On Thursday 26 May 2016 02:16:22 Gregg Eshelman wrote: > Is there a sub $100 PWM DC motor power supply suitable for treadmill > motors, with a rheostat control for manual speed setting plus a CNC > control input, with a switch connection to select between them?
Almost Greg but not in your budget. Empire up in Wisc makes a controller that can handle motors with peak surges to 25 amps, but its fussy about its analog drive, very easily blown as the rheostat is at line voltage potential. I blew up 2 of them before I gave up and bought one of Jon's (Pico Systems) pwm servo amplifiers and built a separate 107 volt psu out of the 2kwa tranny from a phase linear dual 750 watt audio amp. Thats worked well enough, although Jon & I found it needed bigger toroids in the fwd circuit for my use, which I had on the shelf so no biggie. This has its own built in current limiter that has worked very well several times while one on them has been running the 1HP motor of my G0704. I think the best I can say of that driver is that if its properly setup, its bulletproof. Rated at 160 volts and 20 amps max, very linear response in comparison to the Empire driver, you won't need to do any linearity comp at all. Its one of those things that Just Works(TM) for me. > I > tried one of those wee little $20 Chinese ones with a 1+ HP, 110+ volt > treadmill motor. Almost worked, once I got wires to stay connected in > the CNC/manual speed control wire I made from a CD-ROM audio cable. > When you apply plenty of solder and shrink tube, one tends to expect > the wire to *stay connected*. I'm not at all a soldering newb. The > silly thing doesn't have a fail-OFF mode if there's not two pins > jumpered on the three pin header for selecting manual or PWM control > input. It tries to go full blast. Well, connected to this motor that > turns the little 5 amp fuse into a flashbulb, then it quits. So > yesterday I checked my switch wiring again and installed a fuse holder > to use 7 amp ceramic slow blow fuses, soldered the wires to the ends > of a blown 5A fuse. All hooked up and it ran great. I was able to run > the speed up and down with the knob just fine. So I carefully tucked > the wiring all into the box on the back of the 9x20 headstock, > installed the screws then plugged in the power cord and flipped the > power switch. The spindle lurched a little and stopped. > @#%@#%@#$^#$$^$@^!!!!! Broken wire again! No F-in-way. Could NOT be, > not after I'd taken that cable all apart and made ##%^^ certain it > could not fail again. I was right, continuity good on all three wires. > I checked all connections again, PERFECT. Exactly as they were before > I buttoned it up. Put in another fuse and same thing, insta-pop of the > fuse. Soooo, it does look like the output rating of that little power > supply is somewhat overly optimistic, even after I made certain all > the components touching the heat sink were actually flat against it, > with compound added, and the screws holding it all together were > tight. Must have blown some component on it. Oh well, it was cheap, > and unlike the 1995 vintage controller from the treadmill the motor > came from it would run the motor smoothly from nothing up to the point > the 5A fuse decided it self-identified as an incandescent lightbulb. > The treadmill controller would not send power to the motor until the > knob was turned up to 50%, yikes! > then it would start it at that fast speed. > It could be slowed down after starting, but turning it down too > quickly would make it cut power to the motor. Completely unsuitable > for a lathe. Got a few $ for it on eBay. On the good side I do have > the drive belt connecting the leadscrew stepper to that ball screw. I > went with the XL style since I already had a 22 tooth pulley with 3/8" > bore. I got a super deal on a 44 tooth XL pulley with 10mm bore on > jet.com Only had to drill and tap a couple of set screw holes. Yes, I > am mixing metric and SAE with wild abandon. Scrounging and intensive > price shopping like mad. The lathe only cost me $50 in practically new > condition, and I've sold $75 in parts I've removed from it. :) > ---------------------------------------------------------------------- >-------- Mobile security can be enabling, not merely restricting. > Employees who bring their own devices (BYOD) to work are irked by the > imposition of MDM restrictions. Mobile Device Manager Plus allows you > to control only the apps on BYO-devices by containerizing them, > leaving personal data untouched! > https://ad.doubleclick.net/ddm/clk/304595813;131938128;j > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Mobile security can be enabling, not merely restricting. Employees who bring their own devices (BYOD) to work are irked by the imposition of MDM restrictions. Mobile Device Manager Plus allows you to control only the apps on BYO-devices by containerizing them, leaving personal data untouched! https://ad.doubleclick.net/ddm/clk/304595813;131938128;j _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
