Removing a rusty shaft

[davidatperces]

HI. I have just got a 1200 and want to replace the main shaft with a n MSK 200, my question is how do I remove the old shaft without damaging the machine. I have been spraying small amounts of WD40 on to the nut for a day or so but it is still tight. What is at risk of being damaged if I put force into undoing this nut? Also, should it just push through from the honing wheel (wheel and pin removed) or should push through from the stone wheel end?

Thanks

[Jeff Farris]

You don't have to get the stone off to remove the shaft. Remove the drive wheel from the other side, and you can slide the shaft out of the frame in the direction of the grindstone.

[davidatperces]

Ah thanks for that, I didn't want to assume and then bend something. The problem now though is that I have taken the drive wheel off and it wont budge, should I give it some gentle taps and/or spray the bushes with WD40.

[Jeff Farris]

Does it turn freely? Are the bushings intact? If the wheel turns relatively freely, but won't move laterally and the bushings are okay, yes, a few gentle taps on the end of the shaft on the drive wheel side should get things moving.

[davidatperces]

I have now got the stone and shaft off the machine. It was pretty well rusted on so would have been adding an extra load to the motor. I will now order a new shaft and I will probably order a new stone as well. I am turning green wood on a pole lathe with high carbon steel tools though I have just got an electric lathe and will possibly get some HSS tools, any thoughts? will I need to get more than one type of stone or is there one that will be ok on both types of steel?

[Jeff Farris]

The standard stone will work fine for both HSS and carbon steel tools. You will most likely need to order a new stone. If you get the shaft out without damaging the grindstone, you'll be quite lucky. When they get bad like that, it's rare to get the stone to come off without damaging the bonded hub.

[davidatperces]

Thanks Jeff, I had kind of come to the conclusion that I would need a new stone. I must say though the rest of the machine looks very good, I'm impressed with the build quality.

[grepper]

I don't know if this is applicable or not.  Just a stab in the dark...

Lay the grindstone on top of a vise with the shaft sticking down between the jaws, and close the jaws so they are just barely wider than the shaft so the edges of the bonded hub are  supported by the vise jaws.  That way you could tap (bash?) the end of the shaft but not bash the hub from the grindstone because the edges of the hub are supported by the jaws of the vice.  Does that make sense?

I don't know if the damage Jeff is talking about is bashing the hub from the wheel, or damage to the ID walls of the hub due to rust, but if it's the former the above might help.  That would assume that the hub is flush with, or extends past the sides of the grindstone so they would contact the vise...   I can't remember what it looks like.

Anyway, just an idea.  Might save you a new grindstone.  Hope it's helpful. 

[Rob]

building on that idea, why not turn a wooden hollow bushing with the internal diameter a hair wider than the bore of the hole in the stone.  Then the thing you don't want to break away from the stone will be supported through 360 degrees and hopefully, in your vice scenario, just the shaft would exit on the application of persuasion!

[Herman Trivilino]

I wonder if wrapping a band clamp around the outside of the grindstone might help prevent it breaking.

I wonder how effective the new stainless steel shaft is in preventing this problem.

Of course, once you break a grindstone getting it off and pay for a replacement, you get a bit more diligent at keeping it from ever happening again.   

[grepper]

Or a washer or pipe just the right size, or some combination of all of the above.  Anything just to support the hub and the grindstone at the same time.  I suspect it's important that the grindstone be supported too, as it is heavy and it's own inertia or lack thereof could cause the hub to tear from the grindstone when tapping and bashing and mashing on the shaft.