Force mill drill md30b repair

[David Brooks]

I recently purchased a mill drill machine in need of repair. previous owner had a problem with the start capacitor and removed it and tossed it in the garbage. now i need to know what size of capacitor to put into it to get it to work. I thought if someone had the same mill they could get the numbers off their machines capacitor. Any help would be appreciated .

 

[kylemp]

Maybe that's a good opportunity to put a 3 phase motor and vfd on it.

 

[David Brooks]

that would be cool ...but all i need is a $30 capacitor .
it would cost at least $300 for a vfd and a motor

 

[Alexander]

What size motor does it have? I have a 2hp force milling machine. Im guessing parts for that are to big for the milll drill? Have you browesed all the capacitors on the princess auto website?

 

[JohnW]

I think I have the same machine. I took the cover off my motor cap this afternoon. Here is a picture of it:

The mill has a 2HP 1PH 220V motor (using the usual Chinese rating systems). So, 150uF with a suitable voltage (minimum 220V AC 300V peak, but higher is better). The capacitance of the start caps is not all that critical. Anything in the 100-200uF range would probably work fine. Getting exactly the right cap will give you the greatest starting torque. This cap does not give a tolerance, but -20 / +80% is pretty common for that type of cap, so getting the correct value is a crap shoot, and the value probably changes over time as it ages - especially if it gets warm.

 

[David Brooks]

This is the mill I hope it is the same one that would solve my problem .

 

[JohnW]

Mine is the same basic mill-drill, but probably a bit newer - it is cream-ish colored, not green. I got is a bot a year before HOT closed. The motor has the same basic ratings, but looks physically a bit different. My motor nameplate faces the back of the mill which is up against a window. That would make it easy to look at (just go outside and look through the window), but alas, that is a south facing window, and the mill has been there for about 6 years. The motor nameplate has pretty much faded into nothing.

As long as the motor only has a single capacitor (it is a capacitor-start, not a capacitor-start and capacitor run motor), the 150uF cap should work fine.

 

[PeterT]

Not sure if this is helpful or not because the machine models tend to vary by distributer & era built, but this Grizzly mill drill looks somewhat similar. They don't reference capacitor specs in the manual but maybe if you called them?
http://www.grizzly.com/products/Drill-Mill-with-Stand-29-inch-x-8-inch-Table/G0705

 

[JohnW]

Peter, that mill lists both a start and run capacitor for the motor in the parts list. The schematic you attached shows the start capacitor as 150uF, which is the same as mine. Start capacitors drop out of the circuit once the motor has started. The run capacitor is always in the circuit and is included in many more modern motors to help improve the power factor of the motor. Improving power factor on all electrical gear has been encouraged in recent years by people like the EPA (required for an Energy-Star rating), generating utilities and power grid managers.

 

[Dabbler]

If you just want to get it running, you can just go to any motor supply place and get a start capacitor for the HP rating of your motor. Shouldn't be too costly.
In case the motor is not original, and if you want the perfect solution: Usually the faceplate on the motor is stamped, and if you can get to it the current rating can be read if checked carefully. From the current rating and rpm the correct capacitors can be calculated for start and run.

Just for completeness: I have bought a motor in the past where the guy thought it was the capacitor that was shot, and got it cheap. I checked the Cap, and it was good. If it doesn't run after replacing the capacitor, check for a broken winding near the commutator, or a broken commutator collar. (both can be fixed)