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View Full Version : Need help with SAJO 54 P in southern Ontario



dharnell
04-20-2011, 08:10 PM
I've been having problems switching the gear box from low to high speed on my SAJO 54 P vertical mill. I had a bit of down time so I thought I would investigate the problem.

http://i1226.photobucket.com/albums/ee406/dtmachining/DSCF2079_640x480.jpg

Took the gear box cover off, and found that one of the gears that slides on a shaft was binding. Took the shaft out and it appears the shaft was slightly twisted. The previous owner ran the mill in low speed almost exclusively with a 10" face mill. Seems he may have twisted the shaft while running the large cutter.

http://i1226.photobucket.com/albums/ee406/dtmachining/DSCF2080_640x480.jpg

I can slide the gear from one end to the other, but it has to be persuaded with a brass hammer. Does anyone have ideas on how to repair this? I'm afraid that if I try to grind the kink out (shaft is hardened), the gears will be a sloppy fit on the rest of the shaft.

http://i1226.photobucket.com/albums/ee406/dtmachining/DSCF2078_640x480.jpg

I have some jobs coming up soon that I have to be ready for and don't want to ruin the shaft. I can run it in low gear if I have too. Anyone have ideas on how this can be repaired?

Any ideas on what it may cost to grind a new shaft?

Regards,

Dave

Toolguy
04-20-2011, 08:41 PM
That shaft looks pretty big to try to untwist. I would try lapping it with the gear using fine lapping compound. Maybe 400 to 600 grit. That should free it up and get it to move smoothly without removing too much material.

Mcgyver
04-20-2011, 08:57 PM
hey Dave, thats what happens when you let the youngin's run the big machines :)

I can't tell from the pic if its twisted over its length or it there's a bad area.
One idea that struck me is to use some blue to figure out exactly where the binding is. If its everywhere, well you may have to use lapping compound (make sure you use the stuff that breaks down), but you may find that there a couple of spots causing the worst of it that can be stoned off; depends on the nature of injury and can't tell from a pic

As for a new shaft, is it just splined or are those gear teeth? I'm thinking its gotta be just splined..... If so I'd be thinking just make one and forgo the grinding. Use something tough and take my chances on its life span, unless the roller elements play directly on the shaft, I don't think it would be a huge detriment not having it hardened, but maybe I'm not fully understanding its function

Elninio
04-20-2011, 09:37 PM
Is the shaft hollow?

dharnell
04-20-2011, 09:54 PM
Mike, I've told him he'll have to stick with the grinder from now on!

I believe they are splines and not gear shaped. I've blued the shaft and it appears to bind across the entire diameter, but only in one spot. I'm going to start with the lapping compound this weekend. I'll have 4 days to try and fix it.

I'll take measurements of the shaft, and I can always make one later. If I wasn't pressed for time I'd try to make a new one now, but I have a couple of jobs to get out of the way first.

Dave

garyphansen
04-20-2011, 10:21 PM
How long is it? Can you make a new one? Gary P. Hansen

914Wilhelm
04-20-2011, 11:32 PM
https://sdp-si.com/eStore/Direct.asp?GroupID=337

This company sells inch and metric spline shaft. If the ends of the shafting have minor machining it might be easier to start with pre-splined shafting. Once you put lapping paste on your gear and shaft you will forever change the character of your gear spline and I suspect the gear is harder to replace than the spline shaft.