# Magnets



## grelcar (Feb 13, 2014)

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


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## stumpdeez (Feb 26, 2014)

http://www.woodcraft.com/product/2001928/1891/single-hole.aspx try these for mounting without visible hardware.


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## Matus (Feb 26, 2014)

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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## Vangelis (Feb 27, 2014)

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


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## Matus (Feb 27, 2014)

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.


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## grelcar (Mar 1, 2014)

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.


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## Matus (Mar 1, 2014)

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


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## DSChief (Mar 1, 2014)

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?p=magnetic-knife-holder


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## Vangelis (Mar 6, 2014)

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



Matus said:


> 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.


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## Matus (Mar 9, 2014)

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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## Forsberg (Mar 16, 2014)

double post... sorry


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## Forsberg (Mar 16, 2014)

I did it a litle different.
block magnets, http://www.supermagnete.de/eng/Q-40-15-05-N.

Here is a pic guide:

Distance to frontline of the wood was 2 mm. Magnets glued with epoxy. Its very important to clean the wood and magnets before glueing.
https://www.dropbox.com/s/m4i78oukr7ppqwz/2013-12-18 20.59.36.jpg


Make a piece of metal that fits the magnetstrip on the back of your tree. Its important that the metalt is magnetic since it syncronize the magneticfield of all the magnets to what feels like 1½ times the magneticfield. 
https://www.dropbox.com/s/xh1j3vh9ajxoiz2/2013-12-23 23.54.11.jpg

Attatch this metalbar to the wall. You decide the distance to the wall with the litle rubber/plastic cap under the metal. Take note on the way the screwholes is made. The screw need to be under the level of the metalbar surface
https://www.dropbox.com/s/ps64955jz8ln530/2013-12-23 23.54.30.jpg

After this is done, you simply click the tree to the magnetic metalbar on the wall.... And booom Easy to make, easy to assemble and easy to take off

https://www.dropbox.com/s/ikpif6vle7r1ayq/2014-03-16 20.54.38.jpg

https://www.dropbox.com/s/2pgyilbmbnd9ufq/2014-01-24 23.22.40.jpg

In my version 2.0 ill make to magnetic fields on top of each other, with like 2 lines of magnets. That will give the knives 2 fix points so they will not rotate on the magnetbar.
The upper line does not have to be as strong as the one which the metalbar is attatched to.

Sorry for my english... i need alot of technical words, that i have in danish


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## Matus (Mar 16, 2014)

I have seen this style of making magnetic bar from some guys in NZ. I like it very much. And you did a very nice job on this one.


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