This one isn't exactly on sharpening but it does have to do with using abrasives on a tool blade so I thought I'd throw it in here.  This is a copy/paste from blog I posted on the other site a few years ago.


Here's a little background.

The Mora 164 Hook Knife is a blade that's purchased by many a budding spoon carvers. It's affordable, accessible and has the name of a reputable manufacturer of quality blades. You can't spit the words "wood carving knife" into the Google pool without the Mora 106 and 120 blades splashing back up in your face. And for good reason! I own both of them and they are excellent sloyd knifes.

When I decided last year to dip my toe into spoon carving, I did a good bit of research. What I found was that you basically have 3 options when it comes to purchasing a hook knife:

Option 2 was a no-go because I found nothing from experienced carvers to suggest that was anything but frustration and wasted money. Option 3 is definitely my preference. But, in this case, I didn't know if I would even carve a spoon beyond my first one so it didn't seem prudent to go straight to the top shelf. Another reason I didn't go with option 3 was that there are several options from most makers as far as size, sweep profile, left/right handed or dual bevel. Having never used a hook knife, I had no idea which options would suit me best.

So, option one it was! Morakniv makes two other hook knives that are double-beveled in addition to the 164. But from what I read online, that's just an invitation for many a sliced thumb so I didn't really consider those.

Here's my beef.

So I knew from what I'd read online that there were some issues with this knife that prevent it from being a choice for a lot of experienced spoon carvers. But, I got the impression that it was good enough to get a feel for the craft and that it was a solid, functional tool. I'm gonna call that debatable.

The knife does have a sharp edge out of the box. It's a beautiful knife with a beautiful polished steel like all Moras that I've seen. I love the oiled Birch handle which is like the one on my Sloyds that I'm so fond of. But, it just doesn't work for it's intended function very well IMO.

Now, like I said, I was dipping my toe so I had exactly zero experience with hollowing a bowl for a spoon before I got this knife. So I took it out of the package, checked the edge (very sharp), and dove right into a blank I had prepared from a green piece of Apple wood. It would cut and I could see how it worked. But wow, it took a lot of energy to hack out some chips.

I posted the issues I was having in a forum thread. I got some great advice including a link to a YouTube video of Jögge Sundqvist showing how to use the knife. That video was helpful because it clued me in to working cross-grain for hogging the wood out rather than working with the grain as I had been. That little tip was certainly helpful. But, it still seemed to me like I was working way too hard for ugly little chips.

In that thread, woodcox also posted this reply:

I saved those pictures and they are what eventually guided me to the solution I'll detail in a later post. Over the next several months, I attempted a couple of more spoons but never could make the hook knife cut satisfactorily. It's unfortunate that so many aspiring carvers purchase this knife because I can only imagine how many of them get frustrated and abandon the pursuit of the hobby because of it. Even in Basswood I could hollow a bowl and make it presentable but didn't really ever seem to be able to shape it exactly how I wanted and spent way too much effort trying to.

So, long story short (sorta), I came to the conclusion that there were a couple of issues with the knife that prevented me from being able to use it the way I wanted too:

In addition to these things which affect the functionality of the blade there are a couple of more issues I had with the general ergonomics. First, the back of the blade is blunt, coarse and has sharp corners.

Second, it comes to a sharp tip (REALLY sharp) at the end of the hook:

I noticed when I linked the Morakniv site at the beginning of this post that the pictures on there no longer show the sharp tip but show it being rounded off now. Apparently I wasn't the only one that was constantly jabbed and frustrated with it.
 
So, there you have it boys and girls. Why I bought this knife to begin with, how it worked (or didn't work) for me personally, and what I came to suspect were the root causes of the issues I was having with it.

 How I Improved it

I say improved vs. fixed because I think there are still some refinements that will help this knife work better but for what little I did, the improvement in function is remarkable.

As a short recap, the issues that I suspect to be the cause of the poor performance of this knife are:

So to start with, here is what I had:

First thing I did was to dye my blade up with layout fluid so I can see exactly where I'm removing metal and where I'm leaving it.

Next, with a 320 grit belt on my belt grinder, I begin lightly working the outside of the blade. My goal is to combine the cutting bevel and the bevel behind it into one continuous, convex shape to the back of the blade.

After a couple of light passes, the red dye shows me that I'm removing metal where I want to.

A few light passes is all it takes to get me where I want to go. There's still a slight hollow in spots where the secondary bevel was but, for the most part, I have a continuous surface from the cutting edge all the way to the back of the blade.

This is where I stop with the belt grinder. I find a piece of scrap Jatoba that has one side rounded that is a damn close fit to inside radius of the hook. I pulled a piece of 1000 grit wet/dry paper around the profile and tacked it with a couple of staples. I used it to work the inside of the blade to make sure it is flat.

Then I used the flat sides of the same stick to further refine the shape of the outside of the blade.

I switched the wet/dry paper to 2000 and repeated the process. After that, I rolled up a stiff piece of leather and put some polishing compound on it to work the inside of the blade.

Then I stropped the outside on a charged flat leather strop.

And this is no simple feat! This video from Pinewood Forge was a life saver and once you get the hang of it, it's not bad at all ;-)

Finally, I end with this:

It's kind of hard to see in the pictures but, I also rounded the sharp edges off on the back of the blade. Finally I rounded the stabby little tip off the end:

So, that's my quick re-shape of this blade. I decided to take it for a test drive on a Pecan blank I had roughed out:

And WOW, what a difference 30 minutes of work made. I could never get a bowl hollowed that nicely or that easily, even in Basswood, before using this knife.

So, it's a user at this point for sure. But knowing how much better it is now, I'll go back and continue to refine the blade. It's pretty smooth as-is but could definitely be polished out to a finer finish to help it glide through the wood better. But, I ain't complaining, I'm happy with what I've got now so if I don't ever touch it again other than to strop the edge it was well worth the effort!