I see you are getting good a CAD there Wayde! A couple of points:

Why the complicated step in the middle of the drum? It would weaken the drum and be harder to make. It looks like you are driving the drum in the middle - I can't think of any other design that does this; end drive is stronger & cheaper.

The axles at the ends of the drum look overly long; can you possibly shorten them to reduce bending & weight? The weapon would be more effective if the drum went all the way to the outside rails if you can manage the weight

The problem with drum bots is always finding a good motor that is smaller diameter than the drum - the EV would be the right power and speed, but its wide and rare as well. you might look at a geared down Dewalt (fairly cheap but high RPM) or a mid-sized brushless (pricey but variable speed and super light).

The compound shape on the front corners looks cool but it will be VERY hard to fabricate.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

yeah as i said its outdated basically that was made from my origional ideas on using fan motors or ev's for drive so the shaft housed pullies for the belts to drive the wheels so its not anywhere near that complicated and the shaft is considderably shorter

im not positive that i know why the motor has got to be smaller than the drum and i already have an ev along the way

as for the compound shapes for the ends they do look cool and they arnt as hard to make as you would think as i said the bot is gonna be using fibreglass for the armor so for strange round shapes its just a matter of making a wheat bix box mould for the curve and then making it from there polystyrine blocks with some contact paper is good for making those sorts of things too you just make the shape and contact paper it then fiberglass around it

i know having the central section being used to drive the drum does weaken it down but im using it to keep the center of mass as centered as possible which will help against gyro dancing and that sort of thing not to mention it will give it a better acceleration in theory because its got even power to weight distribution (i might be only talking about a margional differance or none at all i was never a rocket scientist so this is just what im thinking up on the spot) to try and compensate for the weakened drum im planning on using an extra thick section similar to the bearingblocks or end caps to span under the lathed out section for the pully to either side where the teath will get bolted to which will give extra strength to the weakened point aswell as add a tooth mounting point) but then again it all depends on weight (i get the feeling i will be drilling/pocketing all of the caps because on a guestimation with out the bearing blocks and endcaps it comes in at about 1.5kg and thats with outh the teeth aswell thats just the drum the shaft and the bearings :S
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

quote:

---

t looks like you are driving the drum in the middle - I can't think of any other design that does this; end drive is stronger & cheaper.

---

hmmmm one thing on that though

it would get wasted by a horizontal spinner if it was on the ends aswell its a hazard of drum bots plain and simple
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

OK, I forgot that one , name another... I think from the Falcon built pages that the drum is one piece and they lathed some grooves for the belts, Wayde's CAD makes the drum look like its in sections, which would make it weaker and more flexible in the middle. A third bearing in that area wouldbe in order IMHO.

I was thinking that if your drum motor is smaller than your drum, you have the option of running inverted. Its handy to have that option with Stealth & El Bravo around!

I overlooked that the armour is fibreglass - much easier to work those shapes in resin. The sharp edge on the front corner is going to take a pounding from horizontal spinners though; you had better reinforce it well.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

yeah as i said it is an out dated design and i might not be invertable but hopefully will be putting in a selfwrighting mech

the only way im gonna know how it goes is to build it and test it
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

ok i went down to edcon steel and got my first 2 bearing blocks and asked for the 3rd one to be 30mm thick (i ended up with 3 that are 15mm thick) no biggy meens i have a spare should anything happen to one of em. i also got the first 2 teath (stupid me forgot to write down that i needed 4 lengths so SABAH!!!! i got em home cause i wasnt thinking about what i was carying and when i got home it dawned on me DOH!!! so i quickly rushed back down to get 2 more teeth and the 30mm cap to find that they had closed DOH!!!x2 so my next day off that their open i will get the other 2 teeth and the last cap

now i couldent get the caps in the right size being 48mm so i had to get them in 50mm no massive drama's just meens i gotta ask jake realy realy nicely to lathe them down and i also noticed that the teeth are well lets just say they dont match (one end there is a 1.5mm overhang from the one that is the right size and at the other end there is a 3mm overhang from the one that is the right size :S) next time im going to ask them to get it right and just explain to them the effects something will have when its not balanced spinning at high speeds. i might have to get jake and russel to cut off the excess with their nifty band saw

