Left or right hand thread to retain pulleys?

[John G]

In the photo below, the belt and pulleys move clockwise.
So would the retaining screws in the centre of the pulleys be left or right handed?

35D6E114-B3EB-46DA-AFD8-7CAA1C7111AD.jpg
I have one of those generic cheapo disc and belt sanders, but my belt tracks all over the place.
On inspection, I think the bearings in the top pulley have gone, as there is rattle in that drum, and it is the vibration that ruins the tracking.
So I want to experiment with replacing the bearings which means disassembly, but the centre screw is stuck tight, so want to make sure I am turning the right way before I strip the head.

[havabeer69]

i would its a normal thread screw, its just done up tight or has some thread locking fluid on it.

[China]

Not trying to be rude, but on a quality item it should be left handed, but being Ryobi it is designed as a through away item, so as above most likely just thread locking fluid or just really tight

[Treecycle]

Do you have access to an impact driver? They are great for tight threads but as already said it should be a normal RH thread so turn it anti clockwise to undo.

[Chief Tiff]

Do the bolts rotate with the pulleys? If so the they are left-hand threads. If the bolts are axles that the pulley bearings rotate around they will be normal right hand threads.

[John G]

Not trying to be rude, but on a quality item it should be left handed, but being Ryobi it is designed as a through away item, so as above most likely just thread locking fluid or just really tight

That's ok, you can be rude. Mine is actually an old GMC, but I didnt have a photo so just grabbed this picture off the web.
These cheap units are all the same though.

Do the bolts rotate with the pulleys? If so the they are left-hand threads. If the bolts are axles that the pulley bearings rotate around they will be normal right hand threads.

The screws rotate with the pulleys.
I actually found an exploded diagram which labelled them M5 screws.

I've been trying to do the physics in my head.
If the pulley is being driven clockwise, I think that means it will try to tighten a RH thread... I think...


But now I am assuming the pulleys are keyed to the shaft and the screw is tapped into the end of the shaft just to stop the pulley sliding off (there isn't enough detail in the diagram to tell).
If the pulley is keyed then it wont want to make the screw rotate at all. Instead the screw probably has some thread lock to stop it vibrating off.

[Treecycle]

I believe your second option will be the correct one with the pulley keyed to the shaft and a RH threaded screw. Now just got to get it undone.

[John G]

Well I've totally buggered that up.

First of all I stripped the head trying to remove it...
Then I tried drill out the screw, but snapped off the screw extractor in the hole...
But at least by then I could dismantle the thing.

The good thing was the 12mm bearings seemed fine.
The bad thing was the rattle seems to be caused by the shaft being under 12mm. Where the bearing sits the surface seems pitted and corroded, and less than 12mm.

So although I have now ruined my belt sander, I take comfort that I can't fix it with a simple bearing swap, and that it was wrecked anyway unless I machine a new shaft.
It also would have been hard to reassemble, as there are lots of press fits used.

[China]

Vertical Linisher / Sander