how do i go on about bending circular tubes for my chassis?

right now i'm on the rear section and was thinking about the vice, but that will not do...

is there a locost way? i know i can buy a pipe bending machine or take the tube somewhere,

I tried and failed.

I ended up buying some scrap bends from a firm and cutting and sleeving them. see pic

I bought a cheap £12 plumbers tube bender.

It did work (with the aid of the heat from a blowtorch) and in the true spirit of Colin Chapman design, broke soon after finishing the last bend!!

Slot tube about 80-90% through at even distances on inside of bend. Bend. Weld up slots. Not the prettiest solution.

Down the tip and look for bed ends, broken climbing frames, old steel chairs infact anything made of 1"tube that has a bend in it.

For the top rail I used 3/4" tube and attacked it with my 22mm copper tube bender... just the job.

Regards Mark

We tried with a hydraulic bender...and failed.Several pieces of kinked tubing later, went to the airport & found a chap that bends tubes for airplane frames. Did a lovely job - if you chat someone up at an airport facility, they may just do it for you for nowt - helps if you show them photos etc. to get them interested in your project

Fill with compacted, completely dry sand (you don't want any moisture in there) and plug both ends (wood plugs), then use an oxy to heat and bend round something with the right radius. The sand stops the tube from collapsing.

I've seen a guy use this method to build a drag racing chassis from steel tubing.

interesting.... so i definitely need heat, something with the correct radius to bend,

i'll look for a plumbers tube
thanks!

Depending on the diameter/material thickness you might be able to bend it without heat. The sand will still stop it from collapsing though.

You can obtain really good and cotrollable bends in 3/4" 16swg round tube (and even square tube) using a bending beam. This is a piece of wood say 4 x 2 inches. Bore a hole through the 2 inch thickness of the same diameter as the tube. My beam is about 5 ft long and I stand one end on the floor and grip it in the vice with the hizontal hole facing you. Chamfer the lower edge of the hole front and back to produce a smooth curve that will allow the bent tube to be removed from the beam. Feed the tube through the hole to the point where you want to start you bend and then gently pull down on the tube. Feed it in a bit more and bend more. Offer the bend up to the template frequently and you will be amazed how easy it is. One further tip is to draw a straight line along the length of the tube using a piece of angle placed against the tube as your staightedge. This reference line will help you to keep your bends in the same plane.

I would attach a picture of my bending beam but despite my best efforts it will not upload. Anyway please feel free to ask if my description is not clear.

John

Thanks to the learned gentlemen from within the Group i can now attach a couple of pics showing the bending beam.


You need no sand and get no kinks. It is that easy I promise.
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam002.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam001.jpg

John

thats pretty straight forward!

so you put the tube in the hole of the bending beam, and you simply lever it down to bend it?

Yes that's all you have to do it really is so easy and if you have a suitable piece of wood, you can do it for zero cost.

Please let me know how you get on.

John

john, i tried this method...but no luck the hole in the wood got bigger and ultimately the whole thing snapped

as a last resort i did the cutting slots and bending which turned out great... but i have some doubts:

the slots have to be welded after right? i blew massive holes until i made it work.,..

do the slots have to be big, small, widely spaced, narrow spaced??

It really might be easier to just have a tube with kinks in it. They should get hidden uner the rear skin anyway. That or find some. I cut up an old bed frame/headboard thing and got 4 nice 90 degree bends in 1" 18swg tube.

I've been thinking, really dangerous, but couldn't you bend square tube in much the manner the book shows bending the windshield frame. Though you might want to make a bit stouter pieces.

Hi Robert,

My beam is hardwood. I thought softwood would work just as well but seemingly not. Do perservere because believe me it does work well. The tube needs to be a reasonably tight fit in the hole. I made a 3/4" hole with one of those flat wood bits that fit an electric drill. The lower part of the hole needs to be flared out downwards. The trick is to bend a little bit, pull the tube out half an inch and then bend a bit more and so on. A little bit at a time. Try to be precise and sensitive as you bend the tube. Don't try to just pull the tube down in one shot. If the tube sticks you need to chisel a bit more of the wood from the lower front edge of the hole. I have used this method to bend both 3/4" and 1" round tube and also 3/4" square tube as well. It is really useful for the tube on the scuttle and round the back of the car.

