pic: Team 100 Prototype Base - Underside

[Dan Petrovic]

Originally Posted by Qbranch

*chuckle* Anyhow, on the more nuts-and-bolts side of life, for what you're building there, why not use a Kit Bot frame from IFI? It's rock solid strong, really light, and sports 1" center free fit holes accomadating 1/4"-20s. I know it sounds tacky to use a kitbot frame... but really, its tough to beat for strength/weight balance.

-q

I wouldn't really consider the kitbot frame rock solid strong...

C-channel has about half as much torsional strength as box tubing even though it has only one less side.

[=Martin=Taylor=]

Originally Posted by InfernoX14

I wouldn't really consider the kitbot frame rock solid strong...

Our team did a stress analysis a while back and determined that the kitbot was actually quite strong. I think its infamous reputation comes from teams cutting notches in it and weakening its structure. Left in its original state it is very strong.

Originally Posted by M. Krass

If you don't mind answering a few questions:

-- From what are the bearing blocks made? They look like they're 1/4" thick, overall dimensions of 2.25 x 1.5. McMaster-Carr, nor onlinemetals.com, seem to carry stock of these or similar dimension. Are they custom made?

-- What machining work was done to the 1x2 extrusion to accomodate the axles?

-- Where'd you find 1/2" bore, keyed sprockets for #25 chain? What were lead times and cost like?

No problem

--Wow that’s the exact dimensions ! We searched and searched for channel stock that came in these dimensions, but it didn't exist . So we just purchased a 2.25 x 1.5 block from a local metal supplier and machined a 1 x 2 slot in it. It took forever on our little mill, but our sponsor will probably be able to get it done in an afternoon.

--We just cut two 0.75" long slots on either end with a 0.75" end-mill. The center slot is vertical, allowing the center wheel to be raised or lowered an 1/8 of an inch.

--McMaster Carr. We had to machine them thinner and broach them, but it wasn't too hard. Just like everything else they carry the sprockets were cheap and arrived soon

[Jeff K.]

This is a really nice example of a modifiable prototype chassis. 55 lbs ain't bad, our mecanum base last year was 80 lbs, while the arm was 30 or so. With all the weight down low, we never were close to tipping over. The method of tensioning is also a pretty slick idea. How heavy are the wheels? Will you be using a similar chassis layout with the box extrusion?

[Cory]

Pretty cool guys. I agree with Travis. Looks extremely well designed. Wish we had ever had our acts together enough to have an offseason project as nice as that when I was on the team

For those criticizing the weight, there's all kinds of weight they could easily remove. The sprocket hubs can be turned down. The gears in the AM shifters can be lightened. The big CIM's can be swapped for small CIM's.

Even without swapping the CIM's, I'd say they could cut 2-5 lbs pretty easily.

[Brandon Holley]

I would not worry about the 55 lb drivetrain you got there. With electronics that is a PERFECTLY acceptable weight. I like the whole setup you got here. Good job.

[Blue_Mist]

It's organized and simple, and very light for a drive train and frame and electronics and pneumatics. However, as Squirrel said, weight down low isn't a bad thing. We try to keep a low center of gravity and almost never tip, although the ramps were sometimes a problem and we aren't considered fast. I like how neat and clean the chains are- no tensioners. If I may, I think the motor wires might do better tied against the frame to keep them out of the way. Just my opinion. I do like the frame extending to protect the wheels in the front and back. That would be a nice place to put bumpers; mount them with bolts on either side of the wheels. And good looking welds, too, from what I can see.

Sorry for bashing the weight. I spent too much time thinking about that one number. It is quite the nice system. How quick is tensioning?

Also, do you happen to know around how much the electronics board in whole weighs? I'm curious as to whether or not this thing would be lighter with a less hefty board.


Very nice, and props on getting something together before the season! I know it's not easy, as all of my attempts at doing this have been shut down.

Props!

[MrForbes]

A piece of plywood can be kind of heavy, or not....depending on what you use. 1/8" lauan plywood is fairly rigid, light, and not very expensive, usually available in part sheets from big building supply places.

[=Martin=Taylor=]

Originally Posted by 114ManualLabor

Sorry for bashing the weight. I spent too much time thinking about that one number. It is quite the nice system. How quick is tensioning?

Also, do you happen to know around how much the electronics board in whole weighs? I'm curious as to whether or not this thing would be lighter with a less hefty board.


Very nice, and props on getting something together before the season! I know it's not easy, as all of my attempts at doing this have been shut down.

Props!

Its a sawed off piece of our 06 ramp, I believe its 0.5" thick. We also used four different fuse boxes because that was all we had. I think the major weight came from the Big CIMs. As Cory said, those big CIMs weigh significantly more than the small CIMs. We used them because we didn't have any of the small pinion gears that are needed for the small CIMs in the AM shifters.

Tensioning is really easy. You just loosen three bolts and slide the bearing block into place and tighten it down. And no, the blocks don't slip. The chains will stay tight until they begin to strech.

Originally Posted by Cory

For those criticizing the weight, there's all kinds of weight they could easily remove. The sprocket hubs can be turned down. The gears in the AM shifters can be lightened. The big CIM's can be swapped for small CIM's.

Even without swapping the CIM's, I'd say they could cut 2-5 lbs pretty easily.

Yes, there are many things we could have done to lighten it. But it all would have taken time and money and the purpose of this system is to create a simple prototype base.

For the competition version we may use 7075 or 7068 aluminum for the axels. Any advice on that?

[Cory]

Originally Posted by Hachiban VIII

For the competition version we may use 7075 or 7068 aluminum for the axels. Any advice on that?

Nothing too special you need to do. ours are just plain old 7075 1/2" main diameter, with 7/16" hexes on either end. No heat treatment or hardening necessaary

[Ross340]

340's proto frame weighs somewhere around there made of 3/4 bar stock. it's so bulletproof. We love it.

[team2061]

What is being used to hold down the electronics and other stuff because in the 2007 season we screwed and bolted everything down.Bad idea it bit us in the butt big time.I heard zip ties are the best way to go.

[caraddicted101]

I have seen some teams use zip ties as they are easy to cut and replace, I have also seen some teams use strong Velcro, as it is even easier to change a component then zip ties. As for me, we had a little room and just put a few extra spikes on the robot unwired that way we would only have to pull the wires off the bad one and we would be good to go.

[kramarczyk]

Originally Posted by Hachiban VIII

For the competition version we may use 7075 or 7068 aluminum for the axels. Any advice on that?

You may want to plug and chug this spreadsheet to play with various materials and diameters. It also includes the possibility of drilling them out.

http://www.chiefdelphi.com/media/papers/1998

[robostangs548]

Looks nice, I bet you with my experience in lightening, that, I could help you loose about 10-12 off of that 55. Other then that looks nice!