Thread: How to bend 10mm or 12mm steel tube

How about one of these. 3in1 TUBE BENDER Pipe Curving Pliers Brake Fuel Line | eBay

Your biggest problem will be the tube kinking or splitting at the bend point; it all depends on how thin walled the tubing is. Start by getting hold of a QUALITY tube bender; I would recommend ones by RIGID or SWAGELOK as they are used for bending stainless tubing. The cheap E-bay copper tube benders will do steel as well, just not for long. The model that Com has linked to will probably die too quickly as it is made of ally, you really need a bender dedicated to the specific size you intend to use; something like this one

If the tube splits or kinks you will need to either increase the wall thickness, or fill the tube. Resin, lead and sand are the traditional fillers; sand obviously will be the easiest to get hold of but you do need to pack it in really firmly and plug the ends to stop it escaping.

As a last resort, you can fill with sand and hot bend; ie heat up the area you want to bend to red and then go for it. This sounds easy...it's not. You really need to draw the outline of the finished bent item on a steel bench with chalk, clamp the tube down and then heat where necessary to follow the drawn lines remembering that the hottest part will bend the easiest. The last problem with hot bending is the surface finish of the tube tends to suffer as scale is produced...and of course you'll need to get some more oxy first...

MetalGeek : Code, Metal and Cleverness
I've used timber forms for light 10MM SHS
James

Have done heaps with this style bender which sandwich the tube between two plates and bend it around a former. This preserves the cross section of round tube through the bend, but square sections fold in on the inner and outer radius. The formers need to be a very accurate match to the tube profile to avoid spreading or kinking. The tool is mounted on a floor mounted column, and operated with a handle that is 1.5 - 2.5m of 50mm steel tube. Minimum bend radius for 12mm would be in the order of 100-130mm

There are a lot of places using similar benders, and a fair bit of skill involved in estimating gain around the bends to form a closed shape of fixed size accurately. I would suggest spending time finding someone with the bender and experience using it, and pay them to get the job done right, rather than paying out bigtime to buy a bender and starting from scratch. Alternatively consider whether you can do the job with mitred corners and cut and weld techniques.

Chances of doing it with anything lighter, like a plumbers bender or brake line bender are very low.

This link shows the bending setup I copied MetalGeek : Code, Metal and Cleverness: How to Bend Tubing and Pipe by Hand

James

Thankyou geniuses all!
Just what I was looking for, a range of alternatives to mull over, particularly the last one, using home made timber jigs.

I was surprised by the size of the minimum radius for 12mm / 1/2", which probably means the ones I have seen tighter than that probably used a lot of heat. Makes me think that it might be easier to make the racks from 3/8th bar, thereby avoiding the kinking problem and permitting a tighter radius, all for not a great deal extra weight.
many thanks!
john

Originally Posted by malb

Minimum bend radius for 12mm would be in the order of 100-130mm...... and a fair bit of skill involved in estimating gain around the bends to form a closed shape of fixed size accurately. I would suggest spending time finding someone with the bender and experience using it, and pay them to get the job done right, rather than paying out bigtime to buy a bender and starting from scratch.

Chances of doing it with anything lighter, like a plumbers bender or brake line bender are very low.

The Rigid/Swagelok benders I use at work for 1/2" hardened SS tube with a wall thickness of 0.08"/2mm bend to a radius of 1 1/2" (3X diameter). They are spectacularly easy to use and calculating the bend gain should be easy enough for anybody who got beyond year 9, although personally I don't bother as I know a couple of even easier tricks to get exact alignment. However, if you do happen to find anybody who has the appropriate gear then by all means get them to do the work. The cheapy type benders like this one or this one on E-bay will do, make sure you pick one that actually states "Stainless" or "alloy steel". These look like they have a 4-5 X diameter bend radius which is much easier to use and less prone to kinking.

Instead of trying to do four bends on one piece of tube, form two "U" shapes and weld them together. Less chance of a mistake; if you measure, mark and bend each piece identically the mating ends will align perfectly.

Contact Melvilles they were on Marion Rd, I use to have a lot of pipe bent there, they might have the size dies that will do the job. They make ladders and also mandrel bend pipe for other customers. As someone said earlier it might be cheaper to get someone to do it for you, by the time you buy the bender and extra tube to practice on. If you want to buy a tube bender try Paramount Browns they might have something that will do the job.
Regards
Kryn