Reinforced frame idea.

Frankenstein

In memory of Frankenstein 1991 - 2018
Joined
Jun 24, 2016
Messages
5,077
I already stuffed a short piece of pipe in it, my concern is the 3rd clamp on each side will create a place for the tube to slowly collapse against with vibration. My other thoughts crossed fiberglass though I really don't like playing with the stuff, I know it would be strong enough though I personally like the idea of being able to drill and tap and drop helicoil in with some extreme strength behind it, and can tighten a bolt down without it bending the steel.

The pipes are basically crimped in place now with the bolts torqued down, taking them out isn't going to happen anymore, the first one I torqued that was too short a gap (oops) wouldn't come out, I had to slice the steel tube open after I removed the portion from the bike.

I like jb weld for what it does, in every application I've used it with proper preparation it just hasn't failed, it seems like a reasonable option, if a good part of the tube volume is steel rods then it shouldn't take a crap load. I don't really mind weight, I seem to do well enough with what I'm using and if I put some on the bike I can loose some on myself to make up for it. I really kind of wanted to make this a slower bike anyway and keep maybe 35 max for what it will do, I can build a lightweight toy bike anytime I please, there's a frame hanging in the basement waiting for its day, I just don't have any particular reason to at this time.

Maybe aluminum rods? Spoke metal isn't always the easiest stuff to cut into, aluminum is light and easy and I can helicoil it if I want rather easily. I can get away with some thicker rods too, it would take a lot of spokes to fill it up.. I don't know what do you think?
 


FurryOnTheInside

Well-Known Member
Joined
Sep 23, 2013
Messages
3,932
Funnily enough I was reading about epoxy filling material, very briefly just the other day, on a yachting forum. There are companies selling specific filling material. Seems metal powders are used to improve compressive strength and fibres for tension, micro balloons for lightness and JB Weld already has metal in it I think was the upshot. I only wanted to make my epoxy resin go further and thought I would check into it a little bit before sweeping the steel filings into my epoxy while making the U clamp saddles (picture in recent photos section).
I think aluminium should be fine in compression but I know nothing really lol.
 

Crisco

Member
Joined
Apr 4, 2017
Messages
205
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.

A nice hard wood like Jarrah perhaps..? :p
 

butre

Well-Known Member
Joined
Dec 2, 2013
Messages
2,502
I'd like to think so too, not convinced.. So do you think it would prevent cracks by making the frame more ridged, or is the slight flexibility part of what keeps it from cracking...
you'd be surprised just how floppy steel is. some big skyscrapers have a big ass vibration dampener up top because the whole thing sways. the one in taipei 101 weighs 728 tons


here you can see how much movement happens. you can't see or feel it when there's not a static reference point like a vibration dampener.
 

Steve Best

Well-Known Member
Joined
Sep 22, 2012
Messages
1,269
Wow, ironic coincidence, was just reading about these as part of a paper on a project for work.
I was surprised how much the Statue of Liberty moved on the day I was up in it.
Not all skyscrapers have these and many of them that do now are dynamically controlled.
 

Frankenstein

In memory of Frankenstein 1991 - 2018
Joined
Jun 24, 2016
Messages
5,077
Wow, ironic coincidence, was just reading about these as part of a paper on a project for work.
I was surprised how much the Statue of Liberty moved on the day I was up in it.
Not all skyscrapers have these and many of them that do now are dynamically controlled.
Railway bridges can be made smaller and stronger over wider passes, easy to build too.

I am not speaking of the flex that will occur in the tops of high standing structures, I'm looking at basically sudden failure protection, and practical form of anchorage into the frame of the bike, which is what you would expect on a heavier piece of equipment. It must also retain rigidity and act against compression. Vibration related failure at connected joints is just rapid pulling and compressing of a spot until it of course fails.

By backing the walls of the tube there is no question it would prevent fasteners from flexing the tube even a tiny bit, no flex means the existing welds should retain integrity too.

The t shape is really strong, it is basically going to be a 1/8 thick plate with a quarter inch steel spine. The clamp saddle will be welded across the 2 and the underside still needs work. It's a hobby I'll probably finish it before I get old.
 

Crisco

Member
Joined
Apr 4, 2017
Messages
205
Yes, that might work, please cut me a section and ship to me from Australia if you don't mind, I'm not going there any time soon so I can't to it myself.

No wukkas. On its way driftwood style..! Although, I'm pretty sure that garbage collector current will simply ignore the address and stamps I put on.
Hmmmm... Even if it does make landfall before we both croak, people will be looking for a dude named Frankenstein getting around with goggles, a stethoscope, and remnants of last year's Movember.
Absolutely, definitely, certifiably, ridonculous..!!;)
We went through a really clever phase of cutting down our old growth, slow growing forests to sell to China. Then we bought them back from the Chinese as value added toothpicks and furniture. It was ok though, because we replaced the magnificent slow growing Carri and Jarrah with fukn pine trees..! And they call us the clever country...
My house is what's known as a miners cottage. ~80 years old, on 2.5m stilts for cooling in a tropical summer and no dramas when we get a cyclone tidal surge. It's made of tongue and groove Jarrah that moves with the weather. Dry season can close and lock bathroom door; wet season will barely close let alone lock.
There are loads of these cottages floating around where I live and they are relatively cheap as they are quite small. No idea what it would cost to actually build one from scratch from Jarrah, but it wouldn't be a pretty number. It's a timber that's reserved for quality furniture these days...

Whippet nose...
DSC_0422.JPG


You can see all wide tongue and groove. Old as the hills but bomb proof..
DSC_0144.JPG


Underneath. Gave doggos old mattress... Yeah I'll do that again.. not..!
1467874819662.jpg
 
Last edited:
Top