Structural Framing Strength?

[VladimirM]

Hello Chief Delphi forum,

My rookie team, Team 5631, was looking at purchasing aluminium structural framing to make up the main frame of our robot. We came upon this website to purchase the framing from.

I had looked at buying 12000mm of 40x40 t-slot framing. It is rather expensive, and as a rookie team we are on a tighter budget then some of the more senior teams. That being said, could anyone give me some insight if 40x40 will be ample strength? Should we move down in size, and save in costs to the 30x30, or should we consider moving up to the more expensive 45x45? Even 50x50?

Thanks in advance for any responses,

Vladimir Milicevic
Team 5631 Robot Captain

[MrForbes]

Our team bought a lot of structural material before our first build season, and ended up not using most of it.

If you are going to get the kit chassis, then you will already have your main frame. Once you decide how your team will play the game, then you can decide what your robot needs to do. Once you know what it needs to do, you can figure out how to build it.

We have been quite successful using rather mundane materials, purchased locally, as needed, such as plywood, aluminum angle and round/square tube extrusions, and sheet metal and polycarbonate. Rivets and sheet metal screws and small machine screws and nuts can be used to hold these parts together. Look at lots of pictures of robots from past competitions, you will find there are many ways to build. Some of them require hard to find materials, long lead times, and lots of expensive machining equipment. Others are quick, simple, cheap, and clever instead.

[FrankJ]

We have used the 80/20 (the other maker of the t channel extrusion) 10 series (1x1) which is slightly smaller than the Bosch 30X30 with no strength issues on the chassis framing. Your (and others) mileage may vary. It is a little heavy for its stiffness, but the adjustability gives a lot of advantages.

80/20 gives a substantial discount to First Teams & they also have metric profiles. Bosch supports at least First team. Bosch might well offer a discount so be sure to ask your distributor .

[hrench]

I've seen lots of teams that use T-slot framing, (brand name 80/20 is popular) but I've never believed it offered any advantage as opposed to aluminum or even steel flat stock and tubing.

As for the drive system frame, if you're a low-resource team, I recommend you consider the kit frame from Andymark. Last year we ran the IM14U and had a very winning season.

And when you use steel tubing, the kids can weld it up in the shop as opposed to sending it somewhere. Anything you can build yourself is a bonus.

I'm interested in the comments of others here, but I just don't see any components that can mount to 80/20 more easily than they could mount to a piece of AL barstock. Lots of wasted strength too. The linear members, it seems to me, will always be way-stronger than the bolted joints.

[Monochron]

If by "main frame" you are referring to the structure that you will attache wheels, motors, and gearboxes to then I heavily recommend that you NOT build that out of T Channel as a rookie team. If you have students / mentors with tons of experience building their own FIRST sized robot chassis then you could be successful, but even then, I would say that you should just use the KOP chassis and focus your efforts on building super structures and game piece manipulators.

The KOP chassis is just so simply to put together, and of perfectly fine quality, that redesigning it isn't going to gain you much as a first year team. Here is the page for the chassis if you are interested. If you are budget constrained, I recommend you spend that limited budget areas other than the chassis.

[JB987]

VexPro has a fantastic supply of structural components that are easy to build with and easier on your wallet...1x2" and 1x1" tubing with pre-drilled holes on 1" centers, a big collection of reasonably priced brackets with holes on 1" centers. Incredibly easy to cut and assemble with rivets or screws. Sure wish we had these supplies available for our rookie year in 2002

[Nemo]

Our team has used Bosch framing for robots. The oldest ones use some 45x45 and even 45x90, and that is SUPER overkill for FRC. Then they moved to 30x60 and 30x30, and it's still significant overkill in my opinion. In 2009 we used 20x40 and 20x20, and it worked fine. The weight savings are substantial. The 20 mm stuff is the best size for FRC in my opinion.

