What metal do you use and how much do you spend on it?
Mostly depends on the year and what parts we need. Most years I’d say we spend no more than $1000 on sheets of aluminum. We mostly order them from McMaster Car or online metals.
So we’re typically in the $7-12K range and have historically bought from McMaster but are trying out OnlineMetals this year.
We only use 6061-T6 and 7075-T6:
- Lots of 0.125" and 0.25" Plate
- Different sizes for billet
- 1x3
- 1x2
- 1x1
- 1.5x0.75
- 5/8 precision ground rod for custom hex
Also want to add on how much you should expect to spend depends greatly on how much you want to do, that’s what’s nice about inhouse machines, you can pick and choose between making your own stuff or going COTS.
My team is spending $1,171.62 on our polycarbonate and aluminum plate for our Cncs. This would allow us to make all of our plates, gussets and belly pan in house.
For aluminum, We’ve had really good luck in the past buying only 1 sheet of 48x48x0.125" of 6061 from a local metal supermarkets (gave us a 15% discount), then going to local sheet metal fabricators and asking them for offcuts. You run the risk of funky thicknesses or having different alloys, but I’ve saved a couple hundred bucks in the past each year by doing this. Sometimes they will even give pretty large pieces once you build a relationship with them!
My old team, after a few years of asking the same couple of people, never had to buy sheet aluminum. The fabricators would leave useful sheets off to the side for us.
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And this, OP, is the key. Even cities small enough for single-A baseball will have a local metal supplier that beats the heck out of McMaster-Carr pricing, even if you pay their standard rate. Find that in your area and hit them up.
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Plus you don’t pay shipping fees! That was one of our huge motivators, too.
This is very true. Being in the Albany NY area, we have a Metal SuperMarkets that provides a discount price. I usually order materials for offseason projects and then purchase more during build season once we get an idea of our needs.
The great thing, I can call in an order in the morning and drive down for pick up in the afternoon!! look around locally rather than pay large shipping fees.
You also have industry like trailer manufacturing or garage door companies or even the humble machine shop that you can get some relatively large (but often weird shaped) offcuts. The key here is to really let them know what you are trying to do and at what scale, build a bit of a relationship, and you may be surprised by what they manage to find that may be useful for the team. Just like @thertenstein said above.
People generally like to be helpful. For folks in the trades they love seeing kids go wild making cool stuff. We are not all that different.
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A year just on aluminum raw stock?
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I reviewed some purchase orders from the past few years and it looks like my team spends in the realm of $1100 - $1800 a year from Coast Aluminum here in California. To cut costs a sponsor generously allows us to have the order delivered to their shipping dock and we cut things into smaller sizes there before transferring to our shop.
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we use varying thicknesses of alum 6061 and i would say we use roughly 2-3k a year? not too sure, we only really make plates and are planning to do work on 1x1/2x1/2x2 on the cnc in the future but a couple thousand would be a reasonable estimate
You CNC your own hex shaft? For less backlash. Or?
Yep, we do a lot of projects and a lot of iterations
Yep, 0 backlash and built in spacers. For most people just using some retaining compound between stock hex and your gears/pullies is a better solutio.
Some old parts/revisions, up until last year these were done by hand with a manual lathe and indexer on a manual mill, these are pre cnc
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Local supplier = $1
Online metals = $2
McMaster = $4
My local metal supplier is inexpensive and delivers any order, up to a truckload, for $25. They’ll also cut to size for not much money.
Side note: Integrated spacers are integrated stress risers. They’re fine if you don’t pass torque through them.
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Some may also let you rummage through their scrap bin for significant discounts. This is how I bought all of the aluminum to teach our students how to layout, mill, and turn parts. I think I walked out with a 30lb box of mostly 6061 for $30.
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1/4" aluminum bar for gearboxes and other thick plate work. We used to buy from online metals when they would do 20%-30% off. This year we bought full length 12’ pieces from Alro and had it delivered to a sponsor. A 1/4"x12"x12’ piece of 6061 was $192 delivered from Alro.
https://www.onlinemetals.com/en/buy/aluminum/0-25-x-12-aluminum-rectangle-bar-6061-t6511-extruded/pid/23484
We have a waterjet sponsor that gives us his larger 1/8" and 1/16" 6061 drops.
A full length 2"x1"x1/8" x 24’ 6061 rectangular tubing was $100 delivered by Alro.
We buy thin wall square, round, and rectangular tubing from online metals.
Our local supplier only has 6063 tube, it’s less than half of what OnlineMetals has for 6061. Would 6063 be strong enough for robot frames or should we stick to 6061?
There are two acceptable places for 6063.
- Architectural trim. We don’t do that here.
- The recycling plant.
To be a bit more detailed in WHY the second option is there and “use on a robot” isn’t, 6063 is about half the strength of 6061. 6063’s alloying elements are aimed at corrosion resistance, not strength. And on top of that, 6063 tends to gum up cutters, which means you have to replace them more.
5052 is more acceptable than 6063, but that’s because 5052 is usually bent and the bends tend to increase strength.
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