"treasure" hutning magnet questions
"treasure" hutning magnet questions
(OP)
I apologize if these are trivial questions. I have several books on order including Moskowitz.
I live in a tourist town with rocky beaches. I'm interested in using magnet assemblies for "treasure hunting". I expect to attach a line to the assemblies and drag them along a beach or from a pier.
I have the following questions:
I know that pole pieces attached to the magnetic faces of a block magnet can focus the field so that a 4 pound pull on each face becomes something like a 16 pound pull on the pole piece edges. Assuming "hardware store" cold rolled flat stock for pole pieces and I was considering making my own assemblies with ceramic or Neod magnets. Is there a very rough calculation that could give me pull values with pole pieces?
Should I enclose all but one side of the assembly for completion of the magnetic circuits and maximum pull?
Some assemblies like the one from Edmund Scientific seems to be design for a straight down, straight up process. In dragging or dredging it does not seem well designed as the line attachment point would leave the magnetic pull area sideways to the search surface. I think a cylindrical shape of some kind with an line attachment on the side would work better. Any suggestions for configurations to reasonably maximize surface area and dragging characteristics?
Thanks,
Dave
I live in a tourist town with rocky beaches. I'm interested in using magnet assemblies for "treasure hunting". I expect to attach a line to the assemblies and drag them along a beach or from a pier.
I have the following questions:
I know that pole pieces attached to the magnetic faces of a block magnet can focus the field so that a 4 pound pull on each face becomes something like a 16 pound pull on the pole piece edges. Assuming "hardware store" cold rolled flat stock for pole pieces and I was considering making my own assemblies with ceramic or Neod magnets. Is there a very rough calculation that could give me pull values with pole pieces?
Should I enclose all but one side of the assembly for completion of the magnetic circuits and maximum pull?
Some assemblies like the one from Edmund Scientific seems to be design for a straight down, straight up process. In dragging or dredging it does not seem well designed as the line attachment point would leave the magnetic pull area sideways to the search surface. I think a cylindrical shape of some kind with an line attachment on the side would work better. Any suggestions for configurations to reasonably maximize surface area and dragging characteristics?
Thanks,
Dave





RE: "treasure" hutning magnet questions
TTFN
Eng-Tips Policies FAQ731-376
RE: "treasure" hutning magnet questions
Mike
RE: "treasure" hutning magnet questions
- I'm not after engine blocks, just various trinkets so I don't think I'll need a crane.
- Regarding what I assume is a concern about corrosion, I likely will Plasti-dip the whole thing before using.
- Furballs, yep, already thought of that. I'll probably tape a 3 mil trash bag over it to keep the sand out.
RE: "treasure" hutning magnet questions
Given the density of wet sand, you'd be looking at lifting around 1 lb of sand for a 2-in diameter object buried 3 inches down
TTFN
Eng-Tips Policies FAQ731-376
RE: "treasure" hutning magnet questions
Which brings me to a slightly different question from my first post, would pole pieces allow field penetration through 3 inches of sand? What strength would my magnet need to be to reach?
RE: "treasure" hutning magnet questions
This is the problem I was thinking of as I got to your last post. The magnets you are talking about would probably not reach down for a two inch object under three inches of sand. They are mostly contact types.
Mike
RE: "treasure" hutning magnet questions
RE: "treasure" hutning magnet questions
The more the poles are physically separated, the weaker the field.
Frankly, I see this as a pointless exercise. I would think that you'd need a magnet with a 6-inch ot 8-inch face to even come close to pulling this off, which means dragging something that'll weigh close to 10 pounds through the sand.
TTFN
Eng-Tips Policies FAQ731-376
RE: "treasure" hutning magnet questions
You would need to space the poles well apart to reach out three inches. Flux wants to travel the easiest shortest distance.
Why don't you toss out some ideas of the magnets and size of your pole pieces. We might be able to comment. I cannot really picture your cylindrical shape idea.
Mike
RE: "treasure" hutning magnet questions