Metal rod bend 90 degrees inside metal tube. 2

[knauf]

Suppose I have a stainless steel rod (D = 1/8 inch) and stainless steel tube (D = 1/4 inch), and I need to bend them. The catch is: I need to bend everything with the rod inserted inside the tube. When the bend is done, there has to be a clearance between a rod and the tube. If anyone has a suggestion, please do share. I know for sure that this kind of procedure can be done. And as far as my understanding goes, there should be used some kind of insert to work as an interface between a rod and a tube during the bending process. Most likely made from plastic. Or am I wrong?!

Best Regards,
Anton

 

[MintJulep]

Wood's Metal aka Bendalloy.

 

[3DDave]

I second the low temperature alloy.

 

[JStephen]

Ice?
The foam stuff they use for ice chests just melts into goo when exposed to gasoline. An un-expanded version of that might be another idea.
Possibly wrap aluminum (or other soft) wire around the rod first, like a coil spring?
Or the same with monofilament line?

 

[SnTMan]

Few or many?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[EdStainless]

So when you are done you expect them to not touch?
I hope that there are not many bends and they are not tight radius.
You will need some permanent spacers, centralizers to keep the rod in the center.
The centralizers are often spiders made from HDPE or some other plastic compatible with your service.
I have also seen tubing filled with soft paraffin for bending.

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P.E. Metallurgy, Plymouth Tube

 

[handleman]

So when you are done you expect them to not touch?

This is a dang good point. When you bend metal you have to go a little farther than your target angle due to springback. I'd be pretty surprised if both the rod and the tube have the same springback angle.

 

[GregLocock]

I'd overbend the outer until the inner was at 90 degrees, and then bend the outer back until it didn't touch the inner. Probability of success with 1/16" clearance, just about zero!

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[handleman]

LOL Greg... Is that zero with or without the Bendalloy?

 

[SnTMan]

The trick is to know the inner is at 90 deg

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[knauf]

Thank you guys for sharing with me some thoughts on this matter! You've helped a lot. I appreciate it!