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

[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

[Stanley Covington]

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

Derek:

I was taught to use vegetable oil, but it goes rancid in a few weeks, so I have been using 5w synthetic motor oil for a long time now. The same oil pot is good for both lubing and rust-proofing tools, and the oil never hardens or goes bad. Mobile 1 has the best smell, IMO.

Mineral oil works very well too. I used to use Olde English lemon furniture polish, which is just light mineral oil with scent, but motor oil is cheaper and sticks to the tools better. I would avoid anything with silicon in it.

I use this same motor oil to lube the soles of my wooden planes too. At first I was concerned that a petroleum product might weaken, soften, or damage the wood, but it has not harmed them at all.

Perfect for saw blades, of course.

Stan

[mike holden]

Stanley,
I have tried searching for "oil pot" which gives me drug related accessories, "oil pot japanese woodworking" which gives me japanese tools, but no "oil pot".
What is this "oil pot" you refer to?
Picture please.
Mike

[Brian Holcombe]

Tokoname yakimono?

[Robert LaPlaca]

Stanley,
I have tried searching for "oil pot" which gives me drug related accessories, "oil pot japanese woodworking" which gives me japanese tools, but no "oil pot".
What is this "oil pot" you refer to?
Picture please.
Mike

How true, "oil pot" definitely brings up some "interesting" references from our friend Google... I would be interested in what a Japanese oil pot looks like also..

[Jim Koepke]

How true, "oil pot" definitely brings up some "interesting" references from our friend Google... I would be interested in what a Japanese oil pot looks like also..

Trying the term > woodworking bench oil pot < found this:

https://holdfastwoodshop.com/

Of course there are a lot of superfluous hits.

The concept is a simple one of having a way to apply a chosen oil to one's tools. My oil pots are actually rags.

A search on > roubo bench oil pot < finds some more relevant images.

My recollection is this was a topic of discussion a few years ago with many benches having a swing out attachment for the purpose.

My recollection is Roy Underhill made a small box with a sliding lock cover for holding tallow to serve the same purpose as an oil pot.

Here is one from Lost Art Press:

https://blog.lostartpress.com/2015/1...bo-grease-box/

jtk

[george wilson]

I think wandering problems might possibly be caused by using a marking knife with too thin a blade. I would not consider using an Exacto type blade. I have no trouble just using a sharp pocket knife blade. I never ever have used a marking knife. I don't think they are necessary. If I did want one,I could easily just make one,using 1/16" x 1/2" wide W1 or 01 tool steel,beveled on 1 side.

Sometimes I just use a wide enough chisel to span the dovetail. Hold it against the rule,tilting a little towards it. give it a bonk to seat it into the wood.

To tell the truth,most of the time I just use a sharp pencil. That can wander away from the straight edge too.

I have made a few different suggestions. Hopefully one will suit you. The very best thing to do is keep developing your skill with tools.

[Stanley Covington]

Stanley,
I have tried searching for "oil pot" which gives me drug related accessories, "oil pot japanese woodworking" which gives me japanese tools, but no "oil pot".
What is this "oil pot" you refer to?
Picture please.
Mike

Mike:

I started a new thread "The Essential Oilpot."

Stan