Woodworker's Journal 1982-6-5, страница 45




Woodworker

Horizontal Boring Jig—byl.a.simon™

A well-built homemade horizontal boring jig won't sit idly in the workshop, it's a tool that will be put to use over and over again. The sliding carriage (E) permits it to edge-drill holes easily and accurately, with little set-up time required.

Although there are a number of specific dimensions shown on the drawing, they are offered more as general guidelines rather than rigid requirements that must be strictly adhered to. The shape of the carriage saddle (parts AA and BB) is left undimensioned since readers will need to cut it to the contour of their own electric drill. A Vt inch Rockwell drill was used with the jig shown in the sketch. Readers with drills that have a different shape may find that even the general carriage dimensions may require some revision.

The jig is designed to edge-drill the center of a V« inch thick board, the size most commonly used. Thicker stock can be drilled by adding a spacer along the top edge of part D where the carriage (part E) rides. Cut the spacer to a thickness that will position the drill to the desired height.

Construction of most of the jig is relatively straightforward, however, keep in mind that in order for this tool to have any value it must be made accurately. The base (A) is Vi inch hardwood plywood while the table (B) is the same material only V* inches thick. The supports (C) are standard 2x4 stock cut to a 10 inch length. The guide (E) is made up of a Va x Va x 10 inch strip glued to a piece of stock measuring Va x 2Va x 24. Before assembly, lay out all parts carefully. Make sure that the corners of part B are cut square and also that part B is perpendicular to part D. Assemble with IVa x #8 countersunk wood screws.

Cut cradles AA and BB to size, then apply the Vt x3A dado. To transfer the profile of your electric drill, wrap a short length of soft solder around the drill, then use the solder as a template to mark the shape on the cradle. Since drill profiles will differ from front to back, you'll need to make two templates. Use a band or saber saw to cut just inside the line, tnen add a drum sander attachment to the drill press and sand down to the line. Position the drill in the two cradles and check to be sure it is level.

Cut the spreader (CC) to dimensions shown, then glue to the two cradles. To cut the Va inch by 2 inch notch, set the

table saw blade to a depth of 2 inches, then locate the rip fence to make a l'/s inch wide cut. Using a push stick, and with the side of the carriage (E) bearing against the rip fence, run the carriage over the blade. Turn the carriage so that its other side bears against the fence and make the same cut. This establishes the Va inch wide groove. Now, move the fence about'/»inch further from the blade and repeat the process. Continue this until all waste stock is removed from the groove.

Secure your drill to the carriage with a hose clamp of adequate size. A small amount of wax added to the carriage will result in a smooth sliding action.



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