Gene Davis
02-08-2015, 7:28 PM
Yes, "templet," that is what they called it. The one I have dates to about 1975, and I bought it new. Watch one of my favorite YouTube woodworkers use one just like mine in this video. https://www.youtube.com/watch?v=XAZG-LGI36w
I have only used it a few times in all the time I have had it. The original bit, in high-speed steel, not carbide, is in my bit collection. I sharpened it a couple times way back, and in sharpening it, reduced its large cutting diameter from 0.500" to maybe 0.485".
I want to use it now to make a half dozen drawers for a project, and am running through the setup with a carbide bit I bought, because I thought carbide might be the way to go. The high speed steel is only good for about ten drawers-worth of cutting, and I lost the sharpening kit I had for steel bits.
So I am set up with some stock I had left over from blanking out all the drawerbox sides, and trying to tune in the fit with a bit I thought was the same as the old steel one. But no, upon measuring, I find the bit I have in carbide is not 1/2 inch, but 17/32 inch in diameter. The carbide one looks to have a 14 degree cutting edge.
So, I did a graphical study to see what happens when you change from the Rockwell (Porter Cable, then Dewalt) bit with its 1/2" OD, and use this templet jig.
Attached is a view of my Sketchup workup for various bits and their cuts, all using the templet, which cuts pins/tails on a 7/8" repeat spacing. Thus the 7/16" half-pitch dimension you see in the pic.
Two things affect the depth of the pins and tails in the cut. The wider the OD, the deeper the cut to maintain the flip/rotate geometry, and the shallower the cut angle, the deeper the cut, also.
One of those cuts, the one with the bit angle of 8.3", cannot be made unless one was to buy a custom bit. I ended up with that geometry because I could not find any specs for the original HSS bit I got long ago, other than its Rockwell p/n and the fact that it is 1/2" OD. The 8.3 degree cut is what I computed using trig when setting the cut depth to what the owners manual says to do to begin the setup.
Just to have something different to use with this, besides the 14 degree 17/32" bit I have, I ordered from Amazon a CMT bit with the 1/2" OD x 10 degree angle, with a 1/4" shank so it will work with the templet. I'll see how it goes when I get the bit.
Has anyone else played around with this old jig, beyond using the original bit?
I have only used it a few times in all the time I have had it. The original bit, in high-speed steel, not carbide, is in my bit collection. I sharpened it a couple times way back, and in sharpening it, reduced its large cutting diameter from 0.500" to maybe 0.485".
I want to use it now to make a half dozen drawers for a project, and am running through the setup with a carbide bit I bought, because I thought carbide might be the way to go. The high speed steel is only good for about ten drawers-worth of cutting, and I lost the sharpening kit I had for steel bits.
So I am set up with some stock I had left over from blanking out all the drawerbox sides, and trying to tune in the fit with a bit I thought was the same as the old steel one. But no, upon measuring, I find the bit I have in carbide is not 1/2 inch, but 17/32 inch in diameter. The carbide one looks to have a 14 degree cutting edge.
So, I did a graphical study to see what happens when you change from the Rockwell (Porter Cable, then Dewalt) bit with its 1/2" OD, and use this templet jig.
Attached is a view of my Sketchup workup for various bits and their cuts, all using the templet, which cuts pins/tails on a 7/8" repeat spacing. Thus the 7/16" half-pitch dimension you see in the pic.
Two things affect the depth of the pins and tails in the cut. The wider the OD, the deeper the cut to maintain the flip/rotate geometry, and the shallower the cut angle, the deeper the cut, also.
One of those cuts, the one with the bit angle of 8.3", cannot be made unless one was to buy a custom bit. I ended up with that geometry because I could not find any specs for the original HSS bit I got long ago, other than its Rockwell p/n and the fact that it is 1/2" OD. The 8.3 degree cut is what I computed using trig when setting the cut depth to what the owners manual says to do to begin the setup.
Just to have something different to use with this, besides the 14 degree 17/32" bit I have, I ordered from Amazon a CMT bit with the 1/2" OD x 10 degree angle, with a 1/4" shank so it will work with the templet. I'll see how it goes when I get the bit.
Has anyone else played around with this old jig, beyond using the original bit?