By: asid61
New: 15-12-2014 21:41
Updated: 15-12-2014 22:46
Views: 1251 times

The (hopefully) final revision of GBX-116. I want to be sure that my design is somewhat sound if it's ever built.

Revisions to last design:
-Added standoffs to caster box for strength
-Changed caster box to 1/4" thick material
-Changed wheel spacer to accomodate a 3/8"-16 bolt over a 1/4"-20
-Made a two-bearing top for the caster box
-Changed small thrust washer to large 5/8" ID 1.125" OD thrust bearing on top. Rated for 2,000lbs thrust.
-Added a couple important arrows on the caster box to mark the location of the bevel gear.
-Added access holes to reach the absolute encoder from the side (not visible in this picture)

CAD and parts list are here: https://drive.google.com/folderview?id=0BzU34PeNVT0QQVVydEl6V1dYekk&usp=sha ring
When you consider the price of all the parts, keep in mind that it includes all the encoders, screws, motors, and the cross slide vise. CIMs come in the KOP, screws are something that many teams already posses, and the same goes for encoders (although some encoders might be cheaper or more expensive). My own team could probably make this for only a couple hundred bucks all said and done, although it would weigh a ton due to a bunch of steel sprockets.
All in all, this costs about as much as or less than your average swerve drive.

11 custom components or modified COTS components. Of those, only 2 are not just cut to length or drilled for a single hole: the caster box and the top 2x1. Thos should be laid out and drilled well or put into the cross slide vise for drilling.

Specific tools:
-Drill press
-Hacksaw
-Heavy vise or clamps secure enough for holesaw.
-Files, prefereably a bastard file for good tolerances.
-CALIPERS. It is absolutely necessary to ensure that you have hole locations correct, especially for the bevel gears.
-Drill bit set, both numeral and fractional if possible.
-Center drill
-Scribe (AKA sharp metal pen thingy)
-Allen wrench/ key set (male hex wrenches)
-1.125" drill bit, reamer, or step drill. Holesaw not recommended unless you are certain you can get good holes for bearings to fit into with minimal play. Does not need to be perfect, but within 0.01" diameter tolerance hopefully.
-5/8" and 3/4" drill bit or holesaw. It needs to be able to drill a hole for the 0.750" CIM boss, so it has to drill 0.751" or more.
-Wrench set, preferably ratcheting
-Pliers
-Cross slide vise (AKA x-y table). Apparently it is impossible to get good bevel gear tolerances by eye alone.
-Edgefinder. Look on ebay; they are available for around $10.
-Deburring tools (countersinks work really well for small holes)
-0.01" graduated ruler, 6"+ long
-Solid square
-Rookies

Weight as shown is 7.48lbs plus chain. A four-module chassis is ~36lbs plus gussets and rivets. This is decent for a swerve module.

Input wanted, as usual.

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