Boring Brick

[mrsam]

So i was watching Series 6 of RW back through and after seeing Supernova again i've decided i really like the design, so i'm putting it to the vote as to which spinner i build. If you like the vertical design i posted then vote for that, if you like the following design then vote for it. Imagine it with bigger wheels and a lipo, design would be a lot like this.

[mrsam]

Caldercrafts it is then for now, i can't see them being massively underpowered as a drive system especially seeing as i'll be running them on 6s. Thanks again to everyone for their input.

[Ellis]

It's likely the caldercraft motors will work better than low speed sensorless brushless. Possibly by quite a lot in terms of control finesse. Nobody has fully cracked sensorless brushless drive, and those who are getting there have high (2 stage) reductions and faster motors. Also, you can probably heavily overvolt the caldercrafts, being such big cans they should dissipate heat quite well.

[mrsam]

Cheers for the advice guys, still not sure how to play it at the moment though. The adaptor plates for the brushless motors is tempting but possibly just to keep things simple for now i could buy a few of the Caldercraft motors and upgrade to brushless at a later date.

[Eventorizon]

Well, one 775 then, but you would need another stage it seems to make the drive match or exceed the Speed 900's.

[Ellis]

You wouldn't need two. 18v 775s have superior power and torque figures than speed 900s at 12v. Once you've put a 775 through double the reduction, on paper, they outperform an overvolted speed 900.

[Eventorizon]

You could go mad and go for 2 RS775 motors per side. Provided they are set up right, that would be a very punchy set up!

You can get them from Banebots, Robot Marketplace and ebay:

http://banebots.com/pc/MOTOR-BRUSH/M7-RS775-18

http://www.robotmarketplace.com/products/0-TRA5675.html

http://www.ebay.co.uk/itm/Traxxas-Ti...0-TRA5675.html

[mrsam]

That sounds great mario I'll pm you

[maddox10]

I do have lasercut adaptorplates that should make it possible to mount 42 or 50mm NTM outrunners were a speed 900 fitted.

[Eventorizon]

I know its not what you will want to hear but building a machine around a part that is no longer in production is a bad idea. Spares will be impossible eventually and it will put the whole machine out of action. Look at brushless drive motors that have the same mounts or go for something totally different, Speed 900's are gone.

[Ellis]

I'm not sure you can trust that to be accurate. It was the info on the selling page on pollin being misleading (they called the RPM at maximum power the no-load speed, which was actually 100% higher) that screwed me up with the motors for Rango. The datasheets on the selling pages often show the true figures direct from Johnson, but in the case of the lower revving motor, there is no datasheet available. No useful google results either. It might well be very low power; low RPM brushed motors are often mild, the popular s900 model was an exception.

That said, regardless of power output, that output shaft is weird as hell. I don't know if it can be removed/cut down, but even if it can be the shaft beneath is probably awkward.

The other model, at 17k no load, will need two stages of reduction. And having "racing" in the name suggests it's timed to be more powerful in one direction which would be a pain.

Sadly very little comes close to the s900.

[mrsam]

I actually had a second look, the first motor i put up is rated for 2060rpm at 12v, might still be worth trying one of those out?

[mrsam]

I did see the Caldercraft ones but i hadn't heard great things and at £60 a pair i didn't want to spend that and have them be rubbish, maybe i'll buy one and see how it goes though.

[adz600]

look for caldercraft on ebay I have two I was going to use on the axe but were not powerful enough but will proably make a great drive system

[adz600]

rpm is well to high