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

[Papa]

I prefer 45T - liquidus is lower than 45, IIRC somewhat slightly north of 1200f. 45 is higher, 1350f or a tad higher. Generic off-the-shelf LFB is noticeably higher still at closer to 1600f (but much more affordable). But all fillers w/silver have gotten prohibitively expensive, so I'm extremely selective what I use it on.

I've been addicted to O/P since about '04. I was weened on O/A, but loading-transporting-unloading the dam heavy bottles (and a sharp rise in filling $) forced me to convert. I've been using BBQ bottles + oxygen concentrator ever since. MIG is usually my goto now - but I had to modify my gas preferences for that too - using straight cO2 now.

 

[My First Ebike]

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

Thank you i will look into adapting to TIG also. i didn't realize it could be so simple.

 

[nicobie]

Have you priced new square-wall lately? And you'll need a head tube and BB shell,... and a fork, handlebar, crankset, brakes, and a bucket full of nut&bolts. So why not start with, essentially free, discarded bicycles?

And here is just 'one' of AtomicZombie's overwhelmingly informative vides...

That's what I would and have done in the past. Wish I had saved pics but it was over 10 years ago and everything didn't autosave in a useful format back then. However I must add that the frame broke at a weld and I was a decent welder even back then.

 

[My First Ebike]

That's what I would and have done in the past. Wish I had saved pics but it was over 10 years ago and everything didn't autosave in a useful format back then. However I must add that the frame broke at a weld and I was a decent welder even back then.

What are you trying to say, What type of weld did you use? Why did your bike fail at the welds?

 

[nicobie]

Stick welding is not good for bicycles. I suppose it could be done but not by a beginner unless used on thick material. Which is not good for anything mobile.

The weld failed because I used a stick welder with the wrong rod on too thin of material.

However feel free to do what you want. That's how I learnt.

 

[Papa]

The weld failed because I used a stick welder with the wrong rod on too thin of material.

Stick & thin tubes

 

[amberwolf]

An intelligent response to that is waaaywaaay over my pay grade Chief.

Over mine, too. :lol:

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..

I wish those were the solution, but to really fix this I think I'd need a new nervous system from the brain right out.

Oh wait!.... you said something about a 'robot'? Yes?

That's a whole other project...and thread, that doesn't require very much welding, if any (but lots of soldering, wiring/etc., and lots of coding that I probably can't do all myself):

Robotics Project: Snuggles, The Wolf

Technical discussion and idea-workout thread for Snuggles, The Wolf, a robot intended for emotional support interaction. Discussion of the project itself is welcome; ridicule or other negative feedback about the idea itself, etc is not. ;) The project concept is pretty complex, so reading all...

endless-sphere.com

 

[amberwolf]

Loving the trailer i love dogs too!
A BBQ DJ Party trailer may be in my future

You might also look into the park bench scooter:

Knotty Scooter 2WD

This is a picnic mobile. I can bring my wife, kid, food and fishing pole all around town. I built the kickstand really strong so the bike can be used as a park bench and table when parked. I had Hallomotor pre-wire the system so I would not have a head ache. I cannot figure out...

endless-sphere.com

 

[505native]

I think that's badass bro. Trial and error and I'm thinking about doing the same. Building my own E-Dirt bike..

 

[My First Ebike]

I think that's badass bro. Trial and error and I'm thinking about doing the same. Building my own E-Dirt bike..

Thanks, i agree. I will post my progress.

 

[Ishikawa]

Thanks, i agree. I will post my progress.

There is nothing wrong with 1/8" thick square tube for the frame. Of course the frame will be heavy, not good for human powered bike but OK for Ebikes. Use a head and BB from donor bike. Stick weld is much easier and cheaper. As other guys said experience/experiment is the way to go.

As for rear swing arm bearing. 6001 has 28mm OD and 12mm ID. I prefer to use a bit larger OD. 6202 has 35mm OD and fits well in 1.5" tube with 1/16" wall that is 1.375" ID. 6202, you have a choice of 15mm, 5/8" or 16mm ID. Also 6003 has 35mmOD and 17mm ID.

