Magnets allowed?¿?

[Yan Wang]

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.

[Matt D]

The word magnet only appears once in the robot section of the manual (5) and not at all on the Q&A site. That reference is talking about how the current sensor works.

According to the Parts Use Flowchart, if you can get it in one of the ok'd places then it's legal.

[Al Skierkiewicz]

Electromagnets are not allowed under the rules. If you follow the flow chart there is a section on electronics where it askes the question "Is the part a motor, solenoid, pump, or other actuator?" Since the answer is Yes you cannot use it. An electromagnet is by definition a solenoid, i.e. a coil of wire, wound around a form, that induces a manetic field by the introduction of electricity, to attract another metalic object. Sorry.

[maxgebhardt]

part of the other trouble its the magnetic force could also possibly interfier with radio of other robots, or pull steel parts off if it was powerful enought to hold the robot... 100 posts! oh yeah!

[Al Skierkiewicz]

Originally Posted by maxgebhardt

part of the other trouble its the magnetic force could also possibly interfier with radio of other robots, or pull steel parts off if it was powerful enought to hold the robot... 100 posts! oh yeah!

Max,
An electromagnet would not produce interference with the radio modem in and of itself. Big coils do have this natsy habit of producing an arc at the switch when you try to remove current from the coil. That arc is capable of a lot of energy in the RF range and might be enough to disrupt the modem.
As to your closing signature, another form I heard "way back when" relates to the F104 fighter. Marines were heard to say it proved if it you put a big enough engine on it, you could get a brick to fly.

[briholton]

Originally Posted by Al Skierkiewicz

Electromagnets are not allowed under the rules. If you follow the flow chart there is a section on electronics where it askes the question "Is the part a motor, solenoid, pump, or other actuator?" Since the answer is Yes you cannot use it. An electromagnet is by definition a solenoid, i.e. a coil of wire, wound around a form, that induces a manetic field by the introduction of electricity, to attract another metalic object. Sorry.

I don't know. It seems the spirit of that rule is an electromechanical device - an electromagnet is not that, right?, only half of that. And yes, you are certainly right, it is a solenoid by defn, but the spirit of that rule..... I mean, one could argue that any loop of wire is a solenoid, but we know the spirit of the rule. Would be rather interesting to see an electromagnet that could lift a robot when attached to a round bar and be able to spend some time on the bar with no battery power when the match is over. And to add to that, i wonder if magnet wire is allowed - i suppose so, but you have to keep to the correct size.... I highly doubt anyone could produce such a device given the rules, but gee, i'd be curious to see a prototype even if it isn't 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