Torque required for hammer to self right?

[RogueTwoRobots]

I think we both use 18V drill motors, slightly larger than the standard ones you get from the likes of Argos and a little tougher. You can still use 12V motors on a higher voltage if your radio transmitter has a feature called dual rates. This allows you to set a lower limit for the drive motors so that they don't get the full voltage and risk being burnt out.

[Coolspeedbot]

I think we both use 18V drill motors, slightly larger than the standard ones you get from the likes of Argos and a little tougher. You can still use 12V motors on a higher voltage if your radio transmitter has a feature called dual rates. This allows you to set a lower limit for the drive motors so that they don't get the full voltage and risk being burnt out.

I'm thinking of using my Spektrum DX5e, but I don't think it has that dual rates feature.
and as I can't afford to waste money I'll use 12v motors and a 18v battery for my ram bot and use 18v motors and 22.2v battery for my axe bot (most likely a upgrade on the ram bot)

[mrsam]

IIRC me and Jamie both use 18v drills that have 600 sized motors (slightly larger than the standard 550 sized you'll get in your bog standard argos drill), i do run both my axe and drive on 22.2v but i reduce the rates on my drive to try and make my motors not dead.

A dx5e doesn't have dual rates unfortunately, there is a switch you can flick to reduce the rates to 50% but that's not really useful in a combat robot.

[Coolspeedbot]

IIRC me and Jamie both use 18v drills that have 600 sized motors (slightly larger than the standard 550 sized you'll get in your bog standard argos drill), i do run both my axe and drive on 22.2v but i reduce the rates on my drive to try and make my motors not dead.

A dx5e doesn't have dual rates unfortunately, there is a switch you can flick to reduce the rates to 50% but that's not really useful in a combat robot.

I see I'll have to make a note of that, do you know a transmitter that does this dual rates?

[Eventorizon]

You would need one of the newer digital transmitters to get anything other than the 50% dual rate switch.

The cheapest I know of is the new Spektrum DX6 at £130. It seems a lot to buy that for just 1 feature but actually it provides a load of additional settings that can make driving much easier. I've only scratched the surface myself but at GSL this year Hatchet was put on the new DX6 and went from being crazy to drive to being downright amazing with about an 30 minutes of tweaking.

I believe it was set up to have 90% forwards on the axe, with just 40% return so it wouldn't waste power or jump around to much. Turning was similarly tuned to be slower but forwards was left at 100% so that it could slam its opponents into the wall.

Its a tad off subject but I would recommend the DX6 despite its price. It can store up to 250 models (Wow.. I was expecting 50 at most) so it can be used on every robot you ever build at the same time and each one can have custom settings to make it suit your driving style, optimise its weapons and control anything from Robots and RC cars to drones and Helicopters.

[Coolspeedbot]

I was looking at Spektrum DX6i the other day as a replacement for my DX5e as it's being used on my ant weight Killer-Wolf and binding would be a pain in the butt.

[joey_picus]

You would need one of the newer digital transmitters to get anything other than the 50% dual rate switch.

This isn't necessarily true - a lot of older transmitters have separate controls for enabling the dual rates and then the amount of dual rate (if that's the correct term) to use, both of my old Futaba transmitters have that system. It works better for me than having to go through menus, but then my preferences are always a bit odd!

The main use I have for dual rates is to reduce turning rate when driving the robot - with mixing, you can turn the rates on the aileron channel down to about 20-40% and that way have full power available for forwards and backwards, but not have the robot spin around like a loon on a carousel with a small sideways movement on the stick. It comes down to personal preference, largely, but they're a good option to have.

(out of interest, James, it's looking like the next AWS will be in Surrey or thereabouts - would that interest you?)

[Coolspeedbot]

Oh sounds like what happened when my dad built a robot in Robot Wars arenas of destruction.

(as for the AWS, Surrey should be ok for my step-dad to drive me there, but depends when it is taking place though)

[Graw]

something like this?

http://www.ebay.co.uk/itm/24-VOLT-30...AAAOSwBLlVcco6

Just out of interest, what sort of difference in power could you get from one of these (http://www.robotmarketplace.com/products/0-A28-150.html) in comparison to a scooter motor for an axe? Just looking at all my options.

[daveimi]

One of those you mentioned is a bit more than double a meaty scooter motor.

[Graw]

One of those you mentioned is a bit more than double a meaty scooter motor.

Cheers for the reply.. how about that motor in comparison to a co2 rack and pinion set up? Could it achieve top end axe power in a feather like little hitter for example? Speaking of that does anyone know the ins and outs of little hitters set up, ram size and what sort of bar it runs ect.

Edit : Just found this https://www.align-trex.co.uk/800mx-b...tor-520kv.html which is much more powerful than ampflow. Cheaper and lighter as well, surely that could match top end co2 power with the right motor to axe sprocket ratio?

[daveimi]

A long story short the motor you linked is the wrong type of motor for what your trying to do. You need a low rpm high torque motor like you mentioned originally.

You get a hell of a kick from a big motor, but gas rams give a lot more explosive power. A lot of the heavyweight hammers switched to gas powered rams as the constant shocks kept damaging the big lecky motors they were using.

[Graw]

Ah right makes sense, I should have looked into that.

I was going ask about the damaging your own motor I assume electric axes must need plenty of spares lol. Looks like I'll be going down the gas route then, I was considering going electric for a couple reasons the main really being its surely much less hassle than gas and im planning to have a almost 2kg hammer head which would of been decent with an electric motor throwing it over 180 degrees as I figure the heavier head with a motor throwing it the better.

I was going to make my own thread but im sure all of my questions have been asked before so I've done a far bit of searching and reading up.

Thanks for your help

[daveimi]

Feather axes don't have much of a problem, it's more the heavyweight axes as the forces involved are a lot higher but the motor technology the same. So it's the same resins holding magnets in place, same materials bearings are made of etc. For some reason electric axes never seemed to scale up well, but some of the feather electric axes have been really reliable.

A lot of the big heavyweight axes (thor, team hurtz etc.) have tried electric power and moved over to gas as it never seemed to scale up as well.

In the same way, gas powered featherweight axes are rare as the technology is hard to get in weight, but at heavyweight a lot of the same regs n valving is used so the weight isn't so much an issue. I've never built an axe, can only comment on seeing the experience of others etc.

[Graw]

Gotcha, I guess it makes sense really with the weight difference between a feather and a heavy everything is going to be strained that much more at 100kgs. Thats interesting I never realised thor had run a electric set up, terrorhurtz is the main inspiration behind what im planning as im sure many others before me - am I right in thinking john reid was the first to come up with the rack and pinion method? So simple but so effective.

I have been wondering about weight, specifically when it comes to weighing a robot that uses gas I assume its weighed with the bottle full? I have a standard 12oz paintball tank that im going to use, if anyone knows roughly what one weighs when full?

I may as well start my own thread at this rate lol