Mixed Metal Dividers

 This is probably not the best title for this post, but I guess it is descriptive. What I’m referring to are dividers and calipers where the upper section of the tool is constructed of one metal, typically brass, while the lower portion of the legs are formed of another metal, typically steel. An obvious question is why bother? Isn’t it easier to make the tool out of one material? I can come with three non-exclusive factors which might influence this method of construction and no doubt there are others.

1.     Brass, being softer than iron or steel, was easier to fashion into the relatively complex shape of the joint leaves, shoulders and often upper legs of the tool. This would not have required smithing and could be accomplished with a mold and hand filing.

2.     Steel or iron lower legs and points remained sharper than brass for a longer period and were less likely to bend.

3.     The upper and lower sections of the tool were separate and could be joined in different combinations. Longer or shorter legs being added later. This is probably the weakest factor of the three.

This construction technique appears to be more common in pre-nineteenth century tools, but does show up in later models as we’ll see. Let’s look at some examples.  

                                                  

A classic pair of map dividers (probably 17th century. 
The lower steel legs are beautifully tenoned into the upper brass legs.

  

 In the example below of an early 15” pair of friction dividers the lower legs are screwed into the upper section. This would have allowed legs of different lengths to be used on the same tool.

                                                    

 

In the two dividers below the steel legs are permanently inserted into the upper brass/bronze body

                                                   

  

Lt. Unmarked      Rt. Marked "Taylor & Drury Mfg. Co." c. 1974

   

 And below an earlier unmarked version using the same technique.

                                                 

The next example brings up a fourth possible factor in the development of this category of dividers: looks. The entire tool is constructed of steel and the brass facings on the upper legs are plates riveted to the steel core.

 

                                                   

         

Finally, a pair of English navigational dividers likely from the early to mid 20^th century. The tenoned lower legs are like what is shown in the 17^th century example shown above. The crossover shape allows the tool to be easily used with one hand. This style is available for purchase new today.