[Erik Mannie]

Here is after my weld pass, which I hoped would do the job. It did not succeed.

[Erik Mannie]

Here is the back side. I failed to go hot enough.

[Erik Mannie]

At this point, I was lost because I had both cold welds and undercut. I decided to just run another bead over the first bead, using plenty of heat. The welder was set at 65A max because the plate had thinned to .063" during the flap disk step.

This is what it looked like after that second pass.

[Erik Mannie]

It looks like I failed to take a photo of the back side after the second pass. It had a very small stretch where I failed to achieve adequate penetration. I will have to wash part of that second bead tomorrow.

I am a little frustrated, but I can see that the increase in cleanliness made for a noticeable improvement.

In my mind, I know a lot of what I need to do, but my lack of hood time is showing here. I just need to practice a bunch more.

[weldin mike 27]

Kudos to your efforts on welding practice, but I think you may be on over kill mode on this job. Could this part be formed in one piece? Either hot or cold? A small hydraulic press or even a screw press may have enough grunt for forming cold.

[Erik Mannie]

Kudos to your efforts on welding practice, but I think you may be on over kill mode on this job. Could this part be formed in one piece? Either hot or cold? A small hydraulic press or even a screw press may have enough grunt for forming cold.

These are just prototypes to test this particular design (specifically the shape to see if it causes mayhem while moving at 40mph). The actual part could never be made of steel because it would be too heavy. The problem is that the tire needs about 27 of these. I am clearly in need of practice so anything that gets me under the hood and lighting up is a welcome development.

The rear of the electric bike weighs up to 340 pounds (mostly the rider) and the front tire kicks up nails and positions them right in line for penetration. The bicycle tire carcass is very thin. My ebike only has this one fatal flaw. Changing a flat tire in the rear takes a long time due to all the hardware and wires. I have been testing this bike for 3 years and I have come to the conclusion that I need to get am impenetrable barrier between these nails and the tube. Most people just run a different (e.g. solid) tire, but this particular fat tire is not available in a solid configuration. Unfortunately for me, I am very stubborn about wanting to run this one specific tire.

Knowing the forces at which a nail would hit this plate, I wonder if you guys think that a brazed joint would be strong enough.

This is all just a hobby for me (I have never sold a bike), so I don't mind the workload. To the contrary, I enjoy it! The whole time I am prepping the work piece, I am anticipating the fun part!

[weldin mike 27]

Fair enough. For this application, I would try simply fusion the steel with no filler. The parent metal should flow enough to join well. It won't be proud of the surface, but it'll do the job. Remember, nice sharp tungsten, short arc.

[Erik Mannie]

Fair enough. For this application, I would try simply fusion the steel with no filler. The parent metal should flow enough to join well. It won't be proud of the surface, but it'll do the job. Remember, nice sharp tungsten, short arc.

I will try to get a good enough fitup to do that.

I always have about six sharp tungstens right next to me when I am welding.

I use a really short arc, which has me dipping my tungsten a lot. I think this has do do with the fact that I wear 2X glasses. Through the glasses, my arc appears longer than it actually is.

[Artie F. Emm]

First, good on ya for developing your own bike, and good on ya for learning to weld!

I'm trying to visualize how this armor plating works. The first post in this thread says you plan to bolt as many as 26 of these onto the bike to protect the tube from punctures. Where and how will these bolt on?

Just trying to catch up to you: in a typical clincher tube/tire/wheel arrangement, the tube expands inside the tire, and the bead of the tire contains the tube. As you say, the thickness of the tire is the only material between the tube and the roadway. Do your armor plates sit between the tube and the tire, in order to protect the tube?

[Erik Mannie]

First, good on ya for developing your own bike, and good on ya for learning to weld!

I'm trying to visualize how this armor plating works. The first post in this thread says you plan to bolt as many as 26 of these onto the bike to protect the tube from punctures. Where and how will these bolt on?

Just trying to catch up to you: in a typical clincher tube/tire/wheel arrangement, the tube expands inside the tire, and the bead of the tire contains the tube. As you say, the thickness of the tire is the only material between the tube and the roadway. Do your armor plates sit between the tube and the tire, in order to protect the tube?