This is my two cents, if you put a tube for rear swing arm, make it a bit wider. I mean longer, between the bearings. Bicycle rear suspensions pivots are way too narrow unlike a motor cycle one, that make the wheel to swing right when you put the power. This is not a problem for direct drive but if you plan to make a mid drive, that gives you uneasy feeling. Anyway, 3~4 inches between the bearings is reasonable.

 

[nicobie]

Custom Framebuilding Forum

Framebuilding Community

forum.customframeforum.com

excellent link!

 

[classicalgas]

"Cheaper" is not a good criteria for choosing (justifying ? ) a welding process on a bike frame.

I saw a basic TIG inverter welder (not a brand name, but set up with auto flow on the shield gas, DC maxed at 100a on 110v input , so a very basic machine, but it did have hi freq start ) for $100 at a local pawn shop last weekend. The whole machine was caryable in one hand, about as bulky a a big lunch cooler. You'd need about another $150 in a small rental argon bottle and regulator/flowmeter to get going, and that would be plenty of power to TIG a bike frame out of .065" square or rec tube. You'd have something you could trust, and be proud of when you were done, too. And a marketable skill.

Pick up an autoshade hood...those show up at pawnshops, working, for under a hundred. Put new lenses in it, so you can see what you're doing.

Factory made ebike frames with no top tube... "step thru"...have been known t snap in half..it's not a great layout from a strength standpoint. The ones that don't fail tend to have a bent spine made of a fairly large diameter and thick wall tube, with lots of area involved in any joints.

 

[jonescg]

I have consistently stick welded 2 mm tube. 1.6 mm tube is possible, but I personally wouldn't make it structural.
I was so sick of YouTubing stick-welding thin steel tube, and coming up with videos where they grab a piece of 4 mm plate and refer to it as 'sheet metal'.

So I made my own video, which somehow garnered half a million views.

Best of luck!

 

[PaPaSteve]

I have consistently stick welded 2 mm tube. 1.6 mm tube is possible, but I personally wouldn't make it structural.
I was so sick of YouTubing stick-welding thin steel tube, and coming up with videos where they grab a piece of 4 mm plate and refer to it as 'sheet metal'.

So I made my own video, which somehow garnered half a million views.

Best of luck!

Your video takes me back to 1968 as budding teenager making tube framed VW powered dune buggies.
Well done.

 

[Papa]

Well illustrated, jonescg
Parent metal thickness is largely irrelevant - controlled application of heat IS relevant.

1.6 mm tube is possible, but I personally wouldn't make it structural.

I'm confused why this statement keeps arising with thinwall. Welding (or brazing) sheet metal is primarily about duplicating (or increasing) the parent metal's original strength... whether used in a structural application or not.

 

[classicalgas]

Parent metal thickness is largely irrelevant - *controlled application of heat IS relevant*.

Which is where TIG shines compared to all other methods (well, maybe not plasma or laser welding ) I've Tigged railings in a new home "after" the carpet was down. It's that clean and controlled.

I can TIG weld the aluminum foil in your kitchen....that doesn't mean it's a good idea, or structurally sound.

On thin wall tube ( 1.6 mm isn't that thin ) by the time you've learned to make a sound weld with a stick (and cleaned up the mess, and hopefully not started a fire with your dancing sparks ) you could have learned to TIG, and avoided all the cleanup, fire risk and aggravation. As soon as your TIG weld has cooled, it's ready to paint ( though you'll be tempted to clear coat it, it looks so nice) Your heat control is so precise, practically any thickness (of a weldable metal ) is doable. People think of TIG as hard to learn, and slow. For most home shop fabrication, on gauges up to about .095" all you need to do is beat the strength, speed and appearance of MIG, on fairly short welds. That's easy....so long as you factor cleanup into the comparison.

TIG has a rep for "hard to learn". It's not. If you can learn to drive a stick shift, I can teach you how to TIG in about four hours. Probably less. Of course, if you care, you can spend half a century getting better at it.

