This is for @geek2nurse and any other woodturners out there.
When preparing a tenon or mortise to mount a workpiece onto a chuck, the best possible fit is when the chuck jaws are nearly closed. This is the only point at which the chuck jaws form a perfect circle. Since the mortise or tenon on the blank is also a perfect circle, the wider the jaws go, the smaller the area of contact between the jaws and the wood. More surface contact == more safety so you don’t want to eyeball these. Or at least not until you have enough experience that eyeballing doesn’t put you at risk or waste your money. Which is why a template comes in handy. Fast. Accurate. Safe. Repeatable.
The chuck can compress onto a tenon or expand into a mortise and this template accounts for both. The template also provides Min/Max versions because a little wiggle room is very handy. Make the tenon oversized and sneak down until the template fits, or make the recess undersize and sneak up. You can’t run the lathe in reverse and put wood back on, after all.
I have Nova chucks so this is sized according to the Nova Accessory Jaws manual recommendations for minimum mortise and tenon sizes with the standard 50mm jaws supplied with most packages.
If using with any other chuck or jaws, please be sure the sizes are within spec for those specific jaws!
Please do not use while workpiece is spinning! If tempted to use the pointy bits to mark the mortise, it tends to melt the acrylic. And measuring while spinning is just asking for trouble.
anyway.
The template has a hole so it can be hung on the lathe. I buy net release magnets and toss out the lanyards. That leaves two magnets with split rings you can attach to templates, hex wrenches, etc. to stick 'em right to the lathe. As a rule I avoid lanyards, cords, wires, or anything like that around the lathe and the net release magnets without the lanyard are perfect for this.
Also, try painting the text with a contrasting color before removing the backing paper.
If this is useful, I have 100mm and 130mm versions I can post. For folks with other size jaws I’d be happy to make templates in other sizes.
Sizing in this template
Mortise: 51.25 min - 56.25 max (Manual says 50mm - 60 mm)
Tenon: 45mm min - 50mm max (Manual says 45mm - 65 mm)
Score lines for Hershey text are black.
Cut lines are red and blue so you can turn off the blue if you don’t need the hole.
