Delta 6X48" belt sander

[Ed T]

I have most of two Delta 6"x48" vertical belt sanders. One was trashed at work when it tipped over and broke the table trunnions and one is from a school auction for $35. On both machines, the aluminum upper drum that the belt runs on is worn out and it is a part that delta no longer supplies. So, my plan is to make some new ones. I have two questions:
1) Are the drums cylindrical or barrel shaped? I think they are cylindrical so that the belt tension is uniform across the width of the belt, but I'm not sure.
2) For ease of fabrication, my plan is to make the parts out of steel, but I was wondering if the aluminum originally used had something to do with helping the belt to stay cool or was it just the cheapest way to go. Could do aluminum, but steel would be easier.
Any thoughts?

 

[kf2qd]

Pulleys are made from Aluminum because it is easy to die-cast. Pulleys can have a slight crown, otherwise it is impossible to keep it centered on the bed.

 

[Hilmar]

I have one and the pulley is Alu and straight.
Hilmar

 

[4156df]

The drum should have a slight crown. You can find information on re-crowning, plus more than you'll probably ever want to know about Delta sander drums on this site.

http://wiki.vintagemachinery.org/Delta6x48Drums.ashx

Dennis

 

[Tin Falcon]

I have a grizzly. I can look at it. a slight crown on the idler makes sense.
Tin

 

[Omnimill]

I have a 6x48 and it has steel barrel shaped rollers.

 

[Tin Falcon]

looks like about a 1/32 crown. use tube or pipe.
Tin

 

[Ed T]

Thanks for the feedback guys. It looks like the majority input favors a slight crown or at least that the middle is a little bigger than the outside edges. Not so hard to do since the OD will have to be turned anyway. Interesting web site.
Thanks again.