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Motor for Radial Arm Saw Model C48BP 113 Class B

onedavo

Registered
I think it is a Sears Craftsman saw but no manufacturer on the motor. The nameplate info is as follows:
Motor Service Number 63608
120 volts
11.8 Amps
60 HZ
1 PH (HP?) clearly it is marked PH
3450 RPM

I bought this saw new over 30 years ago...bought it to build my house. During that process it set outside part of the time and got rained on at least a couple times. (I tried to keep it covered). Eventually though I built a little shop for it which immediately turned into a storage building. The saw set unused for about 20 years. For awhile now I've been needing it to work on a rental house I bought. Last week, I cleaned it up and turned the power on. It ran like a champ!

Knowing I couldn't possibly move it alone and even with another person it would be difficult, I disassembled as much as I could of it. This included taking 1/2 of the housing off the motor in order to un-wire it. Today I reassembled it. Now the motor won't run. It will buzz. Probably because the shaft won't turn. Well, it won't turn without rotating in the housing.

I just need some advice. Is there anything I can do to it? Would be worthwhile trying to find a repair shop or can I buy a replacement? Also, anyone have an idea how I might have broke it?
 

armandh

Sponsor
Last Subscription Date
09/02/2010
review how it went back together
some times a screw a bit to long in the wrong place can jam up the works
no puns please
 

Power

Registered
, I cleaned it up and turned the power on. It ran like a champ!

Knowing I couldn't possibly move it alone and even with another person it would be difficult, I disassembled as much as I could of it. This included taking 1/2 of the housing off the motor in order to un-wire it. Today I reassembled it. Now the motor won't run. It will buzz. Probably because the shaft won't turn. Well, it won't turn without rotating in the housing.

I just need some advice. Is there anything I can do to it? Would be worthwhile trying to find a repair shop or can I buy a replacement? Also, anyone have an idea how I might have broke it?
Well, lets see now - you say it ran good, then you took it apart to move it, and now it does not run. HMM - sounds like incorrect reassembly.

Lets see what we can do. Please clarify what you mean by taking 1/2 the housing off the motor - did you remove an end bell? Pictures are nice.

What do you mean shaft won't turn. Unplug it ( want to keep all your fingers), put a blade on it and see if you can easily spin it, and if it keeps spinning. If not, tell me, and I will suggest solutions.


Radial arm saws use special motors. They are made with no poles or windings on bottom so blade can cut at max depth. The rotor is thin and long for same reason. I would not take motor apart without thoroughly marking everything. When I moved mine, I cranked the arm post out of the base, and moved it with motor attached. All the wiring is in arm. I then moved base alone.

If you take the motor off, then you have to realign everything so you can use the gauges for a straight cut. If the tilt is off 1 degree, when you cut trim, it will not fit right.
 

onedavo

Registered
I sure wish I had posted before I took the motor apart! It didn't occur to me to crank the arm post out of the base. Of couse that would be best. The motor doesn't have end bells. It comes apart in the center of the housing. Let me add here that it was full of saw dust if that might be relevant. Anyway the housing has only two long 1/4 inch bolts holding the two parts together and it looks like one end is not ever supposed to be removed by ordinary means. The end I took off was hard to get off. I had to use a hammer and a block of wood and peck on it.

The same is true about putting the housing back on. It won't just slide on, you have to use some force. Once back together, I can turn the shaft but I'm pretty sure it is turning in the housing as it doesn't turn freely.

Will try to post pictures and many thanks to both of you for replies.
 

Power

Registered
Oh, you really took it apart. The end bell you took off has a shaft brake that must be properly aligned. Mine is older - no shaft brake. Can't help you with that.
The shaft brake has to be aligned, the end bell should go back on in exactly the same position, and the bearing must be free.

When that is right, motor shaft will spin freely.

Hopefully, you marked the wires, and know where each goes.
Then you have to try and align the motor so you can use the gauges to dial in your cuts.

Pix of mine.
 

Attachments

Jim Rankin

Registered
Age
58
I would guess either the brake is assembled incorrectly or you have mismatched the wire pairs.

I have an old Craftsman radial arm too. It is dual voltage and you swap from 2 windings in series for 240 volts to two windings in parallel for 120. Mine also has a 120 volt electric brake that is energized to release, so those two wires are connected in parallel with one winding pair at all times.

Is yours' brake a manual deal (press to apply) or does it apply automatically when the switch is off and you press the brake to release it?

If the shaft will spin by hand, I would swap one of the pairs of wires that you have together and try it. Most likely you have one winding opposing the other one. If that doesn't work you should ohm through the wire pairs to see if one winding has gone open
 

onedavo

Registered
You fellas have got me thinking...
Until I read your replies, my assumption about what was supposed to rotate inside the housing was wrong. There is not much to the brake. It is just a button that you can press and hold or tap - what I'm trying to say is as soon as you take pressure off the button, the brake is off. Most of the time when I used it, I would just tap it two or three times. It rubs against that collar or whatever it is called that is about 3 inches in diameter.

My thinking is now that it is all about alignment. If I hold the motor vertical with the saw end down, the shaft turns freely. Opposite way the shaft will not turn or would be very difficult to turn. With the motor horizontal, the shaft turns sluggishly almost like it is rubbing. I'm thinking that somehow the endbell positions the rotor correctly inside the housing but I can't see what I'm doing wrong when I reassemble it. It looks like it is matching up.
 

Jim Rankin

Registered
Age
58
Many motors have what I call a "wavy washer" as a shim in the bearing socket on the end opposite the drive end. It is possible the rotor is moving slightly back and forth if this was not replaced. Its purpose is to allow the shaft to elongate as it warms up without putting the bearings in a bind. The drive end bearing is frequently fixed in its socket by some sort of retainer so the drive end shaft cannot move axially.

Also possible you just need to shim the brake disk slightly to keep it from dragging, if there is no axial movement in the shaft itself.
 

Arkie

Registered
Last Subscription Date
08/17/2011
Probably some end play shims fell out and stuck to the bottom of your shoes.
Motors that old won't take much worrying of the wires taking them apart and back together again and again and some require a special experienced care taking them apart and re-installing old stuff without creating further electrical and mechanical damage.

Also a replacement motor of that type is not going to be a easy find!


Might consider taking it to a motor shop before you see smoke.

Stay safe!
 

onedavo

Registered
Many thanks guys. The motor is working! I thought it was yesterday but wanted to put it back on the saw to make sure. Y'all got me to thinking about it instead of just throwing up my hands and giving it up for lost.

What I did was set the motor up in a vertical position. That way the shaft turned freely; then carefully put the endbell back on. When I set the motor horizontal, this time the shaft turned freely but I could hear a slight clicking noise on each revolution. After thinking about that awhile, it occurred to me that endbell might be on right but not tight enough since obviously the endbell was forcing correct alignment. I took my hammer and gave it a couple pecks on each side. Voila! No clicking. Today I wired it back up and attached the carriage, it blew a little saw dust out of it and ran like a charm.
 
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