Have I made an error.

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skadder
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Have I made an error.

Post by skadder » Mon Aug 13, 2007 4:37 pm

My son (12) wanted to get into robot building, so I decided to help. However, I have no experience with RC or electronics, so I did some research. I bought:

Barello ant 150 speed controller
two copal 60:1 motors
Technobots 40mhz tx and Rx (12g)
7.2v lipoly 800mah plus charger etc.
Flightlite 2" wheels plus hubs
2mm polycarbonate

(I have ordered a 11.2v lipoly 300mah that weighs 30g but currently don't have the charger for it! My current charger only charges as low as 0.8)

Plus other stuff like multimeter and soldering kit.

I have rigged the bot stuff together on a bit of plastic using ziplocks (or whatever they are called -- plastic trips that when you pull'em tight they lock). It works and drives pretty niftly -- it wouldn't push a brick up an incline though!

My problem is I am already at 170g and have no armour! Also my wheels with hubs and motors attached are 3" long so two of them are 6". They only way round this is to have the motors offset-- one infront of the other -- bit that seems to lack elegance! Any solutions would be great!

Especially where I can save weight.

Adam[/img]

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BeligerAnt
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Post by BeligerAnt » Mon Aug 13, 2007 6:43 pm

Hi Adam and welcome to the forum!

I assume you are in the UK and building to the UK antweight rules (4" cube and 150g) as you have arrived on this forum.

I think perhaps you went wrong in not understanding that US antweights are significantly bigger and heavier than the European variety - hence the size and weight of the Copal motors.

You don't need an 800mAh battery pack for an ant (unless you're planning a very powerful spinner). You can save a lot of weight by going down to 300mAh or so, which is plenty for 2 motors and a servo lifter. You will probably want more than one battery pack to last a competition though.

2mm polycarbonate is usable in ants, but 1mm is usually OK for a chassis if you put some bends in it to make it more rigid.

I'm not familiar with all the bits you list, if you could post the individual weights of each part we could advise where you can make the biggest savings.
Gary, Team BeligerAnt

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peterwaller
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Post by peterwaller » Mon Aug 13, 2007 6:49 pm

One of the problems with buying ant bits from the USA is that their ants weigh 3 times more than UK ants.
The copals weigh 25gms each so thats 1/3 of your total allowance. Over here we tend to use the Sanyo look alike motor gear boxes. These weigh only 9 gms each saving 32 gms and they are only 30mm long so they easily go in side by side. see http://www.precisionmicrodrives.com/pro ... ucts_id=94
They do a range of speeds and two voltages and I normally run the 3V ones from 8.4v (2cell LiPo they go faster and produce more power that way).
The 800 mah cells are bigger than necessary and must weigh about 45 gms. Try a 2 cell 300mah pack (16gms) to save weight. My robot defiant runs 4 of the 212-107 motors shown on the link page from a 2 cell 145mah pack weighing 9.1gms. So if you change the motors and battery you can save about 60gms giving you 40 grams for armour. If you cant afford the weight for armour all round concentrate on the front and hope you can keep it facing the opposition. Hope this is of some help and look forward to meeting you at an event someday.
Looks like Gary has beaten me too it while I was typing away.

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Simon Windisch
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Post by Simon Windisch » Mon Aug 13, 2007 7:02 pm

Hi Adam, and welcome

Come along and see us, we're all friendly, and happy to help, as I proved when I turned up to the last competition having left my robots behind - I got lent a robot to compete with.

There are plenty of resources for you to look at (including my own modest how tos) so keep building and see you soon.

Simon

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Post by EpicentrE » Mon Aug 13, 2007 9:52 pm

Welcome Adam, always nice to see newcomers :)

As Simon said, the best thing you can do is pop along to an event if you can! It's also obvious that you've done a fair bit of research already, which is admirable.

for a Lipo charger for smaller cells, I recommend the Graupner Lipo Charger 4, with the Ultrapower 12v 10a power supply to power it (if you don't already have one). This is probably the best value combo you can get (being that the charger is up to 4 cells and has a very wide charging range, it should suffice for any ants charging needs and be very future-proof). The only thing you need to do is replace the supplied crocodile clips on the charger with banana plugs to fit into the power supply.

About the width of the robot being too much, I assume when you talk about hubs you mean the robot combat aluminium hubs? these are unnecessarily large and heavy for a UK ant, and a much neater and lighter solution could most probably be found. It is possible to fit motors that wide into an antweight chassis, 2 options would be either making the wheels so that they doubled back over the motor. The other would depend on the size of the wheels, and this would be to put the robot into the cube diagonally along its front-to-back axis (meaning that the wheels were diagonally into the corner of the cube). This method depends on the size of your wheels though, as unless they are small enough, you will not gain any width from this method, or may even have less width to play around with.

Anticide is the only UK ant that I know of to use Copal gearmotors, and it fits in the cube by using the wheels doubling back method I mentioned above. Some pics can be found here: 1 2 3.

Hope this helps :) Feel free to ask any more questions, and I look forward to seeing you and your son at an event soon!

p.s. The 'ziplock' things you mentioned are called cable ties, and they are awesome :P
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

skadder
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Post by skadder » Tue Aug 14, 2007 10:57 am

Hey,

Thanks for the responses -- so any one interested in some barely used Copal 60:1 geared motors?!!!

The charger looks great, I will get that when my budget allows meanwhile I willl have to continue the R&D with the bits I have. How do you fix your custom made wheels to the motors? I was try to avoid gluing them as I reckoned a spinner would rip'em off easily.

When is the next event anyway? I am slightly nervous my investment is gonna get destroyed, so I definitely want the armour!

Adam

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peterwaller
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Post by peterwaller » Tue Aug 14, 2007 2:43 pm

I normally make my own wheels and use a grub screw to hold them to the shaft. The dates of the next events arn't quite finalised yet but it is looking like:
Reading Robot Club 13th Oct
AWS24 early to mid Nov
At the reading robot club we usually have speedway, football and nonspinner combat as well as full combat so you can enter three of the four without armour.
Even at the AWS there is normally a non spinner event as well but you would need to check with the organiser nearer the time. They will both appear in the Events section when finalised.

skadder
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Post by skadder » Wed Aug 15, 2007 5:18 pm

I altered how the hubs connect to the wheels and put the wheels on the diagonal and now I can get them in the 4" square --- Yeah!

I will have to shave a little off the outer edge of the wheels though.

Are the copals fast or torquey compare to what most people are using? I guess people using servos are getting more torque but are my bigger copals going to be an advantage over the much smaller sanyo clones?

Adam

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Simon Windisch
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Post by Simon Windisch » Wed Aug 15, 2007 6:11 pm

Because the robots are only 150g it's more down to grip than torque, if you see what I mean, and getting under the other robot, of course. Buy one of Pete's DVD of past AWSs from the shop, or check out some vids on youtube to see how we fight, and what works.

Simon

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peterwaller
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Post by peterwaller » Wed Aug 15, 2007 6:47 pm

They are generally more powerful than the sanyo look alikes but at three times the weight. As Simon says with such low weight robots the difficulty is getting traction with grippy tyres and getting under the opposition so you get weight off their tyres and reduce their grip. All of my robots use the sticky rubber from washable lint rollers from:
http://www.caraselledirect.com/zcart.mo ... le&PID=106
to increase traction. All of my robots have very low sharp edges or spikes to get under the opposition see.
http://i109.photobucket.com/albums/n66/ ... CF0310.jpg
http://i109.photobucket.com/albums/n66/ ... CF0308.jpg

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