Making and setting up pantorouter tenon templates
In this case, I want to use a 3/4" router bit to cut a 1/2" tenon. The center of the router bit needs to pass the tenon half of its diameter away from the edge of the tenon on either side. So twice half its diameter, or just add the router bit diameter.
So 1/2" + 3/4" = 5/4" here, or 31.75 mm. I switch to Metric for calculations.
Since the pantograph scales down by 2x from the path of the guide bearing, the center of the guide bearing needs to sweep around a diameter twice as large, or 63.5 mm. I want to use a 22 mm guide bearing, so I need to subtract that the same way I had to add the router bit diameter, so the template needs to be 41.5 mm wide.
I cut it to a width so that the template has the desired width at the middle of it's
slope. That way, I can adjust the size of the tenon up or down from the calculated
width depending on how high on the taper I run the guide bearing.
Next I mark the center-to-center distance for the rounds on each end. I always work that out separately. For a tenon 2" wide, with a 1/2" bit, the center-to-center distance is 1/2" less than the 2" width, or 1.5". Then double that because the pantograph divides by two, and that's the center to center distance of the semicircular ends of the template.
If I want to use this template for cutting the tenons only then it's already done. But if I want to also use it as a corresponding mortise template, I still need to add a slot in the middle.
Now I need to fill the ends of the slot to make it the right length. I use my same washer to mark how far from the ends the slot needs to go, then glue in some pieces of wood to fill it. The important thing is that the follower will be able to move side-to-side by a tiny bit more than the center-to-center distance of the semicircles at the ends.
I still need to drill some mounting holes. The template holder on my pantorouter has holes on a 3 cm grid. The further apart I put the holes on the template, the easier it is to mount it without an accidental slant.
Using the slot in the template to route out a mortise in a scrap of wood. I already had a 1/2" straight fluted bit in the router, so I just used that. I have to sweep side-to-side to cut the slot with a straight bit. With a spiral bit, it's best to remove most of the material by making a series of plunge cuts.
Then switching to the 3/4" bit that I picked for cutting the tenon. Larger bits do a better job of cutting tenons, and because I usually cut my mortises with my slot mortiser, I don't need to use the same size bit for the mortise and tenon.
I set the vertical alignment by checking how the bit overlaps with the stock top and bottom. If I want the tenon in the middle, I adjust the template up or down until the bit overlaps the wood by the same amount on both sides.
If I make a long tenon, I sometimes only move the router forward half way, cut around, then move it the rest of the way. This especially if the tenon is longer than the cutting depth of the router bit.
Then checking the fit. Surprisingly, the fit was jut right, even though I had, set the guide bearing to roll around the widest part of the template for a first pass, leaving a slightly larger tenon. I can always take another pass to make it smaller, but I can't make it bigger.
Checking the mortise, it turns my bit cut slightly more than 1/2" wide, so the tenon also needed to be a bit larger than 1/2"
Tenon setup on the metal pantorouter using the new segmented templatesNow lets do the same procedure on the metal pantorouter.
I could make wooden templates to mount on the aluminium template holder, but I'll show using the new segmented tenon templates.
I start by looking up the appropriate row and column on the table that comes with the segmented tenon templates. I have the option of making the tenon 1 7/8" wide, or 2 1/8" wide. With my stock 2" wide, the widest I can make the tenon is 1 7/8".
The metal pantorouter has this convenient feature where, placing the stock between the horizontal part of the template holder and a stop on the vertical support will set the template vertical position so that the mortise or tenon ends up in the middle of the stock.
... and again adjusting the template vertical position by placing the stock between the stop and the horizontal part of the template holder. This feature is really handy for getting the tenon centered in a piece of wood.
So I just placed the follower so it goes in the center hole of the template and position the stock centered against the bit, then set the fence stops against my workpiece.
So I move the guide bearing forward a bit, and with the workpiece still clamped I sweep around it again, and check if it fits the mortise. It's best to approach the final fit by small increments because if the tenon is too small, you can't just add to it.
I don't get paid directly for this, but I get a small royalty for each metal pantorouter sold (having invented the machine), and better templates help to sell more machines.
At the same time, I sell plans for the wooden pantorouter. The metal machine and homemade wooden machines don't really compete with each other. Buying a metal pantorouter is not cheap. If you buy tools from SawStop or Festool, then it's in your price range, but its too expensive for people who like to improvise and build their own machines. And building a pantorouter is a fairly involved process, and if you aren't inclined to build machines, it's not for you.
And if you aren't skilled at building one, and its too expensive to buy, consider other alternatives, like pocket hole joinery :)
More about the pantorouter (2010)
Big mortise and tenons (2010)
Slot mortiser (2009)
Dave Tenney making tenon templates (2014)
More about the Pantorouter on my Wooworking website.