Trammel Points - Overgrown Dividers

Trammel points or beam compasses are typically used to measure distances between points or scribe a circle that is beyond the reach of the legs of large dividers. They are used in conjunction with a beam to which they attach that can be of any length. Collecting trammels is a focus unto itself, but since they are related to dividers, the primary focus of this blog, I’ll mention a few variations from my limited collection.

The earliest trammels were likely made of wood and clamped onto a wooden beam which might be graduated or unmarked. One trammel head was usually fixed in place at the end of the beam while the other could slide along the beam a desired distance and be clamped in place with a thumb screw. The tips of the trammel heads were sharp metal points. These wooden tools were typically craftsman-made.

                                                                             

Two head wooden beam compass on a 32" beam with fine adjustment

 

                                                                        

Three head wooden beam compass on 28" beam; possibly for making elipses?

Nineteenth century and earlier cast brass trammel heads with steel points are often ornate and finely crafted, much in the manner of fancy plumb bobs. They are often attached to a short piece of wood, the keeper, separate from the beam. This makes them very portable, as a beam was often fashioned when needed out of scrap wood. One of the pair of trammel heads often provided a means for attaching a pencil or other marking device. There is often a brass shoe under the attachment screw which presses on the beam (below left). This piece is easily lost.

                                                                        

           Left: Unmarked, likely Edward Preston, Birmingham, England.    Right:: Marked "Bumidge"                                   

  

Machinist's and architect’s beam compasses were offered by all the major machine tool companies and can be quite complex with a fine adjustment mechanism and exchangeable points that allowed them to be used for large-scale outside and inside measurements beyond the reach of calipers. Some, such as those offered by Stanley, could be attached to straight or folding rules.

         

Left: Dietzgen #646, unmarked    Right: L.S. Starrett #89A, with cone center and coupling.

                                                                                                          

    

Spring Dividers and Calipers

Of the three broad categories of dividers and calipers: friction, wing and spring, spring (bow) dividers were likely the last to be developed. Within this category there are three major versions:

1.     Lancashire pattern

2.     American pattern

3.     Bent wooden 

The earliest example I could find of what appear to be spring dividers is from a plate in Maya Hambly’s excellent book Drawing Instruments, 1580-1980. The plate is from a treatise by Nicolas Bion first published in Paris in 1709. 

                                                   

Nicolas Bion 1709   Note "C"

 The earliest of the three major versions is the classic Lancashire pattern, where the flattened spring joint is integral to the legs. A bar or wing passes through the legs and a thumb screw adjusts the separation of the legs by working against the spring tension. 

                                                   

Large example is a very uncommon size. Both unmarked.

 This style was likely first developed in quantity in England in the late 18^th or early 19^th century. Martin J. Donnelly states that the firm of Peter S. Stubs of Warrington, Lancashire, England was the first to offer this pattern. German firms (e.g. H. Boker) and, no doubt, those of other European countries also produced them. Boker exported many of his tools to the U. S.  Salaman (Dictionary of Woodworking Tools) states that German-made examples can be identified by a ridge (faint) along the top of the spring bow. Spring dividers of this type are uncommon among U.S. makers except for those of Joshua Stevens Co. 

                                                           

Left: H&R Boker.   Center: Marking illegible. 
 Right: Unmarked

Spring dividers of the “American” pattern have a separate, circular spring joint which notches into the top of legs close to the joint. These are by far the most common calipers and dividers seen for sale today as the have been a staple among machinists for about 150 years. They are the focus of many U.S. patents during the late 19^th and early 20^th centuries. Many of the patents deal with the adjustment nut and involve quick-release variations. I’ll mention and show a few patented examples from my collection, but later spring dividers are not a focus of mine.  

I  believe the first U.S. patent for spring dividers that were actually manufactured is that of Edward Wright granted on Sept. 24, 1867 (# 62,292) and manufactured by L. W. Pond, Worcester, Mass. DATAMP lists the manufacturer (later) as Wright Machine Co., also of Worcester. 

                                                 

Marked with both 1867 patent date and Pond, manufacturer. 

 

T.C. Page and G.W. Hadley patented an interesting double-loop spring caliper on Feb. 8, 1870. This example was produced by J. Stevens & Co. The smaller inside caliper on the right is unmarked and uses a simple, single loop, but the adjustment system is similar and can slide up and down the legs.  

                                                 

Left:" J. Stevens & Co., Pat. Feb. 8, 1870" Right: Unmarked.

The J. Stevens Co., after 1886 the J. Stevens A(Arms) & T(Tool) Co., Chicopee Falls, MA, offered a wide range of machinist tools during the late 19^th century including many dividers and calipers. The tool division of J. Stevens A&T was sold to L. S. Starrett in 1903. Starrett went on to carry many of the Stevens' models.

                                         

Marked J. Stevens A&T, Pat. Feb. 14, 1888.

The L.S. Starrett Co., Athol, Mass. was and is one of the largest producers of machinist’s spring dividers and calipers. Below are just a few of the many tools utilizing patents that Starrett acquired or granted to Laroy S. Starrett himself. Dividers and calipers with round or square legs were generally more expensive than those with flat legs.

                                        

All marked Starrett. The small one is only 2".

 Below are two examples of F. I. Blake & M. D. Reidy’s Apr. 13, 1915 patent, manufacturer unknown, which utilize a simple adjustment system.

                                          

Left: Marked Pat. Apr. 13, 1915.
Right: Unmarked

 On Jun. 30, 1914 Emory Ellis received a patent for spring dividers and calipers that used an interesting adjustment system. The notched bar was used as a quick adjustment and the knurled end screw allowed for a fine adjustment.

                                          

Marked: Union Tool Co. Orange, Mass. USA  and Patented June 13, 1914.

                          The marked date does not correspond with the date the patent was granted

More recently produced spring dividers often utilize a threaded rod that passes through both legs with a center wheel adjustment screw. Most of these are drafting compasses. 

                                          

Marked: Tacro Inc., Germany

The last major version of spring dividers are made of wood where the thin arched bow top provides the force to pull the legs apart. A wing or centered wooden screw pulls the legs together and holds them in place. It is conceivable that this technique could  be the first type of "spring" dividers. The bend in the wood is usually achieved by steaming the wood. These tools are uncommon, as the bent hinge section often dries out and splits. I’m not aware of any dividers of this type that were made other than by craftsmen.                                      

                                                          

Left: A classic French cooper's dividers

                                                             Right: craftsman-made