Belt sander tracking

[BigMike782]

I bought an unfinished shop made 2"x48" two wheel belt sander from a co-worker. It has a rubber drive roller and an aluminum idle roller. I got it finished and working but it has an annoying habit. I can have the belt tracking adjusted and working great and all of a sudden it will take off to the left. I readjust, it works great and then takes off to the left.......ideas?

 

[zkling]

A picture of the unit would help. Are the wheels coplanar? Does one have a slight crown? Proper belt tension? What method does the tracking system use, a tilt or a twist of the idler wheel?

 

[Guster]

Tried other belts? Some belts just wont stay on... had one with a bad joint that would jump off like that. Flipped it the other way round - opposite of what the arrows showed - and it worked well enough to use it up till I can replace it.

 

[Jere]

it might be the belts or the rubber roller getting too much heat and changing shape. I have a cheesy hft belt sander and the belt tracks to either side depending on the side I am sanding on.The plastic rollers and cheap belts seem to deform just enough to mess with tracking with heat. mostly the case sanding metal, with cooler stuff its not an issue.

 

[toolchaser]

Does the idler wheel have any crown?

 

[powerwagon63]

What tool chaser said.

Run a strip of tape around the center of the idler wheel this will help the belt track.

 

[kazlx]

x3 on a crowned roller. If not, you will have a problem keeping the belt tracked with thinner belts.

 

[BigMike782]

The idler does have some crown to it, the bottom(drive) is straight and rubber.
Adjustment is by tilt.
Belt tension is by spring.
The puzzling thing is the issue is not consistent, if it was I could probably identify the cause.

I don't see pics happening......I am pretty stone age electronics wise(flip phone,dial up, reeeally old camera).

 

[kbs2244]

I would guess that the vibration of running is either tightening or losening you adjustment.
Is ther some kind of lock on it?