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PT problem

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Steliz

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I have a problem with my Record Power PT260. It is a similar product to other planer/thicknessers that were available under different badges.
The rollers stopped working so I checked the back of the machine where the motor drive shaft is connected to a pulley wheel by a belt. Sure enough, the belt was knackered but only in one spot where it touched the drive shaft as the pulley wheel had not been rotating and was also very wobbly. The reason for this was that that the wheel should have been rotating freely on it's metal pin but wasn't and it has damaged the fixing point by turning a round hole into an oval one!
I removed the pin from the wheel, which took a great effort, with the intention on freeing it up and putting it back but the fit is so tight that I think some other fettling is needed. The wheel has a brass lining and the pin is steel (see pic).
imgonline-com-ua-CompressToSize-wScc0I23ufcV.jpg

Has anyone encountered this problem themselves? What would be the best way remove a little material to make this work while not compromising the roundness of the parts? I thought I could do it on the lathe with some sandpaper.
 

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Trevanion

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I'm not sure if I'm following correctly Steliz, I've read the post a few times now and I don't fully understand, are you saying the bronze/brass bushing inside the pulley wheel has worn to an oval shape?

It looks like the plastic wheel has also melted a bit, perhaps some of the melted plastic made its way between the bushing and shaft which made it seize in place after the plastic cooled down? If that's the case you might just need to clean the inside of the bore and the outside of the shaft and they should go back together.
 

Steliz

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In the picture, the thick end of the pin goes into the wheel and the thin end goes through a (now oval) hole in the PT casing. Sorry for being unclear. There's no melting, just dirt.
 

Trevanion

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Ah, I think I've got it now, so the shaft is supposed to be stationary and is held in its place by a nut clamping it to the machine but the fact that the wheel had seized onto the shaft meant that the shaft spun in the casting instead which caused the oval hole?

I would say to do what I said in my original post, give the shaft and the bore of the pulley a good non-abrasive clean with something like scotchbrite or a brillo pad to remove the dirt and see if that helps. It was working at some point before so surely it's got to be able to go back together so that it spins on the wheel without removing any material.
 

Steliz

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Yep, that's it exactly.
My intention is to give it a good clean and see if it helps. It was such a tight fit and it didn't look particularly dirty once separated so I wasn't expecting to achieve much by cleaning but, I'll see.
 

Trevanion

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They would be a very close fit because you really don't want the wheel loose on the shaft as it will cause vibration. The size of the shaft and the size of the bore should be exactly the same, any dirt would compromise the fit and it will seize.
 
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