How to make a homemade pocket knife sharpener #2

Here is a picture of the finished sharpener ready to start sharpening small knives..

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Step 1: Knife holder plans

Here is the illustration plan i drew for making the knife blade holder.

smalcolm says: May 17, 2012. 3:52 PM

Thats a neat idea, small problem.
This isn't suitable for knives, axes and lawn mower blades maybe, but not knives.
The grinder heats up the blades and weakens them, even when using oil.
The lansky system is a far better solution.
http://lansky.com/index.php/products/universal-system/

lime3D in reply to smalcolmMay 30, 2012. 6:19 AM

Yes, I agree.

underground carpenter in reply to smalcolmMay 19, 2012. 4:13 PM

If, at 110 RPMs with a wheel that spends 1/3 of it's rotation under water, you are heating up the blade of a knife to over 420°F (the temperature you'd need to change the temper), I guarantee that you are using WAY TO MUCH force against the wheel. I sharpen knives, chisels, and other edges on a Tormek all the time and the blade barely gets hotter than room temperature.

oilitright in reply to underground carpenterMay 19, 2012. 6:29 PM

As underground carpenter says if you are using a wet stone at 110 RPM you are in good shape. I too have a Tormek and this duplicates it in a primitive sort of way. However I don't usually use the Tormek to sharpen knives. It is better suited for more complicated sharpening like wood turning tools. For knives I actually like the paper wheel systems, they are really nice, produce a sharp edge and are quick. I mounted mine on a cheap grinder I bought at Big Lots for like $20 I also use a belt sander mounted perpendicular to the wall with a 15 micron belt. Sometimes it's really a matter of what mood I'm in what method I use to sharpen.

srilyk in reply to smalcolmMay 18, 2012. 7:15 AM

Having used similar systems to the Lansky, I can tell you they're really not that great. They're awkward to hold and use, at least for me.

I find that my cheap $15 diamond stone set from Harbor Freight works just fine. At least until I can afford this: http://www.spyderco.com/catalog/details.php?product=82 ;)

The main advantage of using a grinder like this instructable is if you have knives with damaged blades that need some serious re-shaping - although the heat is a concern, I'm much more concerned about the amount of metal that's removed. The best sharpening uses a smooth straightening steel (http://www.cutleryandmore.com/victorinox-forschner-fibrox/smooth-polished-round-sharpening-steel-p16071). If that doesn't straighten the blade out, then you move to a fine stone, then finish with the straight steel. This removes the minimal amount of metal from your blade so (hopefully) it lasts several generations.

If it's a good blade anyway. If you have a cheep China stainless steel, by all means use this method ;)

coolbeansbaby68 (author) in reply to smalcolmMay 17, 2012. 4:32 PM

Actually it works just fine for knives. The wheel isnt moving fast enough and i am not taking alot of material off . And the water tank under the wheel keeps any heat away..

Bushie says: May 29, 2012. 2:16 AM

Pocket knives should NEVER go anywhere near a power grinder...

Those bench grinders are only suitable for the initial shaping of blades..

IF a pocket knife is worth owning, then it IS worth keeping it sharp correctly ~

And THAT means hand sharpening on a stone, with stropping on leather, and honing in between sharpening, with either a diamond hone or a strip of 'wet-and-dry' emery paper.

flamesami says: May 17, 2012. 12:35 PM

5 degrees?! that sounds like an inredibly fine edge. Do you put a secondary bevel on your knives, or does that edge profile work for you? I have no idea what you cut with those knives, but i would think that such a fine edge would roll before it actually blunted.

coolbeansbaby68 (author) in reply to flamesamiMay 17, 2012. 3:34 PM

The edge works great. And holds it also. No secondary edge is needed . i think thats why 5 degrees works so good .

flamesami in reply to coolbeansbaby68May 21, 2012. 10:53 AM

hmmm, what do you cut with those knives? I can't imagine them holding up to my using them (I'm a wood carver). Maybe my knives are just all c**p ;)

coolbeansbaby68 (author) in reply to flamesamiJul 27, 2008. 4:53 PM

Its just a pocket knife. I could never sharpen one for beans . This works pretty good .The knife is a sog twitch . Very hard blade ..

TIGguy says: May 18, 2012. 9:19 PM

As a professionak welder of 20+ years and a knife collector for longer I can honestly say for normal knives this can work fine. As long as the metal does not turn color it hasnt gotten hot enough to ruin the temper of the blade. I have used bench grinders, hand grinders and belt sanders to repair friends chipped rough edges without hurting blade temper. Keep a container of water at hand and go slowly. If the blade starts to turn any color besides the normal steel color then it is getting too hot. I make one pass and cool the blade in the water. Cool it EVERY pass on the grinder. Make each pass one smooth steady motion also so as not to remove too much at a time.

coolbeansbaby68 (author) in reply to TIGguyMay 19, 2012. 5:06 AM

Can you see the little black tub under the wheel ? There is water in it . Also The wheel isnt turning very Fast .Its like 110 rpms for the big wheel and 3500 rpms for the small wheel on the other side . The big wheel is geared down very low . The only thing i need really is a finer grit wheel.....

TIGguy in reply to coolbeansbaby68May 19, 2012. 7:05 AM

Lol, I wasnt aguing. I was agreeing with you and clarifying for other readers. I think you have a good thing. For a finer wheel go to a welding supply store and ask about the fine ones we use for tungsten sharpening. I dont know the grit but they would be about right I think and after you could ise a polishing wheel for the razor sharpness!

coolbeansbaby68 (author) in reply to TIGguyMay 20, 2012. 5:58 AM

I didnt mean to sound snotty . People keep saying the same thing like your burning the blade i'm like no i'm not lol I was trying to get them to understand that the wheel isn't turning that fast to burn the blade lol

fespósito1 says: May 17, 2012. 3:11 PM

Very nice. Congrats.

I have a similar grinder, but the wet stone wobbles badly and I do not know the better way to fix it.

I will try to follow your idea (as a guide) but will implement it using aluminium instead of steel.

Thanks.

t.rohner in reply to fespósito1May 17, 2012. 11:19 PM

Maybe you need to trim the stone first.
You need to do this from time to time anyway, in order to keep it in good grinding condition. If you don't do this, the grinding causes too much friction and the steel can loose its hardness.

fespósito1 in reply to t.rohnerMay 18, 2012. 1:28 PM

Thanks!

coolbeansbaby68 (author) in reply to fespósito1May 17, 2012. 3:35 PM

Thank you for the comment . If the wheel wobbles then the bushings are bad in the hub.

fespósito1 in reply to coolbeansbaby68May 18, 2012. 1:29 PM

Thank you for the tip.

Ace Frahm says: May 17, 2012. 5:59 PM

Looks like if that blade ever catches on the wheel, it could fling right at you. How about a plexiglass shield?

The Lightning Stalker says: May 17, 2012. 10:57 AM

Can you spare any details on the gearbox?

coolbeansbaby68 (author) in reply to The Lightning StalkerMay 17, 2012. 12:35 PM

The grinder came like it is . Its a cheap harbor freight model . Look up bench grinders and you will see the one with the grinder stone on the side if it ..

pfred2 says: May 16, 2012. 11:43 AM

It is safe to assume you've never seen this?

http://www.tormek.com/en/jigs/svm140/index.php

I still want to clone the Tormek design for one of my grinders. I've done this for chisels and the like:

http://img37.imageshack.us/img37/1992/pict0241.jpg

I just got done sharpening a hatchet on the left side rest, worked great!