Featherweight advice

[billy breach]

Well, after looking at a few bots on the net and all the new equipment available i've decided to make a bot, 2wd drive with a flipper or lifter, maybe a low pressure flipper system. However I would value anyones opinion of the following:

1.I was thinking of the base plate to be made of 3mm aluminium plate, for which I could attach my mounts and fittings onto.With all the bots being so advanced now will 3mm be enough for the base or am I needing 5 or 6mm?

2. I see that 2.4ghz transmitters are all the go now...has anyone ever used this? type or would you suggest another make or type. I used to own JR and Futaba gear but thats very expensive in 2.4ghz.

http://cgi.ebay.co.uk/Turnigy-9Ch-Trans ... 4cf816b6b2

3. 12V Drill motors and blue wheels seem to the rage at the moment however I think sealed lead bateries are out....what about lipo?s if so anyone suggest a volatge ( I would run 12v motors on 18v with nimhs or nicad but what about lipo's?)

4. Speed controllers from what I remember used to be made out of switches and servos.....but they are a few on the market now anyone suggest a good type to get when using lipo batterys


I value any suggestions or comments
thanks
billy

[Mouldy]

Re: Featherweight advice

Hi, welcome to the forum!

Most people use spektrum RC gear these days... its kind of become the standard due to the fact that they failsafe on all channels mostly (you will need failsafe capability to pass the tech check)....

A tech check is an MOT for a robot that gets carried out before any event begins.

I use/ have used the following;

DX3, DX3R, DX5, DX6, DX7...

All of them are good.. some cheaper then others... ive seen second hand DX6 sets go for £40 on ebay and DX3's go for around £20 But if you want a brand new TX DX5's are good and easy to use...the DX3R i use on 360 still retails at over £200 though... so do DX7's... just shop around.

Lipos;

you'd probably want to go for a a 5S pack if your aiming for 18v.... 5s lipo = 18.5v

For more information on suggestions when using lipos see this thread;
viewtopic.php?f=111&t=4091&start=30

Chassis materials;
3mm ali would probably be fine for a baseplate... no point armoring area's more then needs be when its unlikely they will even get hit... just make sure your side/front/top armor is up to scratch. Can you weld etc?

Speed controllers (ESC) options;

Whats your budget?

[billy breach]

Re: Featherweight advice

HI Thanks for the reply.

Spectrum it is then. Stuff has really moved on (failsafe on each channel!!!!!!)

A budget...well don't really have one. If speed controllers that will be up to the job to handle lipos and the torgue from a drill motor are £50 or £100 each then thats the ones i'll need to get, just wont be buying everything at once. I suppose cheap is good specially if they are going to get smashed up but I won't cheap out just for the sake of it.

The spinners now adays are great! look as if no material will survive it, so 3mm aluminium base plate, 25 mm HDPE sides? with aluminium top? my design will be curved so i'll need stuff that bends easy'ish

[typhoon_driver]

Re: Featherweight advice

There are kits that allow you to convert 40meg gear to 2.4ghz. I used one on my futaba 6ex because it's a great transmitter and I didn't want to bin it. They cost around 25 quid tops. Don't have a link atm but I'll get you one later

[Anttazz]

Re: Featherweight advice

A Scorpion XL should do your 2 drills on 18v and you'd only need the one. Quite small too if your trying to squeeze everything in.

http://www.robotpower.com/products/scor ... _info.html

[billy breach]

Re: Featherweight advice

that would be cool thanks.

I was thinking something along the lines of this design

Thanks for the link to the speed controllers, they look good, how do you mount them? with some slight suspension to ease impact? or bolt straight onto a plate/base?

(it's very rough just to give you an idea, big scoop on the front to hopefully take blows of spinners etc), curved to roll when flipped.

[Anttazz]

Re: Featherweight advice

On my bot, I mounted them by just screwing them into one of the nylon bulkheads. I now use an XXL and its in a plastic case but its packed in with stuff to stop it moving but gives it very slight play to move as the robot is thrown about, stops a lot of stress on the wires, thanks go to Craig for that one

[Max]

Re: Featherweight advice

I havn't built a flipper but have heard that for a first build they are very complicated, expensive and dangerous. Most people start off by building a simple rambot or wedge then go on to greater things. I have also heard that it is hard to get a full pneumatic system inside the feather weight weight category, and that you will have to get parts like the ram made specially.

[typhoon_driver]

Re: Featherweight advice

Depends entirely on your own circumstances and experience for pneumatics. A low pressure system can be built from off the shelf parts.

[billy breach]

Re: Featherweight advice

I was thinking of using a low pressure system, not a full pressure system. That way I can build and buy parts.

I was thinking of using a car compresser for blowing up tyres (the heavy duty type for blowing up 4x4's etc) and a buffer tank maybe a dry powder fire extinguisher or tubes rolled up to great a buffer tank. Does anyone know or if anyone still does this method? and any idea who can make a T- joint type of fitting that will thread onto my lower pressure buffer tank (dry powder fire extting?) onto a standard 10mm low pressure (10 bar I think) tube?

Thanks
Billy

[typhoon_driver]

Re: Featherweight advice

As far as I'm aware there are no featherweights that use this method anymore (at least there weren't at the last 3 champs). Yet another very old school method

The best way to build a low pressure system is to use a standard high pressure container attached to a regulator. I believe trevor regulators are the standard these days although I'm sure one of the pneumatics guys can fill in this detail.

For fittings, http://www.technobotsonline.com/pneumat ... -fits.html

[billy breach]

Re: Featherweight advice

HAHAHA looks like mine will be something from WW1 then hahahah. Thanks For the replies and the link to the technobots site, will have a look through the products and see whats available.

[terry]

Re: Featherweight advice

If you want to see a pic of a dry powder bottle with adaptor to 10mm push fit pipe there is some on my robot website.

www.toxicrobot.co.uk

its in the toxic1 tab, there is a good pic.

[maddox10]

Re: Featherweight advice

I was thinking of using a low pressure system, not a full pressure system. That way I can build and buy parts.

I was thinking of using a car compresser for blowing up tyres (the heavy duty type for blowing up 4x4's etc)

Basic formula. Flow*pressure/500= Kw needed. A car-compressor has following limitations. 12V 30A =car fuse on the sigaret lighter. This means at best 360Watts to the motor.
The cheap build robs 35%, and that will translate in pure heat. Leaving 260W peak for the compressor.

Max pressure for commercial-and easely available pneumatic parts 8 bar.
So 8*X/500=0.2 Kw
X= 0.2*500/8= 12.5L minute.
This means a 1 liter buffertank needs 38 seconds to get filled @8 bar.
In effect everybody that used the car-compressor idea in the past tried to get with a full buffer in the arena, and after the first shot, the compressor kept on draining the batteries.

and a buffer tank maybe a dry powder fire extinguisher or tubes rolled up to great a buffer tank. Does anyone know or if anyone still does this method?

A powder extinguisher as low pressure buffertank is seen more in the low pressure users, but those are rare, and most use other storage vessels as the car-extinguishers are rather big for a feather.

and any idea who can make a T- joint type of fitting that will thread onto my lower pressure buffer tank (dry powder fire extting?) onto a standard 10mm low pressure (10 bar I think) tube?

Yes. PM me.

[billy breach]

Re: Featherweight advice

thanks. PM'd