Harbor-Freight 3 in 1 Motors?

[Richie B.]

What quality capacitors were installed to replace the originals?

I'm not sure who that question was directed at, but here's my motor & cap spec.



Two motors; one for lathe, one for mill. Same model motor, each has two caps [start/run]. I'm not an electrical guy, this cap was installed by a garage electrician. It works, but I've been unable to find this cap on the Net. I'd like to get a few spares before I convert to a Baldor setup.

Two questions:

(1) Would the start cap be the same as the run cap?
(2) Is a 2-cap motor 'better' than a 1 or 0 cap motor?

Thanks for your help!

 

[compsurge]

I'm not sure who that question was directed at, but here's my motor & cap spec.

View attachment 90132

Two motors; one for lathe, one for mill. Same model motor, each has two caps [start/run]. I'm not an electrical guy, this cap was installed by a garage electrician. It works, but I've been unable to find this cap on the Net. I'd like to get a few spares before I convert to a Baldor setup.

Two questions:

(1) Would the start cap be the same as the run cap?
(2) Is a 2-cap motor 'better' than a 1 or 0 cap motor?

Thanks for your help!

A quick search yielded these:
http://www.grainger.com/product/DAYTON-Motor-Start-Capacitor-2MDT2
http://www.digikey.com/product-detail/en/PSU27015A/338-2748-ND/1551663
>>>http://www.mouser.com/ProductDetail...=sGAEpiMZZMv1cc3ydrPrF6n/KlM53Ws8/XwlzoF5nMY=
http://www.newark.com/cornell-dubilier/psu27015a/capacitor-alum-elec-270-324uf/dp/72K6679
>>http://www.amazon.com/Amico-300MFD-Terminal-Starting-Capacitor/dp/B0087ZBOLO (300uF, 250V)

You're looking for a 300uF capacitance on the start capacitor. There is obviously a tolerance, and it appears the replacement part you have is around 270uF +/-10%. It should be close enough.

The voltage rating is what it can withstand. If you see a lot of voltage spikes, you may want to go to a higher voltage like the last cap I linked. I'm not entirely sure if the rating on the caps is RMS voltage or not.

My EE buddy says to make sure you run it at least once a month to keep the capacitor charged, otherwise they can degrade over time. It's less of an issue with potted caps, but can happen.

What is the failure mode you are seeing? Is the capacitor exploding? Losing the ability to start the motor?


If I read your motor spec chart right, I believe the run capacitor is 35uF.

 

[Richie B.]

What is the failure mode you are seeing?

Dense gray smoke; acrid smell; motor won't start.

 

[compsurge]

When it works do you hear the centrifugal switch engaging? If it doesn't your motor never decouples from the start circuit and it will burn out since it's not meant for continuous duty. The capacitor could be the weak link in this system and die over time.

Here's a great video on motor function I found while trying to find a sound of the centrifugal switch.

Anyway, I'm trying to find the root cause of your issue versus tell you to go the immediate replacement route. I'm sure the HF motor is very inefficient and getting a Baldor will get you a reliable, well-made motor, but the old motor might be repairable.

 

[Richie B.]

When it works do you hear the centrifugal switch engaging?

When the motor starts, I can't even hear the TV in my shop. The Chinese weren't concerned about noise pollution.

I'm sure the HF motor is very inefficient and getting a Baldor will get you a reliable, well-made motor, but the old motor might be repairable.

Both Chinese/HF motors are in use & running now with aftermarket yankee capacitors. They work OK but my motor guy tells me that a Chinese 3/4 hp motor is not the same as say a Baldor 3/4 hp motor. If I'm going to be replacing caps every 18 months or so, I either need a steady supply of caps or new motors...

I would retire the Chinese motors in running condition and keep them for spares.

 

[wa5cab]

Richie,

The problem with the power rating of Chinese motors these days (I'm not sure this was true with the ones from Taiwan back in the 70's and 80's) is that they are rated by the input, not the output. Your motor nameplate reads 550 Watts. One horsepower is about 746 Watts. So the INPUT power is 0.73 HP. Assuming an electrical to mechanical conversion efficiency of around 70% gives an output of about 0.53 HP. So your Chinese 3/4 HP is about what a US manufacturer would call 1/2 HP.

The replacement start capacitor you bought is about 270 ufd +/- about 20. Your motor nameplate calls for 300 ufd. However, if it starts quickly, I wouldn't worry about it, Your 3-in-one is shouldn't be a hard to start load. And I don't see any reason why you should have to replace the capacitor annually. The run capacitor, on the other hand, calls for 35 ufd. Don't skimp on that one as it could matter.

FWIW, the motors on my 4X6 Bandsaw and my drill press are both over 30 years old and both still work just fine. But only time will tell whether the same will be true of what the Chinese are selling today.

Robert D.

 

[Richie B.]

To be clear - I bought this in 10-31-2002 and it's been in use regularly [weekly] since then. Three caps have been replaced; two on the lathe motor, and one on the mill motor. Not all at once, several years apart. I don't know which were replaced, whether run or start. I'd assume the start since they smoked & wouldn't start up.

I know nothing about motors or capacitors, and the caps have several slide connectors. My motor guy did the connections.

I'll check those links in compsurge's post; at the least I'll have a cap on hand for my motor guy when it next burns out.

Thank you all!

 

[Richie B.]

The black cap I pictured several posts above this (with the motor ID plate) is a replacement from the motor shop. I dug through my old parts box and found one of the original burnt-out caps (the blue one below). I also took the plastic cover off the mill motor and took a pic of that cap (white one). The blue & white are off the same motor but are physically different sizes - the plastic covers are even different (one fat, one thin).



I have no idea which is a start and which is a run...How would I tell???

Should I get spares of each??? Or is there one cap that will work for either start or run???

Thanks for your help!

Edit: My recollection of that blue cap 'burning out' was that it was the first one to go. The lathe started up very slowly...I had no idea why it was turning over so slow since it had worked OK the day previous...Then it started to smoke & stink...

 

[mrbreezeet1]

I would say you see treadmills sometimes in the free zone, but whether you can use the controller or mount the motor easily is another question. I tore down the one we had here thinking maybe to use it on the 9x20. The controller in the treadmill was forward only and the motor was mounted with a custom frame. So there's expense in adapting, buying a motor controller, etc - and I called "not worth the hassle" then threw it all in a box somewhere.

Sounds like at least an import sourced broach would be worth getting for this project LOL.

i am a far throw from a electrical expert, but from my understanding, a reversible switch is quite easy to tie into the motor.
"Every picture tells a story" (that was a good jam)
see if I can find the one I had.
It is a DPDT switch.

 

[compsurge]

On the nameplate you have 300 and 35 uF. The 300uF is the starting capacitor and the 35uF is the running capacitor.