Craftsman 115.7575 Restoration – Part 1
Craftsman 115.7575 Restoration – Part 2
Part 3: Painting, End Frame Disassembly
In my previous post, I had prepped the stand components, the center band, the eye guard frames, the quench base, and the wheel guards. The end frame halves required me to remove the bearings, so they’ll be discussed separately. At this point, I had settled on a paint scheme. The stand, eye guard frames, and center band would be painted close to the original power bronze, while the grinder itself would be done in a glossy chocolate brown. I used X-O Rust bronze and Rust-oleum Professional Dark Brown.
At this point, let’s talk about disassembling the end frames and freeing the rotor and stator. I’ll refer to the left and right sides as you would see them if the grinder was facing you (so the power cord goes in the right side and the lamp comes out of the left).
To separate the two end frame halves, you remove four end-threaded rods with acorn nuts and gently pry or tap the left side loose first. The right side has the centrifugal switch attached inside the end frame, so the easiest way to disassemble it would be to pull the left bearing and end frame, then pull the right bearing, then remove the rotor towards the left side, then perhaps use a long screwdriver to carefully go through the stator and unscrew the centrifugal switch, allowing the right end frame to be removed. I didn’t have a puller, which would have made all of that easier.
Anyway, the left side came off easily, and I was able to pull the bearing off the shaft with firm hand pressure once I gave it a little squirt of penetrating oil (WD-40 was what I had on hand). Remember to remove the retaining rings with a pair of snap ring pliers.
Replacement bearings for old Craftsman grinders can be looked up at:
Replacement Bearing List – Sears Craftsman/Companion/Dunlap Machinery
The original bearings on a 115-7575 were:
Original Bearings: ND (USA) 97503 (seal and retention shield)
Accurate replacement: 6203
The right side gave me a lot more trouble, mainly because I was trying to be gentle, so as not to break anything. You need to disconnect two wires going to the centrifugal switch. One wire comes off the capacitor, and one comes out of the windings on the stator. My wires were pretty crispy, but you are not going to be able to remove them from the windings, as they go in way too deep to access without completely rewinding the stator. My wires were soldered onto the switch, so I used a small flathead screwdriver to remove the two screws holding the switch board onto the right side housing. The board would probably crack easily, so be careful if you do that. You can unscrew them if you’re patient and have a small enough driver. Alternately, see what I suggested above about going through the center of the stator.
At that point, the bloody bearing would not give up the ghost and release the housing, so I spent an hour coaxing it loose. Life would have been much better with a proper ball bearing puller. I finally resorted to damaging the bearing since I was planning to replace them anyway; it was really stuck in the housing. You can usually cut carefully into the bearing race to free it up, but that’s a one-way ticket, of course.
Whew…Next time, we’ll delve into the grinder’s guts.
Did any of this info help you out?
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Hello. I just picked up a 115.7575 grinder today. The seller said the switch was bad and he just bypassed it so he would turn it on and off by plugging it in then unplugging to stop. i replaced the switch and with it off it growls and just creeps like a motor with a bad start capacitor. It runs as expected when turned on. I am not sure if it is wired wrong or something is wrong with it. Do you have a wiring print of this machine. I also learned from your photos that there is a centrifugal switch in the motor. Could the problem have to do with this switch? Any help would be appreciated. thanks.
If I understand correctly, with the power switch off and the machine plugged in, the motor is growling and trying to start, then when the switch is turned on, the motor functions correctly? Sounds to me like the switch is shorting across when it is off, allowing a little current to trickle across – not enough or too intermittent to start. I would begin by checking the resistance across the switch when it is in the off position. I think a single pole single throw 20A switch is what you’d want to replace it, but double check me, since it has been a few years since I was inside mine. Try that and if you are still having problems I will see if I still have my wiring sketch. You can also sign up on OWWM.org and ask the smart guys there.
Edited to add: The centrifugal switch puts power into the start windings on startup (giving the motor spin) and cuts off after a few seconds (cutting the start windings off). If it was not closing, the motor wouldn’t start properly, and it was not opening, the starter windings would burn out in short order. Based on you saying it runs ok, I don’t suspect the centrifugal switch.