Welding e-bike frame from scratch. Questions about the swing arm.

For stick welding, I'd recommend a minimum wall thickness of .100 (2.5mm). 1/8" wall is very easy to find in the USA. That's fine, but 3x as thick as it would need to be if you used fillet brazing or TIG welding.
 
Is the head tube and bottom bracket tube special diameter, i mean can it not be brought as a normal tube from a metal shop?
 
For stick welding, I'd recommend a minimum wall thickness of .100 (2.5mm). 1/8" wall is very easy to find in the USA. That's fine, but 3x as thick as it would need to be if you used fillet brazing or TIG welding.
Ok. Does that mean you could go thinner than 2.5mm with TIG or brazing?
 
For stick welding, I'd recommend a minimum wall thickness of .100 (2.5mm). 1/8" wall is very easy to find in the USA. That's fine, but 3x as thick as it would need to be if you used fillet brazing or TIG welding.
1/8" = 3.175mm
divided by 3 is 1mm
surely that is too thin to build a bike with! 3mm seems ok to me for thickness.🤷‍♂️ The bike is reinforced with plate as well but i would like to get an idea of the required thickness.
 
Is the head tube and bottom bracket tube special diameter, i mean can it not be brought as a normal tube from a metal shop?
Yes - specific diameters, lengths and wall thicknesses (in steel, titanium, and aluminum).

Frame builders supply i.e. Framebuilder Supply

... or, hacked from existing frames.

Apparently you failed to watch the last video link I posted?
 
It's certainly possible to guesstimate and build a frame, and use whatever materials and tools are at hand; I've done this successfully twice (out of several attempts) and evolved the results over several years into the CrazyBike2 and the SB Cruiser heavy cargo trike.

Neither one is optimal, or remotely well-designed or built, but they work. (CB2 took a lot of iterations to get to that point, SBC I'd learned enough from the others by then to make it usable from the beginning, though I've had several structural issues with it, including one major structural failure (that repeated itself due to a poorly implemented repair).

I'm terrible at stick welding so I use a flux-core wirefeed welder (the cheap crap from harbor freight), and most of my welding is serviceable...but it is hard even with this to weld regular bike tubes or other thin metal without lots of burn thru, that I then have to go back and fill in. Tends to look like crap, but most of the welds don't fail. :lol: (well, the *welds* never fail but the metal around them certainly has, for various reasons).

I have threads for my various builds here, if you're interested in them.

Most of what I use is old bike frames as sources of parts and metal, but I also use whatever scrap steel I run across--most of *that* is junk, and has often been a mistake to use...but some of it worked out ok. What didn't work has broken usualy near a weld, or just been so flexible or soft that it couldn't support what it needed to.

If you already have the stuff you can always try what you're intending, and if it doesn't work out, then try something else.

But, based on my own experiences...depending on your intended usage (rinding conditions, speed, etc.) then if this is the first frame you've welded up, you might want to be careful and ride where you can test things out with no chance of unexpected interactions with other people, bikes, vehicles, etc. ;) And expect things to break, in ways you didn't even think of, etc.


Regarding the bike by the builder/company saying he started his company because he broke ohter bikes...if he doesn't state specifically which bikes (model, year, etc) and exactly how each was broken (physically, electrically, etc) and under what specific conditions, then you dont' really know if his *frame* is "overbuilt", or, if it is "overbuilt", what specific conditions it's overbuilt for. :/

For instance, I'm pretty sure that the pictured bike above couldn't handle the cargo loads i'd need it for, even under smooth road conditions (which we don't have in most of the places I have to ride--they're not usually terrible but they're certainly not perfect). It would have to be heavily modified (not counting just adding the cargo carriers).
 
Yes - specific diameters, lengths and wall thicknesses (in steel, titanium, and aluminum).

Frame builders supply i.e. Framebuilder Supply

... or, hacked from existing frames.

Apparently you failed to watch the last video link I posted?
no I watched it. i just wanted to make sure. it just seems like some company should have started rolling that tube out by now. i just wanted to make sure it was actually necessary. i watched the video!. thanks lol
 
It's certainly possible to guesstimate and build a frame, and use whatever materials and tools are at hand; I've done this successfully twice (out of several attempts) and evolved the results over several years into the CrazyBike2 and the SB Cruiser heavy cargo trike.

