Yesterday I ran a small test of the first of the machines I need to make tires.
The first machine is the one that produces the necessary fabric, that must have all the threads going one direction only (normally-woven fabric can't be used, it won't work). I had to figure out how to do this myself, since there is no machine I found that would do it. It is the major obstacle to making home-made tires, so I won't show or say how the machine works--but I can show what it makes.
http://www.norcom2000.com/users/dcimper/assorted/inanities/recumbent/tire_making/test01.html
This piece has a few things wrong, but most of those issues are already solved. The thread count ranges from about 40 to about 50 threads-per-inch, but stopping and re-starting the machine causes that. I was making adjustments to it while I was doing this, but running a whole piece without stopping should get it more consistent.
My goal was for an 80 thread-per-inch finished tire casing, so that requires two layers of 40 threads-per-inch that are folded across each other. 80 TPI is rather high for a cruiser-bicycle tire, but about medium for bicycle tires in general. More threads = a thinner casing and less rolling resistance. Cheap tires will have around 40 tpi while higher-end road bicycle tires will have around 120 tpi.
There are no cross-threads at all, the thread is held together only by the rubber. I only put one thin layer of rubber on and I didn't let it cure very long so it tore very easily. The edges are also frayed because the method I had planned to use to cut it off the machine didn't work so well, but I already have a few other things I can try to help that.
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With commercially-manufactured tires, they have the fabric made separately on large rolls and they just cut off whatever size they need. You can see huge rolls of it in these two bicycle tire manufacturing videos:
Video below is a Continental factory video, in an episode of "How It's Made"
http://www.youtube.com/watch?v=JM_x0qPM8Ok
skip ahead to 1:55 for the fabric
Also there is a Schwalbe video online too
http://www.youtube.com/watch?v=M9RzJAWvOMQ
skip to 3:45 for the fabric stuff
They don't say very much about the fabric itself, but then they don't actually make it at the tire factory either.
I
did find out how it is made but I couldn't make it the same way they do, because making a machine that could produce continuous rolls like that would require a huge amount of thread at once. The machine I have built can only make enough for one tire at a time. The test sample is only a short piece, but the machine can make continuous pieces long enough for a 29" tire.
Also, they make the fabric separately and coat it with rubber afterward. I figured it would be easier to just coat it with rubber during "weaving", since it is easier for me to spread a thin layer of liquid rubber onto it and let that cure than it would have been for me to roll semi-solid rubber into a very thin unbroken sheet.
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I am still quite a ways from making a whole tire, but this is one part that you can't do it well without, and making this part was the biggest problem I could foresee.
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