Circle router jig
This is a jig I have seen on the web and here on LJ in several versions, I cooked up my version and added a cheap curtain aluminum T-track so I always can extend to any length simply by buying a longer rod.
(I think originally the design comes from a woodworking magazine).
Since I had the photos and could see the interest on the post I made this mini blog showing more details for those who want to make one.
The layout is a plywood (plywood for concrete forming) base that are the width of your router base and then app double the length, this will provide a stable base.
Place the router in one end of the base and then mark up for mounting screws and fix the router to the base.
Once the router is fixed, route a hole through the base with a small router bit to locate the center of the bit.
Now mark this line up on the base and offset it to make a rabbet for the circle arm / T-track.
Also make two holes in the center line of the rabbet with a distance of app 7,5 cm (3 inch) for the adjustment rabbet.
Drilled the hole for the router bit, with a cup drill (could be done with the router).
Used my mortise jig as a small router table to route the rabbet for the T-track, in the center of the jig.
Then a smaller bit to route the rabbet for the adjustment between the two predrilled holes.
Drill holes in the T-track for each 5 cm (2 inch), since it can be adjusted free on the jig it do not need to be dead accurate.
A piece of wood or ply fitted in the T-track and bolt mounted in it.
This end will go into the adjustment rabbet on the jig and a wing nut or a knurled bolt will be added on top to tighten it once the radius is set.
Here from the other side.
For the end that need to be moved between the holes again a small piece of wood with a hole in the middle, fitted inside the T-track and rounded in the ends for easy slide.
Through this hole you screw or nail into the center of the circle you want to make.
Here from the other side.
Here the parts for the adjustment.
Rounding the base.
Jig mounted with a short hardwood rod I also made.
Making its first circle.
It works excellent!
Short and long arm, it should cover most needs.
And finally from the top while routing.
Notice the knurled nut for the adjustment in the back under the dust hose.
This is the kind of curtain T-track I refer to, but you can use any T-track or a hardwood strip.
Hope this blog could inspire, and that it will be at help for those who wrote they will make one,
-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.