pic: How's this?



What is your opinion on what I made?

BTW, this is a 2012 Texas Robot Roundup teaser…

All the aluminum is 1/8" thick, 6061 T-6
The 8" FIRST shell is sitting on a 1/2" keyed shaft with AM hubs
That is spun by 2 Fisherprice 9015 on Banebots P60’s 4:1
The shaft is supported buy the two inside pieces of C channel extrusion with bearings set in the wall.
Next is a shaft coupler to attatch it to the P60’s, which are mounted between the walls of another C channel extrusion.
The ball compression is about 1.5"-2"
The camera mount IS 1/8" sheet metal.

This is my first time using sheet metal like this so I’m not sure about the best thickness to use.

The disk is used for a tachometer. There is a Rockwell Automation Photo sensor under the left P60.

The hood is made of the AM hex tube from the chassis kit, space about 1"

Any details? Motors, gearboxes, wheel diameter, wheel material, compression, hood material, range, anything else you’re willing to share?

Also, looks great! I like the design.

Will the hood be lined with something (i.e. lexan, sheetmetal)? If only the bars are there, I foresee a lot of balls getting chewed up.

nice work with the similar shapes. Mind giving us a BOM and telling us all parts we might have issues seeing in the pic if any?

also, is the half black and half white wheel just a finger guard made to look cool when spinning or what?

It looks like your using threaded aluminum hex bars as the cross members in the back. If this is the case, you could probably accomplish the same thing with a much lighter piece, made from (more) sheet-metal or lexan + a few key brackets.

How thick is the metal on that camera mount? Seems a bit overkill… anything over 0.063" is much too much.

In general, how thick is the metal you’re using?

Are those pieces of extrusion mounting the motor? Mounting the wheel bearings? It looks like some clever refinement could eliminate a number of parts / lighten parts in that section.

Good start though! The overall system and system layout looks very clean. I think with some refinement (again, mainly around efficiency and weight reduction) you’ll end up with a real winner. Keep iterating.

-John

I think it an inertia plate

I would guess that it is used for a Tachometer.

It’s probably for an optical encoder. It counts the wheel rotations based on how many times it sees the black and white circle as it spins. You can closely control shooter speed with it. Our shooter has one broken into four parts and an encoder you probably use in conjunction with your drivetrain is similar, just much smaller.

Regards, Bryan

ok, I’m used to slot based encoders (and that is one big honking wheel to use for an encoder)

Things that caught my eye:

  • Has a lightweight look. Nice.
  • The encoder disc is redundant. You could use the wheel spokes with no weight penalty.
  • The rear of the hood may give better results if it is continuous. Check out the Killer Bee’s hood on frc-designs for an elegant way to do this.
  • Using two separate gearboxes to drive your wheel is weight inefficient. Use something like a CIMulator to mount both motors together. Less mounting bracketry, and only a single gearbox housing. Also frees up one end of your wheel shaft for a shaft encoder, if you don’t use the wheel spokes.
  • If you haven’t prototyped it, consider two wheels with a space between. This may effect your accuracy. Let your test results guide you.

Sorry for not posting any info… It was getting late.

All the aluminum is 1/8" thick, 6061 T-6
The 8" FIRST shell is sitting on a 1/2" keyed shaft with AM hubs
That is spun by 2 Fisherprice 9015 on Banebots P60’s 4:1
The shaft is supported buy the two inside pieces of C channel extrusion with bearings set in the wall.
Next is a shaft coupler to attatch it to the P60’s, which are mounted between the walls of another C channel extrusion.
The ball compression is about 1.5"-2"
The camera mount IS 1/8" sheet metal.

This is my first time using sheet metal like this so I’m not sure about the best thickness to use.

Yes the disk is used for a tachometer. There is a Rockwell Automation Photo sensor under the left P60.

The hood is made of the AM hex tube from the chassis kit, space about 1"

ONE thing I need help with is, riveting. What size whole and what rivets should I use for the camera mount? Any suggestions? Also for attaching the sides of the hood the the square tubing on the outside.

3/16inch is a great standard rivet/hole size to use. Size10 bolts fit in the same hole. However, I believe 1/8inch rivets will be fine for your camera mount.

Looks pretty good. Actually reminds me of someone else’s shooter… :wink: Ours is EXTREMELY similar, save the camera placement (we mounted ours on the side of the hood versus underneath the wheel) and the fact that we used two wheels instead of one.

One thing to note: we actually initially designed the “back” of the hood like yours, i.e. bars mounted horizontally to act as the backing/support for the ball. Yet, as the balls exited the shooter, they were compressed inside the spaces between the bars, slowing down the balls’ exit speed to the point where we ended up tweaking this design. We kept the bars there, but added a piece of lexan with stips of foam taped to it, and we zip tied this assembly onto the inside of the bars (facing the shooter wheel). This dramatically improved our shooter’s accuracy/ball speed/backspin on the ball versus using the bars alone.

Hope this makes sense. If not, come check out our pit at TRR.

Are y’all planning to have this ready for Austin?

1/8" is waaaay overkill for most of those parts. You can definitely go to 0.090" or 0.063" for a lot of them.

Also - We use 5052 for our bent stuff, and 6061 for our flat stuff. 5052 bends a whole lot better.

I’ve used a lot of 5/32" rivets in the past for structural. 1/4" rivets for “really beefy overdesigned structural pieces” and 1/8" rivets where 5/32" won’t fit (for the sake of commonization I use 5/32" wherever possible).

The camera mount is way over designed, in my opinion. You can get away with 0.063" metal, and still truss it like crazy. If you design it such that the metal forms closed box sections, it will still be stiff as heck.

-John

do you want the hood to be able to move?

Just to echo what John said for a minute - 1/8th on a shooter is indeed way too much material. We made our whole shooter out of solid plates of 1/8th sheet. Way too beefy, and it raised our CG way too high. The main concern with your camera mount will be to mount the assembly so that it is rigid enough that the high speed wheel behind it won’t make it wobble too much. As long as you have a rigid cross section you can take out a lot of material from your mount and it will do just fine.

Depending on your design, you might benefit from making the back plate of your shooter a little differently. Especially with a single shooting wheel, having some structure to help keep balls aligned is really helpful for repeatability. Here’s a picture of Miss Daisy’s shooter. They have a similar plate-and-standoff design to your own shooter, but they also have some inner plates to help guide balls down the center of their shooter. You can make this out of thin material since it’s even less structural than the sides of your shooter and you should get a bit more of a repeatable shot.

For another reference, we did most of our shooter design out of 0.050" sheet metal. In a couple of spots (on the gearboxes) we had a few 1/8" plates, but for all of the hoods, mounting flanges, camera brackets, etc. we used 0.050" 5052.

-Brando