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Unread 04-07-2007, 12:09
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Madison Madison is offline
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Re: White Paper Discuss: Nothing But Dewalts

Years later, I'm finally looking at this and wondering if it'd be a good project for our team. We'd planned on building something similar on our own, but our driving directive for the future is, as I've probably mentioned elsewhere, the "12 Hour Drive." If we can't manufacture and assemble a drivetrain in 12 hours, I don't want to know from it.

So, I've got a few questions for folks that I've not seen answered elsewhere -- though I'll keep looking.
  1. Is it possible to mount the servo plate (Drawing No. 5) onto the opposite side of the transmission housing than what is shown? I like symmetry and using as little space as possible for anything and everything.
  2. Is mounting the assembly by a shaft collar genuinely sufficient? It seems like these assemblies can put out quite a bit of torque in first gear at stall and holding it place only by friction seems daring. Might it be better to adapt the Chiaphua Plate (Drawing No. 1) to mount directly to the robot in addition to the collar? I want to mount a gear to the output rather than a sprocket and am concerned that a collar will allow too much play in the center-center distance between the gears and create problems there.
  3. We can laser cut .125" and .0625" delrin pieces and chemically bond them together to create a plastic top hat as shown in much less time than it'll take to set up and mill them. Will undersizing the .125" piece by as much as .003" be a disaster? The drawing calls for .128". I'd love to laser cut them, since I can then add a keyway in addition to the pressfit.
  4. Is there a particular reason the modifications to the top hat carrier call for a counterbored hole rather than a countersink? Again, it seems to be it might be easier to countersink the hole than to counterbore it given our tools and desire to get it done quickly.
  5. Is first gear really all that useful, or should I be treating this as a two-speed transmission? It seems like with gearing designed to make the two higher gears useful -- 1:2.5 at the output, resulting in about 1:7.5 and 1:10 -- the first stage reduction then becomes 1:30 and produces way more torque than even the stickiest of FIRST tires can be bothered with. Perhaps it'd be wiser to ignore that first gear all together, since I'm going to be spinning tires there in any case, and gear the second and third speeds down a bit more. 1:10 is awfully fast and 1:7.5 might be illegal on the Autobahn, even.


This looks like a really straightforward modification and I think we ought to be able to get two of these setups up and running in the time it'd take to set up and manufacture the parts for one of the gearboxes we'd otherwise been considering.
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Last edited by Madison : 04-07-2007 at 12:17. Reason: Added a question.
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