Traveling Narrow Pin Scribe Blues (Dovetails and marking knives)

[Prashun Patel]

I love my Blue Spruce marking knife. I love to look at it.

But when I try to scribe with it, it wanders. It is most noticeable when I scribe narrow pins on dovetails. It is hard (even with Brian Holcombe-style Dental chair illumination) to see the bottom of the pin socket through a tail board thicker than 5/8". This means I'm relying on the feel of my knife's registration to the socket wall.

When I remove the tail board, I find sometimes that the knife has wandered - and that's on end-grain. What gives? Any tricks? I've resharpened my knife so I don't think that's the issue; I think it's technique.

Did any of you have this issue while you were learning? And how did you correct it?

[Jim Koepke]

I do not make my joints with narrow pins.

What I have done is set the point of my knife at the base of the tail and lay it down where the edge of the tail meets the pin board. This puts more of the edge in contact with the surface to be marked and the blade is retracted with more of a pulling motion.

jtk

[Prashun Patel]

Jim, it's funny you say that. I am in the midst of a case that uses narrow pins, and I have been thinking the same thing... Like very thinly turned vessels, I appreciate the technical skill they take, but they don't feel any better in my hands or on my eyes than do thicker pins or vessels... This case calls for a bunch of drawers, which you can bet I'll be doing with wider pins.

[Derek Cohen]

Prashun, this is one of the reasons I use blue tape to transfer marks to the pins. The tails I cut are generally very narrow and there is little room for error. The knife has only to cut the tape. It does not have to score the wood. All that is required is a single, light stroke to slice through one layer of paper. A slightly flexible blade can be pushed against a wall. The edge must be sharp, of course.

Regards from Perth

Derek

[Patrick Chase]

I love my Blue Spruce marking knife. I love to look at it.

But when I try to scribe with it, it wanders. It is most noticeable when I scribe narrow pins on dovetails. It is hard (even with Brian Holcombe-style Dental chair illumination) to see the bottom of the pin socket through a tail board thicker than 5/8". This means I'm relying on the feel of my knife's registration to the socket wall.

When I remove the tail board, I find sometimes that the knife has wandered - and that's on end-grain. What gives? Any tricks? I've resharpened my knife so I don't think that's the issue; I think it's technique.

Did any of you have this issue while you were learning? And how did you correct it?

The technique that Stanley recommended here might be helpful.

What you describe happens for one of two reasons:

- The knife twists such that only its trailing edge is registered against the tail

- The knife tilts such that it's only registered against the top of the tail

In either case the result is a cut that wanders even though you think the knife is positively engaged on the tail.

Blunting the blade away from the tip as Stanley described allows you to press the knife (particularly its leading edge) against the tail with a fair amount of force without having to worry about it digging in.

[Prashun Patel]

I love these elegant solutions, Patrick. Thanks. That is exactly the problem I have. You wrote the technique very clearly and concisely. Thank you.
p

[Prashun Patel]

(OT alert): Any Zeppelin fans out there? Squeeze that lemon!!!!

[Malcolm Schweizer]

(OT alert): Any Zeppelin fans out there? Squeeze that lemon!!!!

Actually they stole....er... "borrowed" that from Robert Johnson's "Travelling Riverside Blues". Just giving credit where credit is due. By the way, back on topic, I totally am going to blame Prashun for the fact that I'm now going to try the blue tape thing. I hate the blue tape thing because- well- it's just not traditional, but if it works it works, so I'm going to try it. I do reserve the right to utter bad things under my breath about Prashun and Derek if it doesn't work as described. :-)

https://www.youtube.com/watch?v=ecwW2fX1Yew

[Brian Holcombe]

The blue spruce knife needs a rounded point. I like Stanley's tip of removing the cutting edge from all but the extreme point plus 2-3mm per side.

[Kirby Krieger]

Thanks for the link ... playing in the background. Never liked Led Zep ... always liked old blues. The question here is, how — and in what _exact_ way — is it apposite? Why here, and why now? Why blue?

I hate the blue tape thing because- well- it's just not traditional, but if it works it works, so I'm going to try it. I do reserve the right to utter bad things under my breath about Prashun and Derek if it doesn't work as described. :-)

So here's the same question in another form: do you want to _work_ like "they" did — or do you want to _think_ like "they" did? Only one of them is authentic, imho. The other is just another of the endless productions of Vaucanson's Duck.

[Pat Barry]

Actually they stole....er... "borrowed" that from Robert Johnson's "Travelling Riverside Blues". Just giving credit where credit is due. By the way, back on topic, I totally am going to blame Prashun for the fact that I'm now going to try the blue tape thing. I hate the blue tape thing because- well- it's just not traditional, but if it works it works, so I'm going to try it. I do reserve the right to utter bad things under my breath about Prashun and Derek if it doesn't work as described. :-)

I never heard the Robert Johnson version before and likely no one else would have either were it not for this apparent tribute from Robert Plant so borrowing maybe true but stealing not -- at least according to Wikipedia since it seems Mr Johnson 'borrowed' the same from someone else himself.

[Jim Koepke]

I never heard the Robert Johnson version before and likely no one else would have either were it not for this apparent tribute from Robert Plant so borrowing maybe true but stealing not -- at least according to Wikipedia since it seems Mr Johnson 'borrowed' the same from someone else himself.

Not sure I ever heard the Robert Plant version. My interest in Robert Johnson began with a movie, Crossroads (1986) with Ralph Macchio and Joe Seneca. Then there was that record store in El Cerrito, CA.

jtk

[Lenore Epstein]

The blue spruce knife needs a rounded point. I like Stanley's tip of removing the cutting edge from all but the extreme point plus 2-3mm per side.

Here's a video of Dave Jeske of Blue Spruce demonstrating how sharpen and how to then round the tip of the blade. Even I was able to do it, and I'm not able to freehand anything yet!

[Stanley Covington]

I have mentioned this repeatedly, but it is worth saying again. If you want greater precision in both your layout work with edged tools (marking gauges and marking knives), and joint cutting work (chisels and saws), use an oilpot. The oil reduces the wood's grain's ability to drag, pull, and misdirect your tool away from the line you want to cut. This gives you greater control.

This was another one of Honda san's lessons.

[Derek Cohen]

Stanley, that is a very nice tip on the oil. I always wax my planes and fences, but never thought to oil chisel or plane blades. What oil do you use/recommend?

Regards from Perth

Derek