Pulverizer Build Diary

[Mega Masher]

Re: Pulverizer Build Diary

Would two of these be ok?
http://www.scorpionsystem.com/catalog/m ... 4015-1450/

[archie2000]

Re: Pulverizer Build Diary

the kv of a motor is like RPM per VOLT.
in this case we have 1450K/V
if you run this on 20v (to make the maths easy)
you will get 29,000 RPM
which is quite a lot.
Say you run this on some 5inch wheels (to keep the maths easy)
you get 455530 inches per minuite.
Is it just me or is that about 432 miles per hour.
The maths is probably completley wrong but the message is.
Thats WWAAYY toooo fast.
Im not quite sure what you should aim for as an rpm.
Also bear this in mind.
speed can be changed by gears.
simple.
However gearing systems can be quite expensive and be huge and weigh tons.

Tips
If there is something that possesses you to waste money on a brushless drive get a low kv one
Also if you are in the states can you just edit your location to say U.S.A or someting.
We can probably link you some parts from america in $ for the future.

WOW thats a long post.
Good luck with the build anyway

[Ellis]

Re: Pulverizer Build Diary

In any case, you will need gearing. Unless you have an absolutely huge motor and small wheels a featherweight scale machine won't even move without some sort of reduction.

[typhoon_driver]

Re: Pulverizer Build Diary

Ignore brushless for this application. It's not as simple as turning on and off a mosfet as with a dc motor. They also don't like being stalled or turned on and off quickly. Either on full or off for brushless. You have to remember you can't just hook them straight up to a battery to get them to work.

Stick to brushed motors for a melty brained machine

[Mega Masher]

Re: Pulverizer Build Diary

Thanks for the replies, yes i was planning to use a gear box.
Typhoon Driver, if it HAS to be brushed, then which brushed motor do you suggest.
Archie2000, brushless is not a waste of money and i don't live in the USA.

[typhoon_driver]

Re: Pulverizer Build Diary

Are we looking at feather or beetle?

[Mega Masher]

Re: Pulverizer Build Diary

This is my beetleweight:


And the scorpion motors would be for my featherweight. I will plan to use 75mm Robochallenge wheels, a gearbox made by erm...me, and it will be controlled by an Arduino Uno and an Arduino Proto board onto which i will solder my own motor control circuit. I know you keep saying to go brushed, but only 2 brushed motors i know of will do the job: ampflow motor (too big and expensive), and 2 Astroflight 40 cobalt motors (extremely expensive). If you have any ideas of any brushed motors, please tell me.

[Eventorizon]

Re: Pulverizer Build Diary

Speed 900's might do it. However they are no longer in production. People have been seeking out alternatives and have found some that are pretty much identical. I don't know what they are called but the only S900's were dam good for their size and not ridiculously expensive either at £35 each. There is a thread somewhere called speed 900's alternatives but I cant find at atm.

[Max]

Re: Pulverizer Build Diary

viewtopic.php?p=138153
There is a topic on using brushless for drive- I don't know what ever came of the idea.
I imagine you would struggle to break and accelerate and control a brushless motor fast enough for a melty brain robot and you will probably spend a fortune on gearing it down.
If you do go for brushless then you want a very large gear ratio so the motors can spin at maximum rpm easily and so draw little current- you don't want them under high strain.
It could be a possibly to connect 2 motors together but that also has its problems, for instance 2 gimson motors per wheel

[typhoon_driver]

Re: Pulverizer Build Diary

And you are able to control a 3 phase motor?

http://www.active-robots.com/motors-whe ... 0-150.html

Or if you want a really powerful cheap motor then look at something like motorcycle starter motors. Although these will draw large currents.

[sam_smith]

Re: Pulverizer Build Diary

You might consider the Dewalt 24v brushed motor. Good power, cheap and proven on the battlefield.

[Mega Masher]

Re: Pulverizer Build Diary

Sam, is that the motor you used to power NST's bar?
If so then i will look into that. Where did you get yours from?
Just found it on robot market place, and it looks ideal. Would i need a gearbox?
Sorry for all the questions and thanks for the suggestions.

[typhoon_driver]

Re: Pulverizer Build Diary

Yes you will need a gearbox. You can also purchase those on RBMP

[maddox10]

Re: Pulverizer Build Diary

Just found it on robot market place, and it looks ideal.

It's one of the best brushed motors around, maybe that some high end brushed RC motors can push more power, but you'll pay a premium then.

Would i need a gearbox?

Yes. Even if only to protect the motor from the full brunt of the hits. The motoraxle is rather slim compared to what we see as needed on disks and drums.

[grant_ploughbot]

Re: Pulverizer Build Diary

I think these are the drills with those good motor's/gearboxes that NST uses.
http://www.ebay.co.uk/itm/2x-dewalt-24v ... 4171782033
They occasionally come up very cheap on ebay.