I'm confused why this statement keeps arising with thinwall. Welding (or brazing) sheet metal is primarily about duplicating (or increasing) the parent metal's original strength... whether used in a structural application or not.

Yes, but you have to avoid burning through, even once, on that joint.

 

[Papa]

....all you need to do is beat the strength, speed and appearance of MIG

Few would argue GTAW's merits... but those who boast about it, must also reveal its negatives.

*Slower than MIG and stick - (MIG was originally developed for production - where speed=$)
*Argon is expensive.. as is tungsten
*It's a busy process - 3 individual body parts must be intimately synchronized (stinger in one hand), (filler in other hand) & (heat control (usually by foot)). GTAW process closely mirrors O/A.
*Above average hand-eye coordination
*Excellent closeup eye vision (natural or corrected)
*Load your MIG w/flux core and weld outside in 30mph wind - Likewise w/stick - virtually impossible w/GTAW

Edit: Having taught GTAW at a CC, I was intrigued that females learned it much faster than many men - and often excelled

 

[PaPaSteve]

There are several things that happen during the stick welding process that complicate the process for a new welder.
The molten puddle of metal is the most important and generally is the brightest part of the process.
The flux is often confusing to the operators vision with a slightly different color and swirl pattern.
Then there are the fumes / smoke coming off the process getting in the way of your vision.
Why is flux part of the process ?
Oxygen is an enemy of all welding processes, the molten puddle must be shielded in some fashion.
(caveat . . . Oxy Acetylene welding on steel is done with no protection from ambient oxygen.)
Which welding lens is best ?
For a lower amperage processes a lighter lens will be helpful.
Lens shade choice for electric welding is usually 9 to 13.
Try different lens and colors.
Plastic lens scratch easy and warp from heat distorting the view.
Although glass does break, it's works best for my old eyes.
Personally only run just the lens with no secondary clear protective additions.
Aluminum and titanium reflect more light back to your eyes so they will require a darker lens.
Vision is key, keep the lens clean, replace when needed.
Clean metal . . . A weld inspector would never approve welding on painted surfaces . . .
Some paints give off toxic fumes.

 

[classicalgas]

Women do learn TIG faster than most guys...that's been my experience as a welding instructor as well.

I've compared wire feed and TIG work in the shop many times over the decades. On routine stuff that you're familiar with, have the fixtures and machine dialed in, where appearance is important, strength second, and fast third, TIG beats wire feed... unless you are running several inches of bead on each weld. With MIG you always have to check for clingons ( "dingleberries" ) never with TIG

Lay wire TIG is 75% as fast as MIG...with zero issues, easier access to 3D welds (around small tube) stronger, with no weak but good looking welds, far superior appearance. Zip cleanup of you're going to powdercoat it.

On one off, small projects that walk in the door, where you have to get the weld right first time, TIG beats MIG all day long.

The small gas lenses you can get now let you stick the tungsten out a half inch if you have to (unless you have a fan blowing right on the weld)

One tungsten will last me a month, welding 5 hours a day, five days a week. With a reg and and flow meter, post flow set properly, a bottle will last months as well, welding daily.

No one building electric bikes at home puts down bead at feet per hour rates...MIG is for structural, pipe, and boat building, where feet of bead per minute matters.

All bike frame type welding (and realistically, all "hobby" welding ) should have appearance and reliable strength as first priorities, with speed and cost way, way down the list. That means TIG.

A caveat here. If I were welding 4130 into a bike frame, I'd TIG braze it, fillet weld with sil/bronze rod. Unless you can heat treat the entire frame, your HAZ zone from a steel filled TIG weld is going to be iffy.

 

[PaPaSteve]

If I were welding 4130 into a bike frame, I'd TIG braze it, fillet weld with sil/bronze rod. Unless you can heat treat the entire frame, your HAZ zone from a steel filled TIG weld is going to be iffy.

A quick explanation for a new welder :
The Heat Affected Zone (HAZ) is that area of metal that has not been melted but has undergone changes in properties as a result of being exposed to relatively high temperatures during welding.
i.e. This HAZ term applies when the the parent material is heated high enough to have a molten puddle.

