To accomplish this, they would most often use a straight pin in a pin vise, or a homemade device consisting of a very small gear, from a watch or clock, mounted in a wooden handle.

Today, we have a much simpler and faster method. Available at fabric or craft stores, and on the web, an Excel Ponce Wheel (see fig. 1) allows you to easily run a quick line of nail impressions down a wooden, cardstock, or thin styrene wall.

Ponce wheels are used by sign painters, tailors, and seamstresses to transfer the lines from paper patterns to whatever material they were cutting or painting. After punching the holes in the pattern with the ponce wheel, they would use chalk to make the pin holes visible on the underlying material. The ponce wheel has been around for years, and more recently is being used by modelers.

The Excel Ponce Wheel handle feels just like a standard hobby knife in your hands, and the wheel spins freely. By tightening the collar (see fig. 2), you lock the wheel in one position - or you can leave it slightly loose, which allows the wheel to easily follow curves, without rotating the handle.

The points on the Excel Ponce Wheel are actually little squares (see fig. 3) which, as you would expect, create slightly squared impressions. This is a minor issue as the shape of the impressions is altered by the swelling of the wood once stain is applied. In addition, when looking at a painted, weathered, and finished structure from a foot or two away, it is very difficult to tell the shape of the nail impressions.

My standard procedure is to tape the wall down to the cutting mat on my workbench. This allows me to concentrate on holding the straightedge in place, without worrying about the wall moving underneath it. Using a pencil, I make light tick marks at the top and bottom of the wall, a scale 24” apart. It is then easy to align the straightedge with the tick marks and, with medium pressure, slowly draw the wheel down the straightedge, lifting where windows, doors, and other openings intervene (see fig. 5).

Before staining, I add a few vertical cuts and use a pin vise to add matching nail impressions to represent where individual boards end (see fig. 6).

The Excel Ponce Wheel actually breaks the surface of the wall material, and allows whichever stain you use to be absorbed by the fibers (see fig. 7). You can continue applying the stain, vertically connecting the impressions, which represents the rain washing rust from the nail heads down the wall. If you use chalks, the powder will collect in the depressions, highlighting them as well.

Prototypically, this method also slightly highlights the position of the underlying studs. Another method to highlight the impressions is to use a lead pencil to mark each impression, but I feel this makes the nail impressions too obvious.

As usual, it is best to practice on some scraps of wood to find your own preferred method.

Pros:
- Nice, evenly-spaced indentations.
- Easy to control the depth by varying the thickness of your straightedge.
- Faster than impressing each individual indentation with a pin or a brad.
- Less hand strain.

Cons:
- Indentations are not truly round.
- Indentations are too evenly spaced to represent hand-driven nails.
- Depth of indentations is too consistent.
- Difficult to use where only one or two impressions are needed.
- If your straightedge moves, or your hand slips, it looks like the carpenter was drunk.

Specifics:
- Model 30606 (for HO scale)
- 5” long 5/16” diameter
- Handle has a locking swivel that allows you to freely rotate the wheel support, or lock it in a set position.
- Approximately 21.5 teeth per inch
- Price Range: $6.00 - $8.00
- A slightly larger wheel with fewer teeth per inch is available for “O” and “S” scales.
- http://www.excelhobbyblades.com/

Just a quick note. You will notice that these are often referred to as “Pounce” wheels, but the proper term is “Ponce”.