Bending tubing

[mole53]

Is there a tutorial or could someone tell me how to bend small dia. tubing without kinking it?

[fitforbattle]

Does it have to be hollow? Rods are much easier to bend. Otherwise you can fill it with sand and secure the ends. Or use a springy thingy bender.

Edited July 6, 2014 by fitforbattle

[Ace-Garageguy]

Brass?? https://www.google.com/search?q=bending+small+brass+tubing&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

[cobraman]

I heard putting a pipe cleaner in the tube works but I never tried it.

[Kit Basher]

Putting solder inside the tube definitely works if you can find the right size to fit your tubing.

[Art Anderson]

Is there a tutorial or could someone tell me how to bend small dia. tubing without kinking it?

For starters, you really don't indicate what diameter tubing you want to bend, along without saying just how tight a radius you are trying to achieve.

Some things to consider: Metal, all metal, isn't flexible, nor is it more than minutely elastic, unlike say, soft rubber, which will bend fairly easily and also stretches a good bit without fracturing or tearing. With metal (and of course plastic) when you bend the stuff, since the surface on the inside of the bend really cannot compress (unless it buckles or wrinkles up), the surface on the outside of the bend, certainly with tighter radius bends, has to stretch. But since metals don't have much at all in the way of elasticity, the metal has to fracture or tear apart at least slightly.

Now, with a solid piece of rod stock (I suspect you are thinking of brass here), the rod, being solid clear though, cannot really collapse (kink) due to the relative non-compressibility of solid metal, but its cross section will tend to go from truly round to at least slightly oval in section--tubing doesn't have that solidity, so unles the surface of the outer surface of the bend in the tubing can stretch, the side surfaces will buckle at least slightly, causing the tubing to lose its round cross section, up to and including the point of collapsing, or "kinking". So, what to do?

Staying with what's easily available in hobby tools, K&S Engineering (the folks who make all that small brass and aluminum tubing sold in hobby shops) do offer a set of "tubing benders", which are made from small-gauge spring steel wire, closely wound into coil springs. These are sized for the larger sizes of their brass tubing, in a set that begins at 1/8" and several sizes larger--so if the size tubing you want to bend, those can be an option. However, be advised that you really cannot make very tight bends with these, and still get the coil spring bender off your piece of curved tubing.

Dubro, also a maker of stuff for RC plane builders, makes a single bending tool in brass, grooved for their 1/8" OD brass or copper tubing, that will give an approximately 3/8" inside radius bend, to a maximum of 180-degrees (bend to any more of a circle than that, and you'll not get your bent brass tubing off this bender!). These are intended primarily for gas powered model airplane builders, for bending brass tubing for use as fuel lines.

Another, and easier system would be using solid brass rod! You can bend this very tightly without its kinking on you (for the reasons I noted up above), the smaller the diameter rod, the tighter the bend. Of course, once you have the bent shapes, soldering is by far and away the best way to attach these together, although for applications where what you want to build isn't to be structural (say as in a set of exhaust headers as opposed to a complete dragster or race car chassis) epoxy will work, hold it just fine. K&S offers several sizes of brass rod, from .020" on up, with their 1/32" and larger sizes corresponding to the ID of their smaller brass tubing.

Plastic tubing doesn't work much better at being bent--both styrene and ABS plastics tend to fracture when bent, but styrene rod stock can be bent with the careful application of heat.

Hope this helps!

Art Anderson

Edited July 6, 2014 by Art Anderson

[GLMFAA1]

I have heard of freezing water in the tubing and bending it, another one was filling with sand. I use plastic rod in tubing to bend it

greg

[mole53]

Thanks guys, was thinking of making a set of headers for a double dragster build, but decided go with plastic rod and drill out the end instead.

[kitbash1]

There's a tutorial in the other modeling magazine ( August issue ) that shows you how to bend and solder brass and copper.