1 lb drum bot!

If this actually works, I'll be really happy...

Right now i'm stuck cause no one gives any kind of technical drawing for any small components.
it's unfortunate. but this is what i've got:



using two e-flite 300's (1380 Kv) at 7.4V (2s lipo) - lowering speed of drum with a 1:1.5 pulley ratio to get a drum speed of 6808 RPM (theoretical). drum specs: 1 inch schedule 10 steel (yes, steel) pipe, the OD with teeth is 1.9" and the drum assembly (drum, endcaps, screws + ball bearings) weighs .29 lbs. My one piece 7075 aluminum frame weighs .24 lbs without the top piece. I need to factor in some weight for the wheels, and some weight for the top piece of the frame (and bolts). The total electrical/component weight is .34 lbs, giving me a total accounted-for weight of .87 lbs (which sounds GOOD to me).



if this gets built, expect to see it at GCRS and BARF this summer!!

Dan Curhan wrote:

If this actually works, I'll be really happy...

Right now i'm stuck cause no one gives any kind of technical drawing for any small components.
it's unfortunate. but this is what i've got:



using two e-flite 300's (1380 Kv) at 7.4V (2s lipo) - lowering speed of drum with a 1:1.5 pulley ratio to get a drum speed of 6808 RPM (theoretical). drum specs: 1 inch schedule 10 steel (yes, steel) pipe, the OD with teeth is 1.9" and the drum assembly (drum, endcaps, screws + ball bearings) weighs .29 lbs. My one piece 7075 aluminum frame weighs .24 lbs without the top piece. I need to factor in some weight for the wheels, and some weight for the top piece of the frame (and bolts). The total electrical/component weight is .34 lbs, giving me a total accounted-for weight of .87 lbs (which sounds GOOD to me).



if this gets built, expect to see it at GCRS and BARF this summer!!

wait. So are you doing an Antweight, Beetleweight or both?

did you consider press fitting an outrunner into the drum on this?
Ive seen it done alot on insect bots, its nice cause you save the weight of the pulleys and such

yeahh... i just wanted to use two motors, and i'm not sure i can make it work with two... i mean the ID of this drum is only 1.0815 so it's pretty small. I think i'd have to open it up for just about any motor to fit...
but i didn't put much effort into the idea lol.

and alan, there's more competition in the 1lb division (at least around here), so I thought i'd do an antweight. But we'll see what happens. This is all up in the air right now. :]

well, if your building a 1 pounder, then I have to as well! maybe you should build a 3 instead!

Will Bales wrote:

well, if your building a 1 pounder, then I have to as well! maybe you should build a 3 instead!

I was going to make a 3 lb just to compete against Dan. But, I guess I can make a 1 lb...

we should all build 3 pounders! believe me! it's easier than building a 1 lbs robot!

Will Bales wrote:

we should all build 3 pounders! believe me! it's easier than building a 1 lbs robot!

I would imagine. A 1 lb bot is extremely limited in terms of what can be used.

but the 1lb limit makes the challenge!!

meh.. 3 pounders can be more exciting!

like you wedge lol i know i know its a housebot haha

very funny! It's waaay underweight, so i'd end up just machining another chassis with a weapon! how about that?!

wait you dont already have a solidworks for it?!!haha

Uh, just one question. WHERE DO YA'LL GET THE MONEY FOR THIS? I mean one robot a year is cool. Two or three if you've got the time and resources, but it looks to me like you guys just decide on a whim to make new robot and one week later, there it is.

All I can say is bravo. I guess that how ya'll role in Florida uh?

Senai?

Well Will has a machine shop in his garage and i think Dans dad owns a machine shop/engineering firm (not sure what exactly it is). Dans only come up with CADs so far haha

As far as Will goes, he's arguably as close as you can get to having unlimited resources. Pretty much the one thing he wouldn't be able to do is make a robot entirely out of diamonds.

Cody Harris wrote:

Well Will has a machine shop in his garage and i think Dans dad owns a machine shop/engineering firm (not sure what exactly it is). Dans only come up with CADs so far haha

Dan's dad works at a company that makes contact lenses. Jeff Curhan is the engineer that designs all their automated assembly lines. I think that sums it up fairly well but Dan can correct me if I am wrong.


Also, Dan does a substantial amount of the machining himself. Dan welded Copperhead's frame and machined many of the parts. He also made most of the parts in Dethinator. Sure, Jeff makes the parts that are more complicated, but most of it is done by Dan.

haha my dad designs AND BUILDS the lines lol. but yes. that's correct.
I put out CADs cause i need a solid concept to get the go-ahead to build it. We have enough money to make ..ehh.. two 1lbs and a 15lb this summer. My dad's also hoping to build a 220 this year and next and however long it takes to fundraise lol.
I do practically have 24/7 access to a shop, but not to my dad (who is my access to the shop) cause he sleeps sometimes... but nowhere near will's resources.

lol thanks?

looks good . reminds me of micro touro: http://robogames.net/registration/entry/view/181
i would suggest just using one eflite 400 motor, but if you can fit it all in and be underweight, then two motors is good for redundancy in case one fails. are those vbelt pulleys or round belt pulleys? i would assume roundbelt, but those grooves seemed deep. if you have time, you should come compete at this year's DragonCon in Atlanta since I'll be there =]

dragoncon isn't on buildersdb yet, is it? I didn't see it last time i looked... but if it's before i leave for college I'll consider it. :]
they're round belt pulleys - i just kinda arbitrarily assigned the pulley dimensions. i don't think they make v-belts small enough for a 1 lb bot. McMaster's smallest are 10" outer circumference lol.

I was using e-flite 300s not 400s, because they're .8 oz each and a 1.1" OD, but if you think a 400 is better... I just looked and they're the same od (1.1") but 2.0 oz and 920 Kv (which only gives me 6808 RPM if I use a 1:1 ratio, which i wasn't going to do. I was gonna slow the drum down with a 1:1.5 or so ratio to make it easier to fit the pulley on the motor inside the bot. as it is, 6808 rpm (2s lipo) is a little slow (with the e-flite 400).

we'll see though. I haven't bought anything yet.

well as far as i know, dragoncon is around first or second week of september which probably won't work for you if ur leaving for college. also, it's more of a show up and register event so i believe it's not posted on buildersdb.

yea, i assumed they were roundbelt since vbelts don't come that small, but the grooving was deep so i was wondering if you found some secret source for smaller and more flexible vbelts ;P.

oh jeez my bad. i meant park 370. the sizes of eflites confuse me =[ they should do more convential sizing like axi's, go by stator size. Well if you're looking for high kv, then an axi 2208 or similar would suit you best since they run up to 1600 kv at that size. otherwise, you could try out feigao inrunners which range from about 2.5~4k kv.

yeah 1200 kv sounds better (e-flite 370). still same od, and 1.6 oz (plus i save weight on wires lol so it's less than 2 0.8 oz motors!)... hmmm...
i think i like bigger motors better because after the dethinator project, i don't have much faith in "power in numbers" when regards to little motors.

I found the AXi equivalent (i guess..?) of the e-flite 370: the AXi 2208/34. Same weight, dimensions, etc. AND IT GIVES DIMENSIONS! omg. I'm excited now. and I'm totally using this one. screw knockoffs that don't give any mounting info...

um...


shiiit.
lol.
that's the axi 2208/26 inside my bot. i purposely made the height tall enough to accommodate it, but holy crap, man! I don't know what to do now lol.

it fits better. i need to extend the back another 13mm (to fit the battery... it just DOESN'T FIT anywhere else.... but it works!


is 910 mAh at 7.4v (2s) reasonable for this setup?