With brazing the parent material is not heated to the point of a molten puddle so the changes from heating is significantly reduced.
Brazing is a capillary process where the parent metal is warmed enough to open the micro spaces between the molecules to allow the brazing material to flow in.
The most common brazing technique for bicycle frames is with an Oxy/Acetylene torch with an inline flux bottle.
Best filler rod will be a nickel/silver bronze with a high tensile strength.
Most used rod is bare Welco 17.
I've made hundreds of 4130 cro/mo steel frames with this method.
By far the fastest and lowest cost method to weld bike frames.

Flux bottle is a simple concept.
Basically like blowing in a drink straw and watching the bubbles come up in your drink.
The acetylene goes through the flux bottle before going to the torch.
Mine is made from a scrap piece of 8" diameter schedule 40 pipe and a few other fittings.

All that nonsense aside . . .
Stick welding a thick mild steel tube is a great way to began learning the welding skill.

 

[jonescg]

Well illustrated, jonescg
Parent metal thickness is largely irrelevant - controlled application of heat IS relevant.


I'm confused why this statement keeps arising with thinwall. Welding (or brazing) sheet metal is primarily about duplicating (or increasing) the parent metal's original strength... whether used in a structural application or not.

More to do with me not trusting my own welding. It's probably fine, but I'm just being cautious.

 

[nicobie]

I've always owned MIG machines. TIG takes more work/time when welding dirty stuff and last time I checked was much more expensive. My friends who have TIG say they are more $ to run and too slow for what they mostly weld.

Everybody has different needs.

 

[My First Ebike]

There is nothing wrong with 1/8" thick square tube for the frame. Of course the frame will be heavy, not good for human powered bike but OK for Ebikes. Use a head and BB from donor bike. Stick weld is much easier and cheaper. As other guys said experience/experiment is the way to go.

As for rear swing arm bearing. 6001 has 28mm OD and 12mm ID. I prefer to use a bit larger OD. 6202 has 35mm OD and fits well in 1.5" tube with 1/16" wall that is 1.375" ID. 6202, you have a choice of 15mm, 5/8" or 16mm ID. Also 6003 has 35mmOD and 17mm ID.

This is my two cents, if you put a tube for rear swing arm, make it a bit wider. I mean longer, between the bearings. Bicycle rear suspensions pivots are way too narrow unlike a motor cycle one, that make the wheel to swing right when you put the power. This is not a problem for direct drive but if you plan to make a mid drive, that gives you uneasy feeling. Anyway, 3~4 inches between the bearings is reasonable.

Thanks a lot for that information, it's the type of thing I was hoping for when I asked my original question to point me in the right direction.
And i appreciate the bearing advice i intuitively did go wider after seeing motorcycles were always wide and had a similar design to each other.

 

[My First Ebike]

"Cheaper" is not a good criteria for choosing (justifying ? ) a welding process on a bike frame.

I saw a basic TIG inverter welder (not a brand name, but set up with auto flow on the shield gas, DC maxed at 100a on 110v input , so a very basic machine, but it did have hi freq start ) for $100 at a local pawn shop last weekend. The whole machine was caryable in one hand, about as bulky a a big lunch cooler. You'd need about another $150 in a small rental argon bottle and regulator/flowmeter to get going, and that would be plenty of power to TIG a bike frame out of .065" square or rec tube. You'd have something you could trust, and be proud of when you were done, too. And a marketable skill.

Pick up an autoshade hood...those show up at pawnshops, working, for under a hundred. Put new lenses in it, so you can see what you're doing.

Factory made ebike frames with no top tube... "step thru"...have been known t snap in half..it's not a great layout from a strength standpoint. The ones that don't fail tend to have a bent spine made of a fairly large diameter and thick wall tube, with lots of area involved in any joints.

i may still end up TIG welding it. i recently found out its not too hard to modify my DC machine to run TIG. The Gas is all new to me and is an extra cost but i do see the value in TIG nad yes its a good skill to have.