Magnets allowed?¿?

[Ryan M.]

Originally Posted by monsieurcoffee

What about regular magnets that you can pick up in a store (for w/e you wanted to use it for)? Just wondering, since that wouldn't be an electromagnet.

It would be almost impossible to find a magnet that could hold 130 lbs. for a reaonable cost.

Of course, if you've got money to burn, it doesn't matter does it?

[EStokely]

Originally Posted by Texan

It would be almost impossible to find a magnet that could hold 130 lbs. for a reaonable cost.

Of course, if you've got money to burn, it doesn't matter does it?

You could buy 4 magnets that each hold 35 pounds though.

I seem to recall a surplus catalog showing 100pound+ magnets at reasonible prices (under 50 bucks) of course I couldn't tell you the name of the catalog , thats lost in the buzz of too many catalogs.

I hadn't thought of magnets. But they could be used to help 'find' the bar when you aretrying to hook it.

[Rickertsen2]

Ohhh yes!!! I have a few. I have a pair of 1 1/4" neodymium disk magnets that have easily held me without a sweat.

Preferably you want NeFeB(aka neodymium or "rare earth") magnets with a second choice of SmCo. Ceramic and Alinco magnets are pretty much useless for this sort of thing.

All i can say is don't hurt yourself w/these things. Speaking from experience thye can cause some pretty bad injuries whrn they stick to stuff they're not suffosed to.
Suppliers:
http://www.wondermagnets.com/cgi-bin...manent_Magnets
http://www.allelectronics.com/cgi-bi...370&type=store

As far as isolating them from stuff that shouldn't be too much of a problem. Just put some thin steel sheet against all the unused surfaces and isolate that from the rest of the robot with some Aluminum or Plexi. I have never noticed a problem with RF interference either.

If you want an idea of the strength of neo magnets then bust open an old hardrive and it will contain some very small ones, which actuate the head assembly. (but not too old. If its a 3.5" then it will have them. any older and it may or may not.)

Instead of using them to attach to the bar, I see them as having greater applications moving goals. Simple: Powerful magnet + pnumatic detacher = easy goal dragger. This solves the problem of having nothing to grab onto. It also solves the problem or precisely aligning a mechanism w/ the goal.

[josh_johnson]

The problem with magnets is not that they can interfere with the radio modems, but that a changing magnetic field will create a current flow through wire I don't know how much current this would induce, but it could possibly be enough to mess with the pwm signals or other electronics of other robots. You may have to be careful to avoid this if you use a powerful magnet.

I found this website which has one magnet with 115 lbs. of holding force while weighing less than a pound for about $130. With a few of these, the hard part about hanging on the bar would be finding a way to release the robot at the end of the match.

[ShadowKnight]

magnets change the way that electrons move so that could possibly interfere with the radio signals as previosuly mentioned. It could also interfere with the function of other robots assuming that the magnet was that powerful...some thoughts to consider...

[Rickertsen2]

Originally Posted by josh_johnson

The problem with magnets is not that they can interfere with the radio modems, but that a changing magnetic field will create a current flow through wire I don't know how much current this would induce, but it could possibly be enough to mess with the pwm signals or other electronics of other robots. You may have to be careful to avoid this if you use a powerful magnet.

Even with VERY powerful magnets, it would be VERY difficult to induce enough voltage in anything to cause interference. It would take ALOT of gauss. and remember 1/x^2 rule. Anybody care to work out some Emag? Maxwell's equations Mmmmm...

[josh_johnson]

Originally Posted by Rickertsen2

Even with VERY powerful magnets, it would be VERY difficult to induce enough voltage in anything to cause interference. It would take ALOT of gauss. and remember 1/x^2 rule. Anybody care to work out some Emag? Maxwell's equations Mmmmm...

I'm not sure about the exact amount induced, but I did have problems with using my cell phone when i got within about 6 in. to a foot of a magnet that came from an old hard drive. It did not cause problems with interference, but caused my phone to reset itself.

You probably wouldn't interfere with another robot from several feet away, but depending on the location of the magnet, it might cause problems when the robots are very close to each other.

[DKolberg]

Originally Posted by Rickertsen2

Instead of using them to attach to the bar, I see them as having greater applications moving goals. Simple: Powerful magnet + pnumatic detacher = easy goal dragger. This solves the problem of having nothing to grab onto. It also solves the problem or precisely aligning a mechanism w/ the goal.

Sorry, but the goals are made of aluminum and aluminum will not be attracted to the magnet.

-Dave

[Adam Y.]

