Sharpening a Crook Knife (Mora 164)

Hi all,

I am planning to try making a small wooden spoon, and plan to order a crook knife to help with this. The Mora 164 is locally available locally.

Looking into how to get it sharp I found the following tutorial from Cariboo Blades:

http://www.caribooblades.com/crookedknifesharpen.html

The steps they show are: 1) Flat stones 2) Sandpaper on a cylindrical stick 3) Leather with honing compound on a cylindrical stick

It looks interesting, and I was wondering, could I use my flat Translucent Arkansas as a finisher before stropping on plain leather on a cylindrical stick?

Any other info would be great, unfortunately I can't get onto youtube here in China.

Hi Russell,
the Mora 164 is sold as a single-bevel blade; it is only sharpened on the outside of the curve, so if you want to use it as the factory made it, you'd only really need flat stones/ surfaces and rotate it as you sharpen it, sort of like a large out-cannel gouge (blade perpendicular to the length of the stone, one end of the bevel on the stone, then push/ pull with the edge trailing, rotating the knife end over end 180 degrees). The dowel would still come in handy for honing/ polishing the wire edge from the inside, but you'd only need to put honing compound on the bare wood - no sandpaper.

There are plenty of complaints, mostly on 'bushcraft" forums, about the way the knife is ground from the factory and people either make it a double-bevel knife (beveled from inside and ouside the curve) so it would be sharpened as you have seen on the cariboo site plus using flat surfaces on the outside. Other have had more success with just rounding off the sharp top edge of the single bevel (where it transitions to the flat of the knife, near the spine) so you can get the approach angle of the blade edge lower and take a finer cut. That is what works best for me, but I use gouges for the initial deep scooping of the bowl, then use the bent knife to make smooth finish cuts. At the price of the Mora 164, you could get two and shape the bevels differently - the double would probably work better for deep shaping. Of course, using any knife is going to be a little slower than using gouges, and i think some of the complaints sound like they expect to scoop the whole bowl out in one big cut instead of the reality (like any carving) of rough cuts, then shaping, then fine smoothing cuts. Have fun with your spoon-making- you ought to have access to some really interesting woods over there.
Karl

Thanks Karl.

I've ordered the knife online and when it arrives I'll make a decision about how to have the bevel. As I am a fairly novice sharpener, I lean towards maintaining just the single bevel at the moment.

One more question if that's OK: Would I need to strop the single bevel on undressed leather, or do I just sharpen with the stones, then remove the wire edge with a dowel and compound?

Russell,
I use a stone to hone, then strop on a leather strop glued to wood with green compound on the strop. I use a loose piece of leather with compound and just wrapped around a dowel to work the wire from the inside, alternating inside and outside a few times to get a clean edge. After that, during use, I tend to strop it just on the flat strop to keep it sharp, as i do for carving tools. It works great for me with these knives - you can try it without compound, it might work just as well. The steel isn't terribly hard, so should respond to a variety of methods.

Thanks again, Karl.

I'd like to copy your method as closely as possible, so can I check I've understood it properly?

1) Hone the bevel on a stone, rotating the handle and pushing the blade across the stone in a fluid motion.

2) Strop the bevel on a flat leather strop treated with a CrO honing compound. Here the motion is moving the edge backwards, a trailing stroke.

3) Use a dowel wrapped in leather with compound to remove whatever is left of a wire edge.

4) Repeat step 2) as you work.

5) Eventually, the stropping will round the bevel and reduce sharpness, at which time one should hone with the stone again.

Any feedback would be great.

Btw, you mentioned the woods available here, I've picked up some scraps of a quite nice red-brown wood that may be good for carving, and I should be able to pick up some rosewood scarps for free. The rosewood I've seen before though is mega-dense, probably not suitable for me.

Hi Russell,
You're welcome; I'm sure this will get you started and you can modify if needed as you go. The important thing is to get carving and enjoy it. You've outlined the steps i use pretty well; I don't think you'll need to use the stone too much initially - Mora knives are normally well-sharpened when you get them, might just need the strop for putting a razor edge on it.

Regarding how often i go back to the stone - it helps curb any dubbing or rounding at the edge to go back and lightly stone it periodically - i do it about once every 2 weeks if I'm carving spoons regularly (1-2 hours per night) and i strop about once an hour. if you're using dry wood, you may need to hone and strop more often - just pay attention to the quality of your cuts - if you're going across the grain and start getting fuzzy cuts or tear-out, time to strop again. I do most heavy cutting while the wood is wet - the knife can be a little duller during this rough stage - but when it starts drying it gets tough and sharpness is key to enjoyable results.

