DC Drive Recommendation

[GeoBruin]

It's hard to grab pictures of the drive since it's hard mounted under the cabinet but here's my attempt. I've been cutting away some of the wood on the cabinet to access things but the control is mounted to the piece of ply along the back of the cabinet so I haven't pulled that one off yet.

I've attached several pictures of the wiring diagrams drawn by the original owner as well.

 

[GeoBruin]

And just for kicks, here's a couple drawings he did of the cabinet, hisnsystem for redirecting the drive pulley down through the head, his modification to the drill press to take 2MT tooling without use of an adapter, and a price list of all the original components for his lathe/DP workstation.

 

[great white]

I use a danfoss cycletrol 150 to drive the 3/4 hp baldor dc motor on my atlas. Does the job well, no complaints.

IIRC, it will handke up to 1 hp on 110 mains, for higher hp I believe you need to go with the 220v version.

It does use a braking resistor, so may not fit your needs/wants.

 

[strantor]

I've attached several pictures of the wiring diagrams drawn by the original owner as well.

Wow, impressive documentation! You don't see that every day.

 

[GeoBruin]

Wow, impressive documentation! You don't see that every day.

Yes, he was a pretty meticulous individual. Unfortunately, he passed away so I couldn't pick his brain when I purchased the lathe/DP so all I have are his notes. I also have receipts for literally everything involved in this project, down to the individual electronic components and fasteners.

 

[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?

 

[rabler]

Yes. Go by the motor, not the controller manual in this case. You'll want a fuse that is bigger than 5.5 amps, I'd try 7 or 8 amps. Motors can legitimately briefly peak at a higher current than the rating plate, so the fuse needs to be slightly bigger.

 

[GeoBruin]

Yes. Go by the motor, not the controller manual in this case. You'll want a fuse that is bigger than 5.5 amps, I'd try 7 or 8 amps. Motors can legitimately briefly peak at a higher current than the rating plate, so the fuse needs to be slightly bigger.

Thanks! So, another question then, I also purchased a plug-in horsepower resistor for this thing based on the name plate horsepower. However, based on the math, at 5 plus amps this thing is making more than a full horsepower. Should I up the horsepower resistor as well? And actually, the drive is only rated up through 3/4 horse...

 

[rabler]

Thanks! So, another question then, I also purchased a plug-in horsepower resistor for this thing based on the name plate horsepower. However, based on the math, at 5 plus amps this thing is making more than a full horsepower. Should I up the horsepower resistor as well? And actually, the drive is only rated up through 3/4 horse...

I would try using what the controller recommends for the motor horsepower as rated. Often the drive determines what is the best resistor more than the motor itself. I'm guessing the resistor for larger horsepower motors is spec'd as a higher watt rating and somewhat less resistance. In that case you might gain some braking speed with the resistor for the higher HP motor. Ultimately the fuse should (hopefully) protect the motor during braking as well as normal operation. (see next post)

It is important to be aware of one characteristic of DC motors when working on them especially with setting up a new controller. If the armature is supplied working voltage while the motor is spinning, but the field connection is broken for some reason, many DC motors (not all) will "run away" meaning the RPM will increase above rated RPM and continue climbing. In this case you need to cut power to the motor.

 

[rabler]

Looking at the linked controller manual, it looks like the "plug in horsepower resistor" is not a braking resistor but rather a way of calibrating the controller to motor size. Definitely use the one for your motor's rated HP and voltage. Braking is provided via the "Forward-Brake-Reverse Switch Kit (Part No. 9860)"