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H.O. Studley Calipers Project (Metric Register Calipers)
H.O. Studley Calipers Project (Metric Register Calipers)
If you are a lover of fine woodworking and antique tools, and are not already familliar with the H.O. Studley tool chest and work bench, I strongly recommend a cursory internet search for his work, and acquiring a copy of "Virtuoso: The Tool Cabinet and Workbench of Henry O. Studley" by Lost Art Press, a phenominal tome exploring it. A Boston piano maker around the turn of the 20th century, Henry O. Studley's impressive working collection of hand tools is perhaps only eclipsed by the gorgeous mahogany, ebony, mother or pearl, and ivory wall-mounted tool chest he built to house them. It is nearly impossible to gaze upon this work without a certain sense of wonder, which has spread like a wildfire across woodworking and tool collecting forums and circles.
Many of the tools Studley amassed, made himself, or customized have given collectors and users (including yours truly) cause to burn up the lines and wireless waves hunting down similar tools for themselves. His organization of his tools has also inspired many (again, including yours truly) to give more thought to how their own tools are housed and displayed. The storage and preservation of fine tools is as much an art as the objects themselves, and certianly worth consideration.
Studley's tool chest has also been viewed by all who have come across it with unique sets of eyes, and certain details or tools seem to come to the forefront for each viewer. One tool that particularly caught my eye was a small, unusual (by modern standards) set of calipers hanging on a custom fit holder just left of center on the right tool box pannel. A little research turned up that these were referred to as "register calipers", that is, having a scale present to read the measurements taken by the legs, which can be used as either an inside or outside calipers.
Smitten with this tool were scores of others, who had made reproductions for themselves and others, and even the fine tool giant Lee Valley produced a set for sale at a very reasonable price, so getting ahold of the tool was not so difficult (unless one was after an antique, which rarely seem to come to market).
However, I had a fundamental problem.
I operate in the shop using the metric system, as do many luthiers and fine craftsmen. None of the register calipers available, antique or modern (save for a large, aproximate, and expensive version sold by a Japanese manufacturer I was never able to get a response from) are available with a metric scale. When my own inquiries to Lee Valley to see if they would be interested in producing such a tool were politely brushed off, I decided to purchase one of their Imperial register calipers anyway, and see about changing the scale myself.
Due to the nature of the tool, I knew that using it for very fine work would be somewhat out of the question where pinpoint accuracy of measurement was concerned. Rather, it appealed to me as a rugged way to take ballpark measurements without worrying about perhaps damaging my fine calipers or getting them covered in dust and shavings. This being the case, after I had removed the laser-etched Imperial scale from the calipers using a grinder and progressive grits of sandpaper, I began by laying out new scale marks spaced 1cm (10mm) apart. Because the travel of the tool's legs is greater than the travel of the pointer, this was established by using the register calipers to measure known and confirmed distances of 10mm at a time, and the position of the pointer then marked on the scale with a scribe. I went back and did this again for 5mm intervals as well.
Not satisfied with the readability of the scribe lines, I took a dive into etching the scale markings in to the stainless steel. I had read tutorials about metal etching with a salt water solution, a battery, electrical test leads, and a cotton swab, but thought it too good to be true. However, I was absolutly taken aback by the results I achieved. The etches were crisp, deep, and not difficult to do. The salt water solution was no magic formula: I just put a small pile of salt on the bottom of a cup, and added water and stirred until there was just a little salt left visible, letting me know the solution was as saturated as could be. I etched out the scale lines in the new metric scale, and then darkened the etches with black oil paint.
Pleased with the success of the tool, I decided to make a "Studley-esque" mounting for it inside the lid of my own tool chest. I used birds's eye maple, black dyed curley walnut, and mother of pearl for the mounting, which matched with the rest of my tool chest. The departure I took from Studley's design was the use of rare earth magnets rather than small "arms" to hold the calipers in place. These are quite powerful, and once inlaid, no amount of shaking or impact could cause the calipers to come apart from the magnets, short of physically plucking them off (which is not difficult to do).
I still hope to find someone with the engraving and machining capabilities to someday print a full metric scale in 1mm increments on one of these tools for me, but until then, these coarse metric register calipers remain, at the time of writing, a singularly unique tool.
