Team 254 Presents: Deadlift Technical Binder 2015

[Nate Laverdure]

How do you compensate for the big loss of strength in the HAZs of the 6061? How do you recommend other welded-chassis teams do it? Just blow up the thicknesses and section heights? I assume you don't do any detailed FEA or any post-weld heat treatment.

[thefro526]

Originally Posted by Nate Laverdure

How do you compensate for the big loss of strength in the HAZs of the 6061? How do you recommend other welded-chassis teams do it? Just blow up the thicknesses and section heights? I assume you don't do any detailed FEA or any post-weld heat treatment.

Don't quote me on this, but I think the mechanical fasteners and gussets that help to fixture the weldments also make up for some of the strength lost to the welding process.

I haven't played with a model of a welded FRC robot in a long time, but as along as the welds aren't in a really high stress area, I can't see them failing under most FRC conditions unless the wall thickness is really thin, or you're beating the heck out of whatever it is. (See 67's 2012 bridge arm for more insight)

[thatprogrammer]

Originally Posted by Travis Covington

We used 410 Stainless Steel to make a "disc" that pushed against a High Friction Molded Brake & Clutch Lining Sheet. It works just like a disc brake, except the forces are applied axially about the point of rotation.

As you can see, the disc spins and slides on a 3/8" hex shaft. This allowed us to install the disc brake outside of the gearbox.

I'm not entirely following why the disc rotates. Is it rotating in an attempt to grab onto a specific part of the gear? Also, is there a wall of some sort behind that it presses the gear agaibst?
Thanks for the help.

[Joe G.]

Originally Posted by thatprogrammer

I'm not entirely following why the disc rotates. Is it rotating in an attempt to grab onto a specific part of the gear? Also, is there a wall of some sort behind that it presses the gear agaibst?
Thanks for the help.

The disk is hex broached, and will always rotate with the rest of the gearbox.

The piston pushes it into the brake pad, which is mounted rigidly to the rest of the robot. There's not mechanical features like a dog gear or anything -- it's just pure friction.

Here's a picture I got of it in St. Louis in the context of the gearbox, which may help some. The silvery part is the disk, the off-black part with a fiber texture is the stationary pad.

[thatprogrammer]

Are the splicers for your timing belts just two pieces of metal bolted together? Thanks.

[Travis Covington]

Originally Posted by thatprogrammer

Are the splicers for your timing belts just two pieces of metal bolted together? Thanks.

Sort of. It has a milled belt profile to distribute the load properly. See below.

These carriage bearing blocks were quite intricate, but essentially became the entire structure of the carriage. The carriages themselves were quite weak and not very stiff. The belt and carriage blocks in the corners made the thing extremely rigid.

[NWChen]

Is there any footage/more documentation/images of Skystalker 0.2 available?

[JoeyD]

Originally Posted by Travis Covington

Sort of. It has a milled belt profile to distribute the load properly. See below.

These carriage bearing blocks were quite intricate, but essentially became the entire structure of the carriage. The carriages themselves were quite weak and not very stiff. The belt and carriage blocks in the corners made the thing extremely rigid.

How many individual structural parts are in this carriage bearing block, not including actual screws and bearings?

[Cory]

Originally Posted by JoeyD

How many individual structural parts are in this carriage bearing block, not including actual screws and bearings?

5 (the two arms left and right, the base piece they mount to, the belt clamp backing piece, and the belt clamp itself). There are also 2 alignment pins to clock the left and right bearing arms with respect to the main body.

[cxcad]

Would pat fairbank release a photo album for this year's build?

[Pat Fairbank]

Originally Posted by cxcad

Would pat fairbank release a photo album for this year's build?

I didn't take many photos this year during build, sorry.

[tickspe15]

There wasn't much to take pictures of...

[Mike Schreiber]

Great insight into one of the best teams in FRC (if not the best). I'd like to know a little bit more about your target build schedule if you're willing to share. How much time is spent on prototyping? Building a driveable prototype robot? This is something very few teams do, does this give great insight into how the game will play? When do you start work on the practice bot? comp bot? When do the programmers get it?

[Jay O'Donnell]

Originally Posted by Mike Schreiber

Great insight into one of the best teams in FRC (if not the best). I'd like to know a little bit more about your target build schedule if you're willing to share. How much time is spent on prototyping? Building a driveable prototype robot? This is something very few teams do, does this give great insight into how the game will play? When do you start work on the practice bot? comp bot? When do the programmers get it?

If you haven't read them already I highly suggest going through 254s 2013 or 2014 Build Blogs. A bit long but very well worth it and it covers your questions.