Motor heating up, advice needed

[adidat]

hi guys

Recently bought a Myford super 7 from ukw, seller also had an Ajax power hacksaw which was immaculate and a very good price so I had that aswell.

In using it today I was cutting some aluminium bar haven't managed to get the coolant pump working as its blocked with swarf or something. The machine is in excellent condition and all lubricated nicely. During cutting the metal and blade stayed quite cool and didn't really seem hot enough to warrant the mess involved with coolant.

But the motor is getting seriously hot and keeps blowing the trip on the nvr box, can't see that the saw would be under any high load as its cutting a reasonably small bar and frankley cutting large or small metal is the saws only purpose.

Whilst I know my wood, motors are a new thing for me, so any ideas??

Cheers in advance

Adidat

 

[dzj]

First step would be to remove belt from pulley and see if it heats up with no load.

 

[adidat]

Ahh good idea-!

 

[Wildman]

if it has been stood about unused, is it damp, or in need of shaft lubrication, is the belt too tight. A worn pulley may have caused a slipping belt that was compensated for by overtightening the belt.

 

[adidat]

Ok took the cover and belts off and was amazed how easily the large flywheel spins. Clever little machines uses very low power to do a big job.

So with out load the motor was again roasting!

is it terminal??

Adidat

 

[dzj]

If it's single phase, maybe it's the start capacitor.
It might be worth a try replacing it with a new one, as they usually don't cost that much.
Otherwise...

 

[adidat]

Yeah single phase. Do i need to find one for that motor or will one size fit all?

 

[dzj]

Get one with the same voltage and micro farads.
(It's written on the capacitor).
The manufacturer of the motor might supply you with this info if it can't be read properly.

 

[beech1948]

motor heating up could be a few things.

1) bearings need to be replaced is very likely. To check run motor from cold and see if the end bells heat up...use your hand to tell. If your hand can remain on the warm bearing then it probably is Ok as motors do heat up a little if used for 30 minutes ++

Bearings can be replaced easily by you or more expensively by an electric motor shop. Bearings are usually cheap and you pay for labour.

If you replace the bearings then look on www.owwm.org and read a few threads on the everything electrical forum.

2) Capacitor is unlikely but also cheap to replace. Remove existing and read off the size in microfarads.

3) Have a peek into the motor and see if the brushes are OK, check for grit and dirt and if necessary remove the end bell and clean out.

Send me a pm if you get into difficulty

 

[CHJ]

Is the motor a low cost aluminium cased item with a single capacitor housed on the outside or is it a more sophisticated one with a centrifugal switch starter circuit.
If the latter it could be that the switch is ceased and not disconnecting the starter winding correctly.
(With power disconnected take the fan cover and fan off and look for a switch mechanism on motor shaft with wires connected.)
A read of Bob Minchins doc on the subject may be of help.

http://homepage.ntlworld.com/bob.minchi ... Issue3.pdf

 

[adidat]

Heres the saw


As you can see in famtastic condition. I Doubt its been used for about 5 years?

I discovered why the coolant system wasnt working. The tube was completeley blocked with a mixture of soulouble
Coolant and fine swarf. I need to put some fine netting on the drainage spout as the swarf just gets washed back into the resovior and then back through system.

Looks like a cheaper motor as described chas. The beaing going sounds plausable but would this make the aluminim housing get very hot in about 5 minutes, also would this make the thermal trip kick in?

Adidat

 

[adidat]

Another picture if i can get it working properly a bargain for £150

 

[Eric The Viking]

Does it say "Clarke" on the motor, by any chance?

I mention this because Machine Mart sell Clarke ones, and, if they're similar to other Clarke equipment I have, they might not be "overly wonderful". That said modern Chinese induction motors do run hot-ish. I think they've discovered they can have higher resistance windings, requiring less copper than older designs (needs modern varnish on the wire to take the higher temperature).

Axminster used to sell their own brand of motors. I can't find them on their wonderful web site, so I guess they no longer do, sadly. Point being that pretty much anything that will fit ought to do.

I expect there are rewind/refurb people in Bristol, but so far I've not needed that.

 

[Togalosh]

Just a few thoughts;

There is a cooling fan at the back of the motor with a cover over it.. is that in place & not rubbing against something or blocked with fluff ?

Microfarad is shown as uF.. & if you look the motor's data plate this value will be shown & then you can compare this with the cap' that's fitted - the wrong one could've been fitted. Usually the motor doesn't run at all if the cap' is faulty but I can't remember if it will run hot if not at full capacitance. If you know someone with a multimeter with capacitance test it.. or just replace it (try the local washing machine spares/repair shop).

My bet is on the bearings.. do the bearings make a dry running (?) noise when the shaft is spun slowly, does it stop spinning suddenly or does it come to rest slowly ?

HTP
Togs