Stocking Parts

[adampaskowitz]

I am trying to get a rookie team going. One of the big problems we're running into is our lack of parts. Every time we want to do something, we figure out what part we're missing, and then have to order it and wait for it to show up. We're in the last year of a grant, so want to spend a lot of money to stock up this year, knowing that it will soon be gone. I've found lots of suggestions for tools on this forum, and have ordered LOTS of tools, but am pretty clueless about parts and materials. What should I buy lots of, and in what sizes, so that instead of stopping work to order something new, We can just go to our stockroom and grab what we need? Thanks for your suggestions.

[Timz3082]

The basics:
Polycarbonate, thin for shielding, thicker for more structure
Aluminum Tube and angle: 1" box and 1" equal leg= infinitely useful
Aluminum Sheet metal: 1/8" for gusset and structure
Bolts: buy common sizes and lots of them, assortments are a MUST HAVE!

[FenixPheonix]

Polycarbonate's great stuff. Agreed. Try to stock some 1/8" and 1/4", if you can. The 1/8" is good for exterior shielding, and the 1/4" can do relatively heavy stuff (electronics boards, etc.)

In terms of aluminum, our team likes 1/4"x1" bar stock. Handy stuff to have around. 1"x1"x1/8" angle's good stuff, too. 1"x1"x1/8" box tubing is pretty standard. That's our really common stock. We also like 2"x2"x1/4" angle for the really heavy load stuff (axle mounts, primarily.) 1/4"x2" is good for bracing sometimes. Apparently 0.5" square tubing is good, but our team doesn't use it, so I'm not familiar with the exact specs. 1/4"x6" can also be useful, although largely only for machining parts out of (so if you've got a mill, pretty much.)

Sheet? It can be handy. We don't use it much, but if you've got the capabilities for it, I'd recommend it. 1/8" aluminum sheet will basically do anything you need it to if you can use it right. And if you need major structural support somewhere, a bit of 1/4" could save you (use it sparingly, though.)

In terms of hardware, standardize. Our team uses M6 because of our bosch frame, and, even when 1/4"-28 or something else could be used somewhere else, we use M6. It doesn't matter what set you use, so long as you're consistent. For imperial hardware, you should probably get:
4-40 (largely electronics)
6-32
8-32
10-32
10-24
1/4-20
1/4-28
3/8-16 (sparingly)
3/8-24 (sparingly)

Bolts and nuts for both of these. I recommend socket head cap screws (commonly referred to as SHCS), they're much easier to use than philips or flat-head. You might also want to invest in counter-sunk bolts in some of these sizes (6-32 to 10-24 would be good) if you have a countersink (if you don't, I recommend it.) I'd recommend nylock lock nuts for all of these, taps for them as well, and washers to fit them all.

Hope some of this helps!

[AllenGregoryIV]

So much of this depends on your teams building methods. We can recommend what we use but if you don't design the same way it's useless to stock the same things.

However what we have used most often is:
1/16" Sheet Aluminum for gussets
1 in L aluminum in 1/16" and 1/8" thicknesses
1 in square tube aluminum 1/16" think (with bumpers we find you don't need more than that, and its so light)

1/16" polycarb and a small amount of 1/8 when we need something thicker

1/4" HDPE it's useful for all sorts of things and has a low coefficient of friction which is handy some times. Probably could go thinner

1/2" aluminum shaft (keyed and unkeyed)
1/8in Keystock

Bushings, Bearings and aluminum shaft collars in the same size as shafts that you have.

Sprockets, chain and links are really useful to have on hand.

Fasteners, we use 3/16 rivets and #10-24 bolts for most things (you can get away with using a 13/64" drill bit for both of them so it makes things easy). Lots of lock-nuts.

Zip-ties

Surgical tubing is always nice to have and polycord is useful for games like this year.

Lots of wood and PVC for prototyping (and cardboard but that is free)

For electrical, I would also stock up on wire, common sensors, and connectors (we use Anderson Powerpole connectors everywhere)

That is most of our standard stuff, everything else is game specific.