Reinforced frame idea.

Frankenstein

In memory of Frankenstein 1991 - 2018
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Not the best place for this question but I consider welding to be a frame related task at times, and my main idea involves jb weld..

So if anyone has seen my downtube they'd notice it's missing about half of it, now none of my friends seem to be eager to jump on the bike, even without the engine installed.

Now I understand why, it's missing a lot of tube, anyway the areas I am bolting to are obviously no longer solid hollow tube one side to the other and they also are slightly indented at the 3rd clamp on each side since there is no metal tube in it to brace it, only on the 2 inner clamps on each side.

I glossed over more than a half a dozen research papers, including 2 from asce, all related to circular steel tubing filled with concrete, but with various adaptions of steel rebar type cages embedded in the concrete, overall those designs are capable of maintaining notable structure and rigidity beyond the failing point of the steel tube, which otherwise would have collapsed.

So those ends of my downtube could in theory be filled with jb weld which is rather robust I've found against chipping and crushing to a certain degree, and inside that epoxy I would simply put many (like probably 40 or 50) thin steel rods (or maybe do something with my excessive spoke supply) to act as the "cage" many of these models use to help keep things in shape.

Anyone have an idea if this would be a good thing to do? I've read that some even used steel fiber (whatever that is, combed out steel wool I guess if the researcher had time) as a reinforcement on concrete members which showed to work well. It shouldn't crack very easily, actually I imagine that the steel tube would be practically bullet proof if not actually literally bullet proof after such a treatment.

A side goal is to do this to basically any hollow part of the frame, including chain stays if I can find a way to do it without weakening it at a critical spot, then again nearly any hole I make and eventually fill to the top with epoxy could be quickly sealed over with a tig welder and forgotten about...

Anywho I'd feel a mighty more confident without the idea that the tube will collapse from bending forces should a supportive bar or plate decide to come loose.

I'll also be able to drill holes in my frame at will at that point basically without any reserve if it's not next to a weld connecting 2 different tubes.
 
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6blueoval9

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Shoot some spray foam into the frame.

Shoot some into a cheap straw and see what it does after it fully dries:)
 

Frankenstein

In memory of Frankenstein 1991 - 2018
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Shoot some spray foam into the frame.

Shoot some into a cheap straw and see what it does after it fully dries:)
Funny enough while researching the idea I came across a guy who wanted to keep 18mm steel tube from bending when he hung things on it, somebody said spray foam.

The basic response was that it would technically reinforce the steel tube, but not enough to be worth screwing with, and since I don't want it to collapse and air bubbles and maybe 20 grams of plastic aren't exactly what I'd call structurally sound or very good at preventing crushing I'd have to concur that your idea isn't a very good one in terms of steel tube reinforcement, especially when heavy loads (aka:my ass) are involved. Thank you though.
 

6blueoval9

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Its used in metal subframes to stiffen chassis and even major manufacturers use it in production cars to stiffen areas of a chassis or body....perhaps it must be a flexible material to work?
 

Frankenstein

In memory of Frankenstein 1991 - 2018
Joined
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Messages
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Its used in metal subframes to stiffen chassis and even major manufacturers use it in production cars to stiffen areas of a chassis or body....perhaps it must be a flexible material to work?
Either they have a specialized foam for reinforcement (I can't buy at home depot,) or the foam they use as fire retardant just so happens to act as a form of reinforcment, like the foam in the straw example.

They use steel tubes with concrete to prevent sky scrapers from collapsing during earthquakes. The steel rib/skeleton/cage inside the concrete vastly improves the capability of an otherwise totally failed member to still retain a large amount of its original capability to support loads even after the steel tube has buckled and the concrete totally cracking through and crushing to take the shape of the newly deformed tube.

Cars are designed to be crushed (or more precisely not totally crushed) at car speeds, which are nothing comparable to million ton structures being supported against earthquakes at an energy level of over nine thousand...

Sorry but epoxy is probably easier and cheaper and a lot more reassuring than expanding foam, no matter how great the stuff is.
 

gary55

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Nov 27, 2012
Messages
4,058
Not the best place for this question but I consider welding to be a frame related task at times, and my main idea involves jb weld..

So if anyone has seen my downtube they'd notice it's missing about half of it, now none of my friends seem to be eager to jump on the bike, even without the engine installed.

Now I understand why, it's missing a lot of tube, anyway the areas I am bolting to are obviously no longer solid hollow tube one side to the other and they also are slightly indented at the 3rd clamp on each side since there is no metal tube in it to brace it, or lying on the 2 inner clamps on each side.

I glossed over more than a half a dozen research papers, including 2 from asce, all related to circular steel tubing filled with concrete, but with various adaptions of steel rebar type cages embedded in the concrete, overall those designs are capable of maintaining notable structure and rigidity beyond the failing point of the steel tube, which otherwise would have collapsed.

So those ends of my downtube could in theory be filled with jb weld which is rather robust I've found against chipping and crushing to a certain degree, and inside that epoxy I would simply put many (like probably 40 or 50) thin steel rods (or maybe do something with my excessive spoke supply) to act as the "cage" many of these models use to help keep things in shape.

Anyone have an idea if this would be a good thing to do? I've read that some even used steel fiber (whatever that is, combed out steel wool I guess if the researcher had time) as a reinforcement on concrete members which showed to work well. It shouldn't crack very easily, actually I imagine that the steel tube would be practically bullet proof if not actually literally bullet proof after such a treatment.

A side goal is to do this to basically any hollow part of the frame, including chain stays if I can find a way to do it without weakening it at a critical spot, then again nearly any hole I make and eventually fill to the top with epoxy could be quickly sealed over with a tig welder and forgotten about...

Anywho I'd feel a mighty more confident without the idea that the tube will collapse from bending forces should a supportive bar or plate decide to come loose.

I'll also be able to drill holes in my frame at will at that point basically without any reserve if it's not next to a weld connecting 2 different tubes.
Could you give us another picture love? And shorten the question a bit. I'm drunk as a skunk hungry as f*** and trying my best to cook a casserole.
 
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Frankenstein

In memory of Frankenstein 1991 - 2018
Joined
Jun 24, 2016
Messages
5,076
20170624_180957.jpg


But with less downtube, didn't have room for the sparkplug.

Less happy looking grass in the background too.
 

gary55

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Nov 27, 2012
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Bro I could through a sh*t load of suggestions at you, but none would be what you have not already thought of. Let's hope the angle iron mod you have contrived is stronger than you and I and you buds think it is. If it starts getting sh**ty than a frame with more room is in the near future. You know what the f***s up.
 

Frankenstein

In memory of Frankenstein 1991 - 2018
Joined
Jun 24, 2016
Messages
5,076
Bro I could through a sh*t load of suggestions at you, but none would be what you have not already thought of. Let's hope the angle iron mod you have contrived is stronger than you and I and you buds think it is. If it starts getting sh**ty than a frame with more room is in the near future. You know what the f***s up.
I'm going to weld the bracket together, drill half holes and spot weld basically in the middle of the plates, weld the saddles in, and toss some kind of support bar between the down tube and top tube to prevent flex and try to use the corners as the foundation of that upper bracket.

I saw a few nice frames with so much more room, but without the challenge it's a boring sport..
 

gary55

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Joined
Nov 27, 2012
Messages
4,058
I'm going to weld the bracket together, drill half holes and spot weld basically in the middle of the plates, weld the saddles in, and toss some kind of support bar between the down tube and top tube to prevent flex and try to use the corners as the foundation of that upper bracket.

I saw a few nice frames with so much more room, but without the challenge it's a boring sport..
Dilly Dilly.
 
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