How to sharpen a marking knife

[ShawnE Curry]

I recently purchased a Crown Tools right hand marking knife used off of eBay. It looks like it someone tried sharpening it with an electric kitchen knife sharpener. Isn't it supposed to be flat on one side?

Thanks,
Shawn

[Malcolm Schweizer]

Yes, it should be sharpened flat on one side, and beveled on the other. Usually they have a point with an edge on either side so you can mark left or turn it to the other edge and mark right. I have also seen them with only one bevel and you buy two kinves- one for marking left, and the other for marking right. (or turn around and just mark the other direction on the other side.)

I do believe I have seen a Japanese marking knife that was double-beveled, which I can only assume would be for freehand marking where you are not butting up against the edge.

[Luke Dupont]

You can use a double beveled knife. Just angle the knife so that the bevel is vertical / straight up and down against your square, and ensure the square is covering the good side of the cut.

[Reinis Kanders]

I prefer double bevel for marking.

[Daniel Rode]

If you want to restore it back to a single bevel, I would grind the edge back flat until I erased the bevel on the back. Then I'd grind and then hone the edge until it was sharp.

[lowell holmes]

You can use a double beveled knife. Just angle the knife so that the bevel is vertical / straight up and down against your square, and ensure the square is covering the good side of the cut.

If you use a box cutter for marking, you angle the knife. That's how Paul Sellers taught us. I still use a box cutter. I have marking knives, but prefer the box cutter.

You can really use a knife wall to work to.

[Luke Dupont]

If you use a box cutter for marking, you angle the knife. That's how Paul Sellers taught us. I still use a box cutter. I have marking knives, but prefer the box cutter.

You can really use a knife wall to work to.

Yeah - that's what I was saying. I've actually been using a home-made marking knife which is double-bevel, made from a length of leftover bandsaw blade material. It's in the profile of a box cutter, and works wonders. I made it after watching Paul Sellers working with his knife

I think the bandsaw blade actually makes a wonderful marking knife, because it's exceedingly thin and hard. It meets *very* little resistance because its thickness. Granted, I had to sharpen it on diamond stones, as it would be far too hard for a file or, heaven forbid, a waterstone.

I think my next project, when I have some thicker saw blade material left-over to work with, will be to make a combination marking knife/awl that I saw on the Woodwright's shop (awl on one end, knife on the other. Just a flat piece of metal).

[Jim Koepke]

I like my marking knives flat on one side and the bevels on the other. Two of mine are made out of an old plane blade and one is made from a piece of old saw blade.

Shop Made Knives.jpg

I might give Luke's idea of making one from a bandsaw blade a try.

My first marking knife was made from a piece of an old kitchen/table knife.

A person can use just about anything for marking, become used to it and do fine work.

If it is comfortable and works, who can ask for anything more.

jtk

[Patrick Chase]

I think the bandsaw blade actually makes a wonderful marking knife, because it's exceedingly thin and hard. It meets *very* little resistance because its thickness. Granted, I had to sharpen it on diamond stones, as it would be far too hard for a file or, heaven forbid, a waterstone.

The part about waterstones here is blatant nonsense, as is the suggestion that they're even vaguely in the same class as files.

Conventional hardened-steel files can realistically be used on metals up to HRC 54 or so. There are some milled tungsten carbide files on the market that can go a fair bit harder than that, but they're pretty expensive.

With the right waterstone you can easily go up into the mid 60s HRC, which happens to be right about where the tips of the teeth of quality band saw blades top out. The bodies of bandsaw blades are and must be much softer than that, though, typically down in the 40s-50s ("must be" because very hard steels aren't tough enough to be cycled like a bandsaw blade).

You're fooling yourself if you think that knife is hard enough to require diamonds.

[Pat Barry]

The part about waterstones here is blatant nonsense, as is the suggestion that they're even vaguely in the same class as files.

Conventional hardened-steel files can realistically be used on metals up to HRC 54 or so. There are some milled tungsten carbide files on the market that can go a fair bit harder than that, but they're pretty expensive.

With the right waterstone you can easily go up into the mid 60s HRC, which happens to be right about where the tips of the teeth of quality band saw blades top out. The bodies of bandsaw blades are and must be much softer than that, though, typically down in the 40s-50s ("must be" because very hard steels aren't tough enough to be cycled like a bandsaw blade).

You're fooling yourself if you think that knife is hard enough to require diamonds.

Could be it was a carbide toothed bandsaw blade?

[Jeff Heath]

Could be it was a carbide toothed bandsaw blade?

It certainly could; more information would be required before summarily discounting the statement as "blatant nonsense." The concept of directly calling someone out without getting all the details, first, seems to be a bit counter productive to any thread, and also tells a lot about a person who seems to consistently need to have the last say on something....

