New FW, can you help?

I have begun planning a featherweight, keeping it simple to be a two wheel drive passive robot, it may only compete in UK robotic Games.
We were thinking of using 2 of these motors:
http://www.technobots.co.uk/acatalog/Online_Catalogue_919D_Spur_Geared_Motor_230.htmlhttp://www.technobots.co.uk/acatalog...ared_Motor_230 .html
and gearing them at 11:1

And this speed controller
http://www.technobots.co.uk/cgi-bin/sh000002.pl?REFPAGE=http%3a%2f%2fwww%2etechnobots% 2eco%2euk%2facatalog%2fOnline_Catalogue_919D_Spur_ Geared_Motor_230%2ehtml&WD=controller%205a motor%20sabertooth%20dual&PN=Online_Catalogue_Dime nsion_Engineering_Controllers_34%2ehtml%23a1506_2d 003#a1506_2d003http://www.technobots.co.uk/cgi-bin/...%2fwww%2etechn obots%2eco%2euk%2facatalog%2fOnline_Catalogue_919D _Spur_Geared_Motor_230%2ehtml& WD=controller%205a motor%20sabertooth%20dual&PN=Online_Catalogue_Dime nsion_Eng ineering_Controllers_34%2ehtml%23a1506_2d003#a1506 _2d003

Would this work (with batteries of course, I will get around to them- can anyone reccomend suitable batteries for the motors?)?

(Message edited by Swim2win on July 23, 2008)

those motors are ok, but from where my pc brought the page up for the speedo it looks like you are on about the 5a sabertooth???

I would suggest that you go for the 10a one, but thats just one opinion

i have some similar motors to those that you are on about ill dig them out if you want??

You will want a nicad or nimh batt for that setup.

I have got a 12v 1200a nicad batt if you want it?

Hey Liam,

Good to see youre getting into featherweights - are you basing the design on any of your vapours at all? :)

Firstly, you may be hard pushed to find an upcoming UK Robotic Games event - they havent run since July 2006; 2007 unfortunately didnt go ahead due to lack of funding and there hasnt been any news on the event front for 2008 but since were now over halfway through the year I dont see any major UKRG events running this year. I dont blame the UKRG crew though as I can imagine securing enough funding each year to run their events without making a loss must be a tough challenge. Ive also just noticed their website is no longer up so its possible that the project has had to end due to unsustainability or perhaps the crew have moved on to other things. If this is the case, I applaud their efforts over the two years that it ran as it was at a time when I hadnt yet gotten into full-on featherweights so it gave me an opportunity to have some fun with my Rexs Challenge bot.
Of course, there are plenty of other events running over the country throughout the year for you to run your robot at :)

Motors: theyre fine for running a light robot but I personally feel, if just using two in a featherweight, they are an underpowered means of drive especially if your robot is weighing in at the full 13.6kg. But thats just my opinion on them; I would instead opt for a cheap pair of £10ea drill motors. They can then have cheap blue wheels from Robochallenge screwed directly onto the threaded shaft of the drill motor.

As for speed controllers, I dont know if the 5A one would work for the 919 geared motors, but if you opt for drill motors then its a definite no-no. At the very least Id go for the 10A one (its only £2 more expensive) or spend a bit more and get a pair of Electronize 15A controllers, or spend a little more again and go for a Sabretooth 25A or Scorpion XL. Whichever route you take, it wont be cheap so youre best spending that little bit more the first time and get something that will do the job and can be used in other robots rather than buying a slighty underpowered one then having to fork out more money when it breaks or you need higher specifications.

