Drawing Accurate Latitudinal Lines on a Box

[Steve Shelton]

I want to draw a grid on a turned box to make bead patterns on it. I can draw lines parallel to the axis of the lathe using an indexing jig, but I'm having trouble accurately drawing lines around the box (latitudinally). The lines will only be about 1 to 2 mm apart, so just using a ruler isn't accurate enough to give me visually equally spaced lines. Has anyone come up with a jig or other method to draw these lines accurately?

 

[Marshall Sadler]

Something like this spring divider from Craft Supplies might work. Set it once and off you go.
https://www.woodturnerscatalog.com/p/86/5931/Groz-8"-Spring-Divider?term=calipers

 

[john lucas]

I built a pencil holder that sits on a platform I built to fit the banjo. I actually built it to draw practice lines when indexing to both visually set a reference so I don't screw up when routing but also just to see if the spacing is right. Turns out it works great for drawing lines around a piece either with the lathe running or with it turned off. Too late now, I built is so the pencil is parallel to the floor. It dulls the point really fast. If you build it so the pencil points downhill it will actually sharpen the point if you rotate the pencil between each mark.

 

[hockenbery]

I would use dividers like Marshall. I buy really nice ones at amflea market where there are antique tool dealers.
I tell them I want some to use and they will pull out sets where the names are worn off an sell them at a fraction on the ones with clear printing.

The lines will be exactly that distance apart. The surface distance will vary slightly with the curvature.
You will get different lines if you start at the top, bottom or middle.
If for example you begin at the top you will have to decide how to stop at the bottom mane fudge the last three or make the last one uneven.