View Full Version : DIY magnetic knife bar (holder) - may way

05-05-2013, 08:00 AM
This is will be a long story :)


The influence of this forum had expensive outcome of new knives that do not fit our current knife holder (wooden block). I decided to have a look at magnetic holders. I found one that looked OK here in Germany, but once delivered it was clear that it will not do the job - it had just one row of magnets so the knives would 'dangle' once attached. It was also very narrow (4 cm). Also - the bar was made from 2 cm thick bar that was supposed to be attached directly on the wall - what mean that one had about 1cm spec between the knife-handles and the wall - not practical. I realized that magnetic holder needs 2 rows of magnets and be wider AND further away from the wall to be comfortable to use. I then found a very interestingly looking (and cleverly designed) knife holder from knifekraft (http://www.knifecraft.co.nz) in New Zealand, but the price was high and the wood I would have preferred not available at the time. So I decided to try to make my own holder.

The Design:

As much as I liked the designed of the Knifekraft holder, I could not do a similar one as I have NO workshop or access to one, so I had to keep it simple. What I knew is that I want a knife bar that is about 60 cm long, 8 - 10 cm wide and has some more distance from the wall so that the knives would be easier to grab. I decided to use round magnets (neodymium of course) and it turned out that magnets with 10 mm diameter and 5 mm thickness will do the job. I did install a few 10 mm thick magnets on one side (I bought them for testing), but it turned out not to be necessary.

Once I payed a visit to local shops I ended up with following design:

The bar (holder): 60 cm long, 8 cm wide and 2 cm thick
The spacer bar: 4 cm wide, 2 cm thick and a bit shorter than the holder (for the looks).

The production process:

Just to give you the idea about the tools I had at hand (this is not all of it though):
http://farm9.staticflickr.com/8555/8710261154_4864db05ea.jpg (http://www.flickr.com/photos/31007239@N06/8710261154/in/photostream)

My 'workshop' - the floor in our kitchen. Wooden dust was everywhere (god bless my patient wife)
http://farm9.staticflickr.com/8557/8710261040_213dd441e0.jpg (http://www.flickr.com/photos/31007239@N06/8710261040/in/photostream)

The upper picture show the spacer bar, but bottom picture the test drilling.
http://farm9.staticflickr.com/8534/8709137839_8e7872da84.jpg (http://www.flickr.com/photos/31007239@N06/8709137839/in/photostream)

Detail of the drill bit - I have used one specifically for wood (the top surface is flat), but I have filed the tip as it was way too long and would have punched the front surface of the bar when drilling. I have also got an 'end-stop' that allowed to me keep the drilling depth constant (VERY important) and precise.
http://farm9.staticflickr.com/8255/8709137703_e8113e148d.jpg (http://www.flickr.com/photos/31007239@N06/8709137703/in/photostream)

Adjusting the depth of the drilling - testing with magnets showed the the remaining thickness of the wood between the magnets and the knife needs to be less than 3mm for the magnetic force to be sufficient to keep the knives in place.
http://farm9.staticflickr.com/8132/8709137611_ddc6ea79d7.jpg (http://www.flickr.com/photos/31007239@N06/8709137611/in/photostream)

I did several drills on the edge of the bar to make the inspection easier.
http://farm9.staticflickr.com/8552/8709137525_9c5be95d7f.jpg (http://www.flickr.com/photos/31007239@N06/8709137525/in/photostream)

Sketching the positions to drill. I went with 20 mm spacing - I wanted to get the magnetic field as homogeneous as possible (it worked reasonably well).
http://farm9.staticflickr.com/8264/8710260580_ab17e33508.jpg (http://www.flickr.com/photos/31007239@N06/8710260580/in/photostream)

So - all holes drilled. I used one magnet and a hex key to check that all holes are OK and the magnets do not get stuck.
http://farm9.staticflickr.com/8553/8710260488_1ca10ee83c.jpg (http://www.flickr.com/photos/31007239@N06/8710260488/in/photostream)

Surface finish (no photo).

When I bought the bar, one of its long edges was clipped under 45 deg. I first was not happy about that, but than I decided to round it and place it up on to make lifting a knife more comfortable and save (edge of knife would not hit edge of the bar)

As the bar had no surface finish I went through 3 cycles of: wet the bar with water (not too much), let it dry and polish the surface with sand paper. After each wetting the surface would get a bit rough, but after 3 cycles it was much better. After that I tarnished the surface with hind oil. Thanks to the first 3 polishing rounds the bar remained smooth after oiling.

