MetalworkingFun Forum

Hey guys and gals. 
 
New here and was hoping maybe someone has some experience with a problem I'm having.

I have a project I'm working on which requires making an offset consisting of two tight 90 bends in 5/16" 4130 series round rod. The total offset being 9/16"

The rod is part of a linkage and must pass through a plastic bushed hole with as minimal clearance as practical.

I know that conventional forming says that the inside radius should equal the rod dia. However this does not provide the minimal clearance required.

I am looking at hot forming to obtain the inside radius required without over stressing the material.

Does anyone have process experience or experience with setting up some type of equipment that can aid in a repeatable offset of decent quality.
 

I've no experience, but off the top of my head something like a flat bar bender with a groove machined in the die and also on the moving die should allow you to go quite tight without flattening the round profile of the stock. I'd think with a couple of suitable stops it would be pretty repeatable.

Steve

In any metal requiring that tight a bend, I'd be inclined to go with forging. Cherry red, hammer it over the edge of the anvil, reheat and repeat for the other bend. It may be advisable to 'upset' the bends slightly, if full strength of the 5/16" stock is required. After forging, heat it again and allow it to cool slowly to relieve stress. Then, if required, harden and temper to suit the desired characteristics.

Hand / Hammer forging is not an option. This is for a series of production quality test market samples. The parts are highly visible and cosmetic. Repeatability is a primary factor.
I have posted the same query on other forums also. I think I have been presented a solution.

Thank you Steve and Mike for your input.

Hot forging with a die is probably your best bet.

(02-06-2018, 06:57 PM)Mike s. Wrote: [ -> ]Hand / Hammer forging is not an option. This is for a series of production quality test market samples. The parts are highly visible and cosmetic. Repeatability is a primary factor.
I have posted the same query on other forums also. I think I have been presented a solution.

Thank you Steve and Mike for your input.

Care to share the solution?

If there's room, you could drill a plate made from 1/2" x 1/4" at the required offset. (You said 9/16" offset - is that on centre?) The straight rods can be inserted into the plate from opposite sides and TIG welded in place. Easy production method.

(02-06-2018, 06:57 PM)Mike s. Wrote: [ -> ].....I have posted the same query on other forums also. I think I have been presented a solution.

We'd sure like to know about the solution to this difficult problem;  could be useful to some of us in the future.  Many thanks !

I'm a little late to the party, but since it's a production part, a Z shaped bending/forming die would be worth the effort. It could be angled so that both bends started at the same time and would require the mating parts to have a 5/32" radius on them to keep from flattening the rod. Small die sets are available from McMaster Carr.

Tom