Magnets

[Max]

Max, whats wrong with you?
you have a kilo to spare and you want MAGNETS over a bigger drum??
crazy :P

Too late for a bigger drum, already had my drum made and designed the robot around the drum I have, and I'm on holiday now an don't come back till Monday and have tons left to do so no time to make modifications to the drum!

[Max]

I've bought 50 rod magnets each with 2.5kg of pull, I will experiment with how many I can put on and what effect they have. I've been thinking about having lightpower springs/ hinges to keep contact with the ground to have more force, does that sound like a good idea?

[Mouldy]

I've bought 50 rod magnets each with 2.5kg of pull, I will experiment with how many I can put on and what effect they have. I've been thinking about having lightpower springs/ hinges to keep contact with the ground to have more force, does that sound like a good idea?

In a word.. no..

when you drive between arena floor sheets its not perfectly smooth...there is a ridge of around 2mm... the magnets will hit this ridge and probably chip/crack/shatter... same as if another robot goes underneath you... it will probably crack it.

Not only would this cause you the cost of having to replace them all the time... but it would also be very anoying for the EO and other competitors... bits of chipped magnet stuck all around the arena would be something for other competitors to become grounded on.

[Max]

Sorry I didn't explain it well, I meant have the magnets inside the robot on my steel base then have thin spring steel tabs underneath at an angle so they bend to keep a good contact with the ground.

[Mouldy]

If you have a steel base in your robot and your sticking your magnet directly to that... then you'd need a HUGE magnet to get anything out of it... as your base plate will eat up most of the magnetic force... Hence why ive got a titanium base (none magnetic)...

A picture speaks 1000 words...

[Max]

here you go:
[attachment=0:3utlwe0i]magnet diagram.jpg[/attachment:3utlwe0i]

I thought the steel base would help with the magnetism as it would become one big magnet but i guess it will spread the force out giving less concentrated pulling.

will it help it i dont have the magnets in contact with the steel? with my current plan the magnets would be above the steel base but if neccisary plans can change! (ie. go back to 100mm wheels to give enoigh ground clearance to mount the magnets underneath the robot and then not tell my dad he wasted his money on 75mm wheels)

[Mouldy]

(ie. go back to 100mm wheels to give enoigh ground clearance to mount the magnets underneath the robot and then not tell my dad he wasted his money on 75mm wheels)

Answer;

when you drive between arena floor sheets its not perfectly smooth...there is a ridge of around 2mm... the magnets will hit this ridge and probably chip/crack/shatter... same as if another robot goes underneath you... it will probably crack it.

Not only would this cause you the cost of having to replace them all the time... but it would also be very anoying for the EO and other competitors... bits of chipped magnet stuck all around the arena would be something for other competitors to become grounded on.

If you want magnets in your 2wd robot.... mount them on the centre line of the wheels... on a piece of none magnetic material... with a gap between the none magnetic material and the floor to a minimum of 4mm... any less and you will just ground your self out all the time.

If you dont mount the magnets in the centre line of your wheels... your robot wont drive very well...if at all.

Also... if your having two magnets... be very careful when handling them.

Edit;
Ive added a magnetic strength to distance calculator based on magnetic grade and dimentions to the useful links section of the forum here;

viewtopic.php?f=246&t=4906&start=15