The thing is, even though it sounds simple, it can take forever to get a frame designed and cut and built out of extrusion. We dinked around with that drive base frame for weeks in 2009. In 2010 we switched to pre-made drive bases from AndyMark and Vex, and it has been a valuable time saver. The pre-made drive frames are good and inexpensive, and they get better every year.

T slot framing can be nice for building upwards from a drive base. It has its advantages and disadvantages. I do love regular aluminum square and rectangular tubing, though. It's strong and light and not that expensive if you can buy it in full size lengths from a local distributor. No pricey fasteners required.

[Greg Needel]

Structural Framing is a great way to build your robot, as it is extremely flexible in the way it is placed and assembled. There are no other methods that I know of that give you that level of adaptability. If you know exactly what you are going to want to build, there are better options out there, but if you want to be able to "move things around on the fly" Structural Framing is awesome.

That being said I would highly recommend using the Kit of parts drive train, and adding framing on top for your mechanisms.


My company REV robotics, just announced our structural framing system which will be sold through AndyMark, and available in the next week or so. We designed it specifically with FIRST robot applications in mind and did everything we could to make it an affordable complete solution for teams. You can check it out here, http://www.chiefdelphi.com/forums/sh...hreadid=131136

[R.C.]

Originally Posted by JB987

VexPro has a fantastic supply of structural components that are easy to build with and easier on your wallet...1x2" and 1x1" tubing with pre-drilled holes on 1" centers, a big collection of reasonably priced brackets with holes on 1" centers. Incredibly easy to cut and assemble with rivets or screws. Sure wish we had these supplies available for our rookie year in 2002

What Joe Said,

http://www.vexrobotics.com/vexpro/we...ersaframe.html

http://www.buildblitz.com/

And you can check out the robots made from the versaframing etc...

[DonRotolo]

40x40 is overkill for almost every application in FRC.

That being said, the material is plenty strong, its weakness are where it connects together. Fasteners that depend on friction (such as T-nuts) absolutely will come loose and move. Maybe OK for superstructure, but not for a drive base.

You will be far better served by getting several pieces of extruded box tubing in 1" x 1" with 1/16" and 1/8" wall, plus some 3/4 with 1/16" wall for smaller mechanisms. You will also need some sheet aluminum, start with 4x4 sheets on 1/32", 1/16", 1/8" and maybe 0.093". (It would be very rare to need anything thicker)

Try onlinemetals.com, but beware: They will give you an "extra 5% off" coupon after your first order...so place a small order first, then go for broke. They also run sales on occasion, like 25% off, or free shipping, ror something - so place that first order then see what comes up...

[asid61]

Originally Posted by DonRotolo

Try onlinemetals.com, but beware: They will give you an "extra 5% off" coupon after your first order...so place a small order first, then go for broke. They also run sales on occasion, like 25% off, or free shipping, ror something - so place that first order then see what comes up...

I just missed a 25% off sale they were having for Black Friday. Sign up for their email list and pounce on the sales that come around once or twice a month.

[pfreivald]

We've used Bosch Rexroth for linear motion applications--their drive carriage is fantastic. 30x30 is overkill for most applications, though.

The kitbot drivetrain is sufficiently good that I certainly wouldn't use structural framing for it....

...and for upper mechanical work, with limited manufacturing capabilities I don't think you can go too far wrong using square tube stock, L-stock, and clinch nuts (aka rivnuts aka rivet nuts aka threaded inserts). A couple of bags of 10-32 clinch nuts, a thread setter (the tool used to install them), 10-32 socket head cap screws, and some 19/64 drill bits will go a long way toward cheap, do-it-yourself, easy-to-modify-and-install "structural framing" that is versatile for prototyping, and easy to lock in place with a little Loctite for use on a competition robot.

It takes a more effort than an off-the-shelf solution but is far cheaper and lightweight, it isn't as lightweight or as sophisticated as CnC sheet metal fabrication but requires virtually zero expertise and is more modular. It's a happy medium between the two that I wish I'd known about as a rookie.