80/20 chassis

[=Martin=Taylor=]

Last year we used two 38" long 1020 (1"x2") in our drive.

In 2007 we used four bars of 1010 in our drive.

80/20 is best used sparingly, we don't use much of it outside the drive train. We don't bother with the fasteners. We just tap the ends (1/4-20) and weld it together. Its much cheaper, lighter, and stronger that way.

There is an ebay store that sells the stuff at good discounts. Although we have a supplier here in the Bay Area that gives FIRST teams a discount. Careful who you order from. The so called "80/20 suppliers" don't always keep 80/20 in stock as I have found out the hard way...

[James Tonthat]

16 has used 80/20 for the past two years with pretty good success. See what they're up to.

[BlackBird11891]

our fork lift assemblie used 80-20 last year and for the strength that u get for it its way over weight... the kitbot s alot better... the 80-20 worked well for everything else go and is great for manipulator, lifts etc. we used 1" 80-20

[JDNovak]

We (The Bomb Squad) have used extruded aluminum for all our frames since 2003. We have always used 20mm x 20mm ITEM brand material purchased from the US distributor in Ohio. They offer a discount to FIRST teams.

The material is amazingly strong for its size and weight. As someone already stated, joints tend to loosen from impact but a good design can minimize that. I believe a bare frame can be made as light as any other construction with some practice. ITEM also has a lot of neat fasteners like slides and rollers that make arms and elevators easy to design.

The major issue of this construction is fasteners. To take advantage of the material we use "T" nuts with M5 screws to fasten everything to the frame from gussets to gearboxes. The advantages are no reduction in strength and the ability to slide structures for alignment and chain tensioning etc. The disadvantages are weight and cost. The ITEM "T" nuts cost a dollar each before discount and the 80/20 distributor I checked recently charges $1.25. We usually use two hundred or more a year initially and probably twenty-five more fall out during competition.

I really can't guess how much material you need without knowing a lot more details. We usually use four rails extending from front to back internal of the wheels to support the upper manipulator/drives etc. and then build a frame that tapers at the back to take advantage of our three wheel drive system. U shaped frames for ball pickup are more difficult to strengthen but we have done it.

I would get some material and build a box first and get a feel for the weight and strength and then go from there. You can always use the box for storage if it doesn't suite your needs.

Oh, I think ITEM and 80/20 as well as some other brands I have seen are equivelant but not always compatible between them.

[DonRotolo]

We used Item material also 2 years ago, for the frame and ball shooter. It is great to work with, I recommend it, but note that we went back to the kitbot last year...

Don

[Gdeaver]

Team 104 made our frame from the 8020 quick frame material and connectors. We literaly hacked and wacked our frame together. Held up well in the comp and was lighter than our past kit bot frames.

[BlackBird11891]

As previously mentioned 80-20 does have many different fasteners that do come in handy such as

which was used to attach a solenoid to it &

which we used to connect two pieces at 90 degrees
this is our 80-20 that we used

[Cory]

When I was on 100 we used 1010 80/20 in 2003 and 2004. Didn't have any strength problems.

[JesseK]

Foot for foot, 80/20 aluminum isn't that much heavier than 1x1x0.0625-wall extrusion. The biggest weight difference is in the fasteners -- to stiffen the 80/20 frame, make sure you allocate enough of your weight budget for plenty of bolts. This year our lift overran it's original weight calculation by ~15% due to extra nuts/bolts that were added at the base.

We used 80/20 for our lift in 2008 and noticed severe torsional forces when the lift was high and everything was under stress. That said, I'll echo MOE's comments that the frame needs to be stiffened at the end of every match. Another option is to sandblast/clean off the outer coating, and weld it. Usually a local machine shop is willing to donate an hour for this if you time it correctly and plan in advance. Welding would significantly improve the stiffness of the frame. Even better, you could take a 80/20 'jig' in, bolt the frame to the jig, then the welders would have plenty of room to weld the frame joints together without worrying about having to lay out your frame, or warping as the frame cools.

[Raul]

Originally Posted by JesseK

Foot for foot, 80/20 aluminum isn't that much heavier than 1x1x0.0625-wall extrusion. The biggest weight difference is in the fasteners --

I will say that it is good metal, and easy to work with, but the only problem that we ran into was how heavy it is, because the (1"x1") weighs about a pound a foot.

I do not mean to be rude and correct you guys, but I know from many years of working with these materials that 1"x1" 80/20 Alum is 24.6" per lb. Where as 1"x1"x.0625 wall Alum extrusion is 48" per lb.

Phenolic materials are durable, easily machined, have great mechanical properties, and cheap.

I also want to warn anyone who is machining phenolic that the dust created by machining it is very toxic to your lungs if you breath it in.

[Chuck Glick]

Originally Posted by Raul

I do not mean to be rude and correct you guys, but I know from many years of working with these materials that 1"x1" 80/20 Alum is 24.6" per lb. Where as 1"x1"x.0625 wall Alum extrusion is 48" per lb.


I also want to warn anyone who is machining phenolic that the dust created by machining it is very toxic to your lungs if you breath it in.

I think what JesseK meant by in his first post was 1"x1"x.125" wall tube is roughly the same weight as 1010 80/20 extrusion. We came to this conclusion after taking two equal length pieces of both stocks and weighed them both. The difference was roughly .250-.5 lbs per 8'.

[Rickertsen2]

I once had a job assembling 8020 structures for a distributor and have used it since then on many other projects. We also built a robot out of it back in 2002 so i feel i speak from experience.

8020 Pros:
You can very quickly prototype things and move them around. It doesn't need welding which is a huge plus if you don't have good access to a TIG welder. This and the fact that we got it for free were the reasons we used ut. If you want to be able to move things around then use brackets or anchor fastners. Keep in mind the weight of brackets. If you want something thats strong and don't plan on moving it use end fasteners. Even if your not making a frame out of 8020 they make some very nice parts that come in handy. For a FIRST robot frame i would reccomend 10 series if you are designing in inches or 25 series if you are metric. 15 series or 40 series is overkill. 8020 is a great material and certianly makes for flexibility. In a fast paced design challenge like FIRST this is useful.

8020 Cons:
An 8020 Structure will be both heavier and more expensive than an equivilant welded structure from square or round. You have less freedom with wall thicknesses and there is a lot of mass concentrated in the center of the profile which does little for stiffness. It is particularly week in torsion. Keep in mind the weight the fasteners add.

Drop in T-nuts are your friend. get plenty of these. If you plan on using end fastners , get the jig so that you can drill the clearance holes painlessly. Thre is a fixture for milling the holes for anchor fasners but you don't really need it. Make sure you have a few ball allen wrenches in the appropriate size.

Also there are some older threads about this topic if you dig em up with the search