digest
Short Summary
Main recommendation: Make a wooden chain on a router by building two simple jigs (a box-shaped template and a base with routing guides), then routing each link with flush trim and roundover bits and splitting every other link apart. Steve Ramsey notes the process gets quicker once you settle into an assembly-line routine, and the jigs can be made as long as you like.
Key Points
- The project is built around two jigs: a box-shaped template with a 3/8-inch flush trim bit guided by a bearing, and a base that clamps to the workbench and supports the router.
- Each link is shaped in stages: flush trim to form the outline, then a 1/4-inch roundover bit with a bearing to round the inside edges, then flip and repeat, and finally round the outside edges.
- Every other link is split apart after shaping, which is what makes the chain a true interlocking chain.
- The idea came from The Router Handbook by Patrick Spielman (a 1983 edition; an updated version is still sold on Amazon).
Details Worth Noting
- Concrete instructions:
- Make the first jig: cut a 1/4-inch MDF base and rout a 3/4-inch straight-bit recess using stop blocks (one on the right side, one set 1 inch in from the end). Trace an oval onto 1/2-inch MDF, cut just outside the line, and sand to fit snugly into the recess.
- Make the link template: on 1/4-inch MDF scrap, draw a straight line with two marks 1 inch apart, bore two holes with a 1-3/4-inch Forstner bit in a drill press, then use that as a template to trace and sand the 1/2-inch MDF oval shape to the curve.
- Assemble the box: glue the template assembly into the slot, add 3/4-inch plywood pieces butted against the center piece, and remove the assembly before the glue sets.
- Mount the box to a 3/4-inch base board with some 1/2-inch MDF strips for router support, leaving space for the bit and sawdust (rough holes cut for sawdust exit).
- Set the 3/8-inch flush trim bit with its bearing riding the inside of the box template. Cut link blocks 5/8-inch thick and bore a 1/2-inch hole in each so the bit can drop in.
- Shape the first side with the flush trim bit, then switch to a 1/4-inch roundover bit with a bearing: round the inside edges in the first jig, flip and repeat, then move to the second jig and round the outside edges.
- Split every other link: use a thin-bladed pocket knife, tap it on one side, pull the links apart, and let them break where they will.
- The presenter made a mistake: the box was not built high enough for the router base to ride, so he added 3/4-inch plywood to raise it. Check clearance before routing.
- He suggests the process works best as an assembly line, doing each step on every piece before moving to the next.
- He jokes the chain could be used to lock up his router, as he's not sure what else it's for.
Bottom Line
A wooden chain is achievable with basic router and drill-press work once the two jigs are built correctly, and the real payoff is a repeatable assembly-line process that makes many links quickly.
