making more of his Cobra drives.

Assuming none of you know of any one else with a good driver at a fair price I am going to build six for myself. Does anyone else need any since I am doing a run?

My stepper drivers run 120V DC (no need for a transformer on the supply) and up to 20 amps. They will do ½ step, ¼ step and full step. They will cut current in half after 10 ms of hold. Current control is currently chopper based but I can do PWM if enough people are interested. If you make limit switch connections to the controller it will allow you to jog off of the limit switch but sound an alarm if you try to jog past them.

Double sided board, manual fuse protection, and if I can get a good deal on heat sinks I’ll include those as well, otherwise you can machine one of your own.

I’ll announce the final price when I know how many people are interested but it should be around $350 a drive, not more then $400 for sure. Lead time is looking like three weeks. Not looking to make mucho $$bucks here, just willing to do some extras if people need them.

Keep in mind that because the driver can handle 120V DC (260 VDC peek) you can build a much cheaper and smaller power supply then if you were to try and run at 50 VDC.

By the way I plan to do a unipolar interface to the steppers, but I noticed that you can wire the stepper motors on the Bridgeport’s as bipolar motors as well. Has anyone tried that? If so how did it work out?