How-To: Weld a Custom Bike Frame

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By Sean Michael Ragan
Posted 2011/08/16 @ 9:02 am
Category Energy, Fun & Games, Workshop

Anyone who’s tried it knows that “pipe” or “tube welding” is an art that takes a while to master. This outstanding phototutorial by Amy Qian won’t substitute for the hours of practice needed to draw a good bead around a fishmouth seam, but if you’ve got the chops and are looking at making a bike frame, she’s done a great job of documenting her own process. The wheels she’s used are Harbor Freight cheapies with refit bearings! [via adafruit]

BY Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.

In the Maker Shed

5 Responses to How-To: Weld a Custom Bike Frame

Adam S Brooks on August 16th, 2011 at 4:41 pm said:

This reminds me of the MTV Le Run http://www.youtube.com/watch?v=gssjib_1-n0

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Anonymous on August 16th, 2011 at 8:08 pm said:

Great photos, and an interesting drivetrain design. Wish I still had easy access to a waterjet.

For those thinking about this – For fishmouthing – Try and find the constant pitch hole saws, they have slightly finer teeth which hold up better on thin tube. Also taking a truing pass on the outside (either a lathe with carbide, or freehand with an angle grinder, to reduce some of the set) will help them run smoother, but for sizes below an inch, you are better off with an end mill.

While welding thin tube is indeed a specialist job, fillet brazing is a much easier skill to acquire. You don’t have the risk of burning thru, and if a joint looks like it wet out, its likely strong enough. With thin sections, you are juggling power levels such that you might not get good fusion. (my early attempts at welding tube usually resulted in a blob of bead that didn’t penetrate right next to a burned thru hole. I have gotten better, but it really took practice. Don’t ask about what happened the first time I tried on aluminum.)

While it is possible to braze with a mapp/air torch, its a lot easier if you use fuel/oxygen. Fuel is up to you, when mixed with straight oxygen, any of the three common fuels (propane, mapp, or acetylene) will get more than hot enough.

Don’t bother with any oxygen system that doesn’t require a regulator. Those red tanks that you find next to the mapp at home despot, only contain about 7-9 min of oxygen for their $10 price tag, and they aren’t refillable. I get several hours of oxygen from my high pressure bottle (size C I think) and a refill (actually a swap) is around $15 these days. The bottle cost about $80 to buy (and came full), not sure of the cost of the regulator. Getting the oxygen rig has a side benefit – you get cutting of thick steel as a bonus. (all the kits that have regulators and a torch head include a cutting tip)

Reply ↓
Anonymous on August 16th, 2011 at 8:08 pm said:

Great photos, and an interesting drivetrain design. Wish I still had easy access to a waterjet.

For those thinking about this – For fishmouthing – Try and find the constant pitch hole saws, they have slightly finer teeth which hold up better on thin tube. Also taking a truing pass on the outside (either a lathe with carbide, or freehand with an angle grinder, to reduce some of the set) will help them run smoother, but for sizes below an inch, you are better off with an end mill.

While welding thin tube is indeed a specialist job, fillet brazing is a much easier skill to acquire. You don’t have the risk of burning thru, and if a joint looks like it wet out, its likely strong enough. With thin sections, you are juggling power levels such that you might not get good fusion. (my early attempts at welding tube usually resulted in a blob of bead that didn’t penetrate right next to a burned thru hole. I have gotten better, but it really took practice. Don’t ask about what happened the first time I tried on aluminum.)

While it is possible to braze with a mapp/air torch, its a lot easier if you use fuel/oxygen. Fuel is up to you, when mixed with straight oxygen, any of the three common fuels (propane, mapp, or acetylene) will get more than hot enough.

Don’t bother with any oxygen system that doesn’t require a regulator. Those red tanks that you find next to the mapp at home despot, only contain about 7-9 min of oxygen for their $10 price tag, and they aren’t refillable. I get several hours of oxygen from my high pressure bottle (size C I think) and a refill (actually a swap) is around $15 these days. The bottle cost about $80 to buy (and came full), not sure of the cost of the regulator. Getting the oxygen rig has a side benefit – you get cutting of thick steel as a bonus. (all the kits that have regulators and a torch head include a cutting tip)

Reply ↓
Anonymous on August 16th, 2011 at 8:08 pm said:

Great photos, and an interesting drivetrain design. Wish I still had easy access to a waterjet.

For those thinking about this – For fishmouthing – Try and find the constant pitch hole saws, they have slightly finer teeth which hold up better on thin tube. Also taking a truing pass on the outside (either a lathe with carbide, or freehand with an angle grinder, to reduce some of the set) will help them run smoother, but for sizes below an inch, you are better off with an end mill.

While welding thin tube is indeed a specialist job, fillet brazing is a much easier skill to acquire. You don’t have the risk of burning thru, and if a joint looks like it wet out, its likely strong enough. With thin sections, you are juggling power levels such that you might not get good fusion. (my early attempts at welding tube usually resulted in a blob of bead that didn’t penetrate right next to a burned thru hole. I have gotten better, but it really took practice. Don’t ask about what happened the first time I tried on aluminum.)

While it is possible to braze with a mapp/air torch, its a lot easier if you use fuel/oxygen. Fuel is up to you, when mixed with straight oxygen, any of the three common fuels (propane, mapp, or acetylene) will get more than hot enough.

Don’t bother with any oxygen system that doesn’t require a regulator. Those red tanks that you find next to the mapp at home despot, only contain about 7-9 min of oxygen for their $10 price tag, and they aren’t refillable. I get several hours of oxygen from my high pressure bottle (size C I think) and a refill (actually a swap) is around $15 these days. The bottle cost about $80 to buy (and came full), not sure of the cost of the regulator. Getting the oxygen rig has a side benefit – you get cutting of thick steel as a bonus. (all the kits that have regulators and a torch head include a cutting tip)

Reply ↓
Anonymous on August 16th, 2011 at 10:19 pm said:

mit-ers have some great blogs, here are two more:

http://www.etotheipiplusone.net/
http://scolton.blogspot.com/

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