Thursday, February 08, 2007
Moulding gears
I've been trying to further Viks fantastic idea of moulding gears using the tread of a toothed belt as the mould. I'm trying to include a concentric central hole, and a rim on one side to locate the belt.
To do this I'm using two split halfs I made on the Strat - these locate on each other and are pulled together on a central M8 thread which force the polymorph into the mould's nether regions. You can see an excessive number of bolts on each half to eject the job from the mould when it's set - this is due to my paranoia of the job sticking against the rough-ish surface of the RP mould. Adrian's excellent suggestion of using a thin layer of plazzy bag on the top and bottom faces of the mould drastically reduce stickage, and so only a few bolts would be needed on a Mk2.
Results to come...
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That's looking good. I'm making something similar using a stack of acrylic sheets bored out with a hole saw. Lots of fiddly location holes though.
Vik :v)
Vik :v)
eD, I was just rereading your post (since I'm waiting for money for parts) and noticed you said a rim on one side. Wouldn't you want a rim on both sides to keep the belt from sliding off? I'd wondered about that for a while, so I'm glad I'm finally asking about it.
Vik, good luck with the acrylic - would be interested to see your design. Good luck with the fiddles.
Bart, second rim is of course a must. It's has to be an extra part though, bolted on later, to make ejecting the casting of the gear possible. This makes it detatchable which is an fantastic bonus for the darwin design. As you can see there's no tensioner in the belt loop for the z - I'm relying on joining the belt loop in situe (a quater turn on a ΓΈ50 toothed gear will hopefully be enough contact). It's critical for setup that the belt can be taken off the gears, so a detatchable rim _should_ make this a piece of cake.
Bart, second rim is of course a must. It's has to be an extra part though, bolted on later, to make ejecting the casting of the gear possible. This makes it detatchable which is an fantastic bonus for the darwin design. As you can see there's no tensioner in the belt loop for the z - I'm relying on joining the belt loop in situe (a quater turn on a ΓΈ50 toothed gear will hopefully be enough contact). It's critical for setup that the belt can be taken off the gears, so a detatchable rim _should_ make this a piece of cake.
I discover many moons later that WD40 is an excellent release agent, and that this still rocks as a way of making custom gears!
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