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Thread: Magnets

  1. #1

    Magnets

    I have a beautiful piece of figured maple that I want to use to make a magnet knife rack for my kitchen. This board is about 2 1/2 inches wide, just over 2 feet long and an inch thick after squaring it up.

    What type, size and quantity of magnets should I use? How close should the magnets be from the front surface of the board? Any suggestions as to how I can mount it without any hardware showing?

    Thanks for any suggestions.

    Greg

  2. #2
    http://www.woodcraft.com/product/200...ngle-hole.aspx try these for mounting without visible hardware.

  3. #3
    Senior Member Matus's Avatar
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    I did my own wooden magnetic bar in the past (and still use it - works great). You can find the details HERE

    If anything I would not use any weaker magnets - only if I would dare to leave the wood layer between the magnets and the knives even thinner (I really could not give the precision I was able to achieve). In general - keep in mind that stainless steel knives respond less to magnetic field than carbon steel knives - the difference is quite large. So if you do your own testing use the heaviest stainless steel knife you have around.

    Have fun

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    I have a similar challenge Greg, but I am not going with anything less than 12kg hold capacity per magnet.

  5. #5
    Senior Member Matus's Avatar
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    Vangelis - when the force will get too large it will be unpleasant to put or remove the knife from the bar and you will increase the risk of damaging the blade. In general it is not a bad idea to get stronger magnets - you can then tune the resulting force by varying the thickness of the wood between the knife and the magnet.

    The best shape of magnets IMO would be rectangular - about 1cm wide and 5mm thick (length is not relevant) placed along each other in a row without any (or only very small - less than 10 mm) gap. And using 2 of such rows few cm apart - that will give completely homogeneous force over the whole length of the bar and because there are 2 rows and not just one - heavier knives will not have the tendency to swing or tilt under their own weight.

  6. #6
    Thanks for the responses. I have been researching magnets. I want to go with round magnets so I can use a forstner bit in the drill press. I plan to drill the holes as deeply as I can without risking the center of the bitt penetrating the other side. I thinking of using two rows of 3/4 or 1 inch magnets with the rows being staggered, sort of a zigzag pattern.

  7. #7
    Senior Member Matus's Avatar
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    Yeah, drilling a hole is easier to do if one does not have a more dedicated gear,

    Zig-zag pattern will tend to keep your knives in zig-zag position - in particular with magnets this large. Smaller diameter & more densely packed would make for more homogeneous magnetic field. Something like 1/2" diameter and 1/4" thickness should do the job.

    If the drill bit has too long "nose" just shorten it first.

    Good luck - let us know the result

  8. #8
    Senior Member DSChief's Avatar
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    here's a good link, part way down is a chart to help select magnets based on wood thickness.
    http://www.kjmagnetics.com/blog.asp?...c-knife-holder

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    Hi Matus,

    The space I have is about 6mm (double from yours) and the lenght of the opening for the magnets is 55*8 cm (i didn't drill hole by hole). I can see at your DIY post that you used round magnet 10mm (d) and 5mm (h). The size of the actual wood is 10,5cm width, 3cm height and 62 lenght. I am planning to have on 1 sujihiki 3/4 Gyuto's 1petty 1 parer and a honesuki + 1-2 in the near futur (maybe a 15cm deba max).

    I was thinking to use the following ones: http://www.supermagnete.de/eng/S-20-05-N#img-2

    In two rows of 25 each... my heaviest knife is a K-Sabatier, Do you think it should be ok or should I go for something heaftier

    Quote Originally Posted by Matus View Post
    Vangelis - when the force will get too large it will be unpleasant to put or remove the knife from the bar and you will increase the risk of damaging the blade. In general it is not a bad idea to get stronger magnets - you can then tune the resulting force by varying the thickness of the wood between the knife and the magnet.

    The best shape of magnets IMO would be rectangular - about 1cm wide and 5mm thick (length is not relevant) placed along each other in a row without any (or only very small - less than 10 mm) gap. And using 2 of such rows few cm apart - that will give completely homogeneous force over the whole length of the bar and because there are 2 rows and not just one - heavier knives will not have the tendency to swing or tilt under their own weight.

  10. #10
    Senior Member Matus's Avatar
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    6mm sounds like a lot to me - even with these larger magnets. I would definitely advice you to order just a few (4 would be a good number as it would allow you to test double-thickenss of magnets as well) first and test it (with whatever 6mm thick wood or cardboard).

    Just a world of caution - already the 10x5 magnets I have used were hard to handle. You need to be careful because when 2 magnets "jump" to each other they often chip (or completely broke into pieces, the material reminds of ceramic somewhat) and the chips may be sent flying towards you eye. With 20x5 magnets the force will be so large that you will find it hard to disjoin 2 magnets (5mm thick discs are hard to hold properly in hand)

    If you would be able to decrease those 6mm to maybe 3-4 you may save quite some cash on magnets.

    bar 62cm long should hold comfortably up to 10 knives (as long as not all of them are 50mm wide gyutos) - you do want to have some gaps between to handle the knives comfortably and safely.

    One way or another - please do let us know how did you decide and how strong magnets you need for that wood thickness.

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