Santa has a new ride [Archive]

GoodwrenchIntim

12-04-2008, 08:33 PM

flowable silicone, I put it on like you would for making silicone coated foams like in this article

"Ever wondered if you could make your own silicone sponge tires and save some of the expense plus create custom sizes?
Well, thanks to Trek Lawler you might be able to.
“OK here go some instructions on how the tires are made now. You'll need to go down to your local O'Reilly auto parts and get some flowable silicone, it's made by Versa Chem and is type 750 made for windshield and glass sealer. You will also need some Pliobond contact cement; this is industrial grade and should be available from most hardware stores.
You'll then need to find some foam rubber that is comparable to the kind used in the Wizzard tires. Since I don't know anything about this I simply took off a foam rubber from a Wizzard tire that was no longer any good and took it to my local rubber and foam dealer. In my case it was to a place here in K.C. called Hanna Rubber. These guys looked at it and we found a comparable match. After you get good at this you can experiment with softer or harder compounds of foam rubber. Okay now that we have some of the vital components. You will need to make a tool to cut out a circle in the foam. In my case since I have a lathe I simply turned down a piece of tubing that was approximately .250 of an inch and put a knife edge on it. I then chuck this up in a dremel (everyone has a dremel tool don't they) and cut out the inner circle that the wheel will go into. I also made a tool to cut out the outer circle to complete the tire donut, but I suppose you could just cut it out and true it up later after mounting it on the wheel. I then take the wheel (in most cases I re-use Wizzard wheels, and in some cases will use flanged .250 wheels with the flanges turned down) coat it and the inside of the rubber donut with the Pliobond, this doesn't need to be excessive just a little will do, and press the wheel inside the donut. I usually wait overnight to provide a good tight glue bond.
Once this crude donut and wheel are made I mount it squarely in an old T-jet axle (see these are still good for something) using a JW's tire press, I then chuck it up in my Dremel tool. You'll need to turn this at a fairly high rate of speed around 20,000 RPM. Take an exacto knife and trim the outer edges of the tire so that they are close to the edge of the wheel (don't cut them to close as you'll be able to sand them true later). Use a piece of sandpaper around 200 grit (in my case I simply got some of the stiff finger nail sanding files, I'm sorry I don't know exactly what they are called but they work very well and provide a stiff support and are some what flat). I then start sanding the tires down, you'll want to sand the tires down to around .010 of an inch smaller then what you want the finished product to be (the silicone will add the remaining diameter to the tire). Be sure you make it as square as you can. After getting it to the diameter you want I then sand the outer and inner edges to the wheel.
Now get an adult beverage and clean up all the foam dust you have all over you. OK now you've got the wheel and tire blown off and you're ready to apply the silicone. Chuck the wheel and tire in the dremel, and add just a little of the flowable silicone (just a word of advise, this silicone is FLOWABLE and will drip so don't do it over your wife's good carpeting or counter, yes, I learned by mistake). Work this into the foam and around the outer edges, (don't worry if it's not flat, and just rub it into the foam).
Once the first coat of silicone is rubbed in, hold the tire assembly inside a Dixie cup or some other disposable cup and turn the dremel on as fast as it will go. I have an adjustable one and it will turn up to 30,000 RPM. Please do this inside something that will catch the excess silicone flying off of the wheel (yes, I also learned this by mistake. I also have a very understanding track manager. This silicone will eventually dry and peel off of the wall but it's hard to get off of the dog). You'll notice that the silicone will look rough, this is OK. Carefully take the wheel and axle combination and either leave it in the dremel and stand it up right or carefully take it out of the dremel and mount it in something that will support it upright (in my case I took a block of wood and drilled holes in it for the axle/tire assemblies. This silicone takes around 15 minutes to start to gel, I usually wait around 30 minutes and then add another coat. After each coat check the diameter until you achieve the size you want. If you spin the tire at the speed I indicated the silicone will add about .003" of silicone with each coat (I know this doesn't sound like much but 3 or 4 coats will usually get you in the ball park). If you've done everything correctly you shouldn't even need to true the tire up after it dries. The silicone will dry very flat at that thin of a coat.
Please be patient when trying this, it's not something you're going to master immediately, as a matter of fact I ruined 2 pairs of tires just the other night because I got to zealous with the sanding block and made the tires to small. I've been running these tires for quite some time now and have been doing very well in our MAHOR races here in K.C. I hope this helps, it's quite a bit of work but very satisfying after you achieve the final goal."