bent tubing

[Ana M. Lopez]

I have designed a piece that requires short 90 degree bends in 1/2" dia. silver tubing and I refuse to cast them. After trying commercial tubing benders, the two handled kind and spring wire kind, I tried filling seamless tubing with pitch and then lead and repeated the attempts. I am currently fabricating them in two parts from synclastically and anticlastically raised elements, which is working. However, I wonder if there is an easier solution and welcome any suggestions.

Cheers,

Ana

[Ann Davis]

Hmmmm I've never tried to bend a 1/2" tubing to 90'!! in the smaller tubing I put annealed copper wire as a support through tubing but I've never even done that at 90'  Two parts sounds good...boy if someone knows better I will be glad to learn the answer!!!!!

[Sean Macmillan]

I woul approach this like you are bending a spiculum.  If you hammer the tube to be an oval that is widest in the direction of the turn, as you bend it, it goes back to being round.  I  imagine that this will not be a quick process.  Take your time and anneal often.  I would also reccomend that you bend as much with your hands to spread the force along the bend, instead of focusing the force in one spot on a tool.  How thick is the wall of the tubing?

[Pal Gooz]

Why not cast?  It is hard for me to imagine the magnitude of the challenge. Would you mind telling the other dimensions of the required component?

[2Roses]

We'd do it on a hydraulic press. Carve the tube shape in an acrylic die and press a sheet into it to form half the tube. Repeat with another die for the other half. Solder together.

[marcus marguillier]

Probably my solution is too simple, but did you try filling the tube with sand before bending ?

[Brigitte Martin]

Marcus, this would have been my approach too.

[The Justified Sinner]

There is a commercial tube-bending spring available for plumbers, which you can use, depending on your wall thickness. This is the first link I came across, so it is only to give the idea.

http://www.carairconditioningsupplies.co.uk/caraircon/product.php?p...

 

I have used one of these on reasonably thick brass tubing and it works well.

[Ana M. Lopez]

I'll post a pic when I have finished those parts, which should be today. I attached an image to my original post that should give you a better idea of the shape I am trying to make. I appreciate all the suggestions!

 

Sean - I might try the oval/spiculum thing next time. I could make the wall as thick or thin as needed.

 

Pal - The reason I am not casting is stubborn-ness. I am replicating an existing object in miniature and am determined to do so with metal-forming skill set alone.

 

2 Roses - I thought about the press since I have one but was worried about how deep I would have to go past the 1/2" depth to accommodate the loss of the flared part near the flange. Then again, I would be ready for the next time already. Plus I think I would have had to carve a positive to act as a pusher, and its always a toss-up of the best way to utilize one's time.

 

Marcus and Brigitte - does sand work better than pitch and lead? I have never tried it. 

 

Justified- Yes, I tried those kinds of tubing benders, but they couldn't get the sharp turn I needed.

 

Thanks all!

[Ana M. Lopez]

This one was done by making thick (16 ga) fine silver tubing, notching the bend, then welding and filing. I am actually much happier with this one.

[Ana M. Lopez]

This one is done with the anticlastic and synclastic raising I told you about.

[Pal Gooz]

It seems to me that you managed to come up with a new solution ( well, actually two). That notching and welding seems like a nice one. Thank you for posting the question! On my part I learned a lot. I only tried something similar once, that time I formed the two parts - length wise - by chasing ( in pitch ). I guess that could also be called the poor man's alternative for die pressing:)

[Jennifer Dewey]

Wish I had thought of the notching and bending when I had a mind bending project years ago... a client wanted me to try and make a Klein Bottle (blown in glass typically) out of sterling... involved raising, bending, etc... after several attempts I had to decline the project... still haunts me - LOL