Neodymium magnets are easy and cheap to come by so
price is not a factor. These magnets are dangerous and care should be used handling them. Here are the reasons:
a) They shatter easily. The force of two magnets attaching to each other is enough to break them and cause shrapenel to fly.
b) They can seriously hurt someone. Companies warn people about the power of the little magnets. Bigger ones could accidentally break bones unless care is taken.
c) Once they are attached to something they are really hard to separate. I am not really sure if this would be an safety issue but you would have to be design the robot with some way to easily deattach the magnet.
d) Aparently they can affect pacemakers and other medical devices.
e) They can ignite accidently and burn very fast like magnesium does.
More Safety Tips Wow
Even More Tips
The Japanese have used these magnets with a lot of success in their sumo robots. They actually fought with their robots upside down.
Here is another link to more information:
Another supplier/Faq on magnets

[Rickertsen2]

Originally Posted by Adam Y.

Neodymium magnets are easy and cheap to come by so
price is not a factor. These magnets are dangerous and care should be used handling them. Here are the reasons:
a) They shatter easily. The force of two magnets attaching to each other is enough to break them and cause shrapenel to fly.
b) They can seriously hurt someone. Companies warn people about the power of the little magnets. Bigger ones could accidentally break bones unless care is taken.
c) Once they are attached to something they are really hard to separate. I am not really sure if this would be an safety issue but you would have to be design the robot with some way to easily deattach the magnet.
d) Aparently they can affect pacemakers and other medical devices.
e) They can ignite accidently and burn very fast like magnesium does.
More Safety Tips Wow
Even More Tips
The Japanese have used these magnets with a lot of success in their sumo robots. They actually fought with their robots upside down.
Here is another link to more information:
Another supplier/Faq on magnets

Add keep them away from computers. I just got one too close to my monitor, and ouch! I'm not talking about magnetizing the shadow mask/apature grill and distorting the colors either. The magnet was soo strong that it bent and stretched a few hunderd of the shadow mask wires!! I now have irreparable black lines across about the middle quarter of my screen. I can hardly see what i am typing. Ooops!!! I guess it's my own dumb fault. At least this isn't my good monitor. (or i wouldn't have been messing w/magnets.) (switches monitors)

----------edit------------
Haha. If i hit the monitor hard enough, the bent wires oscillate and i can see the oscillations almost as if i were lookign at an oscilliscope because of the scanning of monitor highlighting them.

O joy, i also just realized its now probably emitting low levels of X-rays as the electron beam bounces off the bent shadow mask wires at undezired angles. (emits X-rays, which are normally emitted backward and adsorbed by the lead infused glass in the back.)

[Adam Y.]

Add keep them away from computers. I just got one too close to my monitor, and ouch! I'm not talking about magnetizing the shadow mask/apature grill and distorting the colors either. The magnet was soo strong that it bent and stretched a few hunderd of the shadow mask wires!! I now have irreparable black lines across about the middle quarter of my screen. I can hardly see what i am typing. Ooops!!! I guess it's my own dumb fault. At least this isn't my good monitor. (or i wouldn't have been messing w/magnets.) (switches monitors)

If you ever get a hold of a black and white television have fun with the magnets. They do no damage the cvt/phospher screen and the magnets actually distort the screen. It is pretty cool.

[Rickertsen2]

Originally Posted by Adam Y.

If you ever get a hold of a black and white television have fun with the magnets. They do no damage the cvt/phospher screen and the magnets actually distort the screen. It is pretty cool.

And once you finally get bored of that, take it apart and rip out the beefy flyback transformer that most old B/W TVs have and build yourself a tazer sparky thingy. There are are actually alot of useful components in old TVs.

[ggoldman]

Maybe a theory would be not to use the magnet to hold up the robot, but maybe help guide an arm with a latchin device right to the pole:

Heres an example:

Robot "FRED" has a slightly flimsly arm that can reach the height of the bar with a latch that will grip onto the bar once it is close enough to it.

The drive runs the robot under the bar and the magnet on top of the slightly flimsy arm attracts to bar with little effor from the driver to position the bot. The robot then lowers its latch which is now a perfect distance from the bar because of the magnet.

Maybe that has some use?


Other wise, the weight to power ratio of a magnet to lift 130 pounds would not be too efficient.


Gabe Goldman

[Rickertsen2]

Originally Posted by ggoldman

Other wise, the weight to power ratio of a magnet to lift 130 pounds would not be too efficient.


Gabe Goldman

With typical magnets yes, with neo magnets this iisn't a prob at all. A 1ib neodynium magnet could probably easibly lift 2 robots.

[ggoldman]

I stand corrected, havent heard of neo magnets. But if a 1 lb mass of neo magnet can hold that much force, it's field will most likely effect robot controllers or maybe "latch magnetically" onto other robots inadvertantly.


If I were an inspector, and my metallic clipboard got stuck to your magnet while I was reviewing your bot, I would be concerned

Gabe Goldman