How to mark two knife lines?

[bill collier]

What is the most accurate way to mark two knife lines when what is important is the distance between the two lines? By accurate, I think I mean repeatable across several parts. For example, two identical boards that have tenons on each end with 12" between the tenons. During marking out I don't care how long the tenons are but the distance between tenons needs to be as close as possible to identical on both boards. In this easy case, I would try to line them up side-by-side based on the first knife line and then transfer the second knife line from the first board to the second. Does anyone have a better way? Being sure that things don't move around is my first worry. What about when the two boards are not identical? For example, a stepping stool with the legs attached to the top with through tenons. How would you mark the top and the stretcher between the legs so the distance between the legs is identical on the top to that on the stretcher?

[Chris Vandiver]

Standard practice is to mark both of the pieces at the same time. Don't mark one and then the other. Put them together appropriately and then with a square and a knife, mark them.

[bill collier]

What about wider parts, like shelves?

[Charlie Stanford]

What about wider parts, like shelves?

Put the shelves face-to-face and mark THE EDGES and then extend the marks across the faces.

Cheers,

Charlie

[Brian Thornock]

I would use a story stick, that will make it repeatable regardless of how many parts you have. Also makes drilling for running electrical wiring really simple...

[Jessica Pierce-LaRose]

Charlies right on - mark the edges first. If you find things slipping around a little too much, you can clamp the two boards in a vise this way while marking as well.

Often if I've got a chisel on the bench and not a knife, I'll mark a little tick on both boards by laying a chisel across the two boards.

If you end up in a spot where you have one piece that you need to mark another off of (maybe you marked two pieces and ruined one of them), putting a wide chisel in the knife line of the first piece and reaching a hair past helps make an accurate tick in the second piece to start marking from.

[Stanley Covington]

If the two lines need to be close together, a two-bladed marking knife is useful.

[Jim Matthews]

If I understand correctly, you're trying to get parallel pieces that are the same width?

Make the first, and mark the second off of it.
If you're cutting tenons, use the shoulder of the tenon as your reference surface for the knife to "ride".

If you're marking out longer pieces, clamp them together so there's no shifting.

If you rely on a square, story stick or any other intermediate measure there's always some degree of reading error compounded.
If you use one piece to mark the others, the positioning error should be constant, and the alignment retained.

When assembling cases (dry fit and glue up) I like to have 90 degree assembly braces to make sure I start and stay square.

[Jack Curtis]

I use a Kinshiro mortising marking gauge, which has two steel legs separately adjustable. Utterly reliable and precise, particularly since I use chisels and other stuff to set up the gauge.

[Jessica Pierce-LaRose]

If the two lines need to be close together, a two-bladed marking knife is useful.

Stanley - I can think of quite a few uses for those - any idea where to look, or what the name of the tool would be? The thought did cross my mind that my wife's real high end tweezers might "disappear" into the shop while she's away this weekend, but I hardly think that's fair. (Although they seem to be made out of some nice tool steel that would probably work fine for a knife; I should check who made them)

[Chris Griggs]

Joshua. LV and highland both sell them. They are sold as inlay knives. I would love one for layout to but they're like $65 and I haven't been able to justify it yet.

[Stanley Covington]

Stanley - I can think of quite a few uses for those - any idea where to look, or what the name of the tool would be? The thought did cross my mind that my wife's real high end tweezers might "disappear" into the shop while she's away this weekend, but I hardly think that's fair. (Although they seem to be made out of some nice tool steel that would probably work fine for a knife; I should check who made them)

This style of marking knife is a standard tool for joiners, especially for those making shoji and ranma that require many tiny mortises. The name translates best as "double marking knife" or "two blade marking knife" (二丁白引き or 二丁白書き).

Looking on the web, I see that Highland Hardware lists one. They call it an inlay knife. I have never heard of anyone using them for inlay, but why not?

http://www.highlandwoodworking.com/i...kingknife.aspx

I have not used this product so I cannot talk to its quality. This is the cheaper, less refined type, but it should be usable. The bow-legged stance and the screws and wingnuts sticking out all over make this style a bit clunky to use, especially for narrow mortices.

