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-   -   pic: How's this? (http://www.chiefdelphi.com/forums/showthread.php?t=107084)

androb4 25-06-2012 23:28

pic: How's this?
 

smistthegreat 25-06-2012 23:29

Re: pic: How's this?
 
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.

Gregor 25-06-2012 23:32

Re: pic: How's this?
 
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.

Peck 26-06-2012 00:00

Re: pic: How's this?
 
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?

JVN 26-06-2012 00:25

Re: pic: How's this?
 
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

class1234567 26-06-2012 00:46

Re: pic: How's this?
 
Quote:

Originally Posted by Peck (Post 1175370)
also, is the half black and half white wheel just a finger guard made to look cool when spinning or what?

I think it an inertia plate

Thad House 26-06-2012 00:58

Re: pic: How's this?
 
I would guess that it is used for a Tachometer.

BJC 26-06-2012 01:02

Re: pic: How's this?
 
Quote:

Originally Posted by Peck (Post 1175370)
Snip/
also, is the half black and half white wheel just a finger guard made to look cool when spinning or what?

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

Peck 26-06-2012 01:23

Re: pic: How's this?
 
ok, I'm used to slot based encoders (and that is one big honking wheel to use for an encoder)

ToddF 26-06-2012 10:24

Re: pic: How's this?
 
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.

androb4 26-06-2012 10:25

Re: pic: How's this?
 
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.

n1ckd2012 26-06-2012 10:45

Re: pic: How's this?
 
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.

Elizabeth Waters 26-06-2012 11:09

Re: pic: How's this?
 
Looks pretty good. Actually reminds me of someone else's shooter... ;) 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?

JVN 26-06-2012 12:40

Re: pic: How's this?
 
Quote:

Originally Posted by androb4 (Post 1175400)
All the aluminum is 1/8" thick, 6061 T-6

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.

Quote:

Originally Posted by androb4 (Post 1175400)
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.

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

Samwaldo 26-06-2012 15:35

Re: pic: How's this?
 
do you want the hood to be able to move?


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