I'm sure many on here have done it with a manual bender like a JD2 or similar. Were you pleased with the bends? Any wrinkles or kinks? Who's bender did you use?
My bud has a muffler shop, Huth bender...sliding mandrels, nice bends, no wrinkles/kinks, but some 'thinness' of cross section at the instep of sharp bends. Was Jerry Huth the original patent holder of this marvelous design??? I remember the power tube bender being introed in Hot Rod Magazine, early '60s... But the first mechanical ones came from an independent mfr., L.A. or San Fernando Valley? ...took some square footage of shop area, a friend had one...I thought it was like Manna from heaven! Bend tube, master anything. Same problem as the big one in tight bends...
Also watch out for the inner radius being pushed into the tube... That is, the tube diameter is less in the bends than it is in the unbent areas. I've never seen a muffler shop bender NOT do this to some extent...hence the need for mandrel benders. This is the big reason for "section" headers. Buying sections and welding them together as required. Then if you want them smooth, grind the welds flush. A bit of work, but it...works. Mike
I made mine with sections. If someone can do it otherwise without a proper mandrel bender then dang, good for them.
That's what I do. I bought a lot of J bends with an extra 90* from a supplier, sometimes Speedway, 1-5/8" and 1-3/4"cut and weld what I need. Granted they are not show quality but do the job I need. They have different radii which also helps.
I have a JD2 bender and with the 1 3/4" die that has a 5.5" or 6" centerline bend radius it will bend down to 16 Ga. but it will almost always slightly wrinkle the inside of the bend. As far as I'm concerned 5.5" or 6" radius is still quite a large radius for headers. I think to do something with a tighter radius to make the bends smooth and not thinned in the bend as mentioned above, the tube would almost have to be bent on a bender that uses an inside mandrel. Just my opinion. Lynn
Yes..Had tube benders at work that would bend 2.5 dia x .035 wall stainless steel tube in a real tight radius, some where around 4" at center of tube..
There are instrument companies who freeze a liquid inside the bell of trumpets/trombones/etc to make a clean bend in the tapered brass tubing... wonder if that would work for steel?
If you can weld at all (if not, that is why they make grinders) it's not that hard to make them off bends. I think I only have a bit over $100 in mine. (I got the flanges for free). I know mine aren't a thing of perfection but for a first try........they will be fine.
I'm just looking to get as nice a bend as possible in thin wall tubing and wondering if a simple manual bender and die can provide that.
Bending a tube comes with the natural consequence of both shrinking and stretching or all of one and none of the other. The stretching on the outside of the gives you some material thinning and the shrinking on the inside gives you the wrinkles. Without any thinning along the outside you'll have plenty of wrinkles and without wrinkles you'll have lots of thinning. The mandrel controls the shrinking whike letting it stretch around the outside with no wrinkles and the muffler shop bends don't stretch too well or too much and they can't shrink tubing the best but they can crowd the metal on the short side and got the wrinkles to prove it.
Something I've always wanted to try, well ever since junior high metal shop anyway, the teacher had put together a box with several burner heads and said with it you could make a tube bend like a wet noodle
I had tried this with limited success, but was given a "hands on" tutorial from a mate of a mate who has been building/rebuilding space frame era racecars for a living for many years. The "trick" to get a wrinkle free bend without the tube collapsing is to limit the heat input and limit where the heat goes. Ian used a heating rose on an OA torch. He just brought up a dull red spot on the outside of where the bend was to start, took the torch away, pull the tube round to start the bend, reheat the tube to a dull red slightly further forward on the tube, pull it round a bit more and repeat along the tube to form the bend, It's possible to get a fairly tight radius by this method, but not as tight as a mandrel bend. The sand needs to be well packed in the tube and absolutely dry -I baked some building sand in the oven at home before I started. The only picture I have of work done this way is on my off topic racecar. All the bends including the roll bar and home made exhaust headers were done by the sand packing method -the rear 2 into 1 was actually two part bends welded together to get the very tight radius in an attempt to equalise the secondary tube lengths. [/url] The Aluminium coolant tube in this picture was bent using sand packing too -obviously Ali doesn't get red hot, but smearing bathroom soap on the tube and heating it till the soap turns black indicates the right temperature to start bending.
Somewhere on the hamb is a Video of a Japanese craftsman making MC exhaust headers. Great one to watch
Haven't done any headers but I bent these tubes for my Cad frame. welded one end solid and pour and packed dried sand in the tube. I then pounded a wood dowel in the other end. I bent them on my steel work bench (1" thick) around a jig, clamping one end. You need to make it long so you have someyhing to hold onto, it gets hot. When I removed the wood plug,I had to tap the tube to get the sand and newly formed glass out of the pipe.
NO! The thin wall is the problem..1/8th wall 2" is not a problem but when you get down to 14/16 gage the tubing needs inturnal support at the tangent of the bend.. I don't think anything else works..
If you can't cut the middle of the bend, rotate 180*,and fuze weld it back together without rod, then the bend is garbage. Preformed bends are too cheap for the results not to use
The Jalopy Journal
