Posted by: Michael Keller Woodcarving | December 19, 2010

Woodcarver’s Proportional Caliper – Making and Using

When we use small figurines or clay sculptures as a model for a larger wood sculpture, a proportional caliper is a handy tool to make enlargements with.  However, there are a couple of  associated problems.  There are dang few manufacturers and the only good ones are a small fortune.

Varitas makes two sizes and they are more affordable than some but they are also more designed for turners than they are for sculptors or woodcarvers.  They have large arcs on each end that make them difficult to use on pure carving work.  Other brands are well suited for carvers but who can afford them?  I don’t understand how two little pieces of aluminum can be worth $200.00 and more.

One day in voicing my frustration with the caliper market to my wife, she said: “How hard can it be to make one, they look simple enough.”  So, I played with a couple of sticks and just got frustrated.  One problem was having to re-measure the sticks and hold them when I was trying to figure out the proportions.  Then I got a big “Ah hah.”

I drove off to my local Ace Hardware to buy a couple of yard sticks.  It turns out that they don’t sell them… they give them to you.  So, after a bit of trial and error, here is how to make a great, virtually no cost, proportional caliper for woodcarving:

1.      Acquire two identical yardsticks and read these entire directions before starting the project;

2.    Place one on top of the other and clamp them together with those little black paper clamps or a couple of small “C” clamps.  Leave them on;

3.    Make marks a 23 3/4″ for a proportion of 2:1, 26 5/8″ for 3:1, 28 ½” for 4:1, and 29 3/4.” for 5:1.  These are not machine shop precise but they are close enough for most woodcarving.  If you want proportions of more or less than any of these, they will be easy to figure out.

4.    In precisely the center of the yard stick drill 3/16″ holes at each of the above marks;

5.    Carve pointed ends on each of both yard sticks.  The points should be precisely in the center of the yard stick.  When the yard sticks lay on top of each other, the points should match up best as possible.  You are almost done;

6.    Acquire a 3/16 X 3/4″ (or so), two flat washers, and a 3/16″ wing nut.  I suggest wide washers.  Insert one washer on the screw and place it into a hole of your choice and place the other washer and wing nut on the other side.

My Caliper

Caution: Although, these measurements worked for me, I suggest that you test the measurements before drilling any holes in your sticks.  Testing can be done by using a small “C” clamp at the point of each of your marks, making them tight enough to hold the sticks together but loose enough to allow you to pivot the sticks.  Spread one end open to at least two inches (3 would be better) and test measure the opposite end.  If any point needs adjustment, make it before drilling any holes.

You are now in business!

As an “aside,” you can use a proportional caliper for reducing the size of something as well… such as copying a large yard piece and reducing it down to a table top woodcarving, etc.

Stay sharp and happy carving!

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  1. Thanks for your great and simple instruction for a very useful tool, and at hardly no cost. I was introduced to a proportional caliper at a carving school in Austria, Stubai made. Very expensive. I like your versjon better!

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