For batteries, if youre wanting to run on 12V, a simple Nimh pack of roughly 3700mAh will see you through a couple of battles before needing recharged.

http://cgi.ebay.co.uk/12v-NiMH-3700mAh-Rechargeable-Battery-Vapextech_W0QQitemZ220237656430QQihZ012QQcategoryZ 34063QQtcZphotoQQcmdZViewItemhttp://cgi.ebay.co.uk/12v-NiMH-3700m...ech_W0QQitemZ2 20237656430QQihZ012QQcategoryZ34063QQtcZphotoQQcmd ZViewItem

Get two packs, link them in parallel to get 7400mAh and that would probably last you an entire event. It all depends on what you can afford and how much weight youll have. But with a 2WD passive robot I dont see you being anywhere near 13.6kg, maybe 8-10kg max assuming you have Hardox armour

Best of luck Liam!

Thanks very much guys :)

I am very grateful for the offers of giving me these things, but I would rather you didnt go to the trouble because it is quite likely (given my last attempts:lame:) that this will never get off the ground, plus I live in Wales, so Im very far away from where most of the action is. I have the money to order most of the stuff anyway (seriously I was just unexpectedly left a large amount of cash), if I get into any money difficulties its time to break open my post office account:proud:

Thankyou very much for the advice though:)

Actually, if it is going to be very underweight Jamie am I right in saying there is a weight class for 6kg robots (Raptors)? If so, are these very unpopular? If they are I will try to add a lifting arm to this robot, but I was wondering then would I need to shell out for another receiver to work the arm?

Raptors are not an official class in this country, but at 6kg it is fine to put in with the feathers.

Aha, thanks

Back to the original plan we go! :)

Also Jamie, where can I find the blue Robo Challenge wheels? The website has a store, but it isnt up yet

(Message edited by Swim2win on July 23, 2008)

Just an email sent to James or Grant Cooper will do the job. Their email addresses are on their profile.

Most roboteers use 75mm or 100mm wheels - these both come with special nut inserts to allow them to be screwed straight onto a drills output shaft (or are available without the nut). Less common but still optional sizes are 63mm and 125mm. Again, as far as I am aware, these both come with the nut insert too

Liam, for a feather the best options are indeed either drillmotors or the 100 to 450 watt motor range from Technobots (such as the feather gold motor). For speed controller I would go for either a Scorpion XXL or a Sabretooth 25A.

Raptors have a different ruleset, they are not just 6kg feathers. Those weightclass robots should be referred to as Hobbyweights, not Raptors.

Hi Liam

I know you said early you didnt want to buy from us as you have funds already but i have some spare 75mm blue wheels lying around doing nothing, interested?? (btw i could post them to you in Wales:))

Also I can help out with the armour and lifter combo, if you need the help as psycho fling has a lifter on

let me know

ps.s any pics of designs for your bot? or havent you got them down on paper yet?

Alex if Liam dosnt want those wheels I will have them.

Dan.

Yeah Dan, its better if you have them, at least theyll definitely be used then

:)Thanks anyway though

Are you sure Liam?They were offered to you first mate.

Yup, you have a robot already, there is a VEEEEERY Big chance this one will never get going, and then those wheels would be wasted, its best I just buy my own

Email sent to Dan

OK Liam,good luck with your robot mate.

Drills can often be obtained from your local tip for a pound each. The Nicad battery packs go and peoople throw them away, even though the drill itself is still good. This has the advantage that it is a lot easier to cut up a drill you got out of skip for 50 p or a pound than a brand new one from Argos. Get a matched pair. Post here if you need help in getting the chuck off - you need to remove the chuck to expose a 3/8 threaded shaft - the blue wheels just screw on to that shaft.

Do you need 2 speede controllers for 2WD?

Yep, you need one speed controller for each side of your drive. So for 2WD, one speed controller for the left motor and one for the right. If you have 4WD, you still only need one speed controller per side (even though each side now contains two motors - just make sure your speed controller can handle the combined stall current of the motors)
And if you have three sides to your drive (the doom that is Triangulary-bot :)) youd need three speed controllers

There are also dual motor speed controllers like the Scorpion and Sabretooth that do 2 motors, left and right, so then you would need only one.