A DIY kitchen knife sharpener

[moshulu]

For years, I used to take my dull kitchen knives to a little man at our local street market, but he got older and older and finally vanished. So I decided to do it myself. I was inspired by a jig that a friend of mine got for sharpening his pocket knife. It's made by a company named DMT:

I bought three diamond-loaded water-lubricated hones, and rummaged around my tiny shop for various bits and pieces of metal and wood. Here is the result:



It looks like this when bolted to my workbench, with a blade clamped into a modified door hinge, and with the movable supports on either side screwed down:



The hone, with its orange handle, is constrained to encounter the blade at a fixed angle that is set by the adjustable height of the horizontal wooden bar:





The table tells me how to adjust the bar vertically, depending on the width of the blade and the desired sharpening angle (can't believe that high school trigonometry is actually good for something!).

This jig works really well. I was improvising as I made it, and would probably design it differently now that it's finished - but that is standard for this kind of DIY exercise.

 

[fast14riot]

Nicely done! The only thing I would change is the ability to clamp the knife with the majority of the edge parallel to the guide to reduce the amount of compound edge angles.


-Xander

 

[cb91710]

That's awesome.
I have a Langsky that I use for my pocket knives, but it's too cumbersome for a blade much longer than 2 or 3" due to it holding the hone in one spot and not allowing it to move along the edge maintaining the same angle.
Imagine your rig with the hone's guide paddle locked to the center of the blade.

 

[moshulu]

Nicely done! The only thing I would change is the ability to clamp the knife with the majority of the edge parallel to the guide to reduce the amount of compound edge angles.


-Xander

My system allows me to do this, but only to a limited extent. This is why the auxiliary wooden supports are adjustable in both angle and effective length (their other function is to keep the blade from sagging). But you are right. If I had to do it over again from scratch, I would probably just have two of the big hinge clamps, spaced a few inches apart.

 

[fast14riot]

it could be as simple as extending the slots in your supports. Overall I think it is very well thought out and executed!


-Xander

 

[Lamar]

Well Done!

 

[Deltaboy]

Well planed and done. Good Job!

 

[ThePatrician]

Dude, that is outstanding! Very innovative, I am astonished! If I may make one suggestion: put a layer of thick electrical tape or duct tape on your modified door hinge, where it grips the knife, to keep the heavy metal of the door hinge from scratching up your knives. I notice that your knives are older, and look almost identical to my family's old kitchen knives. Since they are older scratches and nicks may not be a concern, but I would wager that if word of this gets out you may get friends of yours asking for a "favor" with their "dull and difficult" knives. You know, if you're not busy or anything............

 

[moshulu]

If I may make one suggestion: put a layer of thick electrical tape or duct tape on your modified door hinge...

Thanks, Matt, I will do that. I already put a piece of leather on the lower jaw (you can kind of see it in the pictures) but that was more for introducing a bit of compliance than for protecting the knife blade.

 

[BearHeart]

I am lazy and have cheap knives so I just use and accusharp.

 

[COHunter]

That's a sweet rig. I just use my Lansky, the only issue I tend to have is I would like a wider clamp jaw to hold the knife in place better.
Seems to maintain the angle just fine for most of my kitchen knives, just would prefer a bigger contact patch on the blade.

 

[Alacrity59]

Wow this is a handsome piece of equipment. Pretty darn practical.

 

[moshulu]

I just use my Lansky, the only issue I tend to have is I would like a wider clamp jaw to hold the knife in place better.
Seems to maintain the angle just fine for most of my kitchen knives, just would prefer a bigger contact patch on the blade.

This is indeed the problem: how to keep the blade from rotating without squeezing it to death. My (imperfect) solution was to add two wooden stops on the two sides of the central jaw. I made them adjustable to account for the shape of the blade, given also that the blade needs to be as parallel as possible to the guide. This whole concept still needs some work...

 

[channy]

My victorinox 8" chefs knife and accusharp have treated me well. I also use a honing steel as well in between.

 

[cb91710]

This is indeed the problem: how to keep the blade from rotating without squeezing it to death. My (imperfect) solution was to add two wooden stops on the two sides of the central jaw. I made them adjustable to account for the shape of the blade, given also that the blade needs to be as parallel as possible to the guide. This whole concept still needs some work...

You've done a great job. Commercial units costing as much as $100 with a set of 5 or 6 stones that are only 1/2" wide only use a single clamp and have the same problem of blade rotation... and the way the set screw and clamp is designed, you can't use the 15 degree angle guide because the stone will hit the screw, or even the clamp if you clamp the blade deep enough to hold it securely.

 

[moshulu]

You've done a great job. Commercial units costing as much as $100 with a set of 5 or 6 stones that are only 1/2" wide only use a single clamp and have the same problem of blade rotation... and the way the set screw and clamp is designed, you can't use the 15 degree angle guide because the stone will hit the screw, or even the clamp if you clamp the blade deep enough to hold it securely.

Absolutely. As you can see on the photos, I went to some trouble to get down to 15 degrees. I ground off the lip of the jaw, and used a bolt with a shallow head (there is a threaded insert underneath - for the wooden stops as well). The top half of the jaw must be thin, but it can be very wide, thus giving a good grip on the blade. But if too wide, some contact is lost due to various imperfections. Plus a wide jaw would not be effective for knives with a lot of thickness taper (e.g., pocket knives). Too some extent, the leather that is epoxied to the lower jaw counters this effect.

All this leads me to believe that the optimum solution would have two jaws of modest width. Getting all this good feedback on B&B is almost motivating me to make a new version, but I have too many new projects in the hopper...

 

[Kentos]

You know, is there any need to really clamp it? If you could extend the support maybe you could just hold it in place like the edge pro sharpener.

 

[moshulu]

You know, is there any need to really clamp it? If you could extend the support maybe you could just hold it in place like the edge pro sharpener.

I had to look that up. Pretty slick. Looks easy on the video, but I think it would take some practice to master holding the knife properly while running it along the device, all the while making a completely different motion with the other hand. Still - a nice solution.

 

[Vickers]

That looks better than the furniture in my house. Nice job.

 

[ouch]

I use one of these from Home Depot.