making an exhaust - pipe benders and pipe advice please

[tomarse]

I would like to make an exhaust for my car. It needs to be a custom job since i'm using a non-standard engine and fuel tank layout for the car.

Ready bent sections seem very expensive so i would like to buy some straight pipe and a bender and have a go at making one.

I will be working in 2.5 or 3" and using a MIG for joining sections. Im not worried about it being perfect, just functional!

Where is a good place to buy lengths of pipe from?

I am looking at benders like this - unless anybody can advise differently. I gather its not going to be perfect but should do the job (even it it means me welding multiple smaller bends together to get bigger angles)
any advice on buying one of these or where i should buy/what to look for?

Ta

 

[irondarren]

OK the bender you have in mind isnt designed to work with ERW which is basically what exhaust are made from 1mm - 2mm thick they are designed for use on CHS, commonly know as scaffold type tube, but where there is a will there is a way. The chances are what will happen to the tube in one of those hydrualic type benders it will crush, if you try doing anything more than a slight bend. Answer is simple go to the local builders merchant and buy some kiln dried sand or block paving sand. Cap one end of the tube, then pack the sand in as tight as you can fill it right up and ram it down, then cap the other end. so you now have a piece of tube with caps both ends and totally full of sand, now bend it using the bender. It should help stop the sides of the tube collapsing, which would stop gas flow from the exhaust cut end plates off and remove sand and you should have a nice bend.

best place to buy the tube is from a local steel stock holder (do a net search for your local area), and if i remember correctly ERW comes in 6mtr lengths. If the local steel stock holder won't deal with you try a steel fabricator (steel suppliers are a funny bunch and only like dealing in large quantities), but check prices with a few different fabricators as most tend think of a price and double it, if you cant get it picked up as a 6mtr length don't forget to ask for them to cut it for you and check the price.
60mm ish (2 1/2 inch ERW) costs me about £20 for a full length.
There are other ways to make bends with out a bender but only work for loose or lazy curves, very cheap to do but have a lot of labour involved, but i wont go into that now, but i will tell you how if need be

 

[tomarse]

Thanks - stuffing it full of sand had been mentioned to me! but they had never actually told me if they were trying to use that type of bender.

What does 'ERW' stand for?

I assume it is just thinwall tube then compared with the standard stuff they sell?

 

[irondarren]

ERW is electro resitance welded if i remember correctly or in common terms thing walled tube. 60mm ERW is likely to be 1.5mm think, which is nice to weld as it doesn't need vast amounts of power, but thick enough not to blow holes in it. CHS circular hollow section is normally in the order of 3mm thick meaning you need either to prep the edges nicely or have a welder with a little more power. Stainless steel tube is going to cost you more like £70 but might be worth a thought (i have no experience of bending stainless so i dont know what it bends like)

 

[MrFluffy]

I tried that a while back whilst trying to form some inlet manifolds from large diameter thinwall tube, even went as far as welding the cap on after ramming down the sand but it still creased when past about 30deg bends in one of those crappy "tube" benders. In reality they are pipe and conduit benders and nothing else, handy for knocking up conduit and roll cages mind. I even tried a bending spring, and heating the things up in the hearth and suceeded in doing nothing except getting the spring stuck in the tube. The shoe on the bender even forms its own marks in the side of the tubing after a certain amount of bending. I am kind of picky about how these things turn out it has to be said.

Imo you need a mandrel bender, unless you want to make a cats bottom of the job. A mandrel bender has a shoe that draws the pipe around a circular form of a preset size. You need a different die set for each tube diameter and bend radius you want to aim for.

These guys have some decent ideas for benders :-
http://www.blindchickenracing.com/tools/Tube Bender/Tubingbender.htm
Theres also a uk site that details how to make one from a old car stub axle from a fiesta, very cheap and very workmanlike, Ill see if I can find the link later..
If you have a few projects to make, its worth making a bender as a project in itself, if your just doing your own, its cheaper and easier to buy the bends in and weld them together. And you can get stainless bends too...
Im gonna get me a proper hydraulic one sooner or later as Im supposed to be making a spaceframe for my car, but for now Ill keep on building my car stub axle one for thinwall stuff.

 

[Luke]

Pipe benders from machine mart etc are not up to making roll cages.

A mandrel bender, or a proper tube bender with proper formers (like a tubela) do the job properly.

 

[vtec_lude]

Just buy from this place!

http://www.milneroffroad.com/PIPE.HTM

They are very cheap and also provide a great service! The prices need updating though.

 

[irondarren]

In someways it is often easier and quicker to use pre fabricated parts, with the bend you can just re-cut to get the desired angle, and TIG or MIG away happy, guess it wouldn't take long to turn out an exhaust or manifold that way

 

[tomarse]

another member here has sent me some pictures of what he could achieve with one of those benders - and he wasnt very impressed. He could only get very small angles before it started rippling and that is even with the pipe shoved full of sand.
I think it has convinced me to get the credit card ready and buy the ready made bends i need. It is going to take more measring and planning in advance though

This place also sell bends and are a bit cheaper than jetex

 

[BillJ]

another member here has sent me some pictures of what he could achieve with one of those benders - and he wasnt very impressed.

That would be me, then
The term "rubbish" springs to mind. Then again, I wasn't giving it much of a chance by trying to bend 3" x 16g stainless tube. I ended up slicing and welding the bends instead, since I had a generous supply of tube available.

If I was doing it again I'd probably use pre-made bends. I might give it a go again if I have to do shallower bends in smaller tube.

Look at it this way, Tom. Even if it costs a bit more this time round, you'll never have to do it again. That was my thinking when I did mine - it cost about the same as a ready-made stainless performance system but I got exactly what I wanted, which I wouldn't have got off-the-shelf.

 

[irondarren]

To be honest those hydraulic benders are ment for scaffold type tube, gas barrell. I have even known people having trouble bending CHS with them.

(gas barrel and CHS are similar sizes except gas barrel tends to be softer)

 

[BillJ]

Yes, I only realised my mistake when I came to do it and then realised a proper tube bender that can handle 3" tube was rather out of my budget

 

[tomarse]

That would be me, then

Ta Bill, wondered if you would show up

was going to post one or two of your pics but havent got round to resizing and re-hosting yet!

I've decided against buying a bender now on the strength of your piccys. I wouldnt be happy with that sort of result.

Am going to buy the bends i need or take it somewhere to get it done (or perhaps ask the local garage nicely if i can rent the car lift on a sunday as I dislike lying on the ground!). I have a spare c900 exhaust which i might be able to bodge in as a temporary measure (and then perhaps make a proper SS copy of it later)