but untill i get all the parts its staying put
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

ok spent some time in cad with what i have at the moment and im thinking that it looks ok so far i even worked out how to cad a nyloc nut so yay i have nyloc's on file im still baffeled as to how you make the threads on screws and on the inside of nuts and things byt meh its iconic and in reasonable detail too so im happy i will upload some cads of it on the morow if i got time if not then tomorow night or friday when ever :)but yeha everything on this cad is mesured and exact to the best of my ability with the tools i have though somethings seem slightly larger than they should might just be the angle dont know either way
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

Don't worry about making helical cuts to repesent threads in 3D models. If you start adding too many you will slow your computer down real fast.

Heya Wayde,

Dru design looks super phat and best of luck with it and hope all goes well dude.

One thing that sprang to mind was nicks comment over how large moor was in comparison to the drum which got me to thinking and although youllstill gofor the ev warrior just an idea for down the track or whatever.

I got to thinking about vertical limits how it was able to spin its large 3kg disc upto a reasonable speed with one or two of those small but really cool mini ev's/300 watt compressor motors. I think if u have two of them either both powering one puley into middle of drum transmition idea of have 1 mni ev and belt and pulley at each end of drum u will have a very powerful drum weopon that with right gearing upto soe awesome speeds and stuff, just the thing is youll have to run it at 12 or maybe 18 volts tops as the planners tried this and although when testing very powerful the batteries got hot damn near instantly and desoldered themselves .

But yeah just an idea as when looking at Vl and chatting with Andrew last event and looking at the motors if i was making a robot with a smaller spinnig weopon or something likeyours id prob go 1 mini ev etc persde of drum at 18 volts.

ANyway's, just a thought and im gonna have to agree wth everybody else with having a pulley at end of teh drum and stuff, just alot easier to make and been proven better.

Also just got back from walking the dog and found two ev warrios in my leterbox, one for me, one for u (if u still want it).

THANX TIMMEH
_________________
Andrew Welch, Team Unconventional Robotics

i think the pulley sunken into the middle of the drum would work better myself, and if you have do like the planners or aaron and use some stupidly thick bit of pipe (which i think you are) then just if you get some time on a lathe its no problem to cut a slot into the middle for the belt.

if you can get an ev warrior i say go for it, if you put the drum first, the motor behind it then the drives behind that then you could still make it invertible... IIRC the ev isnt a huge deal taller than a red wheel.

and forget the threads on the cads, they double the file size and in rhino they just look straight out crap in renders.
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

If you are tight for room and want to use an ev for power i would sugest a puly in the center of the drum and use the ev at a 90 degree angle to the drum shaft and use a twist belt configuration .You would need to use the motor its self on some sort of adjustable slide to tensoin the belt as you couldnt us a back breaker tensoiner . but it would work. The main thing to get right for alinghnment is where the center lines on the pulleys would meet if you were to draw it on paper ...its hard to explain in writeing .This system has been used sucessfully in all sorts or small engine powered garden equipment and even high powered machines before hydraulics took over .

yeah i think i know what your saying i will try and etchy sketchy something up in rhino to see if its right but that will have to wait till tomorow night, ofcourse i want that ev if you bring it on sunday if we gonna have a build meet then aswell i will bring ya some monnies just lemmi know how much. i thought of mini ev's i will probably keep it in mind for the next version if i make one as for wheels im planning on using something a little bigger than redwheels

any way more cads are here as i said they would be

Drum front view



Drum angled view



Drum with teeth taken off



hmmmm has any one got a cad of an ev in mm i can download saves me cadding it myself (will check the cads thread first )
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix

it dosent matter what units its in rhino will convert it for you
otherwise just scale it yourself
_________________
Mechanical engineers build weapons, civil engineers build targets

yeah i still think glen is using some funky mesurement either that or the "save as small" feature cause all of his rhino files are frikking tiny and need manual rescaling and i have nfi if its scaled properly
_________________
as a shadow is seen and not heard i am here
-Waddy the phoenix