T-Slot extruded aluminum

Technical Technical Discussion
1

I have read a lot about t-slot extruded aluminum and their advantages (versatility, range of options, prototype ability) and drawbacks (weight, cost) but i haven’t found any figures on just how expensive this stuff is per foot.
I am looking at either 1"x1" 80-20 or 30mm x 30mm bosch or item.
I understand fasteners are even more but i just want to know a ball park figure.

This is for the upper level of the robot and will be used to build the hopper and flywheel mounts and will extend up from the kitbot chassis.

2

3-4 dollars depending on how much you buy for 1x1, www.mcmaster.com page 1522

Mcmaster is your friend for anything mechanical :slight_smile:

The major advantage is that it has very strong fasteners that do not need to be welded and the fact you can slide it around without having to set on a definite shape.
As for strength and shape, the major advantage of this is the T shape, it resists bending very well, and just slightly less it resists torque better than standard square extrusion.

3

the fasteners get very expensive, very quickly.

If you don’t mind doing some cutting, and cleaning up of threads, you can save quite a bit of money by going to your local hardware store and buying a ton of toilet bolts instead of t-nuts.

4

10/10 Costs about $.21 an inch. If you look through the 80/20 website ( www.8020.net ) there is a price list, it just requires a bit of searching.

5

As a follow up to the pricing, 80/20 do give a 50% discount to all FIRST Teams. You need to state that you’re with a FIRST Robotics team, and then make sure that the salesperson you are dealing with is aware of the discount as well.

We’ve been using 8020 for the past three years and love it! Very easy to assemble, modify, replace, and maintain. The weight isn’t as bad as everyone thinks. The weight of 1010 is with 5% of 1" (.125 wall) Al square tube. AND, it’s stiffness in bending and torsion is within 5% as well. The extra weight of the connectors will be about 2lbs for us this year. So, a little extra effort up front to save weight will certainly pay off with the flexibility of this product.

I’ll quickly quote some full prices for you. (You can do the math for the discount.)

Profiles
1010: $.21/inch
1515-lite: $.42/inch

Cut Charges (For pieces shorter than 144")
7005: $1.85 (1010 profile)
7010: $1.85 (1515 profile)

Connectors
3090: $1.20 (Double Anchor for 1010)
3098: $5.50 (Double Anchor for 1515)

Feel free to ask more questions about extruded profiles. OH, we’ve found that paying for them to cut the pieces to lenght FAR outweighs the cost of having a full lenght piece sent! Good luck!

BEN

P.S. We’ve never “broken” a piece of 8020, that’s absurd. As I’ve mentioned above, the 10-profile of 8020 is of the same weight, strength, and stiffness of a 1" square al tube. The joints can be a weakness, if not properly made. The same can be said about a welded square tubing frame. To properly assemble 8020 extrusions, the ends must be machined square and perpendicular, no hack saws here! And end mill on a milling machine is the best way to achieve this. For the connetors, we’ve always used the double anchors (see above.) These handle far more load than the 90 degree brackets, the single anchors, and the drill and bolt together method. And, will these extrusions handle a “fall” from the platform, most certainly. Please, contact 8020 (or similar companies) and ask for a free demo. They’ll bring a truck straight to your door, full of profiles, connectors, brackets, and loads of other fun stuff. You won’t be disappointed.

6

Daniel,

Several years ago (4 I think) we used the T-slot for our base. We were not overly excited about its’ performance for a base. This year we are using the base from the kit of parts. We are using the T-slot for our harvester and launcher platform. T-slot works well for us as for add ons to the robot. Make duplicate parts because in the heat of competition, the T-slot will sometimes break.

Ken

7

We used the kitbot base last year and were very happy with it and are sticking with it this year. Are you using 1" x 1" for your harvester and launcher or something more hefty? Is 1" x 1" strong enough to withstand a fall if the robot tips?

Thanks for all the answers!

8

In addition to the 8020 deal itemamerica.com offers packages at discounts for FIRST teams. I have never compared the deals between the 2 companies but i like to give people options.

