I bought a used floor mount Shop Fox radial drill press. Guy said the motor was burnt out. Press is still fairly new so for $100 I figured what the heck. He stated the drill had no torque and could be stopped by hand. He had the head already disassembled so I have no way of knowing if it was a belt slip issue or the motor. The issue is his version of troubleshooting was to cut the capacitor off, not test it and the lose it. I tested continuity on the windings and they all check out. The centrifugal switch moves freely. Can a bad capacitor result in no running torque or is it just for starting? I suppose even if I had to spring for a new motor I think I got a decent deal. I attached a pic of the only markings on the motor.
Shop Fox drill press motor
- Thread starter rwhite
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SidecarFlip
Minister of Fire
That is definitely a possibility. I think everything on the motor checks out?. I have 3.4 ohms across the main windings and 9.3 across the capacitor windings. Motor turns freely. There is also a good possibility that it's just a cheap motor. The machine is probably a year or two old. I might have even been able to finagle a warranty if the guy hadn't lost the capacitor.
SidecarFlip
Minister of Fire
I'd say that is the most probable answer. Most likely a 'one hung loe' motor. Get yourself a quality Marathon or Lincoln motor and be happy.
Well apparently I forgot to grab the chuck key when I left so the guy messaged me. Said he'd look for the old capacitor. I looked closely at the pulleys and there is definitely evidence of belts slipping. If nothing else I will try a cheap fix and get a new capacitor before buying a new motor. Although I will probably end up there anyway. I'll just see what I can do before I spring $100 for a new motor.
SidecarFlip
Minister of Fire
I'm sure, at some point, you will 'let the smoke out' and take my word for it, rice paper winding insulation reeks. You can always tell a Chineseum motor by the smell when it roasts.
I've roasted a few in my day. They stink. Usually don't pop a breaker, just slow down and smoke.
I've roasted a few in my day. They stink. Usually don't pop a breaker, just slow down and smoke.
Years ago when Woodworkers Supply was in business they sold Reliant brand Taiwanese power tools. They were knockoffs of US equipment, usually okay quality but they were infamous for crappy motors. They had a good guarantee and if the motor went, the guys in the store usually just took one off a floor model and handed it to the customer. They had lots of dead equipment sitting in the back room minus motors.
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SidecarFlip
Minister of Fire
Something about Chinesium motors that they have no staying power....lol Like Grizzly stuff in the ads say'... Now with American made motors... Guess Balolia knows........
Maybe someone can answer the question regarding motor torque. Should I be able to stop a 1/2hp motor by hand? Here are the torque specs:
650 rpms=4.0 ftlbs torque. I cannot stop it.
950 rpms=2.76 ftlbs. Takes all i got but it can be stopped.
Past 950 rpms (1610, 2230, 2920) I can stop it.
I found a capacitor in my shop and wired it up. Motor seems to run fine. I just dont know how much power a 1/2hp should have.
650 rpms=4.0 ftlbs torque. I cannot stop it.
950 rpms=2.76 ftlbs. Takes all i got but it can be stopped.
Past 950 rpms (1610, 2230, 2920) I can stop it.
I found a capacitor in my shop and wired it up. Motor seems to run fine. I just dont know how much power a 1/2hp should have.
SidecarFlip
Minister of Fire
if you can stop rotation on a 1/2 horse motor without removing your epidermis, it's junk.
hmmm i always thought a drill press put out more torque than that.. it sure feels like it when that plate slips out of your hand and continually wacks you... The upper speeds past 950 has no torque left its just speed so ya you would be able to stall it out or slip the belt..
I have some 1/2 horse motors on bench grinders and such and i can stall them out my hand
I have some 1/2 horse motors on bench grinders and such and i can stall them out my hand
I would have thought so as well. The formula is (5252 x hp)/rpm. That's why I'm trying to find something definitive as the the power it should have. Realizing that the motor is probably not high quality but if it's working I hate to buy another to get the same results. More than anything I want to understand the why. What does a person test to see if any motor regardless of country of origin is bad? I guess I'm just not satisfied with "its Chinese so its bad" Here is what I have tested and how I understand it works. The motor has 2 sets of windings, run and start. It gets a jump start from the capacitor windings which then disengage via a centrifugal clutch.
There is continuity through both windings. I removed the start capacitor, no start just hum. I can pull start it with capacitor removed. With capacitor removed it is very easy to stall. I'm guessing that is because it gets to a speed that the clutch engages and it cant restart on it's own. Once it's running the clutch must be disengaged because there is no longer continuity across the capacitor wires. I put a clamp on ammeter and it's around .2 amps running with no load.
Correction...the amp reading was around 4.9.
I went ahead and test ran it. At the lowest rpm I am able to drill 1.5" holes in a 4x4 to 3" deep with a spade bit. I can stall it if I really bear down but drilling normally it works fine. At 950 I can run a 3/4" fluted bit into a 4x4 without stalling. Who knows? I'm just going to get the correct capacitor and use it till it dies I guess. I can't imagine needing to drill any bigger holes than that.
I went ahead and test ran it. At the lowest rpm I am able to drill 1.5" holes in a 4x4 to 3" deep with a spade bit. I can stall it if I really bear down but drilling normally it works fine. At 950 I can run a 3/4" fluted bit into a 4x4 without stalling. Who knows? I'm just going to get the correct capacitor and use it till it dies I guess. I can't imagine needing to drill any bigger holes than that.
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