Help pick a beater for Sting

Here are a coupls of ideas for Sting's beater (3 lbs. bot)

Both are single tooth designs, 1 is conventional and the other is with staggered blades...both are balanced in solidworks

All opinions or other ideas are welcome...remembering that weight is a BIG factor...

single blade beater.....



staggered blades....wierd stufff....keeping in line with my other wierd stuff

maybe filleting/contouring the non-toothed edge so its less resistent to bite

Cody Harris wrote:

maybe filleting/contouring the non-toothed edge so its less resistent to bite

which one are you referring to....or both??

On beater 1, the toothed edge is over 1/4" longer than the back edge, so I doubt that the back edge would ever hit anything, but some contouring would possibly help reduce drag.

The view of beater 2 is misleading...the cutting edges are parallel to each other and to the mainshaft, so again, the angled or back edges would probably not see much if any action.

i didnt pay attention to the tooth front and back lol so disregard to directional arrows hahaha





The red edges with the arrows pointing to them
Even with the round edge im sure itll still bite here and there

It will be interesting to see if it ever will bite in those places, escept for at maybe 10 rpm or something really slow

Not saying that you are right or wrong, but....think about this....

Let's say that the difference in distance between cutting and trailing edges is 1/4"...how fast would the bots have to be moving towards each other (combined drive speed) to get better than a 1/4" bite???

If I make beater 1, a re'balance would have to be calculated to accomodate any changes

If I make beater 2, as long as they are equal, I can do just about anything to the trailing edges....which would also help lose some weight (agood thing in this case) and maybe help with some aero as well

Thanks for the feedback....

Most beaters get great bit with squared edges like that, just figureing you would rather bite with the tooth then other parts but i thing i like the second one better, very different and awesome if it would work

As I said, if anything gets that close....as in more than 1/4" inside the radius of the cutting edge, then I guess at that point, either the beater is not spinning anymore, or if it is, then I'd like to hit them with anything available...hahaha.....cause I'd be in BIG trouble already.


the 2 cutting edges meet in the middle, with no overlap, so alignment between 2 bots would have to be perfect to get a double hit....I might change it to give just a hair of overlap on a second one, if the first works out

what do you think?? the drum has a bit of overlap and the occasional double hit does some pretty serious biting...

Here's the front view of beater 2

Here's the cody beater...hahaha....

Looks like high tech bs...maybe it belongs in the tech toys thread...if it works

Hardly looks like a beater anymore...maybe nobody will notice...lol

looks weird haha
idk if youd have to do the inside edges im sure it would save a little weight

Cody Harris wrote:

looks weird haha
idk if youd have to do the inside edges im sure it would save a little weight

When I get the sizes finalized, I'll cut and test 1 with NO fillets and if it works out (balance wise), I'll cut another with the fillets

I think that round edges everywhere possible might help airflow and maybe drop motor amperage a bit.

Not a true aerodynamic shape, but it has to be better than square edges and as you noted, it'll save a little bit of weight.

On a side note, I might change things so that there is no thru shaft...I have a few ideas on this

Wasn't there someone, with a bot named Redemption, I believe, that was hanging shafts on the end of a beater or drum and then into bearings in the outer sides???

Any pics of that...I'm curious and how did that work out as far as rigidity?

Here's my first attempt

spin it spin it!!

I'm modifying it to lose a bit more weight....AGAIN !!

Another problem is that with a drum, I can put the belt anywhere and keep the drum closer to the width of the bot...

this beater is way shorter, which presents several other problems

Mostly, that I may have to change a bunch of stuff, or end up with an inch or so of unprotected frontal area, cause unless I make a 2 piece beater, the pulley has to hang off the side, while the motor pulley has to be within the front to back inner braces......baaaaaaahhhhh........

Honestly, I never intended to to put a beater on this bot....but things change...lol

So, I might have to spin at well over 40k to get BIG joules......and I don;t know if the wiltle motor will spin a beater that fast, but we'll see

Well...it looks like I may go to a 2 piece beater after all.... I have a pretty cool design in the works, and things should work out better overall.....

what do you mean 2 piece?

Cody Harris wrote:

what do you mean 2 piece?

How about this??

Being that each blade is also balanced, it could be assembled as a one blade or staggered blade beater...shown is the staggered version

is the outside of the none toothed side the same circumference as the tooth?

Cody Harris wrote:

is the outside of the none toothed side the same circumference as the tooth?

Only at the very tip, then it obviously angles away...it could be changed easily, but I'm thinking that in a straight head on blade to blade, nibbling or grinding as well as defending the belt/pulley might not be a really bad idea??

Otherwise, the odds of getting a perfectly straight hit are probably not that great

What do you think? ...knock 1/4" off?

or just straighten out the back edge and leave it offset by 1/4" or more??

btw: are we the only ones left on this forum...

So reconsider the numbers i say since ive never done anything this size but what if you did like 1/16" bigger then to pulley on the none tooth side straight across and 1/4" bigger on the toothed side.
If you would stagger the teeth you are back to what you had mentioned to me before about the bite. With it spinning as fast as it does im sure one of the teeth would hit it before anything does damage to the belt

shoot i forgot shaft holes through the beater hahaha

The main reason for leaving as much weight as possible further away from the shaft centerline, is for balancing/weight purposes.

If I offset as much as in your drawing, the counterweights would have to be much heavier...and weight is a big issue for me on this one...

does that make sense?

btw: that for staying with me on this...

i get exactly what your saying, butttt i thought you could play with that haha

Cody Harris wrote:

i get exactly what your saying, butttt i thought you could play with that haha

I have, but closr to centerline = MORE weight...otherwise, I would just leave it more symetrical and save some headaches..

Whats the reason for throwing out the other one if you dont mind me asking?

Cody Harris wrote:

Whats the reason for throwing out the other one if you dont mind me asking?

I thought that i explained that, but I'll try again

1) I would have to hang the pulley off the side, so the beater would be off center

2) I have to keep the motor pulley inside the inner side frame, or it will hit the wheels, so the beater would have to be shorter and even more off center.

3) If i do it that way, then there is a lot of area on either side of the beater( one side a lot more than the other) that is left unprotected, (chewy aluminum), so I would have to re-think and probably redo the outer sides/frontal area, which = more weight that I don't have.

so, by splitting the beater, I can slap the pulley down the middle, keep the drive motor/pulley all within the inner sides, and the beater assembly will be a drop in replacement for the drum that was there...pretty much....I think..I hope..I dunno..