Here is a list of their deals for FIRST teams for 2006.

http://www.itemamerica.com/FIRST2006.pdf

9

We’ve used 8020 products for several years now - the only problem has been weight at times. It’s very nice to be able to slide assemblies around the robot during build and testing, when unforseen “features” of our robot rear their head. Once everything is where you need it, you can drill through the extrusion or tap weld for extra strength, but we’ve fallen off of ramps 5 ft tall and never had structural damage with the 8020 line.

10

Just an FYI. We have never used any 80/20 (or other brand) before but are strongly considering it this year. I called 80/20 directly yesterday and they referred me to our distributor who was very helpful and was quite familiar with FIRST teams and checked on the discount. The distributor for our area is Bertelkamp Automation in Knoxville, TN and we were quoted only a 40% discount for FIRST teams. Still a great discount! Your millage may vary.

BTW: We are looking at the 80/20 Quick Frame line which is different than the T-Slot stuff. It is the smallest/lightest and cheapest stuff they make. It is basically 1" AL square tube with press fit connectors. The only tools required are a miter saw and a rubber mallet. I have never actually seen it or handled it in person but from the catalog and specs it looks like it might work well for our application. I doubt I would use it for high structural loads though.

Does anyone have any experience with the 80/20 Quick Frame product line?

11

We are using the item profile 5 extrusion which is 20x20mm and is about $2 a foot. We built a chasis out of it and it only weighs about 14lbs, but the nuts and bolts are about $20 for 100. it is deffently worth it to built with the extrusion and i think the item is a lot better then the 80/20.

12

Daniel,

We are using the standard 5/16" slot.

We also are keeping the majority of the weight as low as possible on the robot. Our overall height will be about 36". We don’t expect to be very “tip-able”. We will use gussets (thin aluminum plate) at the critical joints for added strength.

Ken

13

we tried using it as our whole robot 2 years ago but now we hate it. too heavy. too hard to use. standard 1/4 in bolts and angle alumiunm work better i htink.

14

We’ve had great luck with regular 1" x 1" x 0.125" square tube for our frame and drive platform. It’s $1.28 per foot. We make small top and bottom connector plates from 1/8 plate and fasten with a few 10-32 socket head cap screws which are strong, light and about 10 cents each.

15

I would recomend NOT using Bosch 30x30 or 20x20. My old team used this a few years, and the chassis was always heavy and expensive. Bosch is metric, so you have to use metric bolts and you have to buy the special T-nuts, which are rather expensive. Also, the connectors are expensive, and rather weak, especially for 20x20. I can estimate that our Bosch chassis from 2003 was around 600 dollars with all the bolts and beams and connectors, and weighed a solid 30 lbs, and was still kind of weak.

If you are looking into extrusion, try to go for something customary. Bosch sells an inch series, and there is also 8020 and lots of other extrusions that are in inches. Inch series is less annoying to work with (no conversions, as FIRST is generally inch-based), and less expensive because there are more common parts, like bolts and T-nuts.

16

Team 1208 uses extruded aluminum for our frame and will spend in excess of $800 on frame materials and connectors this year.

17

A picture is here

Don

18

Last year we used pretty much all 8020 except for a few machined alumminum plates for various mountings. It works out really nice. However, the T-Nuts (the nice drop in ones) cost about $2 EACH. That was the most expensive thing on our robot I think, lol. This year we tried something different, their Anchor Fastners…they are really strong and form a perfect perpendicular angle (assuming you milled the edge properly). I have to say that being sponsored by Midwest Fluid Power, an 8020 distrubter has its advantages :slight_smile: One, it’s completely FREE…and its a 4 mile drive to their warehouse to pick up pretty much anything we need (1010, 1020, etc) that they have in stock.

19

Our base drive platform, in a 4 wheel drive configuration, cost less than $20 for the aluminum tube. Add eight 1/4 inch bolts and voila, about the cheapest frame you can get. That puts the basic frame assembly itself at about 8 pounds. Topside, we are using aluminum angle, with some polycarbonate here and there.

We’ll probably have $500 to $600 in the structure in the final analysis, but two thirds of that is for pizza or subs during Saturday build sessions. It’s taken us a few years to get our priorities right :slight_smile: