02-02-2004 22:45

Aignam

Re: pic: 2004 chassis 930

Good looking base. The extruded aluminum works incredibly well, as has been mentioned in previous threads. Good luck!

02-02-2004 23:31

Rickertsen2

Re: pic: 2004 chassis 930

Why doesn't anybody use 8020? Everybody seems to use bosch, kanya. Item etc.

Btw it looks nice. Love how you interted bearings directly into the extrusion.

02-02-2004 23:45

Andy Baker

Re: pic: 2004 chassis 930

Wow... very nice use of Item MB extrusions. This is simply elegant.

I have a couple of questions...

Is that mostly "5 series" extrusion, with 20 mm widths?
Do you use mostly m5 drop-in t-slot nuts?
How much does the assembly in that picture weigh?

Andy B.

03-02-2004 00:14

Cory

Re: pic: 2004 chassis 930

We use 8020. We got a whole bunch of it for free last year from some guy who was clearing out a warehouse full of it. It works pretty nice, although it's *REALLY* heavy when you add up all the plates, bolts, and t-nuts. Our frame was 40 lbs or so before we took the plates off and welded it. Based on Inventor's weight calculations, it should be ~14-15lbs now, which makes it real nice

[edit] Andy, it looks like they drilled and tapped quite a bit of it

Cory

03-02-2004 09:54

Stu Bloom

Re: pic: 2004 chassis 930

We also use 8020 (-1010, 1" x 1") for our basic chassis. Problem is the weight, especially if you don't really need the strength. If the chassis pictured is close to the robot footprint limits (30 X 36) then I would conservatively estimate about 64 feet of extrusion used in this design. You are looking at approximately 32 pounds, and that is BEFORE any wheels, sprockets, chain, gears, motors, pneumatics, battery, ..., and any additional mechanisms to play the game. OUCH ... I don't think we could stand that.

03-02-2004 16:36

rlowerr_1

Re: pic: 2004 chassis 930

Ok, seeing as I posted the picture I guess it’s only fair that I answer some of your questions.

All extrusion in the picture, excluding the bearing blocks, are item profile 5 20x20. The bearing blocks are item profile 5 20x80.

The only t-nuts used are to hold the ‘belly pan’ to the bottom of the chassis. All the rest are what are called standard fasteners (see picture).

For the bearing blocks we tapped the ends of the extrusion and milled clearance holes for M5 screws that go through the 20x20. This eliminates the problem that we see many teams facing each year with their pillow blocks shifting around on them. This also allows us to easily remove the bearing blocks if repairs are needed by simply taking out the four screws that hold them in place.

We weighed everything you see in the picture above at just over 20 pounds.

04-02-2004 18:37

NateBot16

Re: pic: 2004 chassis 930

I thought that you could not weld 80/20 because of the alloy its made from. We wanted to last year, but would teacher said we couldn't becasue of the alloy.

04-02-2004 19:38

Cory

Re: pic: 2004 chassis 930

It is made of 6105 Aluminum. I think that is one of the tougher alloys to weld. I don't really know, since we had professional welders from the Stanford Linear Accelerator weld it.

Cory

04-02-2004 19:48

westfalia

Re: pic: 2004 chassis 930

I think the way it works with the 8020 and welding them is that as long as you take a grinder to the parts you want to weld, it will weld fine. It's just the anodization that messes the welds up. We use 8020 (this is our second year) and although it's heavy it makes it really great for new team members to get in on the action of building and repairing the robot, because it's so easy to put together. ...If only we could use extruded made out of titanium or carbon fiber! I know, i know...