Sumitsubo use

[James Pallas]

Derek Cohen made mention of using a sumitsubo and a centerline in marking out in another thread. I have an interest in centerline marking also. Not so much in the use of a sumitsubo but using a centerline. This is how I approach it. I only use it for shorter things like mortises. I use a 6” rule. I mark a center on the work with a .5 pencil. I then center my measurement on the line using the 1/32 scale. I then mark off the end of the scale with .5 pencil only allowing the lead to touch the scale not the lead holder. I then mark the opposing side in the same fashion. Mark another center and edges further along the work. Mark the edge lines using the scale. Your cut line will be on the inside edge of the pencil line. In my experience it is very accurate. Within 1/128” or closer. How do you approach using centerlines?

[Jim Matthews]

I use reference faces and edges.

As I understand it, centerline marking evolved for working with materials in the round.

[Tony Wilkins]

I use reference faces and edges.

As I understand it, centerline marking evolved for working with materials in the round.

or materials that were in the rough and didn’t need to be brought up to quite the level of accuracy that reference faces need.

[Jim Matthews]

My only familiarity with such marking is from Timber framing, where creating reference faces is impractical.

https://permies.com/t/42793/Line-Rule-methods-layout-Timber

[James Pallas]

Several areas come to mind. The angled and twisted tenons on some Queen Anne or Victorian chair seat rails. The front legs on demilune tables with square mortise into the curve. Curved handrail work.

[Jim Matthews]

I'm ignorant of those joints.

Are they not laid out "in the stock" before cutting curves? Otherwise, your likely to select lumber pieces without considering long grain orientation.

If stock is chosen when S4S, this method isn't more efficient and seems more likely to induce errors.

[Jim Koepke]

I'm ignorant of those joints.

Are they not laid out "in the stock" before cutting curves? Otherwise, your likely to select lumber pieces without considering long grain orientation.

If stock is chosen when S4S, this method isn't more efficient and seems more likely to induce errors.

Sometimes a project is being done without S4S stock:

433785

For some projects this piece might be left rough. In that case marking from a reference line might work a lot better than marking from an uneven reference side.

jtk

[James Pallas]

It pays to have lots of tools in your kit. To be confident in laying out from a centerline is just one of them. S4S is not always as good as you would expect. When working with rough you can save some by knowing if you can just squeeze what you need from the middle of your material.