Deleted
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Post by Deleted on Jun 15, 2013 10:30:33 GMT -5
I was foolish and Bought a Harbor Freight motor. I built a homemade grinder with 6" expanding drum on one side and a 6" x 1" grinding wheel on the other. It has worked great for about 4 months Trying to use it today and the trip button goes off after 10 minutes or so. I turn it off, wait a few minutes and it runs fine again. I even tried tried it with the belt off with same results.
I should have bought the warranty, but I did not, Got it for $79 and its only covered for 90 days
Any idea what might be the cause of this and anything I can do myself to fix it?
Cant afford a new motor.
Thanks
Dave
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Post by Deleted on Jun 15, 2013 12:54:45 GMT -5
Is it possible an external bearing is misaligned or seized causing the motor to overload and shut-off?
The motor could be fine!
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Post by Deleted on Jun 15, 2013 14:22:08 GMT -5
I tried it without any load as well, same results I temporary bypassed the trip switch, and it runs fine, motor is not getting hot. I checked the amps and its pulling about 6-1/2 running As long as I am not leaving it running unattended I am gonna use it with out the trip. Maybe its just a weak trip switch.
Dave
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Post by Bikerrandy on Jun 16, 2013 17:11:13 GMT -5
Since you bypassed the trip switch, you should plug it in to a GFI. The motor might not get hot but the wall outlet can. The shut-off after ten minutes could be because of the motor's duty cycle. I order motors from the internet (Ebay) with a continuous duty cycle.
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Post by johnjsgems on Jun 16, 2013 22:19:48 GMT -5
What is the running amp rating of the motor? If more than the 6.5 amps you should be ok. If an open motor, blow out the windings with air. You can check bearings for play but if it isn't getting hot or over amping it probably is a faulty manual overload switch. I would not let it run unattended but with a cabber that should not be an issue. Have you checked voltage? Low voltage could cause problems also using too light a cord or extension cord. GFCI is a ground fault circuit interrupter to shut off if something grounds. It won't act as a circuit breaker or thermal overload. Let's see, 3 months warranty, how long did it last? Most "good" motors have a one year warranty. You gets what you pays for.
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Deleted
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Post by Deleted on Jun 16, 2013 23:00:48 GMT -5
What horsepower is the motor rated?
I'm a dumbass. The title of the OP is 1/2 horsepower. You motor is drawing too much current. 6.5 amps should be a full horsepower. Even assuming less than 100% efficiency your motor should not be drawing 2x it's horsepower rating.
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Post by parfive on Jun 16, 2013 23:28:48 GMT -5
“You motor is drawing too much current. 6.5 amps should be a full horsepower.” Ahem. : )
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Post by Rockoonz on Jun 17, 2013 0:27:32 GMT -5
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robsrockshop
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Post by robsrockshop on Jun 17, 2013 7:05:09 GMT -5
My Grizzly lathe is around 5 years old, it's a 2hp I think and still runs strong. Win some lose some probably. A good motor was tuaruselectric but they are out of stock for awhile.
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robsrockshop
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Post by robsrockshop on Jun 17, 2013 7:11:28 GMT -5
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Deleted
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Post by Deleted on Jun 17, 2013 10:49:17 GMT -5
Lee, thanks. I always seem to learn when you share your thoughts. I appreciate it. OP most likely does too! Not sure what's up with the Grizzly motor rating. Perhaps something to do with maximum load. Rob's 1/2 HP link is showing maximum load amperage at 6.0A for 120V. There is a "conversion" that 1 watt = 0.00134102209 horsepower, therefore one horsepower is 769 watts. 769 watts at 120 V is 6.4 amps. The OP reports a no load amperage. 6.5amp for no load on a half horsepower seems, to me, like something is wrong.
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Tom
fully equipped rock polisher
My dad Tom suddenly passed away yesterday, Just wanted his "rock" family to know.
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Post by Tom on Jul 2, 2013 21:47:30 GMT -5
Rule of thumb is 7 amps per 1/2HP @ 120V, this depends on your motor type, shaded pole, permanent split capacitor or split phase cap start. IMO you have a faulty O/L, leave it jumpered and run it, a GFI outlet is used to protect from electrocution and won't help in this case.
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Post by jakesrocks on Jul 2, 2013 22:19:07 GMT -5
Rob, before buying that motor, I'd contact the seller and see if it's rated continuous duty. His description doesn't say. Otherwise it looks like a good motor.
