First cut and adjusting for accuracy
I made some brackets to clamp the router into the mount on the pantograph.
I also moved it left and right as far as I could, checking that the distance between the router collet and the edge of the table stayed consistent (see red arrows). If it doesn't, it's likely that the main shaft that the pantograph mounts to is not at a right angle to the edge of the table.
Moving the router side-to-side horizontally, I checked that the shaft stays level with the table.
If you don't have a 1/2" shaft, use the 1/4" that you need to make the depth stops out of later. A 1/2" dowel might also work if it's straight enough.
Tweaking the pantograph as a whole is difficult; it's much better to check the individual links for accuracy. Here I'm checking that the router is perpendicular to the front face of the link. This can also be checked just by putting a ruler against the front face of the router, as the front face should be perpendicular to the router.
Making a mortise and tenon template I wanted to make a big mortise and tenon template to test it out with.
I want to make a tenon 1/2" thick, using a 1/2" router bit. The simple formula that
I like to use is:
(Router diameter + tenon thickness) * 2 = follower bearing diameter + template width.
So that works out to (1/2" + 1/2") * 2, or two inches. With the calliper set to two inches, the space remaining between the calliper and the follower bearing is the template width that I need.
The slot should be long enough so that the pin can move as far as the center of the semicircles. I glued in a piece of wood at the end, then sanded the ends of the template again to smooth it out.
I checked that it was parallel to the table by placing a short board on the table and looked over the edge of this piece to check that the template was parallel.
Cutting a test mortise and tenonWith the template mounted, I cut the first tenon in a scrap of wood.
I just used two bar clamps to clamp it to the edge of the table because I don't have a proper clamping solution yet.
I also cut a mortise. This was not easy to do without a plunge lever to help push the router into the wood. I just didn't have very good control pushing it by hand. I need to make a plunge lever, but I didn't want to wait any longer to test it out.
Part of the problem was that I originally drilled the hole slightly crooked, and expanded the hole a bit to allow it to be in straight. But this added wiggle room. I figured my clamp would prevent it from wiggling, but that was not the case.
I stuck a small nail in next to the shaft to keep it from wiggling for the time being (see arrow in red).
Making a new operating lever and follower clampAt this point I decided that my clever follower clamp design really wasn't very clever. It was difficult to make and less effective than the simple block that clamps the follower on my pantorouter XL.
So I re-built the operating lever link to make a new follower clamp for it.
You could also use a piece of 1 1/4" dowel for this, or even make the handle square.
The handle doesn't spin. I figure this helps to prevent the handle from accidentally slipping out of your hands.
More alignment checksI checked that the pins and follower on the operating handle are in line and the right distance.
Since I had to take the pantograph apart again anyway, it was time to check the alignment of the router in the link (which I really should have checked earlier). I made five blocks of equal height, then used those to support the router mount link by the pins and checked that the center of the router was at the same height as the center of the shafts of the link. I also checked that the distance between the router shaft and pin on either side was the same, and that the router was perpendicular to the mount.
I realized this was because the front mount of the main shaft is a tiny bit higher than the back mount. So I removed that mount and cut a tiny bit off the bottom edge to bring the mount lower. I added some shims under the back mount.
Imagine the router was 1 mm to the left of this line. With a tenon that is 3" (75 mm) wide, this will result in both the mortise and the tenon being about 0.6 mm higher on one side than the other. Worse yet, as the mortise and tenon mate, and the mortise is at the same angle, those add up instead of cancelling, resulting in a rather noticeable 1.2 mm difference across the joint.
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