Kbcc 125 DC controller

So I did an amps test. Running under just the lathe load it settled around 8.5-9 amps. Under normal cutting operation about 13-16, and 25 was the highest I could make it to which was almost stalling the motor.
 
So I can see issues now...
Under no load this board would work fine.
This motor is rated to 20 amps.
Under normal cutting the motor is pulling the maximum this board is rated for, 16 amps. So, if I ran this board, I would be maxing it out all of the time...


These numbers seem really high... That's a lot of current....
 
Damn... I wonder if I'd need the 225 board instead.
 
I think if you can accept a little drop in speed with heavy loads you can still use what you have. Try the 1.5 to 2 foot resistor and see if you
can get some decent results- don't worry about the other big resistor getting hot, just make sure the heatsinked parts don't get too hot to touch and use heavy gauge wire to connect the system, that's about all you can do for now. What size lathe are you using this on?
Mark
 
It previously had a 3/4 HP motor, not 1hp. I was mistaken.
 
I did 21" of wire. Seemed to run well for the few mins I tried. I put my hand on the chuck to give it resistance. I tured the IR pot up a bit to compensate speed drop. The motor doesn't seem to be hunting for speed now. Difficult to give it a good test right now. Late, wife gets mad when I wake the boy cause his room is right over the garage. Lol.
That big resistor getting so hot freaks me out. But the SCRs don't get hot at all.
I do need to change some wiring. I used 14awg wire in the feeds to the motor. And I have proper fuses coming this week for the motor output.
I need to make an R8 arbor and another fly cutter, I'll try that this weekend with this setup and see how it goes.
Thanks for the help, mark. I don't know what I would have done. I would have spent the money and have been no further ahead and have to put the old broken motor back on.
 
Good deal Shawn, I think you zeroed in on it. You should be getting around 1.5 HP now which should be plenty for that size lathe. I'd use 12 ga wire feeds to the motor, less loss. That big resistor is part of the power supply circuit, it drops the 120 volt AC down to about 24 V so it dissipates about 2 watts and it's a 5 watt resistor so it's normal to run hot like that. I like these SCR controllers over the Mosfet (treadmill) type because they're rugged and there are no real exotic parts in them, easy to repair.
Mark
ps thanks for the plug Phil :cupcake:
 
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I coiled that 21" wire and soldered it into the plug in plugs and the hunting stopped. So, obviously a crummy connection there previously. That may actually solve some of the heat issues too.
I mounted a fan on the box lid but the kid woke up from his nap so play time was over. Lol. I'da been done this all ages ago if I had a proper amount of time to play in the shop.
But things seem to be headed in the right direction now.

The lathe is strange to me now. It's much quieter so it seems like it's not spinning as fast, but I'm sure it's faster than before. It'll take some getting used to.
The treadmill had a hall effect sensor on the back of the motor. if I knew more about electronics, I'm sure I could have rigged up a display to show rpm, buuut I'm not. So, buying a tachometer and writing it all down will have to do.
 
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