Patternmaker’s Tool Kit Revisited

At first glance the patternmaker’s tool kit might seem nearly identical to that of the furniture maker.  Scribes, squares, dog-leg paring chisels, marking gauges (of which this kit had more than a half-dozen) etc., are identical even though their uses may be a bit different.  But the tools are the same.

Even their differences might be chalked up to meaningless peculiarities, but they are not.  Here is a brief review of some if those items unique to patternmaking, or uses of typical tools for particular applications.

Shrink Rules/Scales

Especially at the industrial scale resides the inescapable fact that molten metals shrink when they cool and solidify, and the degree of shrinkage depends on the metal alloy in question.  For this reason the patternmaker’s kit includes a variety of precision rules that take shrinkage into consideration, and when a new pattern is commissioned the drawings are transferred to a full-scale master made on a new piece of hardwood plywood with the dimensions established by the shrink scale.  In other words if the item being designed is to be 12″ long, in true measurement it would be 12 inches plus some fraction, but all of the scale delineations are created proportionally.  Thus when we were making  pump shell patterns for dredging operations, our main business, sometimes those patterns would measure 6, 8, or 10-feet in diameter (or even bigger).  When cast in grey iron the patterns for a 10-foot shell diameter were actually 10′ + 10/8ths inches in diameter (10′- 1-1/4″) since the shrink rate for iron is 1/8″ per foot of dimension.  This issue is rarely a fundamental consideration for the scale at which I cast these days.  For example when calculating the shrinkage on the Studley mallet bronze shell, with an overall dimension in the neighborhood of two inches given the shrink rate of bronze as 3/16″ per foot, the mallet shell casting would shrink 1/6th of 3/16″ or about 1/32″.  Even though I will use a shrink rule to lay out the pattern, I could probably get by without it.  Once I get done casting the mallet heads I will be moving on to patterns for the Studley piano maker’s vise, and that will be large enough to use the shrink rule for sure.

Dividers and Trammel Points

Dividers are critical for transferring the shrink-layout dimensions to the pattern itself.  This speaks to the importance of the master layout, usually executed on a pristine piece of hardwood plywood, as patternmakers realize and generally live by the ethos that “measuring is the enemy.”  If you get the master layout correct it is a regular routine to use dividers and trammel points to transfer and establish all dimensions for constructing the pattern from the layout.  In fact once the master layout is completed the only thing I can recall using the shrink rule for was when planing the laminar sections for stack laminated construction that was the norm when I worked in the trade.  I think it is pretty much a dead trade, nowadays everything is done with compewders and CNC/3D printing fabrication.

Beveling Gauges

Tapered angles are a huge part of a pattern, particularly in the tapers of edges that are more-or-less perpendicular to the parting line,  This bevel is known and “the draft” and to my knowledge always resided around the neighborhood of 2-degrees.  Thus a machinist’s combination square set with a protractor head was used almost every day, augmented with a bevel gauge for transferring the draft angle to the table saw and sanding machines (see below).  I probably used my protractor head with a 24″ rule more in one week at the pattern shop than in the 40 years since.

Sculpting Tools – Inside (Gouges and Draw Spoons)

Whenever a pattern shape has to be derived by handwork rather than lathe work, the two tool types employed for working the inside curves were gouges, of which there were a dozen or more in the full kit, and draw spoons, usually numbering a half dozen in graduate sizes.  The gouges are peculiar in that they have interchangeable handles, shanks, and heads, and usually made from high-chromium steel with very thin walls, and several are in-camber.  These are pushing tools, not striking tools.

If you have followed my work on Gragg chairs you have seen frequent use of draw spoons for working the swale of the seat deck.  They were used in a similar manner for working for the pattern shop as large, sweeping interior hollows were shaped delicately with the draw spoon.

Sculpting Tools – Outside (Spokeshaves)

Virtually all of the outside sculpting was accomplished with spokeshaves, seemingly undersized by furniture makers but capable of really hogging off material when necessary, or feathering a finished surface.  Patternmakers usually owned and used at least a half dozen brass spokeshaves.

Fillet Irons

Another truth about metal casting and shrinkage is that whenever two surfaces meet at a right angle or anything near, the crisp inside corner needs to be filled with a cove molding to soften the transition from one plane to the other, otherwise the casting will crack at that line.  In my experience this cove was established by shaped wax sticks, called fillets, which were purchased in bulk as literal cove moldings in wax.  I recall many, many hours carefully heating both the polished steel ball serving as the anvil, and the long wax sticks, then pressing the warmed wax molding into the inside corner using the fillet iron of the correct size.

This set of fillet irons even came with a scribed pattern block for making scrapers for each iron.

If it went well there was very little scraping afterwards to achieve a perfect inside corner, other times required some shaping with home made scrapers, one for each size of fillet.

Fillet Cutters

In the days before my time in the foundry fillets were cut from the edges of very thick pieces of leather using fillet cutters to create the roughly triangular fillet.  These tools would be pulled across the edge of the leather sheet, usually along a straightedge, resulting in a cove-ish strip of leather to use as the fillet.   These leather fillets were applied using glue and brads, and the whole assembly was finished by heavy burnishing with the fillet iron.  I never had to use this method but since I have a set of the cutters and live in cattle country, come the zombie apocalypse I will be ready.





Core Box Planes

In the Golden Age of Foundries there was probably no bigger component of the industry than that of making pipes.  Think about the civic infrastructure whether on a single building scale or a national scale.  It was all made from or connected with pipes or pipe-like elements.  Making an outside sand mold to cast pipe-ish shapes is no big deal, all the expertise was applied to the problem of making a sand mold “core” to establish the cylindrical hollow insides.  For that process a special “core box” had to be made for each unique casting.  Often the shape of the box was achieved with core box planes, of which there were many varieties.


Some looked more akin to a set of hollows-and-rounds,


others were similar to the H&R set but instead of full body planes they had a single body with interchangeable soles and irons,

and undoubtedly the weirdest ones were metal frames with notched outriggers to ride on the outside of the core box and were equipped with ratcheting rotating cutting arms that advanced a few degrees around the compass to complete the half-core.  Oh, and these mechanical core box planes looked suspiciously like a Klingon warship.  There is yet a fourth version that is essentially a right-angle sole bisected by the iron, but I do not own one of those.  NB –  metal casting of almost any kind involves core box work regardless of the shape so long as the casting has a hollow configuration.


Power Tools and Accessories

Patternmaking since the mid-1800s has employed a variety of machines for fundamental work.  Included were power planers (I just use my lunchbox planer but if I did lots of patterns I would get my Mini-Max 14″ combination machine up and running) that could quickly and precisely dimension stock to the peculiar measurements required especially for stack laminated patterns, tables saws, disc sanders and oscillating spindle sanders to allow working to the middle of a cut-scribed layout line at a precise bevel angle usually 2-degrees.

If you follow my trek down the metalcasting road you will see all of these tools demonstrated over time.  Well, maybe not the core box planes as I have little intention of casting large pieces of iron pipe.

Stay tuned.

PS  I was wondering if I should make a start-to-finish video on metal casting, but I gotta get the Gragg video done first.