Approximate cost of materials to build a basic chromoly MTB bike frame?

I'd definitely take a class before starting, and will build things like racks and aerodynamic aids before building a frame.
Just speccing costs and what i'm getting myself into.

TIG is not my preferred method, but it'd like to start with what i will end up using in the long run, and the cost of entry is less bad than i expected.

I'd actually rather jump straight to laser welding but the cost of entry is easily 10-20x that of TIG.
 
The TIG machine shown is a scratch start (no foot pedal) meaning the amperage is set to one level and there is no way to slowly add heat on start up or taper down the heat when coming to weld ending.
Gas torch kit is actually a good buy in that it comes with bottles.
Larger production companies will rent the bottles instead as a business write off.
Regulators are on the small side.
Regulators with large(r) diaphragms provide steadier flow.
Pawn shops used to be a great place to find second hand oxy/acetylene torches and gauges.
Victor torches look for tip sizes 2, 1, 0, 00 .
 
I'd listen to Inanek and PaPa Steve. They are, in my opinion, correct. And I can do all of the methods discussed.

This is not a really easy skill to get good at. You'll never get me on a bike that a beginner has TIG welded up. Take a look at what a union journeyman welder earns.

I'm a pretty good welder but you'll never get me on a bike that I've TIG welded. MIG and brazed are much easier to master and will do the job just fine.
 
I learn quick, especially when determined.


But i found a problem with my plans.


The upgraded TIG with better features is $350 but it doesn't do aluminum. I gotta pay $775 for that and it absolutely requires a 220v outlet to handle the thicker material of aluminum ( i won't have that for years ).

But i don't need to do structural aluminum, just things like racks and aerodynamic aids where strength is a lot less essential than say, the frame.

Brazing works well for chromoly bikes and acceptably well for aluminum with the right stick. That's the tie breaker.


Here's the problem with the portatorch though, it's rated to braze up to 1/16th of an inch which is 1.5mm, but headtubes and bottom brackets can be 2mm, so it seems like not enough power for certain things.

What would be the next step up?
 
Welding, brazing is all about heat control, best control equals best results.

With Oxy/acetylene, generating heat is all about tip size and fuel flow.
Victor torches have 10 tip sizes available.
Two stage regulators with large diaphragms have the smoothest flow.

For TIG, having a fully capable, precise power source is ideal.
Some form of power throttle control, either by hand or foot.
DC straight or reverse polarity.
AC with wave form control.
Pulse control.

Machine I currently use is a 10 year old Fronius Magic Wave 3000 inverter style.
Light enough to hand carry.
Currently powered with 220v 50a single phase but can be powered by 460v 3 phase.
For AC it can create any combination of wave form ~ sine, square, or triangle wave form ( i.e. square on top, triangle on bottom or any other combination)
An amazing engineered machine.

For the bulk of my welding career a Miller Syncrowave 300 with pulser did the hard work.
450 pound bulky transformer style that required 200A service.

And then the myriad of torches, tungsten sizes and types, cups and collets etc. etc.
 
Congrats on your motivation to dig into framebuilding! I'm in the process of building a custom cwlb, and from my experience, welding is the least of your problems. A simple diamond shape frame should certainly be easier, yet it also comes with its own challenges. You need access to reliable metal processing heavy machinery since your welds/brazes are only going to be as good as your cuts. Building an adjustable jig is also not a trivial task, and without jig you'll end up with heavily deformed tubings.
For those reasons, I hired an experienced frame builder for that project.

At least here in Europe, there is a resurgence of welders-converted-to-bike-building since the covid crisis, and because most of them can't make a living out of selling hand made frames, an alternative is offering frame-building lessons. If something similar is available in your region, I highly recommend taking one. In some case you can even rent their shop to build your own frame, which saves you the need to buy machines.

Also, there are plenty of very interesting internet threads about people sharing their own experience. This (german one) inspired me to start with the whole project - and the lack of good CWLB on the market meeting my requirements!
 
