linear motion two nested hollow cylinders

[kwfjr]

Looking for advice on a project I am working on. I have two cylinders one with a 6" diameter and a second with a 5" diameter. I need a simple solution for nesting the two to create linear motion. Both ends are open on the first cylinder and one end is open on the second. Both Cylinders are about 8-10" long. I am using a rack and pinion setup to move the cylinders. both cylinders are smooth walled. The interior cylinder needs to move in a linear fashion with a load on of 10lbs/sqin. The exterior cylinder is permanently attached to a production frame. The deviation of the interior cylinder isn't critical.

Does anyone have any advice regarding the material buffering the two cylinders. I want this to be simple . I was looking for a bearing strip I could epoxy to the cylinder walls, but have been unable to locate anything close. Does anyone have any ideas?

Thanks
Ken

 

[eromlignod]

Look at McMaster-Carr under "Teflon tape".

http://www.mcmaster.com/

Don
Kansas City

 

[kwfjr]

Thanks Eromlignod,

I am quite familar with Teflon Tape. I guess I wasn't clear. The inside cylinder needs to be centered. Note the Difference in cylinder diameters.

thanks
Ken

 

[eromlignod]

How about a solid teflon ring? You'd probably have to use flat head screws to attach it (with c'sinks below flush) since Teflon doesn't glue very easily.

Don
Kansas City

 

[unclesyd]

If tapes will work you might look around this site.

http://www.cshyde.com/tapecat.htm

 

[MadMango]

Teflon or acetal should be easy to machine and make work for this. They could be either rings or simple strips arranged 120deg around the the space between the two parts. Check out www.mcmaster.com.

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[rb1957]

what is the ID of the 6" tube ?

how often does it need to translate ? (service life)

what limitations on maintenance ? (would striping it down once a year be a problem ?)

how much overlap is left between the cyclinders at their maximum extension ?

 

[tlee123]

My guess based on the OP's second post is that the ID of the large cylinder is 6" and the OD of the smaller cylinder is 5". So if we're talking about a radial clearance of 1/2", tape is not appropriate.

Why do you need a guide at all if the inner cylinder is already guided by whatever is supporting your rack? Or are you looking for some type of crude piston seal?