My team was looking into using 80/20 for our chassis this year, and we couldn’t decide what sizes to order. Does anyone have suggestions for what size of 80/20 to use for the chassis and/or extremities?
If you worked with 80/20 last year and could summarize the purchases that you made into a basic “parts list” for getting started, this would be great.
We began looking into 80/20 earlier this season and have heard that about 1000 linear inches should be sufficient for a basic chassis. Can anyone confirm? What should we add? Which connectors/fasteners have been successful?
Moe has used 10 series and 45 series 80/20 and Bosch extruded aluminum for the past few years. We found it worked well especially for assembling and testing functions, arms, lift systems, etc. But during competition you’ll find the joints come loose. Just make sure your team tightens the bolts every time your bot comes back from the field.
For our major functions we weld Aluminum angle and tube. After this year we decided to weld the entire frame including the chassis to improve the rigidity of our bot.
You’ll need about 300 to 350 inches in length for a basic box bot and some functions.
1712 has used 80/20 extrusion systems for 3 years. Search cd media for 1712 and you’ll find some chassis pictures. The amount you need varies based on manipulators, etc but I’d be glad to elaborate more if you’d like. For connectors we use the smaller drop in t-nuts and hidden corner connectors. We used to use the plates, etc…less expensive but more weight/space. We purchase all of it from Mcmaster-Carr. Let me know if you want part numbers, etc and I’ll get you some info.
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…
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
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.
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…
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.
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.
I’ve been lobbying for my team to use 80/20 or other extrusion for a few years. We might use it this year, since (a) my employer uses a lot of it (we’ve literally built buildings and cleanroom support structures out of it), so we get a lot of leftover material, and (b) we’re such a good customer that occasionally the supplier lets some stuff “fall off the truck”. I think I’ve got enough basic stock so that we can at least prototype a frame with it this year.
Team 980 has used 80/20 for our robot chassis for years (1010 extrusion). Our six-wheel drive with Andy Mark SuperShifters goes together quickly. Getting proper tension on the chains is very easy. We use simply-machined phenolic bar stock as pillow blocks for the axles with fastener through-holes spaced at 2". Instead of the more expensive drop-in T-nuts, we use economy triple T-nuts. We haven’t had problems with fasteners loosening: just put a bit of Lock-tite on the threads and torque them down.
My team used 1 inch by 1 inch 80-20 last year. It worked very well and we had almost no problems with it. If you have a square frame make sure you put in supprts to keep it twisting, If you take a hit, some of the fasteners aren’t strong enough to prevent it from twisting a little. I still think 80-20 is wonderful and my team loves it. We made a frame for a six wheel skid in the off-season with 168 inches of 80-20. It’s always good to have some extra. We used a little less than 350 inches on our robots frame in the '08 season, but it was a swerve drive and required a little more aluminum extrusion.
Never heard of phenolic. At first glance it looks like a great material for an impact-resistant non-conductive electronics board. How easy was it to machine?
Team 2228 has used 8020 from the start. We almost always stick with 1010. (We did go to 1020 for our 2008 lift). As for fastners, we have standardized on 1/4-20 wherever possible to reduce the need for more tap sizes and tools (DFM). With respect to fastners we mostly use the economy nuts. They are far cheaper than other 8020 alternatives and weigh less. You would be surprised how fast nuts can add up on weight. For the bolts stock up mostly on the shortest two sizes. While it is nice to have a few of the longer lengths in most cases you find these too long and the bolt bottoms in the 1010 extrusion prior to the head pulling whatever tight. We carefully tighten and have had very little problems with loosening. Be sure to properly clamp prior to drilling or sawing for safety.
We have no welding capability at this point and with 8020 I am not sure we will pursue that for some time.
Very old-school material, used as an insulator before there was plastic (like, aaround 80 years ago). Also known as Paper Phenolic, it machines like wood. Not terribly strong in tnesion (as with wood) but super in compression and shear, with some lubricating properties for low-speed rotational bushings. Not terribly heat resistant, and has a distinctive odor when burning.