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qwerkus said:
Congrats on your motivation to dig into framebuilding! I'm in the process of building a custom cwlb, and from my experience, welding is the least of your problems. A simple diamond shape frame should certainly be easier, yet it also comes with its own challenges. You need access to reliable metal processing heavy machinery since your welds/brazes are only going to be as good as your cuts. Building an adjustable jig is also not a trivial task, and without jig you'll end up with heavily deformed tubings.
For those reasons, I hired an experienced frame builder for that project.

At least here in Europe, there is a resurgence of welders-converted-to-bike-building since the covid crisis, and because most of them can't make a living out of selling hand made frames, an alternative is offering frame-building lessons. If something similar is available in your region, I highly recommend taking one. In some case you can even rent their shop to build your own frame, which saves you the need to buy machines.

Also, there are plenty of very interesting internet threads about people sharing their own experience. This (german one) inspired me to start with the whole project - and the lack of good CWLB on the market meeting my requirements!
Click to expand...
Do you have pictures of it?
 
Thanks for the pics, damn nice bike, i would love to build something like that.

How fast can you get that bike up to on pedal power?
 
Papa said:
"Need?" heavy machinery?... For what purpose exactly? I make-do just fine with a flat steel table with a bench vice, an assortment of C-clamps, and a minimal variety of scrap steel for fixtures and one-off jigs. A selection of files, a quality hack saw, and a small ball peen hammer. An angle grinder is handy, as is a bench grinder and small belt sander, but It can be done even without those. I graduated from hand shaped tubing joints to a decent tubing notcher (a cheapy $50 notcher is available at Harbor freight).

The secret to avoiding warpage is snug fitting gapless joints, and strategic MIG tacking. I learned to only use full frame jig for initial tubing alignment and tacking - but the fact is, a full frame jig is NOT a necessity, unless you're doing lugs. My final welding/brazing is done free standing, outside of jigs. About the only tool I wished for early on, was a mandrel tubing bender for thinwall 4130 - but they're expensive, very expensive. So I quickly learned to make smooth, uniform curves by hand... even on .028" 4130.

View attachment 353831
Click to expand...
Reminds me of the easy racers javelin. But prolly stronger. Amazing build!
 
neptronix said:
Thanks for the pics, damn nice bike, i would love to build something like that.

How fast can you get that bike up to on pedal power?
Click to expand...
Thank you, Chief
How fast?... 'twas not intended for speed per se, so I'm not sure I can intelligently answer, nor does it matter... my intent was to just make it as light as possible. I created it at a Community College to give the young welding students a visual taste of HPV building.

maiz said:
Reminds me of the easy racers javelin.
Click to expand...
Odd?... the ER Javelin was a mono - and I believe, IIRC, was designed by Gabe... not Gardner.

Thank You
 
Papa said:
Thank you, Chief
How fast?... 'twas not intended for speed per se, so I'm not sure I can intelligently answer, nor does it matter... my intent was to just make it as light as possible. I created it at a Community College to give the young welding students a visual taste of HPV building.


Odd?... the ER Javelin was a mono - and I believe, IIRC, was designed by Gabe... not Gardner.

Thank You
Click to expand...
The geometry and seating position. I heard the javelin's monotube design had some issues...
 
Papa said:
"Need?" heavy machinery?... For what purpose exactly? I make-do just fine with a flat steel table with a bench vice, an assortment of C-clamps, and a minimal variety of scrap steel for fixtures and one-off jigs. A selection of files, a quality hack saw, and a small ball peen hammer. An angle grinder is handy, as is a bench grinder and small belt sander, but It can be done even without those. I graduated from hand shaped tubing joints to a decent tubing notcher (a cheapy $50 notcher is available at Harbor freight).

The secret to avoiding warpage is snug fitting gapless joints, and strategic MIG tacking. I learned to only use full frame jig for initial tubing alignment and tacking - but the fact is, a full frame jig is NOT a necessity, unless you're doing lugs. My final welding/brazing is done free standing, outside of jigs. About the only tool I wished for early on, was a mandrel tubing bender for thinwall 4130 - but they're expensive, very expensive. So I quickly learned to make smooth, uniform curves by hand... even on .028" 4130.
Click to expand...
That is quite some skill if I might say so. I've never seen someone able to weld a bike frame without jig. If you find some time during your next build, maybe make a few videos showing how yo do it ? I'm pretty sure a lot of people would find that interesting!
 
