In this post, we help you with bending your tubes and frames without spending a bunch of money on expensive tools.
The first thing that you should do (to prevent kinking the tube) is to fill the tube up with sand. You can close both ends of the pipe by welding it or by smashing them flat on both sides. If you have another creative way to do it like a big metal plug, that will do as well.
Note: If you close the tube by welding, make sure the sand is dry (wet sand = turning your pipe into a pressure cooker = losing your face). Make sure the tube/pipe is filled to its maximum.
There are many ways to bend a tube, and we will give you the low-budget ones!
#1 - The Fiesta (suitable for heavy bending and strong/big tubes)
I want to talk about Ford Fiestas. Yes, the small hatchback thingy with four wheels. Specifically, the ones between the J and N registration mark.
What's so great about these Fiestas? Well, it turns out that the rear stub axle is held on by four bolts, and that the rear drum has, roughly speaking, a four-inch radius. Four inches is by a fortunate coincidence the radius that you want for bends in a motorcycle frame.
One of the most elusive pieces of equipment you'll need for building or modifying frames is a tube bender. The hydraulic ones you see in tool supermarkets are pipe benders and don't do an outstanding job for bending tube. So I made one out of a Fiesta rear stub axle and hub and it seems to do a much better job of bending tubes and shouldn't cost more than £50 at the outside.
First, catch your Fiesta. Remove one of the rear wheels, and then take the cap off of the centre of the brake drum and undo the nut that holds the drum/hub on and removes it, you should keep in mind that the left side one has a left-hand thread.
Behind the brake backplate, there are four bolts that attach the stub axle to the beam, once these are undone you can remove the stub axle and leave the brake back plate on the car.
You need the stub axle, the drum/hub, the stub axle mounting bolts, the drum/hub retaining nut and cover, and at least two of the wheel nuts. This bender should work for 1", 1 1/8", and 1 ¼" outside diameter tube, but you'll need to make a former and slider for each size so it might pay to grab the other hub while you're there.
Materials you need are about 14 feet of 40 mm x 80 mm x 3 mm wall box section, a foot of 1 ¼" by 1 ¼" by 1/8" wall box section, a foot of tube or pipe that will sleeve over the tube you want to bend, some ¼" plate and something about 6 feet long to make a handle out of as well as various other odds and sods.
Read more about it here (we only took a piece of the story, to make this post more manageable)
#2 - The Wood Bender (Small) (suitable for light bending)
Here, I show a quick and dirty method to bend aluminium tubing. I am documenting how I built a new bow rail for my sailboat.
Step 1: Build the jig
Here, I trace the curve that I want on some scrap lumber. This scrap will be used to build the bending jig. I'm just using a couple of old 2x4's.
Your wood should be somewhat thicker than the diameter of the tube you wish to bend.
Step 2: Cut the lumber
Just cut out the traced jig. Use a bandsaw if you have one. I don't, so I just used a jigsaw. Cut the jig to be little smaller than the desired curve. This will allow for the spring action of the tubing. Since I used two pieces of 2x4, I made a little gusset to hold the two together (2nd pic). Hint: Add a small bevel inward on the bottom of the cut. This will keep the tubing from popping off of the jig when bending.
Step 3: Don't bend like this
If you do this, then you will almost certainly get a kink in the tubing.
Step 4: Ready to bend
Here, you can see that I take a piece of scrap (from the earlier cut) and attach it to the table to complete the jig.
You will want to bend from one side only while ensuring the tubing is supported while bending. While bending, try to keep the pressure against the jig instead of the pipe.
You may want to practice with some cheap aluminium conduit to get the hang of it. When you are ready, get the polished stuff.
Read more about it AND SEE ALL PICTURES here (we did only take a piece of the story, to make this post more manageable)
#3 - The Wood Bender (Big) (good for heavy bending)
A homemade stainless tubing bender, which was built for bending 7/8" diameter 304 stainless steel tubing (3/64" wall thickness). They needed a tubing bender to make a custom spray dodger (and possibly also a bikini top) for our 20' cat ketch sailboat. The cost was about $50 in materials and 6 hours of labour. About half of the $50 was spent on plywood and bolts, and the other half was for the 7/8" round nose router bit. Much cheaper and more effective than any of the other options they explored.
#4 - Small Tube Bender out of metal
#5 - Making your own Tube Bending Die
Some more information on Wikipedia can be found here.
# 6 - Using a Cheap Bender
Well, these work pretty well IF you DO NOT want to create an excessive bend. The tube will kink, and you could prevent it A BIT by filling it up with sand, but that's it. It will not work on thin exhaust tubes, etc.
The plus side of these little machines: They are pretty cheap...
You could also choose to do it by hand (this only works with small, light, thin tubes) with a tool like this one.
We hope this gave you some inspiration on how to bend tubes for your cafe racer projects!
[Edit] We found this one on the web as well. Very nice and simple :)