belt pully crowning 1

[jamesfd]

Im building a drive system with sync. belting and I'm looking for some info about tracking. I know that a belt will try to find center on a crowned wheel but does it have to be radiused or can it just have a taper.

 

[Tmoose]

The synch belt people want 2 flanges somewhere on the pulleys/sheaves.
Some of our timing belts (mounted on shafts with real good alignment) have had a noticeable tendency to "track" one way or another, and flipping the belt reduced or even reversed the tendency to track. I think the manufacturer's catalog mentioned flipping as sometimes necessary to correct tracking issues

Flat belt pulleys are often crowned a little for good tracking (specs in machinery handbook, among others) but I'm not sure timing belts, which tug on the pulley major diameter, would like

 

[jamesfd]

Thank for the response,
I have a flanged drive pully but the two tention wheel are smooth and run on the back of the belt. the arrangement is for a linier drive with the belt stationary and the drive moving along it's length. I'm having trouble keeping the belt centered and tracking straight. I presently have guides on either edge of the belt to keep it in line. this is working well, but I'm concerned about wear to the belt edge over time and would like to find a more precise method. the tention wheels are turned from 120mm 6061 and are 40mm wide. I can place a slight taper to crown them but I don't have the tooling to radius them. I was wondering if anyone knew if this would work.

 

[EdDanzer]

It will depend on width to thickness ratio, alignment of the pulleys and amount of crown. Before crowning, try adjusting alignment. The shafts need to be parallel in two different planes to start. If running on edge or always running to the same side, angle the shaft so it is wider on the side the belt wants to run off and you may be able to keep it centered. If that fails having a centered taper may help of the belt is not too wide in relation to the width.

 

[jamesfd]

The belt that I'm using is 25mm wide and 4.5mm thick. My shaft alignment is parallel and stable, yet the belt tends to wander radomly, this is what lends me to believe that crowning might be the solution. I guess my main question is do you think a centering taper would suffice or dose it accually have to be a radused crown.

 

[EdDanzer]

Your belt is thick in relation to the width. A centered tapered crown may work. Conveyor belt pulleys use a 1/16” per foot taper.