I'd like to see more too!

I would bet the tubes of that bike make for somewhat of a suspension?
The construction looks simple.

I love how this is kind of a midway point between CLWB and LWB
 
qwerkus said:
That is quite some skill if I might say so. I've never seen someone able to weld a bike frame without jig. If you find some time during your next build, maybe make a few videos showing how yo do it ? I'm pretty sure a lot of people would find that interesting!
Click to expand...
Some traditional frame builders all along built their frames in a workstand, held by the seat tube. They lugged and pinned the joints, and verified alignment with string. So not only don't you need a jig, you don't even need a table or a reference surface other than the BB faces.
 
Papa said:
"Need?" heavy machinery?... For what purpose exactly? I make-do just fine with a flat steel table with a bench vice, an assortment of C-clamps, and a minimal variety of scrap steel for fixtures and one-off jigs. A selection of files, a quality hack saw, and a small ball peen hammer. An angle grinder is handy, as is a bench grinder and small belt sander, but It can be done even without those. I graduated from hand shaped tubing joints to a decent tubing notcher (a cheapy $50 notcher is available at Harbor freight).

The secret to avoiding warpage is snug fitting gapless joints, and strategic MIG tacking. I learned to only use full frame jig for initial tubing alignment and tacking - but the fact is, a full frame jig is NOT a necessity, unless you're doing lugs. My final welding/brazing is done free standing, outside of jigs. About the only tool I wished for early on, was a mandrel tubing bender for thinwall 4130 - but they're expensive, very expensive. So I quickly learned to make smooth, uniform curves by hand... even on .028" 4130.

View attachment 353831
Click to expand...
Have you ever put any trike frames together? If so, I'd like to see.
 
Common bicycle frame fixtures like the David Kirk designed Anvil, the frame can be left in the tool when doing fillet brazing or silver brazed lugged frames.
Using this fixture for TIG or MIG welding there is not enough working room between fixture and the frame to see the welds or maneuver the torch.
When doing volume production with TIG welding the fixture is custom designed for best torch access and won't be adjustable to accommodate other frame designs.

kirkframeworks.com

David Kirk

When you deal with Kirk Frameworks you are really dealing with one person – me – Dave Kirk. I’ve worked for companies both big and small over the years and these experiences have shown me that what I enjoy the most is working one on one with each customer. This person-to-person relationship...
kirkframeworks.com kirkframeworks.com

For one off builds or every type including trikes the "keel" style fixture works really well, highly versatile and often open enough for more complete / full welding.
Keel refers to an ancient boat building technique where the project starts on the bottom center and builds up and out.

Chop Source - Motorcycle Frame Jig Parts / Fixtures - Chopper / Bobber

Motorcycle Frame Jig Parts / Fixtures For Sale - Customize your Harley, Yamaha, XS650, Honda, CB750, Suzuki, Kawasaki, Triumph, BSA, etc.. Chopper, Bobber
www.chopsource.com www.chopsource.com

An expanded version of the "keel" concept is the "picture frame" technique where there is a perimeter frame (picture frame) that functions the same as a keel but adds a little more precision and control to the frame being built inside the "picture".
 
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Papa
That's a nice looking bike, great color, 24.4 pounds is fantastic low weight.
Really, the connection between the rear fork to the main frame makes it a mono tube . . . correct ?
Are the rear wheel stays front fork blades ?
Asking because heavy mountain bike fork blades didn't hold in that application up on our Pursuit design.
But that was 1992 materials.
Yours built 2004 ?

1717293103444-jpeg.353831
 
PaPaSteve said:
Are the rear wheel stays front fork blades ?
Asking because heavy mountain bike fork blades didn't hold in that application up on our Pursuit design.
Click to expand...
Yes. The blades are 4130 - anything else likely wouldn't survive. They flex noticeably, but remain well below yield. I've put somewhere north of 2k on it so far.
 