The plates bolt to the inside of the tire. Disregarding the tread (knobbies), a nail would first penetrate the wimpy .100" rubber tire carcass and then encounter the .080" mild steel, and no nail can get past that. The tube is protected by 1/2" yoga mat foam (Nitrile rubber, NBR, https://en.wikipedia.org/wiki/Nitrile_rubber). Thee nut on top of the plate and the plate itself would carve up the tube in a hurry without this (fortunately lightweight) protective layer of foam.

The uninflated tire has a diameter of 28", but this grows to 30" when it is inflated to 20psi, so the circumference that I am trying to protect expands from 88" to 94".

It would be pretty easy to just bolt in plates (low profile bolts pictured below) before it is inflated and call it good, but this leaves 6" of unprotected area. This would have 6.4% of the area completely vulnerable, thus the "protective overhang".

[Erik Mannie]

Here is the "shop" that I will have while I am at The Hobart Institute. I will only be there two months a year, and the shortest lease for a house or shop that I could find was 12 months.

I will outfit this cargo area specifically for making these plates. I plan to make about 330 of the plates in the 8 weeks that I am at school. I need to choose brazing because this van is the only place that I have to store an O/A setup.

I am also choosing brazing in order to keep my power requirements to a minimum. I have an AC/DC welder here in CA that I will not take to OH. I don't want to buy a DC welder in OH when I already own a perfectly good welder.

I will use an inverter for charging the battery powered cutoff wheel, flap disk and angle grinder.

There will also be also be a bench vise and drill press. I will be using cheap (think Harbor Freight) tools.

[cj737]

Just a thought... but have you considered building a ring roller and constructing the internal shield from a single piece, then welding just 1 seam? That would be a huge time saver, not to mention consumables (gas and filler) and other necessary work (grinding, pressing, etc).

[Artie F. Emm]

I was thinking a strip of kevlar in between the tube and the tire.
https://www.mcmaster.com/kevlar-fabric

[Erik Mannie]

Just a thought... but have you considered building a ring roller and constructing the internal shield from a single piece, then welding just 1 seam? That would be a huge time saver, not to mention consumables (gas and filler) and other necessary work (grinding, pressing, etc).

You mean a single, integral hoop? That was my first idea, but when it was discussed on an ebike forum it was pointed out that it would bend or otherwise deform in use. When there is weight on the bike, the bottom of the tire (where it is contact with the ground) is a line rather than an arc. As the bike moves forward, this line ("flat spot") moves along the circumference. I wonder if this would heat up the metal. Also, hitting a bump could cause an unwelcome deformation in the hoop that 20psi would not push back out.

There are flat resistant tires that use a hard plastic liner. I don't think that this plastic liner would expand by 6%.

With a fat tire, a certain, limited plushness in ride quality is achieved by the buoyancy of the pneumatic tube. With the independent plates, the tire can expand to a larger circumference upon inflation, and I am hoping that the plates can articulate enough to withstand lateral (while cornering) and radial (while hitting a bump or having a 340 pound load on top) stresses.

Also, I had been practicing my welding on scrap material, which is fine. I have been looking for an actual project which involved a lot of welding because I need a lot of hood time. I am trying to learn all of the processes.

[Erik Mannie]

Here is the most recent bead that I made. I gave up on the wire wheel for removing the mill scale. I also tried 60 grit emery cloth pulled tightly on a large flat file, but for some reason the surface of the steel sheet was not flat after its trip to the hydraulic press. I now use the flap disk.

I am still wondering if brazing with silicon bronze can be made just as strong. I read this https://www.brazingbook.com/brazing-vs-welding/ and almost at the very bottom it says "Brazing advantages: joint strength,..". I didn't expect to read that; I think that many people would disagree!

[cj737]

If an internal rim had ribs running lengthwise, it would be VERY strong. The pressure from the inner tube against it will limit deformation. The weight bearing on it directly at any point is limited to the weight directly above it. The balance is then distributed. Just an FYI.

[Erik Mannie]

If an internal rim had ribs running lengthwise, it would be VERY strong. The pressure from the inner tube against it will limit deformation. The weight bearing on it directly at any point is limited to the weight directly above it. The balance is then distributed. Just an FYI.

If the ribs were on a single hoop, the hoop (and ribs) would have to expand from a circumference of 88" to 94" upon inflation. I wouldn't know how to make that happen with any metal. I will be limiting my testing to multiple independent plates (with overhangs) until such time that this design flops. I am still trying to TIG weld 26 plates, but working 7 days/week is slowing down the progress.

