Useful Tools

[shocwav3]

I am attempting to make a 180 degree bend in some aluminum tubing 5/8 (.032 wall) dia with a 1.5 CLR. I have used sand successfully but I need to potentially make hundreds of these.

In my quest to find a quick, economical, and effective way of doing this I found this guy-

http://www.useful-tools.co.uk/our_products.html

I have yet to find a mandrel bender in the price range, never mind that it looks like a quality made tool.

Anyone have anything from here? or have any experience with the tooling?

Looks like it could be a real viable option for my purpose.

 

[Kevin54]

Being a Toolmaker and Designer I have made benders for tubing of different styles and sizes. I've done the sand, frozen water, and so on with limited success. I had to come up with a way to bend some one inch aluminum tubing so that the tube did not deform at all and had to retain the roundness within .005. I took two aluminum blocks and I cut the radius of the tube in each side so that when the halves were put together, they had the roundness and correct angle of the tube being bent. It worked perfectly. The only downsize was the time it took to unclamp the halves to remove the tube. The tube was pushed into the form using an arbor press.

 

[shocwav3]

I have used press dies with great success when forming sheet and solid stock, I never really considered using it for tubing though. I would probably have to bend in progressively with 2 or 3 dies sets since my final result is a "u" bend.

 

[theoldwizard1]

I am attempting to make a 180 degree bend in some aluminum tubing 5/8 (.032 wall) dia with a 1.5 CLR. I have used sand successfully but I need to potentially make hundreds of these.

Get yourself a cheap bender and then make a die set like Kevin4 suggested. After making the bend, lock it in the die set and apply high pressure (water or oil). Not sure what pressure would be required but .032 Al shouldn't be too crazy.

 

[Guster]

I had to bend some similar tubing into an s-bend style curve. My mandrel benders were all to large to allow me a second bend so close to the first. I tried something one of the local toolmakers mentioned when doing a small run or complicated one-offs. They make the formers out of quality MDF and soak the working surfaces with epoxy resin being careful to avoid runs and drips. They had long since made a holder that allows them to add the MDF former into a steel press brake frame. Allows them to make fast cheap dies for their hydraulic press... get 'er done!

Couple of weeks ago I needed to put a sharp bend on 22mm alloy tubes that had a EVA foam covering. It would not fit the mandrel bender due to the foam and the larger size die would damage the foam and crush the tube. Time to rifle through the offcut bin. Thanks to the large supported surface area the foam was not damaged and the tube bent beatifully.

 

[theoldwizard1]

I had to bend some similar tubing into an s-bend style curve. My mandrel benders were all to large to allow me a second bend so close to the first. I tried something one of the local toolmakers mentioned when doing a small run or complicated one-offs. They make the formers out of quality MDF and soak the working surfaces with epoxy resin being careful to avoid runs and drips. They had long since made a holder that allows them to add the MDF former into a steel press brake frame. Allows them to make fast cheap dies for their hydraulic press... get 'er done!

So you just pressed the end of the tube in to the "die" ? Any kind of lube used ?

Hard to believe that the tube did not kink outside of the die from the pressure and that the leading edge of the tube did not catch on the epoxy surface.

Now a days, you could make some dies for a job like this with an inexpensive CNC router table ! Yes, router ! Carbide cutter, slow feed, minimal cut depth, multiple passes.

 

[theoldwizard1]

Even simpler !

Buy a cheap mandrel bender and bend the tubing leaving the ends long. Make an MDF "die" as described and mount it in an arbor press. Here is the cool part !

Get one precision ground steel ball bearing, ground to the exact ID of the tube (Kevin54, what would the tolerances have to be ?) Placing the pre-bent tube in the die and arbor press, insert the "precision ball" (with lube) into tube and press. Use slightly smaller ball bearing to push the "precision" ball all the way through.

Not fast, but cheap and precise !

I just remembered seeing this on "How's it Made" for making brass musical instruments.

 

[OccupantRJ]

If your bender does not utilize something inside the the tubing during the bend process, it is not a mandrel bender. The mandrel is a mechanical device used inside the tubing or pipe to hold internal diameter, shape, and to prevent distortion. It is withdrawn after the bend is made, or either the pipe repositions over it until the next bend in a series is made. One type of mandrel looks similar in design to the ball chain used on a sink stopper. The balls curve as the pipe or tubing is bent, and can be withdrawn afterwards as they are flexible.

 

[Guster]

In the case of the S-bend the tube was pressed between two formers following the contour of the bends. The CLR was about 1.5" though the bend was only 30degrees. with about 2" between centres of the bends(ie. like the bend on a bike handle bar) The formers had halfrounds machined using a router on a routertable.

I've also done small CLR bends with small tube using a rotary draw method using MDF formers too. 5/8" is pretty small and tends to be less prone to crushing depending on the material. Good to anneal alloys before bending anyway as tubing may be work hardened when it was drawn. Also varying success between alloys despite annealing.

The epoxy simply binds the surface of the MDF to prevent it splitting, especially on the sides of the former on the working surface. Once cured is very smooth and can be sanded smoother if needed. Any good quality hardwood wood have worked except for the cost and having a supply of offcuts handy in the right sizes to be useful. Many outfits in my area have large chunks of MDF in their skips out back. Since I do a lot of composite work I always have bits of resin spare and a small amount goes a long way.

The only reason I mention it is to the 'quick and economical' part of the OP request. Nylon and aluminium are easily machineable alternatives too. Since most people have woodworking tools MDF is an easy option. For building a little bend former like the one originally listed you will still need some metal parts like the pivots and the frame between the die pivot and the wiper or follower die so some 'experimentation' will be implied and a solution will depend on tools at hand.

 

[OccupantRJ]

Even simpler !

Buy a cheap mandrel bender and bend the tubing leaving the ends long. Make an MDF "die" as described and mount it in an arbor press. Here is the cool part !

Get one precision ground steel ball bearing, ground to the exact ID of the tube (Kevin54, what would the tolerances have to be ?) Placing the pre-bent tube in the die and arbor press, insert the "precision ball" (with lube) into tube and press. Use slightly smaller ball bearing to push the "precision" ball all the way through.

We use this process at work occasionally to correct tubing deformity during some tube dimpling operations. A carbide ball is used for wear resistance.

 

[fredybender]

Hey, your tubular A arms are on my car... Modified a bit, but still going strong!
I recognized your screen name
Cheers!
Fred