Save time? Use aluminum extrusion kits!

[Gui Cavalcanti]

So here's my question; what's the difference between this and 80/20? It looks like the same extrusion profile from these pictures, except 80/20 has a lighter version with four holes running down the length of the extrusion as well as a solid version.

[KenWittlief]

these have grooves that allow you to put fastners anywhere along the length - you hook them in and they will slide anywhere - also the end pieces are easy to use

its like a hi-tech erector set - except you are not limited by holes in the metal for placing attachements.

[Loren 930]

Hello Gui -

Hopefully I can answer your question regarding the differences in extrusion systems. My engineering company used many other brands in the past, but because we require performance and value, we settled on the "item" brand (not to be confused with the IPS brand - which is not and has never been the same as "item") extrusions in our shop. As Tim mentioned, there are wide differences in dimensional tolerances and alloy which in turn reflect on the strength of the extrusion. Equally important is the method of attachment - other systems have copied the item fasteners but they do not work unless you have a high strength extrusion to use them in. item has been in business for over 26 years and is the world sales leader in structural aluminum systems. So why is this important to you? It means you get a highly engineered and respected building system with very high level of engineering support. item is committed to staying at the top which is why they have decided to support FIRST teams with an outstanding value in the form of "kits" that contain the neccessary extrusions and fasteners to put together a modular and strong robot. Team 930 has used these kits exclusively for the past two years - and as anyone that has seen our robots will attest too - they are strong, rigid, and light and we have never had a fastener break or come loose. If you or anyone else reading this post has any questions about applying the system to your project, please contact me at loren@aes-wi.com.

Good luck this year - it is a great game!

Loren
engineering lead
Team 930
www.team930.com

[Loren 930]

Hello,

As a side note, I would like to clarify what size extrusion is in the kits. The extrusion size(s) - depending on which kit you use - has 20x20 and 40x20 size extrusions. This is the outside dimension size in millimeters. The weight (size 20x20) is 0.48kg/m (approx. .33lb / ft) and the 4th moment of inertia is 0.72cm4 - for those that want to do the calc's - which I highly recommend you do when comparing systems. The pullout strength for a fastener connected in the t-slots is 500N (112lbs.). More engineering information can be obtained at www.item-international.com or contact me at loren@aes-wi.com.

Hope this helps.

Loren
engineering lead
Team 930
www.team930.com

[Matt Adams]

If you're really looking for quality, then you want to go with Bosch 20 mm.

Bosch Rexroth:
3m of 20x20 for $20.00 (no discount)
I = .67 cm^4, (.016 in^4)
W = .4 kg / m, (.269 lbs / ft)
Pullout = 1700 N, (382 lbs.)
Tensile Stress = 250 N / mm^2

Item:
3m of 20x20mm for $25.50 (discount)
I = 0.72 cm^4
Weight = 0.48kg/m (.33lb / ft)
Pullout = 500N (112lbs.)
Tensile Stress of Aluminum = 245 N / mm^2

I'll leave the choice up to you.

It's considerably lighter, just slightly less rigid, about 20% cheaper, and has better fasteners.

Hope this helps. Good luck boys and girls!

Matt

[Aignam]

I believe Raider Robotix's 2002 robot, Silver Scorpion, used extruded aluminum. That robot was the one that required the least maintenence of all. It practically never broke, or required much more maintenence than a change of battery in between matches.

[Tim Skloss]

The Bosch extrusion is NOT a superior product. A local business that builds industrial robots out of extrusion has completely quit using the Bosch because it is notorious for vibrating loose. And on a FIRST robot that is too risky.

Furthermore, some of the numbers you quoted are funny. The pullout strenght of 300+ lbs for the 20x20 is simply impossible according to the tensile strengh claimed. The material will fail and release the fastener before you get to 300 lbs.

The specifications claimed for the item extrusion are from actual test data posted by the manufacter. You will NOT see actual test data for the Bosch. Since in europe--where item originates--manufacturers claims must be absoluetly guaranteed, you will see very conservative estimates of structural strength. In our experience the material can be up to 3 times stronger than claimed in the catalog.

Which is better for a FIRST robot? You have to weigh strength and reliability against your pocketbook... But remember the free market ensures that "you get what you paid for".

[activemx]

WE have Used Bosch in the past two years. 2002 we used 30x30 and it was very heavy but extreamly strong. 2003 out entire robot was pretty much built with 20x20 and 20x40 and we also had a linear sliding elevator on bosch.

pics are included below
pros: Flexiable chassis, strong structure, fast assembly if designed and cut right, flexible designing and quick changes.
Cons: Heavy(welded chassis can be much more stronger and lighter then bosch), high maintainance(we had to have 5 ppl with tork drivers to tighten all the nuts after every couple matches) and expensive. wow each t-nut was almost a buck each. tnuts break or bend quickly on over tightening, allignment is difficult at times.

2003
includes delrin sliders



as you can see we made many many many custom plates to hold the extrusions.

WE are planning to use Bosch again this year!

[Jay TenBrink]

We use an extruded product from AMC Quick Connect in Rochester Hills, Mi. their smallest section is 25.4 mm square. They use 6063-T6, which is a heat treated aircraft aluminum. They have a wide assortment of fittings and have given us excellent service. We are very satisfied with the ease of use and performance of this material and are sticking with this brand.

Our Martian robot had over 100 matches on it last year and held up extremely well. We did have to retorque fasteners from time to time. I would recommend that anyone with a bolted together frame to check and retorque the joints. A torque wrench might also be handy.

[blindguyinanorg]

i saw that last year i wanted to use it this year. i spent 2 months looking for it and didnt find squat sence i didnt know the name. by now we've settle for a lot less pretty material. and too bad i wont be here next year.

[activemx]

im wondering if Item or anyother company sells extrusions. also are the 20/20 profiles for Bosch rexroth and ITEM the same? can i use bosch with item fasterners and back. Bosch rexroth fasteners are really expensive, t-nuts $.75 a piece and blocks $1.50. Im wondering how much is item and will it work with Bosch and if i can buy without the package. Other companies would work too. Does anyone have any experiance with the inch series?
info would be great!
Thanks!

[Cory]

You could try 80/20. They make 1"x1" 1"x2" 2"x2" and many other sizes. We used the 1"x1" last year and are using it again this year, and have found it to be strong enough for our needs. It is actually lighter than comparably sized aluminum tube, until you add the fasteners. This year we welded the frame and saved nearly 20 lbs from not using fasteners. T-nuts and fasteners do add up, both in weight and cost, however.

Cory

[Veselin Kolev]

Originally Posted by Cory

You could try 80/20. They make 1"x1" 1"x2" 2"x2" and many other sizes. We used the 1"x1" last year and are using it again this year, and have found it to be strong enough for our needs. It is actually lighter than comparably sized aluminum tube, until you add the fasteners. This year we welded the frame and saved nearly 20 lbs from not using fasteners. T-nuts and fasteners do add up, both in weight and cost, however.

Cory

Yea well our school is not allowing us to use our welder so we cannot use the weld material. So need to get bosch and i want to find out where i can get the fasteners for cheaper. thanks
AmX

[Mike M.]

Originally Posted by Cory

T-nuts and fasteners do add up, both in weight and cost, however.
Cory

not to mention t-nuts can be almost as big of a pain as set screws

[Cory]

Originally Posted by Mike M.

not to mention t-nuts can be almost as big of a pain as set screws

Well, seeing as this is a thread about aluminum extrusion, theyre kind of inevitable. They dont come loose all that often if you use them properly. We never really had trouble over two competitions, although they do need to be tightened periodically.

Cory