Need Help With 1 Hp Motor

I tend to agree with J.R. If the saw cuts fine in higher speeds the motor and gearbox are good. Less tension on the belt will help. Man I am enjoying this discussion. Let us know what how you are doing
 
upload_2015-10-5_17-50-23.pngupload_2015-10-5_17-50-23.png Just curios that the saw cuts on higher speed but not at low speed.Are the pulleys set like? Agine just curios.upload_2015-10-5_17-50-23.png
 
Mr. Fixit said:
Just curios that the saw cuts on higher speed but not at low
Click to expand...
You have it backwards. The saw cuts fine at the lowest speed. That would be with the belt in the highest position which uses the smallest pulley on motor shaft, and largest pulley on gear box shaft. JR49
 
That is my mistake I believed that it would not cut at low speed. Thanks for the reply. I always say run it till its broke.
 
9Sec93LX said:
A 35 MFD capacitor is NOT a start capacitor, it IS a run capacitor. Start capacitors have a much higher mfd rating and it is always given as a range of values (124-149mfd, 149-174mfd, 174-208mfd, etc.). For a 1hp motor it would be in the neighborhood of 124-149 mfd or 149-174 mfd it depends on the original engineers calculations when the motor is built. Just look under the cover of your average 1hp sprinkler or pool pump. The motor didn't start because it had an open circuit when you removed the capacitor or you used a 5 mfd capacitor that it is not designed to use. Run capacitor values are more critical than starting capacitor values, because they remain in the circuit at all times. Even a slight change of 35mfd to say a 40 mfd will affect the way the motor works. If of the wrong value the motor will run hot, lack torque and generally not perform well at all. It IS quite possible that the mans RUN capacitor is weak and causing his problem. Any electric motor shop should have a "Capacitor tester" and be able to tell him if his is within spec. Sorry. If you don't believe me Google it for yourself.
Click to expand...
So - my final word on the start/run question: 9Sec93LX, you were right, I was wrong: I now agree that it's a run cap. (It even says so right on it ("RUNNING CAPACITOR.") A more thorough check of the industrial catalogs shows nearly all the start caps are above 100, and the runners below. Thanks for setting me straight.
BTW JR49 - you've probably already figured how to get the cap out, but if not: it's really easy to get to because it's under an external plastic cover, just pull the two philips head screws. Usually you can pull off the quick-disconnects from the cap, but if not, you can cut the wires right at the cap so you may have enough not to have to splice them. If you don't have any QD's that fit, the motor repair surely will. Good luck!
 
Mad Monty said:
So - my final word on the start/run question: 9Sec93LX, you were right, I was wrong: I now agree that it's a run cap. (It even says so right on it ("RUNNING CAPACITOR.") A more thorough check of the industrial catalogs shows nearly all the start caps are above 100, and the runners below. Thanks for setting me straight.
BTW JR49 - you've probably already figured how to get the cap out, but if not: it's really easy to get to because it's under an external plastic cover, just pull the two philips head screws. Usually you can pull off the quick-disconnects from the cap, but if not, you can cut the wires right at the cap so you may have enough not to have to splice them. If you don't have any QD's that fit, the motor repair surely will. Good luck!
Click to expand...

No Problemo Monty.
JR,
Motor caps are NON-polarized so you don't need to mark which lead goes where, they are interchangeable, which simplifies things for you.
Can't wait to hear the results of the Cap. test so we can see if that's really your issue or just an underpowered HF motor.
Tommy
 
Humm, That's odd to have a run capacitor without a start capacitor on a motor.... You generally don't get into run capacitors on a motor until you get into the 3-5 HP and higher range.......
 
4gsr said:
Humm, That's odd to have a run capacitor without a start capacitor on a motor.... You generally don't get into run capacitors on a motor until you get into the 3-5 HP and higher range.......
Click to expand...


See my earlier comment on PSC (Permanent Split Capacitor) motors.
It's actually very common on smaller inexpensive motors, as the engineers use BOTH sets of windings in an attempt to give the motor more guts. Not to mention the additonal cost savings by not have to use both a Governor (rotating Starting switch) and a stationary Starting switch, that's Harbor Freight for you. How else do you think they sell the things so cheap? Besides Slave labor wages of course. LOL


9Sec93LX said:
I understand your confusion on the matter Monty and while I am NOT an electrical engineer I'll try my best to explain my point.
My father started our motor shop in 1960 (the year I was born) so I can only tell you what we have experienced first hand on the job.
The HF motor in question is what's called a "Permanent Split Capacitor" (PSC) motor.
It uses the Start AND run winding AT ALL TIMES in order to boost the HP rating of the motor (usually done on less expensive motors that do NOT require excessive starting torque).
They do this because Iron (motor laminations) is expensive and so is Copper for windings (Although I'd venture a guess that this HF motor used Copper COLORED Aluminum windings). So by utilizing both sets of coils together the motor is smaller (cheaper to manufacture) and uses slightly less Amperage due to the increased resistance of both windings vs. using only the Run windings.
A PSC motor is used on applications like fans or drill presses and bandsaws and Not on a water pump because as you correctly stated the pump starts under a heavy load and the saw is allowed (or should be allowed) to come up to full speed before it's lowered onto the material to be cut.
By removing or changing the capacitor you are effectively deleting the Start winding from the picture completely, which is why you need to roll it over to start it.
With the capacitor removed you could roll the motor over in EITHER direction and it will run equally well (for the most part). Bandsaw probably won't CUT very well in reverse though I'm guessing. LOL

The major difference between Start caps and Run caps is the Start caps are rated for intermittent duty and the Run caps are rated for continuous duty.
The easiest (NOT SAFEST) way to prove my point would be to insert a KNOWN Start cap in your motor and run it.
KA-BOOM will ensue in a very short order as the cap overheats and fails.

I've included a link to a wiring diagram that shows how the circuit is connected and should help you to visualize what I'm saying.
I hope this clarifies things for you, if not LMK.
Tommy

Skip down to mid page for the PSC motor diagram.

http://eng-electric.blogspot.se/2012/08/microchip-ac-induction-motor_11.html
Click to expand...
 
Last edited:
Mad Monty said:
I took a look at my own HF bandsaw motor, and here is what I learned: under the hump on the side, there is a start capacitor, necessary to get it going from a dead stop. It is not a run capacitor, which if bad, could have explained your results.

I verified it was a run capacitor by cutting its leads. The motor hummed but didn't start moving. ...............
Click to expand...

You cut the leads to the starting capacitor... of course it's not going to start. What you need to do is bypass the capacitor, connect the leads together. This will complete the circuit allowing the motor to start. Put a larger mfd rated start capacitor in the circuit, this will eliminate any starting problems...
 
You must log in or register to reply here.
Back
Top