Simple Shaft fit question

[Gorpomon]

I have a shaft, 2-7/8"OD that rotates @ 60rpm and several ft.-lbs. of torque.

I want to slide over that, a second metal tube. This metal tube will attach to the rotating shaft via set screw. What should the ID be of this second tube be? I was told to try and find 2-15/16"ID, but as far as market availability goes I can only find 3" ID, will the 3" ID work given my few requirements below?

The second piece of tube will be frequently slid on and off the rotating shaft, however I want the set screwed tube to hold firmly to the shaft, so I'm worried the 1/8" play I talked about above will be too much. Materials are all low-carbon steel, with no lubrication being used, and use of lubrication would like to be avoided so as to not get it on nearby sheet material. The tube will need to be 54" long, and occasionally we'll use a longer 76" tube.

If there's other information you need, please ask and I'll get it to you ASAP.

Any help is sincerely appreciated.

 

[byrdj]

how about 3 set screws per plane with several planes along the lenght. thus two screws will set the outer pipe to be concentric and the 3rd be the clamp.

 

[boo1]

would a coating like HDG help?

 

[dvd]

How about welding a 2-7/8" shaft collar centered on each end of the available tube?

 

[Tmoose]

does the outer tube recieve the torque? are there any radial or axial loads? How long must this run, transmitting torque?

 

[Gorpomon]

Thanks for your input everyone. I haven't considered welding a shaft collar on, I'll look into that. The goal of this machine is to roll sheet onto the outer tube, and as it can get quite heavy the shaft is rotating with several foot pounds of torque to ensure sheet keeps rolling up on to the outer tube.

I really just want to know if anyone has seen from experience that the 1/8" play makes this idea unworkable. Currently there are cardboard tubes with the 3" ID on the shaft, but we have trouble bonding them to the shaft so I want to use metal tubes with set screws. Those 3" cardboard tubes don't really seem to have an issue with play when rolling up or taking down sheet, but I just wanted to confirm if this might be an issue using metal on metal.

 

[MintJulep]

Consider something like a Fenner Trantorque keyless bushing.

http://www.fennerdrives.com/keyless_bushings/trantorque_gt.aspx