I still wonder if you guys think these plates can be brazed because I will have a lot of time to make a few different designs on my upcoming vacation. Brazing is the only welding process that I will have access to during my 8 weeks away from home. I will have time for destructive testing and I will post the results here. My destructive testing consists of clamping a plate in a vise and trying to hammer a very long, hard and sharp nail through it with a sledgehammer. I wonder if this will bend the overhang on a brazed joint.

I learned to braze with bare silicon bronze rods and brass brazing flux (liquid as opposed to powder), and that was fine. Now I see that LFBFC rods are available. I will have time to try these rods, and I wonder if I will end up using the flux coated rods or the bare rods and liquid flux. A 10 pound box of these https://www.amazon.com/Blue-Demon-RBCuZ ... demon&th=1 costs $79.40. I learned of these in this video: https://www.youtube.com/watch?v=OL-2yNndGC0. In that video, Bob Moffett sure makes it look like a very easy process. Not that I am looking for easy; I am looking for the completed plate to pass a bend test. I don't know if you would call striking it with a sledgehammer and nail a bend test. More like an impact test.

Since the mild steel is .080", I will start with 1/16" rods, but I may end up going to 3/32".

[Erik Mannie]

So like in posted in another thread, my mobile brazing van project has completely fallen through, so I am back to TIG welding all of these parts.

I will be making some of these plates in titanium, but I need to see if I can drive a nail through .078" titanium https://www.onlinemetals.com/merchant.c ... &top_cat=0. Once I decide on the thickness of the titanium, I will inquire about how to back purge this plate. This shouldn't be too hard since it is such a small part. Maybe I could make a box out of aluminum and clamp the titanium plate in that purge box?

I have never seen a purge box. I have a dual flowmeter on my Argon tank https://store.cyberweld.com/viredfm150d ... K4EALw_wcB, but this would be my first experience with back purging. I wouldn't want to waste Argon.

If the titanium were any more expensive, I wouldn't use it! Titanium Joe sure has better prices https://www.titaniumjoe.com/index.cfm/p ... eet-plate/. Titanium Joe has mostly Grade 5 and alloys instead of the Grade 2 (which I gather is pure Ti). I just need it to stop a nail or screw, and the lighter the better.

I have never welded Ti before. Should I choose either Grade 2 and Grade 5 in order to make the welding job easier? I will also be looking at the hardness ratings, assuming that hardness is the trait that would resist a puncture.

[LtBadd]

I will be making some of these plates in titanium, but I need to see if I can drive a nail through .078" titanium

I doubt it

I have never seen a purge box. I have a dual flowmeter on my Argon tank but this would be my first experience with back purging. I wouldn't want to waste Argon.

If you're welding two flat plates, it may be possible to clamp them to an aluminum backing plate that would dissipate the heat. Make sure both materials are clean so you get good contact between them, if this isn't possible then an aluminum purge box can work.

I have never welded Ti before. Should I choose either Grade 2 and Grade 5 in order to make the welding job easier? I will also be looking at the hardness ratings, assuming that hardness is the trait that would resist a puncture.

As long as you have the right filler, choose which one best suits your project, Ti is really easy to weld, just got to have the gas coverage issue under control.

[Erik Mannie]

I will be making some of these plates in titanium, but I need to see if I can drive a nail through .078" titanium

I doubt it

I have never seen a purge box. I have a dual flowmeter on my Argon tank but this would be my first experience with back purging. I wouldn't want to waste Argon.

If you're welding two flat plates, it may be possible to clamp them to an aluminum backing plate that would dissipate the heat. Make sure both materials are clean so you get good contact between them, if this isn't possible then an aluminum purge box can work.

I have never welded Ti before. Should I choose either Grade 2 and Grade 5 in order to make the welding job easier? I will also be looking at the hardness ratings, assuming that hardness is the trait that would resist a puncture.

As long as you have the right filler, choose which one best suits your project, Ti is really easy to weld, just got to have the gas coverage issue under control.

Great news! I am looking forward to TIG welding on Ti.

I will be MIG welding a few of these plates, too. We'll see how that goes.

[burnt drzl]

Have you looked into other options as well? We had issues with the backhoe constantly getting nails in the construction site sowhat we found out later and not from the tire repair guy was foam filled tires. And if it could hold up a backhoe i’m pretty sure it could handle an ebike. That would definitely save you alot of time and money with production.