Thread: Ways to remove stubborn set screw in motor pulley?

You have got 2 grub screws holding ,make it a sliding fit and secure with only the grub screws,if concerned put another grub screw in put 2 grub screws together, don't use loctite.

It's not that I want to use loctite, heaven forbid after wasting 3 days due to some fool who has used it. I think it's now a fair bet it wasn't a factory decision done because of some known issue, rather it was just some whacker who likes putting loctite on everything.

It's that in reassembling it, to make a nice job (though why waste more time is also a good thought), it seems to me that the pulley is too tight a fit on the shaft. A push-fit would be nicer. So, since it's a fine tolerance to go from the current force fit to a push fit, I'm wondering if to use valve-grinding paste to lap the pulley onto the shaft. Or not, since it might just have the effect of bell-mouthing the pulley and/or tapering the shaft, rather than giving me a uniform 1 or 2 thou reduction in diameter.

I don't think lapping is an option. Do you know anyone with a lathe in Canberra? I think there's at least one forum member in Canberra. Would be a fairly simple job.

Do you have the ability to measure everything so that you have a starting point?

I have a lathe and micrometers here. I thought given that it was such a small amount to take off that it would be easier to use lapping paste. But I can set it up in the lathe and take a very light boring cut in the pulley.

Measure it and see what needs to be taken out, you might be able to knock it off with a bit of emery or a fine flap wheel.

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Well anyhow while we were discussing that, I was trying to get off the pulley from the cutting head arbor. Drilling out the grub screw (once again, heat did nothing) I noticed again green loctite/whatever glue come out in the swarf. The pulley won't move with heat/puller/impact. I'll have to cut that one off with a 9" grinder. BobL might be right, brick dust water might have gotten into that one. Anyhow, it's tougher than the motor pulley was.

So I'm thinking the replacement might as well be taperlock pulleys. They don't seem too expensive in that size (about 80mm OD). Am I right that I wouldn't need to worry about matching the keyway size, because I can do without a key?

Originally Posted by Gunnaduit

Well anyhow while we were discussing that, I was trying to get off the pulley from the cutting head arbor. Drilling out the grub screw (once again, heat did nothing) I noticed again green loctite/whatever glue come out in the swarf.

Nickel plating is often used as an anti-corrosive coating and nickel compounds are often green. Nickel won't last indefinitely under the caustic nature of masonry dust.

19mm would be 3/4 imperial. I think metric motors are 20mm...but i stand to be corrected....i dont have the data in front of me as i am using phone

Originally Posted by eskimo

19mm would be 3/4 imperial. I think metric motors are 20mm...but i stand to be corrected....i dont have the data in front of me as i am using phone

Both shafts at the pulley are 19mm / 3/4". I'm probably looking at taper lock bushes type 1210 which are commonly stocked for 19mm bore.

Even though the motor is 'high torque', the torque calculated from rpm and rated power is only 5Nm, and the 1210 taper lock bush is rated 407Nm.

If that means the bush is still able to grip the shaft at 407Nm, then I can't see that I'd need a key for 5Nm. That's if I'm interpreting the specs correctly.

The thing is, those 19mm type 1210 bushes come with a 6mm wide keyway, and the existing shafts have 3/16" keyways, so to avoid hassle of re-milling the keyways, I'd go without a key if possible.

However that pans out, the two taper-lock bushes and two taper-lock pulleys combined cost about $40 all up, which is alright. Might even get away with using the old belts.

If I had my time again I would have got out the grinder 3 days ago and cut those pulleys instead of all this fuss - pay $40 instead of 3 days hassle.

Originally Posted by Gunnaduit

However that pans out, the two taper-lock bushes and two taper-lock pulleys combined cost about $40 all up, which is alright. Might even get away with using the old belts.

That's very cheap. Where are you getting that price?

Originally Posted by jack620

That's very cheap. Where are you getting that price?

Blackwoods website -- https://www.blackwoods.com.au (needs login to see prices).

And backup, PT Parts -- https://www.ptparts.com.au - but they work out to about $55 all up plus delivery.

Both give prices inc GST.

Originally Posted by Gunnaduit

The thing is, those 19mm type 1210 bushes come with a 6mm wide keyway, and the existing shafts have 3/16" keyways, so to avoid hassle of re-milling the keyways, I'd go without a key if possible.

How about milling one side of a piece of 6mm key stock to 3/16" (i.e. make a T shaped key)? Like this:

Step Key Oversize Tolerance Assortments | MAK-A-KEY

Originally Posted by jack620

How about milling one side of a piece of 6mm key stock to 3/16" (i.e. make a T shaped key)? Like this:

Step Key Oversize Tolerance Assortments | MAK-A-KEY

You're right, that would be much easier than remilling the shaft keyways. Thing is, if the motor torque is vastly less than what the taperlock can handle, maybe it isn't even necessary. I guess I'll know when it's all put back together and I take some cuts on the saw.

Hi Guys,

Originally Posted by Gunnaduit

I have a lathe and micrometers here. I thought given that it was such a small amount to take off that it would be easier to use lapping paste. But I can set it up in the lathe and take a very light boring cut in the pulley.

An adjustable reamer would help here !