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"
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!
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
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.
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Building: Run 2 ltr Black Top in single seater race car.
posted on 27/2/18 at 10:29 PM
quote: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
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....
quote: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
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....
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.
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Building: Run 2 ltr Black Top in single seater race car.
posted on 28/2/18 at 08:31 AM
quote:Originally posted by 907
quote:Originally posted by redturner
quote: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
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....
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...