I use carbide bandsaw blades from Starrett in my larger bandsaw, as I have my own sawmill, and never really know what I might find inside a tree of questionable origin. I rarely saw 4/4 with the woodmizer, and find myself resawing 8/4 or thicker stock a lot. Those carbide blades are expensive, and when they give up the ghost, I keep them for repurposing into other tools, just like this thread. A waterstone won't even make a scratch, but a diamond grinder and diamond hones sure do the trick. No blatant nonsense about that....

[Stanley Covington]

There are many different styles of marking knives. In function, most are either double beveled or single beveled, with variations thereof, and either variety can do a great job, or screw the pooch, depending on how it is used.

Here is a clever sharpening technique that was taught to me by a man that made a living for over 70 years with a marking knife, and was awarded a medal by the Japanese government for his lifetime contribution to the highest levels of Japanese traditional woodworking. He did amazing work; Some of it is in museums here in Tokyo. I suppose this technique would work for double beveled knives, but I have only used it for single beveled knives. It will definitely work for kensaki (spear point) style marking knives too.

Shape the marking knife's blade so it's cutting edge is at a low angle, perhaps 15-20 degrees from a square point. This makes it easier to keep the maximum amount of the blade's width in contact with the guide edge of the metal square or bevel gauge during the stroke, without riding up onto the square or bevel's blade, and while keeping the knife more upright during the stroke. This provides you greater control, and keeps the knife from running away.

Now for the tricky part. Drum roll please, Doc. After sharpening this cutting edge, stand the knife more or less vertically on a medium grit stone's face, with approximately 2-3mm of the cutting edge's tip hanging off the edge of the stone, and drag it towards you, totally dulling all but this 2-3mm of the tip of the cutting edge. One stroke should do the deed.

Did you say something? I was sure Honda san was hallucinating when he told me this all those years ago.

Strange as it may seem, these tiny details make a marking knife a more precise and obedient tool. The knife follows the guiding edge more faithfully, it shaves significantly less steel from the square or bevel gauge, and the depth and width of the lines it cuts are more uniform.

Give it a try... Your layout will improve and your steel square will thank you.

Stan

PS: When using your marking knife, it helps to stab the tip into your oilpot from time to time. You do have an oilpot, right?

[Patrick Chase]

It certainly could; more information would be required before summarily discounting the statement as "blatant nonsense." The concept of directly calling someone out without getting all the details, first, seems to be a bit counter productive to any thread, and also tells a lot about a person who seems to consistently need to have the last say on something....

I use carbide bandsaw blades from Starrett in my larger bandsaw, as I have my own sawmill, and never really know what I might find inside a tree of questionable origin. I rarely saw 4/4 with the woodmizer, and find myself resawing 8/4 or thicker stock a lot. Those carbide blades are expensive, and when they give up the ghost, I keep them for repurposing into other tools, just like this thread. A waterstone won't even make a scratch, but a diamond grinder and diamond hones sure do the trick. No blatant nonsense about that....

How would you go about making a marking knife out of a carbide-toothed bandsaw blade? (other than by removing the carbide teeth and using the soft steel body) I had actually thought that possibility through....

But yeah, point taken. I shouldn't have reacted like that.

[Luke Dupont]

I like my marking knives flat on one side and the bevels on the other. Two of mine are made out of an old plane blade and one is made from a piece of old saw blade.

Shop Made Knives.jpg

I might give Luke's idea of making one from a bandsaw blade a try.

My first marking knife was made from a piece of an old kitchen/table knife.

A person can use just about anything for marking, become used to it and do fine work.

If it is comfortable and works, who can ask for anything more.

jtk

Wow! That one in the center with a turned handle is stunning. Definitely share with us if you make another! I also like the blade profile. I was considering a single side bevel, spear-point style marking knife, but decided against it because I like a straight angle that allows me to hold the knife at a very low angle to the wood, as opposed to a higher angle that other profiles necessitate. Your knife has a rather acute angle between the edges, though, which would allow one to hold it rather low to the wood.

I guess a chisel-style blade is a possibility too. A square profile, with a bevel on three sides and a flat back? You could then have the best of all worlds: single bevel, ability to mark on either side of a square, cut at a low angle to the wood, and you could even pare to your line on the waste side without switching to a chisel! I guess you might want something thicker than a bandsaw blade for that design, though.

Do you find you have any difficulty with the single beveled knives digging into the side of your square, though? I hadn't considered that, but Stanley's comment brought it to my attention.

[ShawnE Curry]

Thanks for all the great replies! I ended up grinding it on my water stone freehand until the bevel was gone from the other side. The primary bevel was a very shallow angle so I figure it was supposed to have a secondary bevel and I worked both. After honing it cuts easily in any direction even in the end grain and turning long grain.

I can see the advantage of having a bevel on each side for left and right marking. I think I do like having the one side flat though - so I think I'd want to go with the spear-type if I decide to make one or buy another?