DC controller recommendation for drill press and Lathe

[GeoBruin]

I recently purchased an old Taiwanese Jet lathe on craigslist and it came with a Rockwell 15" drill press mounted on the bench next to it. Both were wired to an 80's era Sabina DC controller with a selector switch to choose either the lathe or the DP to run. It's quite an impressive setup but I'd like to separate the DP from the lathe, each with their own controllers. I'd also like to order modern controllers with Nema 1 enclosures rather than the very large controller board I currently have with all the components exposed.

I went to purchase KB Controls KBMD-240D controllers with the appropriate horsepower resistors for both but I just heard from the seller than they're backordered and have been for almost a year. I'd like to order comparable controllers and I'm looking for other options, especially from those of you who have used them. Here's what I need to run:

1 (Drill Press): Baldor 1/2 Horsepower 180 volt DC shunt motor
1 (Lathe): Baldor 1-1/2 Horsepower 180 volt DC shunt motor

I need variable speed on both but I don't necessarily need reverse on the DP unless someone has a good reason why I might. The lathe has a threaded spindle so I probably don't need reverse on that one either.

Thanks in advance for the help.

 

[GeoBruin]

Quick update. I found another model by KB controls, the KBWM 240, which is rated up through 3/4 hp. It doesn't have the option to add a FBR switch but again, that probably won't be an issue for the drill press. Anyway, I ordered it so assuming it works, I should be good to go on the DP. Still looking for something for the lathe however.

A little research shows the Sabina drives were actually really quality stuff and they were retrofitted onto a lot of Monarch 10ee lathes, so I'm tempted to try and get it running and just use it but I'd have to go back to EE school to figure it out.

Anyone have experience with Dart Controls?

 

[American Locomotive]

I can't comment on Dart controls, but I've always heard positive things about KB Controls.

FWIW: There's quite a few new, new-old-stock, and used KBMD-240D's on ebay...

 

[oldmachinenut]

I have KBMG 212 controllers on my machines. They work very well and are easily configurable.

 

[oldmachinenut]

https://www.kbelectronics.com/data_sheets/kbmg212d.pdf

 

[oldmachinenut]

https://www.kb-controls.com/product.sc?productId=47

 

[tool_scrounge]

Dart is quality stuff. You can buy the KBMD-240D on eBay.

 

[GeoBruin]

Good thought looking at ebay. Every seller has like a million of the plug-in resistors so I can pick one up from there and search eBay for the controller.

 

[GeoBruin]

Okay, I picked up this KB controls KBWM- 240 controller for the drill press. It doesn't ship with an armature fuse since they don't know how big your motor is so I need to pick one up. I'm looking at the chart in the manual and it recommends a 4 amp fuse for a 1/2 hp motor and assumes the motor is drawing 2.5 amps. But, the tag on my motor, despite saying 1/2 hp, also says 5.5 amps at 180 volts.

I'm obviously new to DC motors so maybe there's something I don't understand, but at full current, won't my motor blow a 4 amp fuse?

 

[American Locomotive]

That's a little beyond me. I'd think you'd need to contact KB about that one.

 

[dogdog]

at full current, is it the armature current plus the field winding current ? or just the field winding current that is 5.5 AMP ? There seems to be 2 fuses , AC line fuse is 4AMP and recommended DC armature fuse is 2.5Amp. according to your pic.

 

[GeoBruin]

at full current, is it the armature current plus the field winding current ? or just the field winding current that is 5.5 AMP ? There seems to be 2 fuses , AC line fuse is 4AMP and recommended DC armature fuse is 2.5Amp. according to your pic.

Yes, there is a 5 amp AC line fuse installed from the factory. And I see that a 2.5 amp fuse is called for based on a 180 volt, 1/2 HP motor. The problem is, the nameplate says 5.5 amps right on it. Like I think the poster above might have been alluding to, that could have something to do with total current vs just the armature but I don't understand shunt motors enough to know better.

 

[GeoBruin]

Okay, I'm back to ask for some more help. The drill press is done and working great. So I started to tackle the lathe. I was able to find a KB Controls KBMD 240D controller on eBay. It showed up in great shape and all I had to do was pop in the appropriate horsepower resistor for my motor rating.

I cracked open the motor to wire it and to my surprise there were six wires coming out of the motor instead of the four I had on the drill press motor. The wires are labeled A1, A2, F1, F2, J and J.

I have a much better understanding of shunt motors after all the reading I did for the drill press project but I went back trying to figure out what the extra wires were and it turns out there was a whole lot more reading to do. My first thought was that this could be a compound DC motor. Meaning it has both a shunt winding and a series winding. That would explain an extra set of wires, however based on the convention I can see, they would have been labelled S1 and S2.

The other thing I ran across is that it looks like some motors have a built-in thermistor to monitor the temperature of the motor. It could be that these two wires are just available for tracking temperature and potentially cutting out the motor if the temperature reaches some threshold. It also turns out the J may be related to the J type temperature wire that is used for such a purpose.

In any case, I got impatient and wired the Armature and field leads to my controller the way I otherwise would have and just left the two J wires disconnected with wire nuts. I flip the switch and almost to my surprise, the motor started spinning. The speed control knob works perfectly and everything seems to be running great.

I almost started to celebrate, but in the back of my mind, I can't keep from wondering if I really do have a compound motor and somehow I'm spinning the motor using only the Armature and shunt windings and not using the series windings. I don't even know if that's possible, or if the motor would spin at all in such a scenario, but I would love it if somebody with more knowledge than me could confirm or assuage my suspicions.

Sorry for the long post.

 

[dutchgray]

I would bet its a thermistor if the labelling of wires meets the convention for that.
To check connect those wires to an ohm meter and the measured value will change with the temperature of the motor, if its a winding it won't change.
I would probably test with the motor cold and then test again after running it under moderate load for say 20 minutes, it will have warmed up by then.

 

[GeoBruin]

Great idea! I'll do that.

 

[American Locomotive]

Internet seems to suggest that Baldor uses "J" for thermostat or overheat protection wires.