Rebuilding a Delta Bench Grinder

There was an Email on the CAMS server last week for a couple of Delta bench grinders for sale CHEAP (one 3PH, one 110V). Both had floor stands. Too good to be true, but I Emailed that I was interested, and forgot about it (too late, I thought). Well long story short; I ended up with the two grinders (less stands), after the lucky buyer took the bases out of the deal. I would have liked to have gotten the bases, but this deal was good enough to grab up, anyway. I wired the 3PH grinder up with my new test circuit, and lo and behold: it worked!
Unfortunately the 110 volt grinder seems dead, but was complete enough to be worth saving. I stuck it off to the side, planning to play with it after a while, but started to think about all the “future projects” I’ve got around here, and decided to pass some of my good luck along to the next guy. It took one Email to sell the bad grinder to another CAMS guy for 20$, and he is plenty happy to have the parts to get his grinder up and running.
Heres some pics:

 

This is the 3 phase grinder as it arrived at my shop. I wired it up, and it spins (3450 RPM), and noisy as hell, but it works!. I took it apart right after these pics, to replace the bearings, but that won’t get documented till I get a little more work done on my Atlas mill. The wiring was junk, but thats no big deal, the work lights in the guards are complete, and it shouldn’t be a big deal to get them working.

Heres the motor tag.

This is the back side of the motor, with serial number. I don’t need any parts, but this would make getting parts real easy, if I did.

Heres the “junk grinder”. Pretty good parts donor for 20$, Huh? If I didn’t have so many unfinished projects around, I’d be tempted to fix this one. I have 3 or 4 grinders already, so I don’t really need it, but the chance to get a 1/2 HP 3PH grinder cheap really appealed to me. 3PH motors just don’t stall like 110 motors do, and sometimes I get “a little aggressive” when I’m grinding.
I don’t plan on getting over the top with this overhaul; its going to get bearings, and new wiring. Thats it. Grinders get nasty real quick, and I just don’t see the need to make it pretty.
I’ll post some pics of the re-assembly, when I get the bearings. I’m anxious to hear the thing run without that howl that accompanies bad bearings, 3PH motors usually run very smooth. More later………

12/27/2011: Not much progress lately; We’ve had out of town guests for the holidays, but I did get the bearings in stock for later installation……..

These are MRC 88503 bearings from the local electric motor shop. They are a “bit of an oddball” according to the shop owner, and had to be ordered. The inner race is wider than the outer race, and they are shielded on both sides. They came in the next day, and were 60$ for two bearings. I wasn’t thrilled about paying 30$ for each bearing, but looking at some of the Delta parts suppliers prices, this wasn’t too bad at all. This brings the total investment to 80$ so far, and I can’t cry too much about that. All thats left is to slap the grinder back together (maybe this weekend)……..

1/9/2012: I’ve got a couple of projects going right now, but really wanted to get back to this because its not a real tough job. I managed to get an hours work done on it before I went to work on the Atlas today, and it went pretty well.

Heres the parts that support the stator (and wheel arbors). I just gave them a quick cleaning, I’m not turning this grinder into a showpiece.

This is the right side bearing support. It has a locking ring, to hold the right bearing stationary, so that the left side bearing can be shimmed for zero endplay.

A shot of the left side of the arbor. The inner threads lock the wheel hub to the inner race of the bearing, to keep the runout to a minimum.

Before the left side bearing goes in, there are shims that control the side to side endplay. I just put the old ones back in to check the free play; perfect right out of the gate.

The assembled body of the grinder spins very smooth, with no resistance, as it should. I still have to hang the wheel guards, but they will need a little clean up, and the lighted safety shields have to be cleaned up, and rewired. I just didn’t feel like doing any cleaning tonight. I still have a couple of hours of work left to do on the Atlas. More later………..

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