Delta Milwaukee 6X48 refurb drum question

[Janderso]

Hey all,
Question,
Were these sanding drums crowned?
If so which one?
I added a pic showing no crown on the lower and I also checked the upper - no crown.
This early finish sander has seen better days but, it's still got some life left in her.
It had the wrong motor, 3,450 RPM. I guess that explains the small pulley on the drive side.
I am just about done with it but before I mount a belt and start fiddling with tension and adjustment I want to make sure I don't need to take it back apart and put a crown in one of the drums.
Thanks for your help!
Jeff

 

[Cadillac]

Your drums look to be in good shape with no wear marks so I would say they do not have a crown. The upper drum should have provisions to tilt the drum for tracking the belt.

 

[Janderso]

I didn't know if the tracking guide was all I needed. I had one of these before that kept it's track well once it was dialed in but it was in much better condition.
This one is for my son's wood shop.

 

[talvare]

Jeff,

I rebuilt one of these Delta Rockwell sanders quite a few years ago. I fought with belt tracking for about 10 years until I finally decided to check to see if the pulleys had been crowned. Zero crown. I put the upper pulley in the lathe and turned a 2 degree taper on it and have never had to adjust the tracking since.

Ted

 

[Larry$]

I think you will find tracking difficult if there is zero crown. Only one end needs a crown, don't know that it matters but would pick the idler end myself. I just made new wheels for a small sander and put 1+- degree on each side of center. I didn't carry the crown all the way to the center. I left a "blend" area. Tracks great. I have two older 6 X 48s, both have crown. A belt will always try to "walk" to the high side. Center, on an evenly crowned accurately adjusted machine.

 

[Janderso]

Larry and Ted, I tend to agree with you. It just makes sense.
I'll have to pull it apart again. The lower drum is easier to remove. By the way, left hand threads on the free end. Ask me how I know

 

[projectnut]

Jeff,

I rebuilt one of these Delta Rockwell sanders quite a few years ago. I fought with belt tracking for about 10 years until I finally decided to check to see if the pulleys had been crowned. Zero crown. I put the upper pulley in the lathe and turned a 2 degree taper on it and have never had to adjust the tracking since.

Ted

I would agree with the 2* crown. I have a circa 1955 Rockwell Delta machine that has a 2* crown on the idler roller. In my case the roller is a 2 piece affair. Looking at an old parts list it gives the description as" Part number 406-03-362-0003-Idler drum (pair)"

 

[Janderso]

I would agree with the 2* crown. I have a circa 1955 Rockwell Delta machine that has a 2* crown on the idler roller. In my case the roller is a 2 piece affair. Looking at an old parts list it gives the description as" Part number 406-03-362-0003-Idler drum (pair)"

Yeah, it's a two piece. I think I found this one is circa 1949 based on the serial number.
2 degrees. Thanks

 

[Larry$]

Two piece! Does that mean the bearings are located near the centerline? Old craftsman ones had diecast idlers that had bearing mounted deep inside to make die casting possible. Bad design! bearings should be located as close to the ends as possible. Tricky on the bearings also, ID was imperial, OD was metric, not available from bearing supply houses, only Sears.

 

[projectnut]

Two piece! Does that mean the bearings are located near the centerline? Old craftsman ones had diecast idlers that had bearing mounted deep inside to make die casting possible. Bad design! bearings should be located as close to the ends as possible. Tricky on the bearings also, ID was imperial, OD was metric, not available from bearing supply houses, only Sears.

If you look at the first picture in the first post you can see the bearings are on the shaft outside the drum. The shaft extends through the drum. The assembly is mounted in a yoke with a bearing on either end of the shaft.