Forum Etiquette inquiryIs it rude to ask how to design a home project?

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Discussion Overview

The discussion centers around the inquiry of whether it is appropriate to ask for assistance in designing a home project involving the magnetization of a sheet metal surface. Participants explore the physics of magnetism, the factors affecting magnetic force, and practical approaches to achieving the desired outcome for personal use.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions how many magnets are needed to magnetize a sheet metal surface to a specific attractive force, expressing uncertainty about the calculations involved.
  • Another participant raises the issue of whether the attractive force of a magnet diminishes with distance, regardless of the material in between.
  • Some participants suggest that due to many unknown variables, a trial and error method may be more practical than attempting to calculate the number of magnets needed.
  • A participant shares their experience with a magnet vendor's calculator that shows pull strength from various sized magnets at different distances, noting the high cost of large magnets.
  • There is a discussion about whether steel can amplify the power of magnets, with one participant cautioning against the assumption that it can provide a significant increase in magnetic strength.
  • Another participant provides examples of how magnetic strength can be increased using steel armatures or configurations that concentrate magnetic flux, citing specific increases in pull strength with certain setups.
  • One participant suggests an arrangement of magnets and steel strips to create a magnetic support system for tools, while also noting potential downsides to magnetizing tools.
  • A light-hearted suggestion is made about using Velcro as an alternative method for tool storage.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of using steel to amplify magnetic strength, and there is no consensus on the best approach to achieve the desired magnetic force for the project.

Contextual Notes

The discussion includes various assumptions about the properties of magnets and steel, as well as the practical limitations of different methods proposed for achieving the desired outcome.

mikedunbar
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Hello... I'm trying to figure out how many magnets I need to put on one side of a piece of sheet metal in order to sufficiently magnetize all the surface area of the other side to a specific attractive force to other pieces of steel in contact with the sheet. It has been too long since college. I can't remember how to calculate this.

Is it rude to ask here?

It's not for commercial use. I want to magnetize a big piece of sheet metal, hang it in my garage, and keep tools on it, wrenches and sockets and such.
 
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I guess the gist of my question is: Does the attractive force of the magnet diminish with distance regardless of whether a ferrous or non-ferrous material occupies that intervening distance?
 
Welcome to PF, Mike. It's not rude at all. That's what we're here for. Unfortunately, your particular subject matter is not within my arena of knowledge. Someone else will be along to help you, though.
 
mikedunbar, Welcome here to Physics Forums!

Since there are so many unknown variables it appears not useful to try to calculate "how many magnets..." My suggestion is get yourself lots of magnets, put up the sheet metal, and hang up your tools using the trial and error method.
 
Bobbywhy said:
mikedunbar, Welcome here to Physics Forums!

Since there are so many unknown variables it appears not useful to try to calculate "how many magnets..." My suggestion is get yourself lots of magnets, put up the sheet metal, and hang up your tools using the trial and error method.

That's kind of what I did. I found a magnet vendor who had a calculator which showed pull from various sized magnets at various distances. It turns out that the reason you don't see big magnetic walls is that the magnets required are not cheap at all.

Unless there is a way to make a big flat electromagnet, and I think there is not, this is another of my ideas which has come and gone.

The only way it could still possibly work with neodymium magnets is if steel somehow amplifies their power, and that question is still open.

I've sent twenty emails to members of university physics clubs with this question, and I'll wait on more astute replies from this august body, as well.

Thanks for your reply.
 
I would recommend against hoping steel is going to amplify magnets' power! Our revered conservation laws prohibit getting a "free lunch".
 
Bobbywhy said:
I would recommend against hoping steel is going to amplify magnets' power! Our revered conservation laws prohibit getting a "free lunch".

Yes, but look at this...

<i>Magnetic strength can be multiplied by up to 32 times by using steel armatures to concentrate magnetic flux. Such armatures may take the form of backing plates, channels or cups. The maximum increase in power is obtained when magnets are sandwiched between two plates.

Channel Magnet Assemblies, Industrial MagnetsFor example: A 0.187" thick x 0.750" wide x 1" long rubber magnet has 4 oz. of pull strength. The same magnet bonded to a channel (assembly #RMCH-10) will pull 5 Ibs., which is 20 times greater. Furthermore, the same magnet sandwiched between two plates (assembly #RMSA-10) will pull 8 Ibs.—32 times more than the magnet alone!</i>
 
The magnetic supports I have seen consist of strips of steel / iron with magnets between them. This is like a horseshoe magnet, in essence. A set of strips with alternating polarity (N S N S N S) would provide an area which would hold your tools. I reckon that only one of these little high strength magnets would be needed between each pair of strips.

=============== strip
N
S
=============== strip
S
N
=============== strip
N
S
=============== strip

etc.

Magnetised tools are not always what you want, though, and they are sure to become that way.
 
velcro :wink:

(then you could just chuck 'em at the wall! o:))
 

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