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jamesp
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Post by jamesp on Jul 3, 2013 4:03:15 GMT -5
I am thinking a lot less amps with out a load.
Seems like 7 amps would be under decent load
7 amps = seven 100 watt light bulbs=lot of energy (110 VAC)
If the motor is not hot then I say thermal overload is wacked(like hot enough to dry water off in less than 10 seconds)
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Tom
fully equipped rock polisher
My dad Tom suddenly passed away yesterday, Just wanted his "rock" family to know.
Member since January 2013
Posts: 1,557
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Post by Tom on Jul 3, 2013 21:53:33 GMT -5
Yes that rule of thumb is a motor at full load, that being said small HP motors don't have a huge difference between no load and full load currents. There are tons of fractional HP motors that have no O/L protection at all. Again, IMHO I would just run it.
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QuailRiver
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Post by QuailRiver on Jul 12, 2013 2:51:03 GMT -5
I've been using a Harbor Freight Smith+Jones brand 1/2hp motor on my old HP cabbing unit for a couple of years with no problems. It strains a little when starting but runs fine once it gets moving. I figured the strain was due to all of the weight I have it pulling. I've got the arbor loaded with 45-50 lbs of weight including the arbor shaft and wheels. The motor instructions state "...the facility power circuit, and connecting wires, must be rated to at least 20 amps of current". So if you are using HF's Smith+Jones 1/2hp motor then you need to make sure you are using it on a 20amp breaker and that the power cord is 12 gauge wire (12awg should be stamped on the wire's plastic insulation). If not then that may be what is causing your problems with this motor. Here is a link to the owner's manual for the Smith+Jones brand motors that Harbor Freight sales: manuals.harborfreight.com/manuals/67000-67999/67839.pdf
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Post by parfive on Jul 12, 2013 10:20:55 GMT -5
@ quailriver – That generic 20 amp blurb in the Harbor Freight “manual” is beyond useless.
Specs are listed for five different size motors - most of ‘em dual voltage - but no current ratings?
A half-horse motor draws less than 10@ and would run just fine on a 15@ circuit.
Meanwhile, the 3 hp motor would need a 30@ circuit, and that’s at 230V.
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Post by johnjsgems on Jul 12, 2013 12:17:15 GMT -5
It is always better to have too much wire capacity rather than maxed out. A 10 running amp motor will draw much higher for the second to two seconds it takes to start. Better to use a breaker for circuit protection than the wire. Most manufacturers will spec 12 gauge extension cords to be on the safe side.
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QuailRiver
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Post by QuailRiver on Jul 12, 2013 15:29:34 GMT -5
Parfive, Johnsgems is correct. There are varying contributing factors that can add to or subtract from the amps a given motor pulls at a given time. Not all electric motors of equal horse power are equal in performance and requirements. I've had a couple of pieces of woodworking equipment with fractional horsepower motors where the owner's manual stated requirements of 20amp breakers and 12 gauge power cords. Fifteen amp breakers have commonly been installed for most 115v household outlets. And frequently people don't pay much attention to the size circuit breaker their outlet is on. If the plug fits they just use it. The rest of us are all just trying to help out Dave with his motor problem here. But in general, your posts have seemed on the argumentative side lately, so before you snipe back at me again how about taking time to do a little research Take a look at this G&G Electric and Plumbing Distributors Inc. information sheet linked below. Scroll down to page 2 and in the second column from the left find 1/2hp motor then track right to the next box for the requirement under the heading of circuit breaker...it states 20amp. www.groverelectric.com/howto/20_How%20to%20Calculate%20Wire%20&%20Fuse%20Sizes%20for%20Electric%20Motors.pdf
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Post by Rockoonz on Jul 13, 2013 0:21:40 GMT -5
Most likely the reason they specify a 20 amp breaker is because code for a 20a breaker is probably 12awg wire, and because that one motor won't be the only thing plugged in. I learned years ago about wire gauge with lighting circuits on classic import cars. If you run the headlamp wires to relays, then increase the wire size from the power source to the headlamps a couple steps even standard sealed beam lights will get brighter, and the surface of the headlamp will be noticably cooler to the touch. If the same principal applies to AC motors then larger conductors should cause the motor to have more power and less heat. Since the breaker on a motor is thermal protection, less heat is a good thing.
Lee
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