Need Help With 1 Hp Motor

JR49

JR49

Active User
H-M Supporter Gold Member
Joined
Mar 20, 2014
Messages
440
My H.F. 4X6 bandsaw has the original 1 HP motor that it came with. Don't know how much use it's had as I got it used. Today, while cutting a steel plate 5" wide by 1" thick (this took longer than any piece since buying it), when it got almost to cutting through the bottom, the blade stopped. I assume, as it was cutting through a tooth caught and jammed the blade. I lifted up on the saw and the blade began moving again. I figured that the belt was slipping, because surely, the motor has enough power to slip the belt, especially since I run the belt pretty loose to make speed changes easy. But, to my surprise, it was not the belt, the motor was stopping, and as soon as I lifted the blade up it started turning again. I tried this a few more times and each time the motor stalled rather than slip the fairly loose belt. Are these H.F. motors that underpowered? The motor temp was about 138* F. with a laser thermometer, if that makes a difference. Is this motor junk? I would think with a little more power the blade should have pulled right through the cut. Does this motor have replaceable brushes, and would worn brushes cause the lack of power? I can probably fix it If you electrical gurus tell me what to fix. If need be, I can get a new motor, cause the saw is in really good shape, but I'd rather fix this one if I can. Please Help! Thanks, JR49
EDIT, Forgot to say, blade is 10-14 TPI, so there were plenty of teeth in the cut
 
The first thing I would look at is the motor wiring. If it is a dual voltage motor, is the motor wired for the voltage that you are running? A motor wired for 240 will run on 120 but at much reduced power, and certainly may run hot. But 138F is not really that hot. The other possibility is that you lost one of the windings and in that case to only practical option is to replace the motor. It would cost more to repair the motor than it would to replace it.
 
JimDawson said:
The first thing I would look at is the motor wiring. If it is a dual voltage motor, is the motor wired for the voltage that you are running? A motor wired for 240 will run on 120 but at much reduced power, and certainly may run hot. But 138F is not really that hot. The other possibility is that you lost one of the windings and in that case to only practical option is to replace the motor. It would cost more to repair the motor than it would to replace it.
Click to expand...

Will do Jim, and thanks. So can I assume that worn brushes wouldn't cause this power loss ? JR49
 
For a cut that deep into a 5" piece, it is common for the chips to jam the blade. Before deciding the motor is toast, try it on a shallower cut.

Motors, particularly inexpensive motors are often optimistically rated. My 4x6 has a 3/4 hp motor and will stall occasionally when cutting large pieces.

Which pulley configuration are you running on? For a piece of steel that size, you probably would be better off running with the smallest drive pulley. It will slow your cutting down but you will gain quite a bit on torque. You can also back off on the cutting pressure which should reduce jamming. My saw has an adjustable spring to accomplish that.

Finally, if your cut is almost through and you are still jamming, you can rotate your work so the 5" dimension is vertical. Your previous cut will guide the blade to keep your cut straight and the saw will cut through much faster.

If you don't have the manual for the saw, here is the link.
http://manuals.harborfreight.com/manuals/93000-93999/93762.pdf

Here is the link for the Grizzly 4x6. The saws are all pretty much alike and Grizzly does a better job with their manual.
http://cdn2.grizzly.com/manuals/g0622_m.pdf

Bob
 
JR49 said:
Will do Jim, and thanks. So can I assume that worn brushes wouldn't cause this power loss ? JR49
Click to expand...

That is an induction motor, it doesn't have brushes.
 
RJSakowski said:
Which pulley configuration are you running on?
Click to expand...

Thanks so much Bob, I new I could depend on Jim to give me the electrical side of this problem, and now you have given me a lot more to think about. The saw was running on the middle pulleys (120 sfm), so I could have gone to the lower 80sfm pulley. I would have thought (wrongly, I guess) that even a 1/2 HP motor would slip the pulley in the somewhat loose belt, rather than stop spinning, but hey, what do I know. Not much about elect. motors, I guess, and this is the first metal cutting saw I've ever used. So, If you say your saw stalls sometimes, I guess that's just the way it is. I will try all suggestions tomorrow. One thing still confuses me though. Why would they give it two higher speeds If the motor can't use them? Thanks again, JR49

EDIT, Just had another thought Bob, I've read posts where guys complain about stripping a tooth or two when using a blade with too few teeth on thin material. My motor would certainly stall out, and possibly blow a breaker before it would pull hard enough to break a tooth. What do ya think?
 
Last edited:
JR, I use my saw to cut a variety of materials including plastic and aluminum and, in fact, mostly use the highest speed. A 1" x 5" slab of steel is a challenge for a little saw like this. The 4 x 6 capacity is just stating the maximum size of work. It doesn't imply that the saw is going to easily slice through a 4 x 6 bar of steel.

Bob
 
Like I said above, I don't recall ever stalling my 1/2 HP, it always slipped the belt. But like you I ran the belt a tad loose so it would slip rather than fry the motor if it jammed when I walked away from it on a long cut.

I burnt up more than one belt, and always kept a spare on hand.
 
Jim, I can't believe I did this at 10:30pm. Just went out and took a picture, using a flashlight, so quality is poor. Correct me If I'm wrong but this is the only info on the motor, and I think it is saying that this is only a 120 volt motor. Will check back in the morning. JR49Band Saw Motor.jpg
 
You must log in or register to reply here.
Back
Top