20-01-2005 18:56

Rickertsen2

Re: pic: 1123 Frame

You can save yourself alot of weight by using end fasteners or anchor fasteners instead of gusset plates. It will still be very strong.

20-01-2005 19:01

Spikey

Re: pic: 1123 Frame

80-20 is a great tool, we have used it for the past 3 years, and we will use it again this year. Its a great way to build your frame. It looks very firm. You could replace those plates, the anchor fasteners work just as well.

20-01-2005 19:07

sanddrag

Re: pic: 1123 Frame

The first three years of our team we used 30mmx30mm Bosch extrusion. We absolutely loved the stuff because you could build things fast and you always had a place to screw something in without ever having to drill a hole. We loved it so much we bought a whole bunch of it. But then we got to thinking what it would be like to save some weight and weld it together instead of using gusset plates. And then we got to thinking that it would be easier to weld regular box tubing. And then we decided we wouldn't mind drilling holes. And then we weighed some box tubing against some extrusion and BAM! What a difference. That extrusion is heavy stuff. From the minute we found out just how much weight we were wasting on that, we went with box tubing and we are never going back.

While extrusion has its upsides, I prefer box tubing all the way.

20-01-2005 20:33

greencactus3

Re: pic: 1123 Frame

yes. this stuff does tend to be quite heavy id advise against making your ENTIRE robot outta this like we did, as its too ewasy to go overweight and you'll find yourself drilling holes anyways

20-01-2005 21:33

dlavery

Re: pic: 1123 Frame

80/20 and the 30mmx30mm Bosch extrusions both make wonderful tools for prototyping (for frames and lots of other stuff). But, as pointed out, it is very heavy stuff. Use it for designing your frame, locating parts, and validating the everything will fit. But when you have done that, replicate the structure with welded aluminum square tube for your final robot. You will have an even more rigid structure, and will lose at least 1/3 of the weight (or up to 1/2 if you have used a lot of the stock faseners).

-dave

20-01-2005 21:48

Rickertsen2

Re: pic: 1123 Frame

Last year we used 15 series 80/20. We liked it alot bc it was very flexible but then we realized how much it weights.
1" .62 walled Al tube weights .274 pounds per foot
15 series weights somewhere aroung .5 pounds per foot + the enormous weight of fasteners.

21-01-2005 08:00

ShadowKnight

Re: pic: 1123 Frame

It does weight more than I would like it to, but there's something to be said for the ability to move an entire crosspiece. Additionally, we do not have the capability to weld a frame together. Also, an 80/20 supplier helped sponsor us, and I have no problem showing off their product when I think it's some really great stuff.

21-01-2005 09:20

Andy Baker

Re: pic: 1123 Frame

Seth, this is a good drive base frame. Kudos to you guys and good job for using excellent materials.

As for the weight issue, sure, as people said above, there are lighter options. However, you are also putting the weight where it needs to be. I always worry about making a drive base that is too light. We make efforts to lighten gears, wheels, and frame material. Yes, this does save weight and it allows you to put weight on other areas of your robot. This is what always worries me. This action of saving weight in the drive base essentially raises the Cg (center of gravity) of your robot. Having a strong, beefy drive base frame helps you keep that Cg low and makes you resist a tip easier. Having a light weight drive base generally raises your Cg and allows you to be tippy.

This is yet another trade off when designing a FIRST Competition Robot. While this frame may weigh more than others, it provides a solid foundation and a low center of gravity for a robot.

Andy B.