Magnets

[Max]

Hi,
I have a spare kilo in my drum spinner so have thought about adding some neodymium magnets, I know other people have used magnets so have some questions,
1) what strength of magnets do people use, I've seen from less than a gram to over 85kg!
2) what problems do people have with magnets near electronics and motors?
3) what problems so people have with sticking to other steel robots?
4) do the magnets make it hard for a drill motor powered robot to move around the arena? Does it affect handling acceleration top speed etc. ?
Thanks

[typhoon_driver]

Re: Magnets

With drills I wouldn't bother. You will be putting them under a fair bit of stress basically asking them to move a middleweight around if you go for a decent sized magnet plus with it being a drum there is no point as impacts push you into the ground anyway

[Max]

Re: Magnets

But web the drum is inverted it will be pushing me up won't it? After looking at YouTube videos of nst I also thought my horizontal bar spinner could do with some magnets looking at the number of times NST flew out the arena after a hit with it's blade

[xtreme]

Re: Magnets

no point if your using drill motors mate, and the only reason you would want them in a drum spinner is if you have gyro problems and want to be able to spin your drum full speed and still keep the robot stable.

[psychostorm]

Re: Magnets

Hi,
I have a spare kilo in my drum spinner so have thought about adding some neodymium magnets, I know other people have used magnets so have some questions,
1) what strength of magnets do people use, I've seen from less than a gram to over 85kg!
2) what problems do people have with magnets near electronics and motors?
3) what problems so people have with sticking to other steel robots?
4) do the magnets make it hard for a drill motor powered robot to move around the arena? Does it affect handling acceleration top speed etc. ?

Ok, for the record I'm with Gary. Don't bother. Health & Safety nightmare for a start.
1) 540's downward force is about 35kg. However, roughly speaking, the drive would have to move said added weight on top of it's own. Also the majority of the force used to throw your machine will stay in your machine, possibly damaging it further.
2) Not had any so far but it can potentially block radio reception & ruin non contact current limiting. You can shield for this but more hassle.
3)No example so far. I'm quite keen to see how that fits in with the rules...
4)Oh god yes. All of the above goes downhill with the more force applied. 540 was designed with it's magnets in mind & the motors still caught fire.

[PJ-27]

Re: Magnets

I think Invictus is one of our qualifiers...

Magnets are a great idea Max! But the later in the build you put them in the better.....

[psychostorm]

Re: Magnets

I think Invictus is one of our qualifiers...

Magnets are a great idea Max! But the later in the build you put them in the better.....

Not before I'm fighting Centrifuge. I may get to see that judges decision first hand! Kaizer is gaining steel forks so I may need Bitza to seperate.

[Max]

Re: Magnets

What if I reduced to 75mm wheels then do you think I could have magnets?? I found a set of 5 magnets each with a pull of 5kg so I could get those and expirment with how many I could put on?
On an unrelated subject what charge rate can I use on 12v 2300mah nicds

[Mouldy]

Re: Magnets

The above comments about magnetic force means your moving extra weight isn't strictly true...

In 540 on a steel floor, pushing the robot along by hand is no different to pushing it along without the magnets in place... Just make sure you position them on the centre line of your wheels and you'll be fine...

Also remember if a magnets rated to hold 50kg.... Thats probably true... If its stuck directly to a sheet of steel.... In a robot it isn't...

540's magnet is 50x50x25 neodymium... 5mm g/c + 1mm of titanium =6mm away from the floor.... The magnet was advertised as having 180kg of pull... After the above mentioned gap it probably gives around 20-30kg of down force...

Ceri - those dewalts blew up without the magnet in place.

[harry hills]

Re: Magnets

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

[Max]

Re: Magnets

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]

Re: Magnets

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]

Re: Magnets

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]

Re: Magnets

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]

Re: Magnets

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...