Knives
What's the point?
I have a lot of tools. Way too many tools. In fact, for the 30-odd years (some of them a bit too odd) of my career, I've spent a goodly portion of my dough on tools of all kinds. Power tools, pneumatic tools, big tools, small tools, elegant tools, you name it.
But, when you get right down to it, I do most of my real work with some rather modest tools. Being a repair guy, I spend a lot of time with hand tools. I'd like to share some of my observations about knives, and a bit of technique, too.
First, here's a very popular knife:
It's the X-acto hobby knife #ll. As a kid, I made my share of wood models, and did lots of other projects with these little fellows. So, having grown up with this knife, it took me quite a while before I decided to put it down. Quite a few years ago, I noticed that I had abandoned the old X-acto completely. In fact, I don't use this knife for anything at all any more. Later, I'll talk about exactly why I've given up on hobby knives.
This is the knife I really use a lot:
It's my favorite. This knife is sold as a "violin maker knife" and is made in Germany. It comes in various sizes, and I use two of them. The big one pictured above has a blade 15mm wide by 2mm thick. That translates to about 5/8" x .080"
It's pretty hard steel, and the blade is sharpened on both sides with wide flat bevels which yield a low cutting angle, and a long sharp point. I try to keep from breaking off the slender point. . .
This is the smaller knife I like, the 8mm wide version of the German violin maker knife:
On this one, I've cut back the handle for a bit more clearance and a closer grip.
Most instrument maker knives have full length blades that are mounted in handles. That means they have a potentially long life because you can cut back the handle as the blade wears and is reground.
This is a part of my collection of knife blades I've tried and abandoned, or have yet to try:
The upper two are high quality American blades which are essentially the same as my German violin knife. The lower two are Japanese laminated steel, which is legendary for its keen, hard edge.
Just look at the cool brand, and the layers of folded, hammered, laminated steel:
It's the stuff of samurai swords!
Check out the cutting edge:
The multi-layered heavy part of the blade is a softer steel, but still quite hard. The actual cutting edge is super hard. The idea is that the softer laminated backing supports the brittle hard cutting portion so that it doesn't simply break off in use. Most Japanese knives are sharpened on one side only, and are flat on the other. They come in left and right handed versions.
In recent years the Japanese style chisels and planes have also become popular among fine woodworkers in the West.
The Japanese knife is another kind I've tried and abandoned. Why? Well, it's that damn hard edge. Sure, I suppose it should keep an edge much longer because it's harder, but for me that's just not how it works out. I can use one of the Japanese knives for only a few days before I make a curving cut into hard wood that causes the fine edge to shatter and crumble. Now, the blade doesn't really break off, but the very edge crumbles away, almost microscopically, resulting in a seriously dull and rough edge.
OK, enough for a while about the kinds of knives I don't use.
Here's my current collection of most-used knives:
At the lower left, you have my violin knives. These are the ones that really get a workout in my shop. Directly above them is a knife I made after I saw a live demonstration by Abel Garcia, a fine classical guitar builder from Paracho, Mexico. This guy can really handle a knife! So, I traced his "cuchillo" and made myself one just like it and mounted it in a handle. From time to time, I work with it, but I must admit, I just haven't warmed up to the curved blade yet. But then, it's only been a few years, and I get as stuck in my ways as anybody.
To the right, in front of my curved blade cuchillo, is a regular manual training type "utility" knife. I have this one in the drawer to use when I'm cutting open a box, or doing something that might injure my instrument knives. That is, I have it in the drawer, or on the bench, or somewhere. . .
The knife I actually use for utility is my pocket knife, which is always in my pocket when I need it. I've carried a pocket knife daily since I was seven years old, and I feel positively nekkid without it! This knife is a "whittler" style with three blades. In my case, that means three blades in varying degrees of sharpness.
This is a photo of me scraping a little hollow area in the foot of a mandolin bridge:
The curved blade is just perfect for the job, and I don't mind dulling the knife by using it to scrape ebony. In case you don't know this little bridge fitting trick, it's a matter of making the bridge "feet" slightly concave, so that they are easier to fit to the top by rubbing on sandpaper fixed to the face of the instrument.
The little "pen knife" blade is perfect for deburring and other rough jobs:
Here's a pocket knife buying tip: Go to a gun show. Gun and knife dealers usually have boxes of "user quality" knives which they sell really cheap. You can often pick up terrific bargains because the collectors are choking on quantities of non-collectible high quality knives by top manufacturers.
The knife at the top of the group photo is a special one. It's a Japanese knife used for splitting bamboo. I bought it because it looked interesting in the catalog and it wasn't expensive. I use it for splitting spruce patch material to avoid runout:
It works like a champ. I suspect, though, that any big old carving knife or cleaver would work about as well, and would cost about half a buck at a garage sale. . .
Sharpening is important, for sure. The only thing is, I don't really believe in wasting a lot of time trying to produce a perfect edge. As I use my knife, it becomes slightly duller and I have to accommodate that as I go along. I don't like working with dull tools, but I really don't want to spend all my time sharpening, either.
