35 - Revolving Tool Station, страница 27
TIPS & TECHNIQUES CIRCLE CUTTING JIG An easy way to cut the large circular workpieces on the revolving tool station (page 16) is to use a router that's mounted to a simple jig, see drawing. The jig is just a hardboard base that pivots on a bolt. This bolt passes through the base and into a centered hole drilled in the work-piece. To determine the location of the hole in the base, you'll need to know the radius of the workpiece. The hole is drilled that same distance away from the inside edge of a straight bit, see details 'a' and 'b.' rout. Before routing the circle, it's a good idea to first cut the workpiece to rough size. (I used a sabre saw.) This way, there's not as much material to remove as you rout it to final size. MODIFYING A SPADE BIT the pipe. There wasn't a spade bit available that matched the lVie" outside diameter of the pipe. So I modified a larger (lVs"-dia.) spade bit by filing the sides until it was the correct size. To ensure that the bit is balanced and cuts evenly, the impor- TUBE LEVEL_ ■ Before you can get an accurate reading on the torpedo level (page 6), you'll need to check it on a known level surface and adjust it if necessary. One way to establish a level surface is to use a clear plastic tube filled with water. The basic principle here is simple — water finds its own level. To take advantage of this, fit the ends of the tube into notches in a flat piece of plywood and add water (a drop or two of food coloring makes it easy to read the level). Then slide one end of the tube up or down until the water column is flush with the surface ShopNotes tant thing is to remove the same amount of material from each side. A handy way to do this is to use a nail and a scrap block to position the bit, see drawings at lower left. After filing one side down to the top of the scrap block, repeat the process on the other side. of the plywood. This will move the water column at the opposite end either higher or lower. To create a level surface, just shim the "high" side until the water columns are equal. (I used playing cards.) ■ I wanted the wood collar •blocks on the tool station (page 16) to fit snug around the iron pipe. But I ran into a snag when it came time to drill the holes for ▲ Use a nail to position the side of the spade bit V32" above a scrap and clamp the bit in place. No. 35 FIRST: CUT WORKPIECE TO ROUGH SIZE WITH SABRE SAW NOTE: DISTANCE FROM INSIDE EDGE OF BIT TO CENTER OF PIVOT POINT EQUALS DESIRED RADIUS POINT 1/2" STRAIGHT BIT SECOND: ROUT TO FINAL SIZE ▲ After filing one side of the bit flush with the scrap, repeat the process for the other side. |
