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Tire Truss Plates

 
gardener
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Did I bring this up before?
I couldn't find any sign that I had.
I was reading about a geodesic dome connectors that was cut out of  flat pieces of roofing rubber using a water jet.
Naturally I thought of something cheaper,  used tires.
The dimensions of  the sidewslls and treads don't seem to be a good fit, and working used anything into a manufacturing line takes a bit of human attention or advanced robotics.

Site built trusses are by thier nature a bespoke sort of thing.
Homesteaders are usually doing them to save money.
The plywood used in the truss plates is often the most expensive part of the truss.
Could bits of tire work as truss plates?

I'm sick right now and juggling many projects, poorly, but I want to try this idea out.
 
pioneer
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I'm not an engineer but I would say if the tread weren't ground down to the wire one could cut a section from a tire and gusset a truss.
I think I'd use bolts with fender washers all the way through instead of using nails or screws. The pressure of the rubber against a nailhead because of movement due to temperature deviations might back it out.
Similarly, a screw head might cut it's way through the rubber and loosen over time. A fender washer over a wood screw would probably work.
I don't know that I would depend on this old material used in a new way in my home unless I had an engineer test it properly. A chicken house or shed probably wouldn't be big enough to give you a clear indication it would work in a larger structure like your new home. You'll have snow loads to consider among other things that relatively few of us could actually figure and guarentee against failure. I doubt seriously that an architect would approve it's use without trials and testing to back up its potential.
I had never given anything like this much thought, but that's one hell of a good idea you have! You have the potential for quite the business sitting right in front of you! Gussets from used tires! Outstanding!
 
pollinator
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Hmm, cool idea..


I have never built a geodesic dome, and I am not any sort of engineer..

I am thinking there is a potentially significant difference in loading between geodesic dome 'star' gussets, and some of the gussets in a standardish gable roof.


If you picture the most basic of gable trusses, it is a triangle. I think the top gusset doesnt  generally see much load of any sort; the two struts are balancing and spreading the forces. The outer gussets, where the bottom chord of the truss connects to each side, are in tension; they are stopping the walls of the building from spreading.

As long as they do their job, no additional loads are introduced to the top gusset. If you skip the bottom chord of the truss, you've got rafters with no rafter tie, and we all know how that goes...

The potentially important difference is that the spreading load will increase dramatically as the angle of the triangle gets shallower.

The triangles in a geosdesic dome, not being very shallow by the nature of the shape, will help keep this loading modest. And, the need for a gusset that isn't flat makes the flexible material a neat fit, while this is not a benefit for a standard truss..

It also seems possible that force on a given gable truss may be notably higher than any one component of a dome..


If I decided to use tires in this way, I would do some redneck destructive testing. Calculate the expected load, and then make up some gussets and use them to lift a load around 2-3x the expected load, with a piece of heavy equipment.

The weight of steel items is fairly easy to calculate, if one doesnt have a suitable scale..
 
William Bronson
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Thanks for the replies!

Even the geodesic dome connectors were not intended for heavy loading,  but for repeated demonstrations.

I think screws are not preferred for trusses because of expense, shear strength and the chances they might back out.
Naturally I would use them anyway, at least to test these ideas out.

The danger that any fasteners used might tear through is real.
The steel will help, washers would help but add expense and complicated assembly.
Don't laugh, but I think staples would be ideal.
A multitude of staples, each having a very good chance of straddling a strand of steel.

Cutting the tire material itself is no joke.
The combination of dragging rubber and steamed steel dulls and heats cuttting surfaces .


I'm not sure if it is at all a viable idea, but tires are everywhere for free, so I like thinking of new uses for them.
 
gardener
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Hi William.  To cut up tires I usually use a thin cut off wheel that I keep touching a bar of soap with.  The soap just helps it from sticking to the cut off wheel like when grinding aluminum.  Be prepared for a lot of smoke.  Good luck.
 
William Bronson
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That is great tip!
After years of using diamond edged grinder disks that were intended to cut masonry to cut cut metal instead, I bought one that that was intended for use on metal.
I promptly misplaced it!
I'm sure to find it once I buy a new one, but meanwhile I'm wondering if these disks would benifit from the soap trick.
 
Christopher Shepherd
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I think it will help on most materials. I think it is kinda like using oil on a drill bit to cut faster.  It works well on drilling sappy pine too.  I use the cheap thin abrasive cut off wheels from harbor freight.  I just get mad at myself when I can't find the good quality one somewhere in the shop.
 
pollinator
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I use the thin good quality inox discs. they are 1mm thick and are fantastic.
One thing with all discs, dont plunge the disc in any more than you need, they last much longer.

As for the Dome connectors I think as an Engineer they would be worth playing with.
I doubt most engineers would be able to prove them ok or not without testing.
Best way is to try.

The main purpose is to hold the ends of the triangles together, without having the bolts pull through either the connector nor the triangle arms
and the 'connector itself not come apart.
The stresses involved could be measured with strain gauges, but its complicated and who wants to do that.
They just have to work.
If they dont break they must be ok.
Every dome I have worked with has not had a permit and has not fallen down.
But they leak water easily, thats the hard part. Too many joins.
 
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