Simple enough, what size stock metal (particularly aluminum) does your team purchase for the build season. Flat bars, sheet metal, square bars, etc any and all advice would help.
For context our team recently got access to a 10x12 waterjet, 3axis and 5 axis mill and have been training with our sponsors on these. We would like to know what other teams with high level fabricating capabilities purchase to make full use out of their machines. Thanks for the advice.
Our team doesn’t really have a rhyme or reason on what sizes we order. It’s typically a mixture of approximately the size we need for the robot and the limits of our machines
So you guys order after kickoff? or atleast the bulk of it after kickoff? do you have a local supplier to ensure fast shipping times
We have some random stuff on hand but we have a local supplier that can be ready same day.
We’re purchasing 4’ x 8’ sheets of aluminum/poly for whichever thicknesses we usually use and then some 1x1s and 2x1 of aluminum tubing of iirc 1/8th and 1/16th thickness. We also have a fairly decent amount of leftover material from past years.
How big are your machines?
How big are the doorways between the outside and the machines?
How big is the storage area for stock?
How big is the thing that gets the metal from the metal place to your shop?
Find the restriction, make simple adjustments (larger storage area), and then get the largest/longest stuff you can.
The actual material depends on construction style and local availability to an extent, but the box tubing+riveted gussets style seems to be prevailing at the moment. Most of those teams will be stocking up on 1/16" and 1/8" wall 1x1" and 1x2" box tubing, 1/16", 1/8", and 1/4" sheet, perhaps 0.090" as well. All in 6061-T6 aluminum of course.
We use 6063 because it’s the only thing we can get locally that is in 1"x1" or 1"x2". We don’t weld it so it works out great for us.
I am terrified, having accidentally built an arm out of unknown temper thin wall 6063 once.
godspeed
How have riveted gussets worked for you if youve used them? Our team hasnt explored that path, but it sounds like it could have some beneifits
we normally just use nuts and bolts
We transitioned from mostly box tubing weldment robots to completely box tubing and gussets between the 2018 and 19 seasons, basically copying the formula VersaFrame laid out. VersaFrame - VEXpro - VEX Robotics
Never bought much from Vex and just CNC router’d almost every gusset. All 3/16 aluminum pop rivets with a steel mandrel. Works great once you adjust to thinking about how gussets will get in the way and be loaded in operation and impact, and a pneumatic or electric rivet gun is a must.
fwiw we stocked the exact same material for welded frame robots.
Just for reference, 6063 is about 1/2 the tensile strength of 6061. (Source: I looked at McMaster’s page for aluminum 2x1 tube, set for 6061 and 6063. As an extra note, McMaster sells 6’ lengths and will ship them.)
I’ve also been on 1714 which when I was on it made their robots entirely out of polycarbonate
Our supplier (Alro) lists their 6063-T6 as 35ksi UTS, 31ksi YS, and has 6061-T6 at 45ksi UTS, 40ksi YS. Unfortunately they do not make any 1/16" wall in 6061-T6 but we have not had too much problem with their 6063-T6.
This is what we ordered for the past 2 years:
2022 Season
2023 Season
Note that we ordered more for 2022 since we skipped ordering in 2021 and needed to restock more than usual.
Machining/working with 6063 is like nails on a chalk board 
We couldn’t find 2x1 x0.095 rectangular tube in 6061 T6 so I had a local supplier make some for me. There was a 1000 pound minimum order which worked out to 1800 ft (150 12’ lengths) - a multi-year supply. 3 weeks delivery snd A LOT cheaper than buying it online. I’ve been selling it to teams by the length and they pick up at our location. It doesn’t go bad.
That’s pretty awesome, I have found some 1/16" online but like you mentioned it’s not as cheap.
Currently we get the 6063-T6 donated so i can’t complain, but it definitely has it’s weaknesses. Atleast most of the machining we do is drilling and miter sawing so don’t have to deal with it machining poorly much.
For comparison, we’re selling it for CDN$65 for a 12 ft length. No tax. We make a bit on them.
Where do you purchase your 4’x8’ of poly from?
