# Central Machine Mill Motor Has No Oomph



## Rapidrob (Nov 4, 2015)

When using the mill portion of the Central Machine (Harbor Freight) Model T5980 Lathe/Mill, the motor will not start by itself. I have replaced the Capacitor which was leaking and it still cannot overcome the belt and pulley friction. (belts/pulleys are not tight). If I give the motor a spin,it will take off and run normally under load.  The motor does not have a Start Switch built in. (centrifugal) 
No smoke when running or arc traces noted when I took the motor apart. Windings look normal. No shorts or grounds. Armature ohms out OK.  Bearings sealed and very smooth.
 ON/OFF Switch is good.
The motor does not have a model number that can be cross referenced to an American motor.
Nor is there a HP rating. With the Watts listing and current draw,I think the motor is 1/2 HP. ( or a large .33HP)
The model listed is a YYH71M4.
What I would like to find out is it a 56C frame type motor?
The motor has a body 7 1/2" long
5" in diameter
5/8" shaft
shaft is 1 1/2" long and keyed
1640 RPM
30 uF capacitor 
The motor mounts to an end-bell flange (4 bolt) cast iron and has the belt tension-er built in. This mount holds the motor via 3 adjustable U-slots and bolts.
I have read that these motors are poorly made and fail frequently.
While this motor runs well,it cannot start with any type of load on the shaft without me helping it. I can stall it by holding the shaft. (I would never do this unless I knew the motor had problems)
I'm sure it's on it's last legs.
Any ideas as to a good replacement motor that is reasonably priced. And what is the proper frame size?
Than you for your help.


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## JimDawson (Nov 4, 2015)

This might help,  http://www.leeson.com/Literature/pdf/1050/MotorDimensions.pdf

It sounds like it might be a special frame designed for that machine.  You may have to build an adapter to fit another motor.  A NEMA 56C frame with an adapter plate might work fine.

I suspect that motor might be metric.  Did the motor ever work correctly?  The reason I ask is it sounds like it is wired for 230V and running on 115V or something like that.  Or it's just fried.


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## silence dogood (Nov 4, 2015)

It sounds like that you still have a start capacitor problem.  It's either bad or maybe too small.  However, I keep getting reports that the hf motors have given a lot of problems.  I own a hf 12sp bench drill press.  It's okay, but the motor seems wimpy.  I'm am on the look out for another motor.   I don't know if any one has done it, but if you can.  See if you can replace that motor with a variable speed DC motor.  ( maybe one out of an exercise machine  with its controls)  Good luck, hope this helps.


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## Str8jacket (Nov 5, 2015)

I have a cold saw with the start run capacitors, it is a chinese motor d90l frame from memory , it is metric. I have just had to buy a new motor for the same reasons, no power. 

3 phase motor with vfd has actually ended up being a cheaper option than a similar size single phase motor.


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## Rapidrob (Nov 5, 2015)

silence dogood  I think your right. I bought a new capacitor that is supposed to be 30uf and it now reads 10uf. Way out of spec. I will try a new cap and see what happens.
Thanks Jim for the motor spec sheet. I may still need it.


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## silence dogood (Nov 5, 2015)

One thing that I should have mentioned is that electrolytic capacitors have a shelf life.  It's too bad that suppliers don't put a date on them like a jug of milk at the grocery store.  Any way, I hope a new cap will solve your problem.


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## Rapidrob (Nov 9, 2015)

The new 30 uf capacitor showed up today and it solved the problem. The motor was able to overcome the drive belt and cold bearings frictioin as it jumped back to life.
Thank you for the ideas.


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## dmbaile2 (Nov 16, 2015)

Are you sure it is set at the correct voltage?


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## Ulma Doctor (Nov 16, 2015)

D71 is a metric frame designation very similar to what is installed in the milling machine with the exception of a 14mm shaft rather than the 5/8"  shaft you have listed above.
being that there is YY in front of the motor frame designation, that generally means that there is something special about the motor.
sometimes it's shaft length, sometimes it's shaft diameter, sometimes whether the shaft is threaded or keyed or both, sometimes it indicates a special wind on the windings for better torque or RPM set in a specification from an end user.
here's a link to better understand the metric frames
http://www.motorsanddrives.com/cowern/motorterms5-print.html

i wish the best of luck!


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