Torque Measurement Standards
NOTE 17: This has been a subject of discussion lately between clubmakers and shaft manufacturers. The Club Scout approach is to clamp five inches of the butt and place the torsion arm on the tip of the shaft. The beam length with this set up is therefore about 39" or 40" for a wood shaft. If you look at pictures in catalogs of other torque testers you'll see much the same set up. A few years ago the industry got together with the American Society for Testing and Materials, ASTM, and tried to standardize the testing of shafts. The specification was designate F08.18. Unfortunately it was never finalized and/or approved. I have a copy of draft 3 and don't know if this was the final attempt or not but it shows a torque measurement setup very similar to the one I've recommended. A least one shaft manufacturer as taken a very different approach. The butt clamp has been moved up the shaft to produce a beam length of 32". A measurement is taken and then the tip of the shaft is clamped as if it were the butt and the torque arm applied to the butt. Again with a 32" beam length. The two readings are then averaged. There is nothing wrong with this approach except that their results are quite different (lower) than anybody else's. Trying to duplicate this approach with a Club Scout is a bit of a pain. To get the reversed measurements the clamping unit requires some kind of bushings to clamp the thin tip of the shaft and the torsion arm had to be modified to attach to the butt. In doing this, the torque measurements were reduced by 15% to 20%. I hope to contact a number of shaft manufacturers and see what approaches they're all using. Using a Club Scout at least you can compare one shaft against another even though your results may not match the manufacturers published numbers.