Neither one is optimal, or remotely well-designed or built, but they work. (CB2 took a lot of iterations to get to that point, SBC I'd learned enough from the others by then to make it usable from the beginning, though I've had several structural issues with it, including one major structural failure (that repeated itself due to a poorly implemented repair).

I'm terrible at stick welding so I use a flux-core wirefeed welder (the cheap crap from harbor freight), and most of my welding is serviceable...but it is hard even with this to weld regular bike tubes or other thin metal without lots of burn thru, that I then have to go back and fill in. Tends to look like crap, but most of the welds don't fail. :lol: (well, the *welds* never fail but the metal around them certainly has, for various reasons).

I have threads for my various builds here, if you're interested in them.

Most of what I use is old bike frames as sources of parts and metal, but I also use whatever scrap steel I run across--most of *that* is junk, and has often been a mistake to use...but some of it worked out ok. What didn't work has broken usualy near a weld, or just been so flexible or soft that it couldn't support what it needed to.

If you already have the stuff you can always try what you're intending, and if it doesn't work out, then try something else.

But, based on my own experiences...depending on your intended usage (rinding conditions, speed, etc.) then if this is the first frame you've welded up, you might want to be careful and ride where you can test things out with no chance of unexpected interactions with other people, bikes, vehicles, etc. ;) And expect things to break, in ways you didn't even think of, etc.


Regarding the bike by the builder/company saying he started his company because he broke ohter bikes...if he doesn't state specifically which bikes (model, year, etc) and exactly how each was broken (physically, electrically, etc) and under what specific conditions, then you dont' really know if his *frame* is "overbuilt", or, if it is "overbuilt", what specific conditions it's overbuilt for. :/

For instance, I'm pretty sure that the pictured bike above couldn't handle the cargo loads i'd need it for, even under smooth road conditions (which we don't have in most of the places I have to ride--they're not usually terrible but they're certainly not perfect). It would have to be heavily modified (not counting just adding the cargo carriers).
Thanks for the info its appreciated and makes sense. You do have a lot of threads you could link me to some from your build. i would like to see the weight you are carrying.
 
You do have a lot of threads you could link me to some from your build. i would like to see the weight you are carrying.

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View attachment 345186 View attachment 345187
A Piano!
 
Yes. I had to mod the trailer to carry that; you can see the changes in the Mk IV trailer thread.

If it would actually fit everywhere I need to go, I'd have the *trike* built like that (but wider) to directly carry things on it like that...but it has to fit between bollards and the like for bike paths, and doors, and such, so it's much narrower and more limited in the size of things it can directly carry (though it can carry several hundred pounds of stuff if I'm careful riding to not hit bumps, potholes, etc., as it has no suspension).
 
I'm terrible at stick welding so I use a flux-core wirefeed welder (the cheap crap from harbor freight), and most of my welding is serviceable...but it is hard even with this to weld regular bike tubes or other thin metal without lots of burn thru, that I then have to go back and fill in.
Gluing thin stuff is relatively easy if the proper technique is applied. Yes, even .062 (remember those exercise frames I mentioned AW? many are .062"). The technique is called continuous stitch welding... The secret?.... Do not allow excess heat to increase unnecessarily under the arc - if you burn-through, you're either going too slow, back-tracking, or amps too high. Resist the urge to stop and fill-in a molten crater you just created - Just keep going, and fill it after it has cooled.

Low machine settings, tack a few thin practice pieces to 'warm-up & settle the nerves. Then start TACK welding (one second down, 3 seconds up,) one inch or so between tacks - then ever so slightly increase the tack length to 1/4-3/8". DO NOT STOP MOVING, or back-track over the existing puddle with a hot arc. If you burn through, speed-up a little. Tack all around the joint, then repeat the loop until you've filled all the gaps. To increase tack length, you'll need to increase travel speed, so only go as fast as you feel comfortable.

One more time: DO NOT STOP MOVING, or BACK-TRACK OVER THE EXISTING PUDDLE WITH A HOT ARC.
 
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Unfortuantely I don't have sufficient physical control of my body to continuously go steadily in a single direction regardless of time/length of movement; my muscles can jerk around in various ways at random times (though worse the harder I am trying to not do this) and I may move in any direction, either whole body or just one muscle...then there are the numbnesses that happen in my hands randomly (it's like wwhen you hit your elbow in just that one spot..., like an electric shock and then I can't feel my skin for a short but indeterminate amount of time; sometimes I can stil feel the muscles and bones inside, and sometimes it just feels like sat on my hands for a few hours).