Once I started to put magnets in place I realized that they do not want to 'sit nicely' in the holes, but would jump around or tilt inside the holes. To mitigate this problem I have paced baking sheet (iron) under the bar and of course the magnets would all attach it to the bar and sit as they should.
http://farm9.staticflickr.com/8409/8710260332_927aef3a73.jpg (http://www.flickr.com/photos/31007239@N06/8710260332/in/photostream)

Gluing. I used 2 component epoxy glue - a 'slow' one that remains fluid about 30 minutes after mixing - this would give me enough time to slowly drop a bit inside each hole. As I had 60 holes to fill I still needed around an hour to get it done. But I had not clever applicator to do it. Note - I did not put ANY glue UNDER the magnets. That would just increase the space between magnets and knives. Note: you do not need too much glue - layer of 1-2 mm on top of the magnets is enough (epoxy is very strong).
http://farm9.staticflickr.com/8541/8709137033_865784dd21.jpg (http://www.flickr.com/photos/31007239@N06/8709137033/in/photostream)

The spacer bar. I have decided that the attachment of the magnetic bar on the wall will be in 2 steps. First I would attach the spacer bar to the wall and then I would attach the magnetic bar to the spacer - for the case I would want to attach the magnetic bar in a different way in future. So here you see my FIRST approach - I just nailed these threaded pieces in the bar (drilled first of course), but then I realized that this is not the best way, as these stick out of the bar and would make attachment to wall problematic. So - I did NOT use this way.
http://farm9.staticflickr.com/8139/8710260140_64885c1b07.jpg (http://www.flickr.com/photos/31007239@N06/8710260140/in/photostream)

Instead - I have glued female screws inside the bar. Actually - I first glued TWO of these together before I glued them inside the bar. To make sure I will not get epoxy on the threads I did not hammer the threads in the bar, but pulled them with a acre from inside. So I did get epoxy on the screw, but not on the female screws.
http://farm9.staticflickr.com/8117/8710260044_3d85230aed.jpg (http://www.flickr.com/photos/31007239@N06/8710260044/in/photostream)

Finally - the result. The bar mounted on the wall with all our kitchen knives.
http://farm9.staticflickr.com/8560/8709136701_36e09ce6b7.jpg (http://www.flickr.com/photos/31007239@N06/8709136701/in/photostream)

Side view - you can see the spacer bar. You can also see the rounded upper edge of the bar - it makes lifting a putting the knives back on the bar really easier and decreases the chance of damaging the edge.
http://farm9.staticflickr.com/8416/8710259862_75c24ebb22.jpg (http://www.flickr.com/photos/31007239@N06/8710259862/in/photostream)

Magnetic bar: 60 cm long, 8 cm wide, 2 cm thick. 60 neodymium magnets with 10mm diameter and 5mm thickness. Magnets mounted under 3mm from the bar surface. Spacing of the magnets 20 mm (axis to axis).
Spacer bar: about 55 cm long 4 cm wide 2 cm thick.
Use your heaviest STAINLESS knife (stainless is a bit less magnetic than carbon steel) to test before you decide on your final design.

So - mission accomplished :) Now I am ready for your praise and questions :D

05-05-2013, 09:09 AM
I am really glad you put this together. Well done.

05-05-2013, 09:17 AM
it neodymium magnets?
You can specify the size and number?

daddy yo yo
05-05-2013, 09:31 AM
the wood is the best, MADE IN AUSTRIA !!! :lol2:

05-05-2013, 10:46 AM
it neodymium magnets?
You can specify the size and number?

Yes, neodymium magnets. 10mm in diameter and 5 mm thick. Class N50 (if I remember correctly).

05-05-2013, 10:46 AM
the wood is the best, MADE IN AUSTRIA !!! :lol2:

Yes - and the price was high - I payed about 15 Euro for 1 meter long 8 cm wide and 2 cm 2 thick piece of wood. Now that is crazy in my opinion.

05-05-2013, 10:47 AM
Very nicely done! And thanks for the WIP.

05-05-2013, 12:02 PM
Great job, thanks for the WIP.

05-05-2013, 12:09 PM
Looks great. I might need to try this sometime.

05-05-2013, 02:41 PM
Very nice!

05-06-2013, 02:48 AM
Really nice WIP. Thanks for putting it together and sharing.

05-06-2013, 08:20 AM
Congratulations on a very nice job! :doublethumbsup:
Just as a point of interest for anyone planning on making one of these blocks, if you add steel washers behind the magnets you can increase the holding power quite a bit.