Fig.1 The Fulwood Measure from Kissimmee River Pottery (www.kissimmeeriverpottery.com) is an example of a Western pot gauge. When the rim meets the hinged pointer, it folds out of the way.
More than likely you’ll get to the point where
you’d like to throw multiples of an object. Getting work to look the
same when making more than one of an item takes a bit of practice
because it’s not as easy as it looks! To help assure you’ll get some
sort of consistency on your next set of mugs or bowls, you need a
throwing gauge—a way of keeping track of the measurements from the
first piece to the last. There are several options for throwing gauges
based on designs from both eastern and western cultures, as well as ad
hoc solutions that use items around your studio.
The Western Pot Gauge
Production potters in Europe and America have used throwing gauges for centuries. These usually consist of an adjustable arm on a metal or wooden stand. The arm adjusts in and out as well as up and down for both diameter and height measurements. An example of the Western pot gauge is the Fulwood Measure (figure 1), which features a hinged pointer that breaks away when the clay touches it. Another variation, though not as fully adjustable, can be made from a wood block base drilled at intervals with holes that dowels can slip through. Several dowels can be used at the same time for more complex forms (figure 2).
Fig.2 The tombo measures the inside depth and width of a form. Two sources of tombos are Bamboo Tools (www.bambootools.com) and Chris Henley at http://hominid.net/toolpage2.htm.
The Japanese Gauge
The Japanese developed a throwing gauge for making duplicates that
measures the inside dimensions of a form, unlike the Western gauges
mentioned above, which measure the outside dimensions. The tombo (which
means dragonfly in Japanese) works well for throwing matching cups,
mugs and bowls. Shaped like a lowercase “t,” it consists of a thin
vertical piece of wood or bamboo that has a small hole or holes bored
through it to accept a stick or dowel. The tombo is held by the top of
the vertical stick. The length of the horizontal stick represents the
diameter and the vertical length below this stick measures the depth of
a vessel. The disadvantage of tombos is that they’re not readily
adjustable. On the other hand, they are relatively inexpensive (and
even easy to make), so potters usually have several tombos in their
collection. Another advantage is that tombos can be used for throwing
off the hump.
If you’re just throwing a set or two, you can get by with an improvised tool. When height is not a factor, calipers, a ruler or a marked dowel work well enough to get plates and platters to the same diameter. If height is a factor, as when you’re making cups, mugs and bowls, you’ll need to take an additional measurement and keep track. You can improvise a basic throwing gauge that works for both height and width or throw a piece that you want to duplicate, then set a lump of clay that’s taller than your piece on the wheel worktable and stick a dowel sideways through the clay, so it is perpendicular to your wheelhead at just the right height. Position the dowel so it just touches the rim of the piece you threw.