If you are a lover of fine woodworking and antique tools, and are not already familliar with the H.O. Studley tool chest and work bench, I strongly recommend a cursory internet search for his work, and acquiring a copy of "Virtuoso: The Tool Cabinet and Workbench of Henry O. Studley" by Lost Art Press, a phenominal tome exploring it. A Boston piano maker around the turn of the 20th century, Henry O. Studley's impressive working collection of hand tools is perhaps only eclipsed by the gorgeous mahogany, ebony, mother or pearl, and ivory wall-mounted tool chest he built to house them. It is nearly impossible to gaze upon this work without a certain sense of wonder, which has spread like a wildfire across woodworking and tool collecting forums and circles.
Many of the tools Studley amassed, made himself, or customized have given collectors and users (including yours truly) cause to burn up the lines and wireless waves hunting down similar tools for themselves. His organization of his tools has also inspired many (again, including yours truly) to give more thought to how their own tools are housed and displayed. The storage and preservation of fine tools is as much an art as the objects themselves, and certianly worth consideration.
Studley's tool chest has also been viewed by all who have come across it with unique sets of eyes, and certain details or tools seem to come to the forefront for each viewer. One tool that particularly caught my eye was a small, unusual (by modern standards) set of calipers hanging on a custom fit holder just left of center on the right tool box pannel. A little research turned up that these were referred to as "register calipers", that is, having a scale present to read the measurements taken by the legs, which can be used as either an inside or outside calipers.
Smitten with this tool were scores of others, who had made reproductions for themselves and others, and even the fine tool giant Lee Valley produced a set for sale at a very reasonable price, so getting ahold of the tool was not so difficult (unless one was after an antique, which rarely seem to come to market).
However, I had a fundamental problem.
I operate in the shop using the metric system, as do many luthiers and fine craftsmen. None of the register calipers available, antique or modern (save for a large, aproximate, and expensive version sold by a Japanese manufacturer I was never able to get a response from) are available with a metric scale. When my own inquiries to Lee Valley to see if they would be interested in producing such a tool were politely brushed off, I decided to purchase one of their Imperial register calipers anyway, and see about changing the scale myself.
Due to the nature of the tool, I knew that using it for very fine work would be somewhat out of the question where pinpoint accuracy of measurement was concerned. Rather, it appealed to me as a rugged way to take ballpark measurements without worrying about perhaps damaging my fine calipers or getting them covered in dust and shavings. This being the case, after I had removed the laser-etched Imperial scale from the calipers using a grinder and progressive grits of sandpaper, I began by laying out new scale marks spaced 1cm (10mm) apart. Because the travel of the tool's legs is greater than the travel of the pointer, this was established by using the register calipers to measure known and confirmed distances of 10mm at a time, and the position of the pointer then marked on the scale with a scribe. I went back and did this again for 5mm intervals as well.
Not satisfied with the readability of the scribe lines, I took a dive into etching the scale markings in to the stainless steel. I had read tutorials about metal etching with a salt water solution, a battery, electrical test leads, and a cotton swab, but thought it too good to be true. However, I was absolutly taken aback by the results I achieved. The etches were crisp, deep, and not difficult to do. The salt water solution was no magic formula: I just put a small pile of salt on the bottom of a cup, and added water and stirred until there was just a little salt left visible, letting me know the solution was as saturated as could be. I etched out the scale lines in the new metric scale, and then darkened the etches with black oil paint.
Pleased with the success of the tool, I decided to make a "Studley-esque" mounting for it inside the lid of my own tool chest. I used birds's eye maple, black dyed curley walnut, and mother of pearl for the mounting, which matched with the rest of my tool chest. The departure I took from Studley's design was the use of rare earth magnets rather than small "arms" to hold the calipers in place. These are quite powerful, and once inlaid, no amount of shaking or impact could cause the calipers to come apart from the magnets, short of physically plucking them off (which is not difficult to do).
I still hope to find someone with the engraving and machining capabilities to someday print a full metric scale in 1mm increments on one of these tools for me, but until then, these coarse metric register calipers remain, at the time of writing, a singularly unique tool.
Click picture for more detail
Click picture for more detail
Studley's register calipers and mounting system