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tenfingers
04-13-2003, 01:06 AM
My little Grizzly G1005 Drill-Mill was getting hot, so I gave it a rest. When I came back and turned it on, it just groaned. If I take off the belt, it spins real slow. Blows a fuse if I leave it on too long.

I wrote Grizzly to see if they still sell replacement motors, but I was wondering...

Could it just be a capacitor -- How can you tell?

Should I try a better or bigger motor? This one lasted 15 years, but I've been working it harder than I used to.


Any advice?
10fingers

Thrud
04-13-2003, 01:29 AM
An American, Brazilian, or German motor will solve your problem. They do not put the best motors on most machines new, so I think you had good service out of it.

If you can hear it click on start-up this is a centripetal starting switch. They are not expensive,but can be a pain to replace. If it is capacitor start it is possible the cap is cooked.

yf
04-13-2003, 02:00 AM
Does the shaft spin freely?
If not the bearings might have seized.

spkrman15
04-13-2003, 10:46 AM
Tenfingers,

I had the same problem with my motor. A wire had broken off of the centrifugal switch that thrud was talking about. I fixed it but the bearings kept going. So i returned it for a new one. http://bbs.homeshopmachinist.net//smile.gif GUARENTEE!!

It isn`t hard to check but it will be difficult to re-assmble, and if you can`t do it yourself it isn`t worth it sending it to a shop. Go slow and good luck.

P.S. Also check the capacitator.

tenfingers
04-13-2003, 06:42 PM
Thanks everybody for the advice. The motor spins freely, so it's not the bearings. I think it might be the capacitor, because the motor will keep on going if I start it with a spin.

I'm going to order a capacitor from McMaster-Carr and give it a try. I notice that the replacement capacitors with the same rating are a lot larger than the original equipment.

Thanks again,
10fingers

PS I still chuckle every time I think about that Davy Crockett history lesson you gave a while back, Thrud.

Alistair Hosie
04-13-2003, 07:05 PM
sounds like the capacitor is burned out to me sorry. Alistair

Mcostello
04-13-2003, 10:28 PM
Davey Crocket history lesson ??? Enlighten us, O teller of the Great Lost Stories of Days Past.

darryl
04-13-2003, 11:41 PM
I'm going to say it's an open circuit to the start winding. The winding itself, or the centri-----al switch, or a wire to the switch.

mikem
04-14-2003, 12:32 AM
I think also that the start switch is bad. Sometimes you can clean them and they will work again. My 12" disc grinder motor wouldn't start so I made an external momentary contact switch that I hold til the motor is up to rpm and then release. I know that this sounds like a duct tape fix but this has been working for about 15 years like this with no more problems. Good luck--Mike.

tenfingers
04-14-2003, 12:45 AM
Here's the history lesson:

One of the members was complaining that he was attacked just because he was from Texas and the attacker didn't like Davey Crockett.

Thrud agreed with the attacker because it turns out that Davey C. had some hygene problems that were so bad that they were still worth fighting over.

(I had originally posted Thrud's quote, but I edited it out because it lost something when I typed it)



[This message has been edited by tenfingers (edited 04-15-2003).]

tenfingers
04-14-2003, 11:14 AM
Mikem, darryl,
The open starting circuit is a good theory. I looked at the switch and the contact didn't look too good so I filed it clean. Was really hopeful, but it didn't work. Then I direct wired the capacitor, bypassing the switch. Still no luck. Now it's either the wires leading to the switch, or the capacitor. I already ordered the capacitor, but I guess I should have checked the wires first. By the way, I like the momentary switch idea. Might come in handy some day.
Thanks for your help,
10fingers

docsteve66
04-14-2003, 12:36 PM
When most single pahse motors won't start and will start when spun by hand the problem is in the starting circuit some where. Capacitor can be checked with an ohm meter. Meter on high ohms scaleshould kick up and return to infinity rather slowly. Not a definativetest, but if it doesnot kick at all the cap is probaly open, if it shows a steady resistance (assuming the leads are disconnected) the capacitor is shorted. NExt most common (or maybe more common, but hard to get to is the centrifical switch. at rest, the switch should be closed and measue zero ohm (or what ever your meter reads with the test probes connectedto each other), The neaxt ohm metertest is theto measure accross the start winding. One probe on centrifical switch, other on line in. both lines will probaby read some thing, the lower readingis the resistance of the start winding (if one probe is kept on the cent. switch. Best measuing tool is a incadescent lamp when checkin the strat switch and motorleads. a good (sensitive) meter can fool you.

The machanical part of the cent. sewich can betroublesome. There are "time delay" relays to replace a defective cnet switch. they keep curnet flowing through the capacitor a few seconds then open. They are horse power rated so if you must use one besureto choorse thePROPER size for the horsepower. More hp rated is just as bad as an underrated one. Usely, if the start winding is defective you will see charred wires, If the varnish looks good, the most likely culprit is a broken wire some where. Also those spade lugs some times look good but the connection is bad.

tenfingers
04-15-2003, 10:19 PM
Just wanted to thank everybody for the help. I installed a new capacitor and the motor cranked up just like old times. Total cost about $11 dollars.

Monkeyed around trying to see if I could tell good capacitors from bad using DocSteve's ohmmeter method, but I think the old one wasn't totally fried (motor still turned slowly) so it's hard to tell. Both increase in resistance, but maybe not at the same rate.

Thanks again,
10fingers

docsteve66
04-15-2003, 11:01 PM
10: the ohmmeter test is not a good test. But it is safe. If capacitor is open it will as yu noted charge slower than one of the same size. If it does not "kick" at all the cap is probably open, if it rises to a cerain value of resistance and stays there, it is probably leaky. Nothing beats swapping with a known goodone though.

And congrats on the fix. Thing to remeber is that there only a few elecrtical things (resistors, capacitors, inductance, and those mystery solid state parts), most important is that no matter how many wires are involved, each wire has only two ends (a tapped wire when thetap is removed then has only two ends. Piece of cake when you master those simple concepts. and also, in low frequency circuits, a wire has zero electrical lentgh ( for most purposes) the voltage is same at both ends, the currrnetis the same every place in the wire, what goes into the wire must come out.

Thrud
04-15-2003, 11:36 PM
10fingers

Testing a capacitor with an ohm meter can result in a cooked ohm meter. Some caps like the new "Gold Caps" can be the size of a coin cell or larger but have up to 40 Farad capacity - these are dangerous to handle if not properly discharged! Although you are unlikey to run upon these - they are used instead of battery backups for computer and memory circuits - be careful around multi-Farad capacitors! The Cap must be discharged with a load resistor before testing.

A Cap/Inductor tester is the best way to test them, there is ESR, internal shorts, leakage, and a few other things that are difficult to test for with out the proper gear.

gunbuilder
04-16-2003, 11:22 AM
I put new caps in a 5 Hp single phase this winter. Acted the same way, spun slow and made too much noise. A large farmer near here had a AC Cap tester and new caps. Had to replace all the caps. Motor runs like new.
I polished the contacts too. Some motors have dual contacts.

I do like it when the caps have a bleed resistor, much safer to work on.

Paul