It is difficult to explain the tecnique without being able to demonstrate it but I can post some stage by stage pictures which i will do tomorrow. I hope that will help.

Regards

John

are these for back panel supports ??? , if so could bend a batch up in 19mm tube on our machine for a couple of quid which will be dead easy as i bend the stuff all the time Postage is the problem though, will be bending 19mm on tuesday next week if anyone wants one let me know what dimensions etc

best regards

marc

Hi Robert and everyone else interested in bending tubes.

First a big apology. My instruction was wrong. You gradually feed the tube into the beam and not out of it. The rest is ok but that is actually really important so sorry for that. They say a picture is worth a 1000 words so I've taken a few that might help the explanation.
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam001Medium.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam002Medium.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam003Medium.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam004Medium.jpg
http://i93.photobucket.com/albums/l57/bonnett_2006/bendingbeam006Medium.jpg

cheers

John

quote:

---

Originally posted by John Bonnett
Hi Robert,

My beam is hardwood. I thought softwood would work just as well but seemingly not.

---

quote:

---

Originally posted by robertst
john, i tried this method...but no luck the hole in the wood got bigger and ultimately the whole thing snapped

as a last resort i did the cutting slots and bending which turned out great... but i have some doubts:

the slots have to be welded after right? i blew massive holes until i made it work.,..

do the slots have to be big, small, widely spaced, narrow spaced??

---

.... dunno... i was using a short tube though. so the levering force was not too high...
the tube is 1.5mm by 20mm diameter.
if i use the 2 metre tube. it will bend... but i wont really have much control of the accuracy of the bend...

i'll try hardwood and your formulae in case of deep frustration

thanks!

Is this what you are all after? Did all the bends for my car, wishbones included, cost £1.50 at a boot sale - Ideal
Rescued attachment PipeBend.jpg

yeah i saw this pic of yours on an earlier thread... isnt that for fixed radii though? you get 90º bends, but which are really long right?

The bender shown in the picture will only bend one radius determined by the mandril. This is an excellent way of producing consistent bends say for the rear corners of the frame.

The bending beam allows whatever radius you require and by offering the tube up to a template you can accurately produce the bend you need.

The secret of success using the bending beam is bend a little bit, push the tube in say no more tha 1/2" and the bend a bit more and so on. If you bend too much in one go, it will distort and then you will not be able to push it in any further.

I'm sure everyone is totally bored with my rabbitting so unless you have any more specific queries, I'll shu up on this subject.

Best of luck with you bends

John

I bought a heavy duty pipe bender from e-bay. £12 delivered and it's new, guy sells loads of them but I would advise a little heat as it is hard work, unless you have arms like popeye, which I do.

A pipe bender is great but you are restricted to fixed radius bends because the radius is dictated by the former.

John

I'd think the pipe bender would work great for it's normal radius, plus any larger radius. Bend a little and push it along, bend again, push along...

I mean, how perfect does it have to be? Usually "perfect" isn't needed for our cars.

[Edited on 7/31/06 by kb58]

I have bent 3/4" (19mm) tube with just the vice and a blowtorch with great success to make anti roll bars etc, just heat a bit and bend a bit at a time, be gradual and controlled and its no problem.

I've just seen a guy bending half inch steel conduit with a pipe bender.

Try your local electricians, they might be able to bend larger sizes of steel tube for you

The attached picture shows bends that I made using a bending beam. There are no right and wrong ways to do things, you just find a way that works for you. For me, the bending beam is simple cotrollable and involves no cost.

http://i93.photobucket.com/albums/l57/bonnett_2006/PC130005Medium.jpg

John

I bent the rear corners from 19mmx 1.5 by just holding a steel disk about 180mm dia and 20mm thick in the vice with one end of the tube trapped under it against the vice. I then gradually bent it around the disk by hand without having to heat it at all and had very little distortion.Maybe a brake disk could be used.I made two seperate bits and sleeved and welded them to the straight bit in the middle.
Paul.

The anti-roll bar (grey bar in the pic below) in this pic was bent using a 4" record vice, a disposable cartridge plumbing blowtorch and my arms and eyes and that's it.

You can do the same it's not tricky!



Grasser rebuild, race in 1 wk!