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B&S Challenger Surface Grinder needed a repair

pdentrem

pdentrem

Well-Known Member
We have the above unit 6X12 size. Likely many decades old. Anyway recently I replaced the oiler that had stopped working. Naturally as soon as I did that, all the ways are being lubed again! New complaint! The head drops after the operator stops lowering it down. Oil makes things slide! Ruins the work of course. The leadscrew and nut are worn out in the middle of travel. We are not going to wait for a hard to find 7 1/2 tpi screw so boss ordered a 8 tpi and new bronze nut. He hands it to me and says “make it work”
I had a used screw from a previous junked machine, which gave me the upper bearing portion and I made it fit into the new leadscrew with a press fit and a pin. Heated the top of the screw to expand the hole and get a tight fit when cold. Screw is soft as purchased.
I cut the bronze nut to fit and installed the parts today. The hand wheel has 50 graduations which now I have to replace with one that has 40. The users are happy again!
Roton supplied the parts. Under $100 CDN.
Pierre

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Just an update.
Since the leadscrew and nut combo is not perfect, about .010” backlash, the wheel can drop a little bit as one is working. So I made a backlash reducer. Purchased another nut and added some splines, edm a matching arm and added some Belleville washers to add downward preload. The arm could move back and forth through a small arc but tends to not do so.
Pierre
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Nice. I have the same machine, haven't noticed any droop of the head, but my Y axis lead screw was worn to the point of a half rotation of slop in the middle of the travel. I had a local club member help me make a new one. Only other thing I had to do was replace the lovejoy rubber coupler, mine had deteriorated and was causing chatter marks in the work.

I have my doubts about the oiler actually delivering oil to the top of the lead screw. I should just oil it once in a while or before each use when I pump the one shot.
 
The Y axis is on the boss list as well! It has half rotation on the handle like yours. The top oiler does two jobs. Oils the gears at the top and also does the vertical ways. Do you have the manual?
 
I have a pdf copy of a Rev "A" manual from 1973. I have no idea how old the machine I have is. The other thing is the base cabinet has a big filter assembly and suction fan, but I don't run it cause I had to put a VFD on the main motor to get 3 phase and didn't want to spend to put one on the fan motor too. I maybe should now that I think about it and the inconvenience I've been going through hooking up the shop vac....
 
Does yours have the dust collector built into the base cabinet? I just went to put a new VFD on to run the fan, but the one I got from Amazon for $80 showed up broken (terminal block board snapped off inside).

Bummer as I was hoping to get that done over Christmas and now need to order a different VFD.
 
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