Tony's Router pantograph
Tony Raunikar writes:
"I wanted a simple machine to trace lettering so I could rout numbers into a scoreboard for a dart board cabinet that I built, but there were no plans on the internet and I didn't want to spend $70 on this so I made my own. I used 3/4" plywood that I had in my shop and some odds and ends that I found in my junk drawer.
The guide rails are 34" plywood ripped down to 1 1/4". I used this width because the scrap of plywood that I had was only big enough to accommodate this width.The pivot, articulating arms, and guide are 6-32 screws 2 1/2" long that I had in my screw bin. I chose this size because it happened to thread nicely into the plastic buttons (that I happened to have in my junk drawer) and they were the only screws that I had that were long enough to raise the rear rails off the table 3/4".
I was going to use wooden buttons and drill a hole in them until I ran across these plastic ones. These buttons act as a friction bearing between the articulating guide arms as shown in these pictures.
The button on the bottom of the screw allows it to slide easily along the bench during the routing process. I drilled a 3/8" counter bore into the upper guide arm for the button to seat in. This made for a really smooth articulating elbow.
I made the router base out of the left over piece of plywood after ripping the rails down. I had this old B&D router under my bench for years and only used it for quick work so I decided to fabricate the base to fit this router. It is lighter than my plunge router and I don't mind leaving it mounted to the machine as I rarely used it anyway. The contraption hangs nicely on my pegboard so storage is not a problem.
The guide rail adjustment is just a 2x4 ripped to 3" and dadoed out to accommodate the guide arm. This adjustment, as it turns out, is probably not necessary as the 2 to 1 reduction of the pantograph is already small enough.
You can see how big the lettering has to be to make reasonable sized routed letters. The printed lettering is 1 1/2" high yielding a 3/4" high routed letter. Any smaller and they wouldn't have been legible. If anything the adjustment should be able to move closer to the guide, increasing the size of the routed letters. These guide rails adjustments are capped with 1/2" plywood and they pivot on a 1 5/8" drywall screw. I put 2 fender washers between the router base and the guide rail adjustment to act as a friction bearing as well. I used fender washers instead of buttons because I wanted a larger surface for the guide rail adjustment to rotate around. This articulation arm also supports the weight of the router so I didn't want it tilting, it just has to pivot in one direction.
I found that the distances between all of these pivot points had to be exactly the same for the reduction to be exactly 2 to 1 and the height and width ratio to stay the same. I chose 16" center to center. This worked out to be a good decision. So the distance between the pivot points is 16" and the distance from the guide to the pivot is also 16".
The finished product is shown in this picture. The first time my buddies came over they pointed out that I had omitted the bulls eye score on the board, so since I didn't have any more wood at that time I just set it back up and routed the "B" in front of the hashes. Looks funny but it works. Next time I have some more 1x12 I will re-route these scoreboards but for now were throwing darts.
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