Wood lathe Nova Jaws mortise/tenon gauge

thingiverse

This is a set of laser cut gauges to be used with a Nova chuck on a woodturning lathe. Creating a mortise or tenon on a piece of wood (such as a bowl blank) normally requires measuring and transferring the chuck and taper dimensions to the wood. These gauges simplify that. They provide gauges for the max/min/optimal diameters, plus the maximum depths and taper angles. The svg has 3 different gauges, one each for the 50mm, 70mm, and 100mm Nova jaw sets. These should work with the Nova G3 or Super Nova 2 models. The Precision Midi and Titan have different max diameters. They will work with those models as long as you don't need to rely on the exact size of the max diameter part of the gauge. Which you shouldn't be doing anyway since the jaws won't hold as securely at those diameters. How to use for a tenon: * Cut a tenon parallel to the bed of the lathe. Slide the mouth of the gauge over the tenon. The ideal size will just barely fit the "best" mark. The tenon is too small if the "min" section fits over the tenon. It's too large if you can't fit the "max" section over it. It's a good idea to leave 1-2mm excess if you are adding a taper. * Cut the tenon a bit short of the maximum depth. The maximum depth is the length of the two bits at the corners of the gauge to the right (when held with the lettering upright). * Cut the taper if using the 100mm jaws (the 50mm/70mm jaws don't have a taper). You hold the gauge parallel to the lathe bed, with the mouth to the left, and position the outside tip along the tenon. See the photo for an example. How to use for a mortise (recess): * Cut the desired diameter of the recess. Check against the diameters that are opposite the mouth of the gauge. The recess is too small if the "min" section won't fit inside it. It's too large if the "max" section fits inside it. It's a good idea to leave 1-2mm to allow some extra material for when cutting the taper. * Cut the recess to a bit less than the maximum depth. The depth is the depth of the dovetail-shaped bits on the top and bottom of the gauge to near the left side (when held with the lettering upright). Turn the gauge so that the mouth is pointing perpendicular to the lathe bed and insert the dovetail shape into the recess to check the depth. * Cut the taper into the recess. Use the gauge in the same way that you did to check the depth. The angles on the dovetail shape are the proper taper angles for the recess. I've also included a f3d file of the original design. It has user parameters that you can tweak that, in theory, should be able to make a version that will work for any manufacturer's chuck.