The following is information pertinent to making a wooden magnetic knife holder for hanging knives vertically.

💡 I assume that the knives are suspended without actually sitting on anything, i.e. the magnet has to do the job of stopping the knives from sliding down. (Otherwise much weaker magnets could be used. For a cheaper, succinct option, but with magnets visible and flush on the surface, see * below.)

You will need one magnet location per blade unless one of the following:

• You use a closely spaced row of magnets (all poles facing the same way). This becomes expensive.

• You have a lot of knowledge in the design/manipulation of magnetic fields

• You can experiment a lot, using steel to extend poles to where you want them along a strip.

Otherwise, choice of magnet depends a lot on the distance between the magnet and the knife blade. Note that:

• The pull of any magnet drops off very rapidly with distance. So with a few mm distance through timber, you need large magnets, which are expensive.
• Thinner blades are less attracted, but they are normally lighter so this is not likely to be an issue unless the handle is particularly heavy.
• Consider using the longer shaped magnets, say D10x10, in holes drilled right through the timber, then finish the front with 1mm veneer – not so hard to cut with a circular saw.
• Although it may be aesthetic to have hidden magnets, visibility enables the chef to see where to place the knife.
• Some knives may be made of materials (eg certain alloys of stainless steel) that are poorly or non-attracted to magnets.
• Specialised “Pot” magnets are great for pulling directly to steel, but increasingly hopeless as the distance from the steel increases. They are rarely suitable for a knife holder unless they are in contact with the knives.

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Practical Tests

I did the following tests using a 180g chef’s knife, with thickness at the back of the blade of 2.6 mm.

💡 There is the problem that minimal, medium, and good security (in holding knives) are very subjective terms.

Insufficient knife security:

Knives tend to slide down

Through 1 mm:

• D8x8 mm

Through 2 mm:

• D15x4 mm (with a countersunk hole)
• D15x5 mm
• D10x10 mm
• D12x6 mm

Through 3 mm:

• D15x4 – stacked in pairs for 8 mm thickness
• D15x5 mm
• D20x3 mm

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Minimal but “acceptable” security:

Holding a heavy knife

Through 1 mm:

• D10x10 mm
• D12x6 mm

Through 2 mm:

• D15x5 mm
• D20x3 mm

Through 3 mm:

• D20x5 mm
• D12x16 mm

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Medium knife security:

Thin gap:

Through a thickness of no more than ~2 thicknesses of copier paper (i.e. magnet jammed or glued into the timber more or less flush with the surface, and no timber between the knives and the magnets.)

• D10x10 mm
• D12x6 mm

Through 1 mm:

• D20x3 mm
• D15x4 (with a countersunk hole)
• D15x5 mm

Through 2 mm:

• D20x5 mm (with a countersunk hole)

Through 3 mm:

• D20x3 mm – stacked in pairs i.e. 6 mm magnet thickness

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For good security:

Thin gap:

Through a thickness of no more than ~2 thicknesses of copier paper (Magnet jammed or glued into the timber):

• D15x5 mm

Through 1 mm:

• D20x5 mm (with a countersunk hole)

Through 1 or 2 mm:

• D20x3 mm stacked in pairs i.e. 6 mm magnet thickness

Through 3 mm:

• D20x3 mm – stacked in threes i.e. 9 mm magnet thickness
• D20x5 mm – stacked in pairs for i.e. 10 mm magnet thickness
• D25x6 mm – single magnets

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Other Notes

A cheaper, more succinct option is possible with the magnets visible and flush on the surface:

This can be done with D10x5 magnets which have countersunk holes, capped with D10x1.5 (without holes) for a tidy, flat finish, say 0.3mm below the surface (to eliminate any scratching).

For each knife, drill a hole from the front surface of the timber, say 6.7 or 6.8mm deep. Screw in the 5mm thick magnet – suitable screws, or nuts & bolts, available from Steelmaster (online). Then tidily “cap” that screw with the 1.5mm thick magnet. (Combo releases at around 2.4kg direct pull… more if you stack two or more of the D10x5)

The tricky part can be drilling a hole tidily. Perhaps plane the surface after drilling. Perhaps use a Forsner bit, but they come only in limited sizes.

This can also be done using my D12x3 magnet (with hole) capped with D12x2mm, releasing at around 2.8 Kg.).

Or my D15x4mm (with hole) capped with D15x2.5mm, releasing at around 3.3kg direct pull... more if you stack two or more of the D12x3)

Another perspective, with possibly lower knife-holding expectations can be found here.