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Unread 31-12-2007, 12:30
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Re: pic: 499 Prototype drivetrain final layout

Madison, that is a really cool design. What is the purpose of having movable gearboxes? Tensioning? Either way, its a very neat modular design. Truely innovative.
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Unread 31-12-2007, 14:29
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Re: pic: 499 Prototype drivetrain final layout

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Originally Posted by Hachiban VIII View Post
I really like this design Madison. This would be a very friendly prototype layout since it would allow you to use however many wheels you want.

As for machining the slots, all that results in is a loss of movement (and you really only need an inch to tension the chains). The real purpose of using 80/20 is that it allows you to tighten the bolts anywhere along the track, in other words, no need for a tensioning screw or other such contraption.

Will these be using AM Gen 2's? Perhaps you should start another thread

[edit] One thing you may not have considered (and I did not consider it the first time I designed my drivetrain) was tightening the bolts on the bearing blocks. From the looks of your design it would appear the wheel prevents people from reaching the outside bolts. [edit]
I uploaded the image to the gallery: http://www.chiefdelphi.com/media/photos/29458?

This never got as far as having motors implemented, really, because it was primarily meant to examine construction methods. A lot of things are placeholders.

The advantage to using 80/20, as I see it, is that the stuff that requires a mill when implementing a sliding wheel tensioning system -- the slotting -- is preformed into the your frame rail. If that's the case, milling a clearance slot for the axle to slide in eliminates any time or resource savings obtained by using 80/20 in the first place. If you're going to be milling anyway, just use rectangular or square tubing and mill slots for the axle/bearing block clearance as well as through bolts that hold the bearings in line with one another.
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Unread 31-12-2007, 15:09
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Re: pic: 499 Prototype drivetrain final layout

I would be highly interested in a sort of synthesis of these two designs. I like Madison's design for the lightness of the frame components, but I think there's a lot of advantage to the style of bearing blocks the Andrew has designed. As I understand it, the main purpose of 8020 is to simplify chain tensioning, and Andrew's block only need three screws on the top for adjustments. Madison's, while somewhat lighter, would take require loosening 2 screws outside the frame and 2 screws inside the frame, which seems more troublesome to me. Admittedly, the loading on Andrew's blocks wouldn't be quite what you'd like, but I don't think it would really present a problem. If Madison's using 1515 Lite instead of 1010 on those side rails you could probably bolt them straight on.
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Unread 01-01-2008, 21:37
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Re: pic: 499 Prototype drivetrain final layout

Madison,

I like the design you have presented here, with it's effective use of extruded aluminum rails. However, as a pretty experienced user of 8020, I'll make several comments:

1) The 1010 material you are using is actually fairly flexy in torsion. Add that to the bending stiffness and your deflections start to add up. With a cantilevered setup like this, those middle wheels may induce enough flex in the rail to either throw a chain (#25) or negate any drop you had to begin with. Anything you can do to add a x-plate or similar will stiffen up that center axle tremendously.

2) The 8020 fasteners are very prone to coming loose. Locktite does work, but there aren't many threads in those types of slide-in fasteners. I would make sure that you have access to the outer bearing block screws either through the spokes of your wheels or with a quick removal of the wheel.

3) There is quick a bit of "slop" in the fit of those slide-in / drop-in fasteners. You can easily get +/- 1/16" loss of accuracy in the placement of those blocks. If you machine a flat recess into the plates, you can ensure the proper alignment based on the fitment of the plates, and not the mounting holes and hardware. (though I see this doesn't work with your existing bearing placement...)

Best of luck with this design. I like seeing more and more teams come up with innovative ways to work with this material. If only 8020 ponied up and became a bigger sponsor and/or supplier for the KOP.

Bengineer
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