Build report - Stingray

ewan · Post by **ewan** » Sat Sep 02, 2006 2:55 pm

I've now decided upon my ant design and chosen that I will do my best to build an antweight version of the successful US heavyweight Sewer Snake.

True to the heavyweight design, I will make every attempt to make this thing 6wd (with some foam wheels painted a Sewer Snake trademark red - if I can find a suitable paint) complete with the lifter weapon. This may take a while to make - and chances are I won't be able to make AWS21, but hopefully it'll be worth it.

Picture of the heavyweight machine with old lifter design (I hope to be able to implement the new design with linkage to top-mounted turning-over arm as those of you who've seen it will understand):

I'll try to post progress of this build as and when it happens!

ewan · Post by **ewan** » Sat Sep 09, 2006 8:20 pm

I've begun designing with a scale diagram taking in all of the parts that I currently intend to use. I've stuck a 300mah li-po battery in there for now as (if I can afford the weight and space) a nice long run time would be rather conveniant. Space is a no.1 problem at the moment, mainly considering the squeeze of fitting the internals in a ~20mm body height.

I've yet to come across a suitable transmission solution - belts must be the way to go I'm thinking but I may have to get some custom pulleys lathed and use rubber bands for the space available! Any ideas for this would be very much appreciated!

Flippt · Post by **Flippt** » Sat Sep 09, 2006 8:28 pm

Well it lookes great Ewan, but dont you think 11V 300mAh is a way above? Some ants use only 7.2V - 8.4V 145-250mAh, which take alot less space. I dont know how you thought about it, but I think you need to include all the wires! They take alot of room, even if you dont think so.

EpicentrE · Post by **EpicentrE** » Sat Sep 09, 2006 8:55 pm

2x Sanyos on 12v and a servo on 5/6v will run fine off a 3-cell 145 pack. I only suggested bigger because I thought you were going for 4-motor drive, even then I would suggest 250 cells, not 300's. about transmission, Marco used some small pulleys with elastic bands in one of his bots, seemed to work perfectly well.

ewan · Post by **ewan** » Sat Sep 09, 2006 9:40 pm

Hmmm, maybe I shall size down the battery if only to accomodate a little more room for stuff up front.

Heres a second diagram with smaller battery and revised metal geared lifter servo mounted to one of the side bulkheads (only slightly different in size, more torque).

I'm pretty confident that I'll get away with some cleverly placed tight bends and micro-gauge cables for the wiring.

I haven't done any weight calculations yet (!) but I'm pretty sure in its current state i'll have a decent enough weight left over for armour and the lifting scoop mechanism.

Simon Windisch · Post by **Simon Windisch** » Sat Sep 09, 2006 10:19 pm

My robot Dynamite http://windisch.co.uk/robots/dynamite/d ... 060622.htm is similarish to your design.

I just made 150g with four Sanyo copy motors, although I had to use less armour than with true Sanyo's because the copies weigh a little more.

I would estimate you'll weigh 180-200g if you plan on having a lifter as well as 6 motors plus board, battery and receiver, but I'm happy to be proved wrong. Good luck anyway.

Simon

Edit: I've just re-read your post, and spotted that you're probably going to use two motors and belt drives, so you'll save 38g on motors, plus a little bit back for the belts and pulleys. Your foam wheels may also be lighter than my lego ones. It looks like an interesting project. Good luck anyway.

P.S. I recommend you work out your weights before you start spending, you might have to make some compromises.

You're also going to have to be careful that your body is thinner than your 25-30mm diameter wheels, or your won't be able to run both ways up. You'll also need to make sure that you mount the wheels centrally, especially as you're planning on having the control board above some other components.

EpicentrE · Post by **EpicentrE** » Sat Sep 09, 2006 10:28 pm

Simon, its only 2 motors, with drive through belts and pulleys. complicated for a first design but I couldn't convince him otherwise

Basically same component set as Void for example, with the exception that I use Scorp minis instead of barello's, and the servo will probably be different, and in Void I have more than enough weight for the chassis/armour etc, and I havn't weightsaved anywhere (excluding the wheels because they were weightsaved already).

Edit: Simon just re-read his own post and realised his mistake. I reply far too fast

Simon Windisch · Post by **Simon Windisch** » Sat Sep 09, 2006 10:32 pm

Cheers Scott

Simon Windisch · Post by **Simon Windisch** » Sat Sep 09, 2006 10:36 pm

Oh, one more thing. I think that those motors take several amps, so don't make the wires too thin, or they'll overheat. My motors get pretty hot anyway... and try to minimise the wiring runs, or you're like to get interference.

Simon

ewan · Post by **ewan** » Sat Sep 09, 2006 10:44 pm

I'm just realising how like featherweights my one will be - simpler I'd say

hehe, I think I've got this design sussed