A I sharpen my violin knife, I try to maintain the acute cutting angle by holding the bevel as flat as I can while rubbing it across my oilstone. I have a full selection of Japanese water stones, but the reality is that the stupid old oilstone is in a covered holder the one that's actually ready for use, so that's the one I use more often. So, even though it's not as fine an edge, I get adequate results with my oilstone:
I'll give my knife a good going over with the water stones when I get around to setting them up to sharpen my plane blades.
Oh, all right! Most of the time, I don't even get out the oil stone. I'm always in a bit of a rush, so out comes the scrap of 1200 grit (or whatever) and I take a hike over to the bandsaw:
All my knives have really stout blades, especially when compared to the X-acto type hobby knife or scalpel. That's the real reason I don't use hobby knives any more. When my knife starts to get a bit dull, I start to push a little harder, and I can still get great results. I can't push hard with the hobby blade, because it bends or breaks, or loosens in the handle.
If I make a strong, curving cut with a hobby knife, the blade flexes, and "chatters" in the cut. While the hobby blade appears to be sharp, the cutting angle is not as acute, so it takes a bit more effort to push it.
Well, speaking of stout blades, take a look at this behemoth:
This violin bow makers knife has a one-inch wide blade that's a full 3/16" thick! It's completely flat on the back side, and is slightly hollow ground, but the acutal cutting edge is provided by a secondary bevel. The cutting angle is very steep, that is, not acute. In using this knife, the bowmaker slides the flat edge along the bow stick, and takes light cuts. Because it has a steep cuting angle, it is less likely to tear out grain, and operates almost like a plane. When curving the cut, this blade really stays on track. I bought just the blade and made my own ebony handle. Oh, yes, it was made by Daniel O'Connor of Kaufman, Texas, and cost me about sixty bucks.
The NEXT examples are from the article on repairing a broken Martin D-18 peghead with a "backstrap overlay."
Here's an example of a technique that would be impossible with a hobby knife:
I have my right palm braced on the vise jaw, and I'm using it as a fulcrum as I "lever" the knife with my left hand:
I'm able to shear through 1/8" mahogany and 3/32" rosewood end grain simultaneously, while maintaining good control:
Here's another one that just doesn't work with a hobby knife:
I'm using the knife a bit like a plane or spokeshave, by laying it flat along the wide bevel, so I cut only the high spots as I slice along.
The blade is so stiff it works really well as a small scraper:
To keep from destroying my sharp edge, I use the back side, which I occasionally flatten on the stone to produce 90 degree cutting edges.
Another leverage technique:
By planting my thumb firmly at the back edge of the knife, I can generate a lot of forward cutting power as I lever the handle backward. Because my thumb is anchored to the work, and I'm using a lever action, there's literally no chance of my knife slipping forward no matter how much force I use. I can carve right up to the edge with full force.
I often use a "paring" grip:
Now, I can pull forward quite vigorously, again with really good control. Notice that my thumb is well below the line of my cut. If the piece splits, or my knife slips, it will miss my thumb by a couple of inches. This is important stuff. I remember my mother cutting carrots into the stew pot by cutting directly against her thumb. Give her a really sharp knife and she'd cut herself! (It happened once.)
If I need to produce a little thin strip, say for a saddle shim, I can cut it easily with my knife. I'll get a much cleaner cut and I'll avoid setting up the bandsaw, or other power tool.
All I do is lay my steel rule along the edge in question and draw the knife over the wood with a long, clean stroke.
See how I'm holding the knife:
The idea is to hold it comfortably, and keep it vertical while pressed against the guide:
Chances are that my first cut won't go all the way through. I'll just draw the knife through the same path over and over until the cut severs the strip cleanly. It only takes a few seconds to cut through 3/32" maple.
Here's another one I learned from Abel Garcia:
It's an incredibly simple and easy to use guide for producing identical veneer strips:
Just a piece of hardwood - maple in this case.
I stab the fine point of my knife through at the appropriate location:
And the tool is ready to use:
I simply hold the veneer sheet on a thin work board, with the edge overhanging just a bit, and draw the knife and guide along the edge:
Here I have a piece of 1/8" thick spruce. I draw my knife firmly over the face of the board, and flip it over and repeat the process:
I'm not measuring, and I'm not using any guide. I keep the cuts aligned (sort of) by holding the knife down on the board, continuing the cut around the edge as I flip it over.
It breaks easily at the cut:
See, the cuts aren't really aligned at all, but it doesn't matter for this use:
It's easy to split off a chunk:
Here's another cut that takes too much force for the hobby knife to handle:
It's a hard push but a very easily controlled one. In one quick motion, I have a bevel on the end.
A more delicate bevel on the edge:
And I have a nice little rectangular reinforcement "cleat" that will clean up nicely with just a few strokes of sandpaper
While builders are turning more and more to "precision woodworking" with jigs, fixtures, power tools and even CNC machining, it's clear to me that in general the repairer is bound to be more efficient, flexible and successful with hand techniques.