As for your wood; if you have any Chinese woodworking or arborist friends, you may want to check with them to see if certain unfamiliar woods may be toxic before you make a spoon from it. Not to be paranoid, but you don't want to get told 'everyone knows you don't ever put qua-ming wood in your mouth" in an emergency room. Rosewood would be a challenge, but I've seen some bamboo "tea sets" (Japanese-style; whisk, stirrer, small spoons) that would be relatively easy to do with shallow shaving cuts. I'm not sure if rosewood is known for causing sinsitivity or not, though; some resinous woods do.

have fun,
Karl

Cheers Karl.Yeah, I totally agree about the toxicity issue, the mystery wood would only be used for practising using the knife. I like the idea of using some bamboo, it's very abundant here.My 164 should arrive this week some time, so when it comes I'll try giving it a strop. Any tips for maintaining the correct angle while stropping a crooked knife? I'm gonna pick up a basic stropping board and compound from a local leather-worker's shop.

Hi Russell,
you shouldn't have trouble finding the angle with the wide, flat bevel on the knife blade - I put a finger right behind the center of the bevel and press down; that keeps it riding on the bevel. look at the blade, though - if they put a secondary bevel on it, you'd just have to find the primary as above, then lift a little bit more. It's just a medium-pressure polishing action for half a dozen strokes or so; if you do so and it isn't close to shaving arm hair, do a little more. Having the extreme curve in the blade makes it more tricky, but you'll get the feel for how it is "dragging" on the flat part, then when you bring the handle over it should have similar resistance. You should be ready to carve pretty quickly, then just periodically maintain your edge.

Hi Karl,

OK, great, now I feel confident to strop it when it arrives. I'm probably gonna get a Mora 120 to go with it and with those two try to make a spoon.

I don't want to repeat myself too much, but thanks again for your taking the time to help me :)

Hi again,

Another question - I have a horse leather strop designed for straight razors here at home, but it's not 100% flat (slightly 'dished'). Would that be a problem for stropping my knife with honing compound? I also picked up a cheap veg-tan leather strop here in Shanghai, but later found it has a slight hump in the middle.

If this would be a problem, I could just try:

- Hone on a fine stone
- Work burr with dowel wrapped in leather charged with ultra-fine compound
- Strop on untreated strop

Also, what could count as a dowel? Could I just chop the end off a bamboo chopstick (slightly tapered cylinder)?

Sorry for so many questions, but I want to give myself the best possible chance of getting it right, especially as I have no teacher to rescue me if it goes wrong:o

OK, first thing is, nothing can go that wrong that you'll need to be rescued, so relax a little - save the energy for carving!

I don't think a slightly dished strop woulde be a problem, nor would a humped strop (is it glued to a board and still humped?), especially for the hook knife, since for that knife, at any time during your stropping stroke, only a narrow portion of the blade is in contact with the strop. If the dishing is pronounced, you can still use it for the flade bladed knife, you just work whatever portion of the blade is in contact with the strop and slide the knife laterally as you move it down the strop. It doesn't need a lot of pressure, just a bit of firm down pressure to allow the strop to polish the bevel and remove any wire edge.

for a dowel to work the inside of the hook knife, i think a chopstick may be too small in diameter; just use a dowel about 1-2 cm in diameter - or even a stick will do if it's relatively smooth. You can wrap a piece of charged leather around a stick or use fine sand paper - it will be just a touch of work with this to reverse/ remove the wire edge.

Thanks for the reassurance. Today I had a try at the stropping motion on plain leather and managed to find a natural motion. I put my right finger on the back of the blade as the left hand held the handle (the opposite as for honing on the stone).

I've ordered some 0.5 chromium oxide paste from a Chinese company, that should do well as a stropping compound.

I'm actually on a 2 week trip to the mountains and countryside from tomorrow, with any luck I may be able to come back with some green wood to carve :-)

Hi Karl,

I just got back from a holiday away from the internet. I picked up some chestnut wood that was cut about 2 months ago to make way for an oil pipeline. It seems to have been a 7 year old tree. I'm gonna try carving that.

As for the stropping, I'm gonna order some pure 0.5 chromium oxide paste. I've practised the motion on the undressed strop, with the handle in my left hand and my right index finger on the back of the blade, and I think I should be able to get decent results.

The blade arrived unsharpened (checked around the web, apparently quite common) so I'll have to run it over the stone first.

This should help with stropping.

https://www.youtube.com/watch?v=j4KS0IYF938

I got a Mora 164 last week. The bevel was sharp, with a slight hollow grind. It honed well, but later when I sharpened it, the bevel became slightly convex and the new required angle no longer sliced wood, stuttering through it instead. As has been noted by others, the bevel angle of this tool is too steep. I tried to rework it with a coarse diamond stone, but too much metal had to be removed. I considered ordering a proper hook knife, but Pinewood Forge has a long wait presently, worth it but still delaying my carving for perhaps 2 months. Additionally, "if you can't sharpen you can't carve" stuck in my mind. I envisioned getting a fine knife and then screwing up the later necessary sharpening.
First I ground a new much more shallow bevel on a 60 grit belt of a portable sander mounted upside down in my vise. Then I used PSA sand paper of 240, 400, and 800 grit on wood slips, clamping the knife in a vise and using Donegan binocular magnifiers and a LED lamp for accuracy. I could see what was happening to the helical knife edge. It worked well and the Mora is and will remain satisfactory. I'll not mention the failures except to note that the virtuoso sleight of hand rotation of the blade on a series of waterstones was way beyond my skills.