I have a couple of jobs coming up that would benefit from being able to bend tube. First one is to make up a section of exhaust to adapt one system to another (2.5" tube). The second is to bend some custom water (coolant) pipes. I guess these are about 1.5" diameter.

I don't fancy my welding skills enough to make either out of pre-bent sections and not have them leak.

In fact the coolant pipes are currently made from steel sections joined with flexible hose bends and they do seem to leak!

The likes of Machine Mart sell '12 tonne' pipe benders that can bend up to 2" tube. They don't specify a maximum wall thickness but the second page of the manual suggests that a 'medium to heavy' tube would have a wall thickness of 3.5mm which is plenty sufficient for my use. The only problem with the Clarke one from Machine Mart is that the mandrels only go up to 2" and my exhaust is 2.5"

Link to manual: https://dccf75d8gej24.cloudfront.net/documents/CHV12%20PipeBender.pdf

This one on ebay however (ebay link) comes with mandrels up to 3" and claims 16 tonne of force although whether I believe that I'm not sure.

OK it's a (probably) Chinese knock-off but these are just a bottle jack in a frame so 'how hard can it be?'. I guess worst case the mandrels could be poorly cast or perhaps the jack used isn't up to bending as thick tube as the Clarke one but for just doing the sort of jobs I am thinking of my guess would be that it is sufficient.

So, has anyone got any experience of these cheap tube benders? Are they just as good as the branded ones?

Or in general, how difficult are these tools to use? I'm guessing there is a knack to positioning the tube in just the right place to get the bend where you want it?

Any experiences you want to share are gratefully received!

Chris

Hi Chris

Those pipe benders are for thick wall nominal bore pipe, not for thin wall o/d tube.


Pre bent mandril bends are the way to go and then weld to straight pieces to complete.



Some one down your neck of the woods will weld them for you I'm sure.


Cheers
Paul G

First of all the die sets are for pipe not tube, they can bend heavy walled pipe, but I found anything less than 5mm the pipe just collapsed. So no is the answer for thin walled tube for an exhaust

David

Thanks for the replies. That could have been an expensive mistake! I was assuming those cheap pipe benders would have a maximum wall thickness not a minimum one but it does make sense in hindsight that they will just crush a thin walled tube.

OK, back to the drawing board then

i am making my exhaust up from bits ordered from every exhaust part i have ordered everything with a swage so welding is made easier and its 3"bore

This guy did an interesting video on the cheap ebay style pipe benders:


Seems to be a bit hit and miss,

Hope that helps.

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Originally posted by ChrisW
Thanks for the replies. That could have been an expensive mistake! I was assuming those cheap pipe benders would have a maximum wall thickness not a minimum one but it does make sense in hindsight that they will just crush a thin walled tube.

OK, back to the drawing board then

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Originally posted by redturner

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Originally posted by ChrisW
Thanks for the replies. That could have been an expensive mistake! I was assuming those cheap pipe benders would have a maximum wall thickness not a minimum one but it does make sense in hindsight that they will just crush a thin walled tube.

OK, back to the drawing board then

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If you don't have access to a mandrill bender then why not fill the pipes for bending with silica sand and weld a cap in either end. The sand must be really packed tight and you shouldn't get any collapse....

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Originally posted by 907

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Originally posted by redturner

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Originally posted by ChrisW
Thanks for the replies. That could have been an expensive mistake! I was assuming those cheap pipe benders would have a maximum wall thickness not a minimum one but it does make sense in hindsight that they will just crush a thin walled tube.

OK, back to the drawing board then

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If you don't have access to a mandrill bender then why not fill the pipes for bending with silica sand and weld a cap in either end. The sand must be really packed tight and you shouldn't get any collapse....

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Tube (thin wall) has a totally different sizing system to pipe (thick wall) so even if filled with sand, sand & candle wax, or cerrobend, tube will not fit a pipe former.

Pipe is often joined by threading, so the o/d of the pipe will always match the threading die, BSP or NPT, British Standard Pipe or National Pipe Thread (USA).
The o/d stays the same and the i/d changes as the wall thickness differs, hence its referred to as Nominal Bore.

Example:- 2" tube is 2" (50.8mm) o/, where as 2" pipe is 2-3/8" o/d, (about 60mm) so 2" tube would not fit a pipe former no matter what it was filled with.


HTH
Paul G [/quota

A few weeks ago I watched a friend who makes exhaust systems for a living, bend some aluminium pipe to be use for water rails on a historic racing car. The pipe was 1 1/2" o/d x 3/16" ish wall. This was in his normal pipe bender which he uses for exhaust systems. This has the same type of dies as the one shown in the pictures. We have a large hydraulic bender at work which will bend thick wall pipe up to 90degrees (for fencing) without a problem and a friend bent me a piece of CDS2 to make a new roll hoop for the single seater, Complies with MSA BB without any kinks / ovality...

[Edited on 28/2/18 by redturner]

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