Even when I'm not having those troubles, I cannot always tell where my body is, or I can "tell" it to do something but it doesn't always do what it should have...I too-frequently clean up messes where I *know* I put a dish/etc on the counter fully, then find it's on the floor, either because my hand didn't let go of it when commanded, or didn't put it where I intended, even if I'm staring right at it I can't stop the problem from happening.

Even my brain has never consistently worked, and cuts out thoughts I have to figure out where I was going with it...so realtime conversations are often difficult if they are not just "boilerplate" stuff like when I'm helping people at work...and even then).

So...knowing what to do and being able to do it are separate things for me, unfortunately.

(these are all reasons I do a lot of things in the computer that I would rather do by hand, because I can edit my mistakes out with the computer....for instance, all my music is created that way, for instance, or else I would never have anything any other person would ever want to listen to....).
 
An intelligent response to that is waaaywaaay over my pay grade Chief. 🤔

I often use a prop under my wrist, then two-hand the stinger. An auto-dark hood frees the hands so even a sharp downward nod isn't necessary. But damn, what else can I say..

Oh wait!.... you said something about a 'robot'? Yes?
 
1/8" = 3.175mm
divided by 3 is 1mm
surely that is too thin to build a bike with! 3mm seems ok to me for thickness.🤷‍♂️ The bike is reinforced with plate as well but i would like to get an idea of the required thickness.
0.9mm (.035") wall straight gauge tubing is the baseline for most inexpensive chromoly steel frames. Butted tubing is usually 0.9/0.7/0.9 unless it's fancy/expensive (thinner).

I used a mix of 0.9mm and 1.25mm (.049") wall chromoly tubing for my cargo e-bike frame, but I used the thicker kind only because it was easy/cheap for me to get. The pedicab manufacturer I used to work for prototyped all the trikes in 0.9mm tubing, but went into production with 1.25mm to add structural margin.

I think you should cut up some cheap junky frames made of mild steel ("high tensile" in bike industry jargon) so you can see for yourself what thicknesses are used for mass market bikes.
 
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Loving the trailer i love dogs too!
A BBQ DJ Party trailer may be in my future 😁
 
0.9mm (.035") wall straight gauge tubing is the baseline for most inexpensive chromoly steel frames. Butted tubing is usually 0.9/0.7/0.9 unless it's fancy/expensive (thinner).

I used a mix of 0.9mm and 1.25mm (.049") wall chromoly tubing for my cargo e-bike frame, but I used the thicker kind only because it was easy/cheap for me to get. The pedicab manufacturer I used to work for prototyped all the trikes in 0.9mm tubing, but went into production with 1.25mm to add structural margin.

I think you should cut up some cheap junky frames made of mild steel ("high tensile" in bike industry jargon) so you can see for yourself what thicknesses are used for mass market bikes.
Thanks a lot for the information, I think i will cut up some bikes. i have two that i collected for free.
 
Thanks a lot for the information, I think i will cut up some bikes. i have two that i collected for free.
If you miter and sand off the pieces you cut up, you can try stick welding them to see if it's feasible. My guess is it won't work with normal bike tubing, but I haven't tried it, so I can't say so with certainty.
 
Should your welding power supply have a DC output then adapting a TIG torch is fairly straight forward.
For an AC output power supply then 6010, 6011 or 6013 rods are the easiest to maintain a stable arc.
A 1/16" rod diameter if available.
Thin rods obviously are more flexible so use one hand to hold the rod clamp and the other hand to steady the rod near the weld process.
Rule of thumb : amperage setting is equal to rod diameter.
i.e. - .060" rod diameter = 60 amp setting. +/- (per conditions and skill).

TIG torch
 
Thin rods obviously are more flexible so use one hand to hold the rod clamp and the other hand to steady the rod near the weld process.
Skinny, small diameter rods? Cut'em in half w/dremel or angle grinder w/cut-off disk. And use both hands on the stinger grip.
 
When you start playing with .049 and thinner, you'll need to use O/A (I use O/P) torch, or gtaw

Oxypropane works great with 45% silver, brass, or silicon bronze. Subject to gross heat limits, for sure.
 
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