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I would say that if you are a master tradesman with years of experience then tig is the way to go. But if you are a relative hobbyist it is very much likely that a braze weld would be stronger, especially on thin tubing.

I wouldn't even be that concerned about the relative tensile strength between the brazing material and the underlying steel. The reason being that the fillet created by the braze material will have a thicker cross-section then the tubing that it is joining. So even though the ultimate yield strength, or whatever, of the bronze is somewhat less then steel there is more area to the bronze. So it makes up for it and the chances of the braze breaking before the tubing bends into something unusable is almost zero.

And there is also slightly different processes... from low temperature to high temperature: soldering -> brazing -> braze welding -> welding. The middle two are often conflated as "brazing", but they are slightly different. Under braze welding the surface layer of the steel is melted and alloyed with the brazing material. It doesn't require the super-tight fitment that proper brazing does.

A good place to learn some welding that isn't too expensive is a local community college that has trades classes. Things like AC technician, electrician classes, plumbing, welding, etc. They tend to offer two types of "welding classes". One is for artistic for people interesting in metal sculpture. The others type would be tradesmen that want to obtain certifications for employment. The artistic ones are a complete waste of time. Go for the real ones 100 times out of a 100, even if you are only interested in sculpture. if you are not pursuing a job learning about the basics of engineering and metallurgy is fantastic.


Also there is a lot of interesting videos on Youtube for people making custom choppers and other odd and fantastic bikes. They tend to use a wide variety of pipes and tubing.. just whatever is available and looks to be the right size and is steel.

Like this guy:

The guy obviously has a huge amount of experience doing this stuff. He also doesn't hesitate to cut stuff off and re-do things when it doesn't work.

So even if your goal is to have a slick and practical bicycle for handling hills and whatnot.. slapping together bicycles using used parts and tubing from a scrap yard or cheap structural tubing from local metal supplier might be a quick and cheap way to build the skills necessary to make something slicker and more lightweight later on without blowing your budget.

Also when choosing a process... I like gas welding, but the thing that sucks is that is really difficult to find places that handle explosive gasses to refill containers that are open during non-working hours. Were as stick, flux core, mig welding... you can pick up supplies at any decent sized hardware store. So if you work 9-5 and want to do stuff on the weekend or in the evening this might be a big consideration.
 
Thanks so much for your advice.

The point about the brazed area being bigger ( making up for it's lack of strength ) was good.

Yes i hear that brazing supplies are getting expensive. TIG is interesting to me because there seems to be less expensive consumables and cheaper upfront costs lately. I'm told that a small TIG machine that runs on 120v would be adequate for working on a chromoly bike.

I would be willing to put in the work to learn how to do TIG, including attending a class. I see that there are procedures to inspect weld quality detailed online. I would be interested in hiring someone to provide an evaluation on my best welds to see if they could be trusted to hold a bike together.

It seems like examining the quality of practice welds isn't rocket science.

1717629073887.png

The ability to join different metals with brazing is a plus. But i don't want to work with recycled material, i want to specifically tune diameter to provide a middle ground of stiff/strong and bendy for best ride quality characteristics.

I'm told that a setup like a portatorch would not be adequate for brazing chromoly up to 2mm. Is that correct? if i go the brazing route, would there be a better starter kit?

Port-a-torch:
https://www.lowes.com/pd/Lincoln-El...YMzMT_lg2j6v4o0VU1hoCXP0QAvD_BwE&gclsrc=aw.ds
 
A copy / paste from the Lowes product page overview :

"As supplied, the outfit is capable of cutting 1 in. and welding up to 1/16 in.
Able to cut 4 in and weld up to 1/2 in with larger tips and large acetylene cylinder."

Apparently the torch handle is a Harris brand relabeled for Lincoln . . . that's the place to look for larger tips
 
1/16 inches is 1.5mm and the thickest metal i need to join is 2mm ( headtube ).
It sounds like i need something bigger.

What do i need to weld up to 2.25mm thick chromoly?
 
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