The more refined version is shown in my second jpeg. You can't tell from the photo, but the two tapered blades are joined at their tales by a solid rivet. After sliding off the rectangular steel collar, the blades can be rotated for sharpening. I haven't been able to find this one in an English language web retailer, but here is a Japanese one (the only one I could find, BTW). Again, I have not used this particular tool so I don't know about its quality. http://kanna-ya.net/sirabiki/ If you want one, send me a PM and I can check into it for you.

Twice the price, but for narrow mortice layout this style is vastly superior. The downsides are that its narrow stance makes it useless for laying out wider mortices, and you need to make a wooden shim/shims (postcard paper will work) to match the mortice width. Not a big deal if you use the tool a lot for only a few standard mortice widths, which is exactly the case for professional joiners of course. The tool stores here in Tokyo I have enquired at within the last year are out-of-stock and will not be getting any more in. I bought mine (made by Kiyotada) at Suiheya Tools in Tokyo about 28 or 29 years ago. Even back then, they were hard to get. If you want one, send me a PM and I can check into it for you.

Stan

[Mark Dorman]

That's good input . I have some sliding dovetails coming up and that is how I will lay them out

[Chris Vandiver]

This style of marking knife is a standard tool for joiners, especially for those making shoji and ranma that require many tiny mortises. The name translates best as "double marking knife" or "two blade marking knife" (二丁白引き or 二丁白書き).

Looking on the web, I see that Highland Hardware lists one. They call it an inlay knife. I have never heard of anyone using them for inlay, but why not?

http://www.highlandwoodworking.com/i...kingknife.aspx

I have not used this product so I cannot talk to its quality. This is the cheaper, less refined type, but it should be usable. The bow-legged stance and the screws and wingnuts sticking out all over make this style a bit clunky to use, especially for narrow mortices.

The more refined version is shown in my second jpeg. You can't tell from the photo, but the two tapered blades are joined at their tales by a solid rivet. After sliding off the rectangular steel collar, the blades can be rotated for sharpening. I haven't been able to find this one in an English language web retailer, but here is a Japanese one (the only one I could find, BTW). Again, I have not used this particular tool so I don't know about its quality. http://kanna-ya.net/sirabiki/ If you want one, send me a PM and I can check into it for you.

Twice the price, but for narrow mortice layout this style is vastly superior. The downsides are that its narrow stance makes it useless for laying out wider mortices, and you need to make a wooden shim/shims (postcard paper will work) to match the mortice width. Not a big deal if you use the tool a lot for only a few standard mortice widths, which is exactly the case for professional joiners of course. The tool stores here in Tokyo I have enquired at within the last year are out-of-stock and will not be getting any more in. I bought mine (made by Kiyotada) at Suiheya Tools in Tokyo about 28 or 29 years ago. Even back then, they were hard to get. If you want one, send me a PM and I can check into it for you.

Stan

These tools are most useful for marking across the grain, like when marking for the half-lap joints in komiko. They're quite tricky to use with the grain as it is easy for them to errantly follow it. I personally have never seen them used on Japanese timber framing(joiners work) but I have seen them used for shoji work and in tansu but always across the grain. It's a bit of a relic and not a common tool used in work today. It definitely requires a bit of skill to use. With the grain it's better to use a marking gauge of some sort.

[Stanley Covington]

These tools are most useful for marking across the grain, like when marking for the half-lap joints in komiko. They're quite tricky to use with the grain as it is easy for them to errantly follow it. I personally have never seen them used on Japanese timber framing(joiners work) but I have seen them used for shoji work and in tansu but always across the grain. It's a bit of a relic and not a common tool used in work today. It definitely requires a bit of skill to use. With the grain it's better to use a marking gauge of some sort.

Chris

Thank you for stating the obvious. They are called "marking knives" not "marking gauges" or "mortise gauges," so of course they are used for cross-grain layout. Of course, they are too small for timber work. Too small for most tansu work even. They are still a common tool used by at least one trade. As I wrote: "This style of marking knife is a standard tool for joiners, especially for those making shoji and ranma that require many tiny mortises." Any tool shop in Japan that sells mortise chisels will sell the first type of double marking knife along with mori nomi, sokozarai nomi, and kama nomi. This tool is also readily found on internet tool retailer websites, so obviously someone is still buying them. Of course, by definition, shoji have kumiko.

In my experience, the level of skill required to use one is not exceptional, but they do require one to pay attention to prevent them from wandering. Actually, the idea of using them for freehand or curved inlay work seems a bit daunting.