Quote:
Originally Posted by yash101
(Post 1313363)
I'm no expert, but I learned last year, try to have all fasteners work with the same screwdriver size/wrench size, etc. That way, you won't have to keep getting a different wrench for different bolts. We have some special-colored tape on our main wrenches so it is easier to recognize them!
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These are two really good things for every team to do.
Regardless of what size hardware you use, it's awesome when it's all similarly sized and can be installed/removed with the same series of tools. If you color code the tools for each different hardware size, or each different use, it makes fixing stuff on the fly much, much easier.
Quote:
Originally Posted by Pratik341
(Post 1313526)
In general, our team decides on what fasteners we are going to use for that year, and then orders a large amount of them form McMaster. We always have left overs at the end of our season which are sorted and kept in containers in the shop closet. When prototyping, we use the leftovers, but when assembling the robot we use the new bolts/screws/rivets. In general, we use socket head cap screws (SHCS), but also use button heads, low clearance, or even counter sunk bolts/screws when clearance is an issue. For rivets, we pretty much only use 1/8" blind aluminum rivets.
Last year specifically, we used a standard size of 10-32, of varying lengths. Occasionally we used #6 and rarely used #4 bolts. From what I've seen #10 and 1/4-20 are pretty standard in FIRST.
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What Pratik said. Our standard is 10-32, SHCS with a 5/32" Internal Hex Drive, so about 75% of our robot can be taken apart with a single pair of wrenches. Any exceptions to the 10-32 standard are dictated by a COTS part, specifically if a motor/transmission/etc requires a different screw, we'll use it. Otherwise, for sheet metal metal connections that shouldn't need to be undone, we'll use 1/8" Pop-Rivets, usually Aluminum Body with a Steel Shank and for isolated electrical components we'll use good velcro or 3M Dual Lock.
If you're trying to define your own standard, or just get an idea of what hardware makes sense, here are some of the common sizes found on some of the more common COTS parts:
1/4-20: Pre-2014 Kit Bot (2014 Hardware size hasn't been announced), VexPro Axle Stock, Some AndyMark gearboxes
10-32: CIM Motors, Mini-CIM Motors, Versaplanetary Gearboxes, Banebots P60s
10-24 Self Tapping: AM Wheels, Sprockets, etc
8-32: VexPro Sprockets, Wheels, VersaFraming, etc
6-32: Victor 884/888 Mounting Holes, DSC?, etc
Metric:
M3 - RS550 Motors, AM-9015 Motors, Fisher-Price Motors
M4 - BAG Motors, RS775 Motors, PG-Series AM Gearboxes
M6 - Power Distribution Block Main Studs
As far as lengths are concerned, most of them will be application specific, although you can probably guess pretty close based on previous year construction methods.
