Circle /arc jigs don't need to be complicated

[Cherryville Chuck]

I'm in the process of building a thickness sander and I needed to rout arcs in the bed frame and in the sides of the sander frame so I can adjust the bed height. The bed swivels on a 3/8" diameter steel rod. I clamped the two frame halves together and drilled both sides at once so that the holes would match. To attach the bed to the bar I split a 2 by 4 and routed half the groove in each side so that they sandwich the rod between them. The bed screws to the 2 by 4. Where the arcs in the bed and frame needed to be routed was between 32 and 33" from the pivot (36" bed length). 1/4" Carriage bolts with rose head knobs take care of clamping the bed at the desired height so I just needed 1/4" wide arcs at that distance.

There aren't any circle jigs made for that long so I just took a length of 5/8" thick ply I had that was around 2" wide and drilled a 3/8" hole in one end. I stuck a 3/8" bolt in the hole and pinned the jig to the sander frame and the bed. I added a scrap piece of OSB about 6" wide on the end against the router and held the router to the jig with a couple of strips of plumber's strap material (comes in 25' rolls). Worked perfectly. Cost no money and took 15 minutes to make. Admittedly one of the ugliest jigs I've ever made. One picture shows routing slots in the bed frame. The other shows the jig attachment to the router.

[Nickp]

I'm in the process of building a thickness sander and I needed to rout arcs in the bed frame and in the sides of the sander frame so I can adjust the bed height. The bed swivels on a 3/8" diameter steel rod. I clamped the two frame halves together and drilled both sides at once so that the holes would match. To attach the bed to the bar I split a 2 by 4 and routed half the groove in each side so that they sandwich the rod between them. The bed screws to the 2 by 4. Where the arcs in the bed and frame needed to be routed was between 32 and 33" from the pivot (36" bed length). 1/4" Carriage bolts with rose head knobs take care of clamping the bed at the desired height so I just needed 1/4" wide arcs at that distance.

There aren't any circle jigs made for that long so I just took a length of 5/8" thick ply I had that was around 2" wide and drilled a 3/8" hole in one end. I stuck a 3/8" bolt in the hole and pinned the jig to the sander frame and the bed. I added a scrap piece of OSB about 6" wide on the end against the router and held the router to the jig with a couple of strips of plumber's strap material (comes in 25' rolls). Worked perfectly. Cost no money and took 15 minutes to make. Admittedly one of the ugliest jigs I've ever made. One picture shows routing slots in the bed frame. The other shows the jig attachment to the router.

If it works, it ain't ugly...