Creative Woodworks & crafts 1998-09, страница 21

The Forstner Jig

Here is what you need to construct the 4" Jig: Wood: two pieces 1" x 4" x 4", two pieces 1" x 4" x 6" (for the sides of the cube holder); one piece 3/4" x 8" x 16" (for the base); four pieces 1/4" x 3/4" x 1" (for the hold downs) Other supplies: Glue and wood screws

2-1/2" cube insert

Plan Views of the Jig

Place the insert into the larger jig and use it while boring the holes in the smaller cube

4" Forstner bit jig

Forstner Bit Jig Assembly Prawing

Fasten the four sides together with glue and screws to make the cube holder

Fasten the cube to the base with glue and screws ,

2"-Dia. vacuum relief hole

Clamp the base to the drill press table

-1--

Cube holder

Pore 2"-Dia. thru for

vacuum relief

Screw the hold downs in place so they swivel

Base

Cube holder

thickness

For safety, build four hold down tabs to keep the cube from sucking up while drilling

Making A 5maller Cube

For those who wish to make a smaller version of this cube, such as the 2-1/2" cube pictured, you'll need to make an insert for your jig and bore slightly different holes.

First, make the following insert for the 4" Forstner bit jig. Size two pieces of stock to 3/4" x 4" x 4" and two pieces to 3/4" x 4" x 2-1/2". Glue and staple these pieces together, making sure that they are perfectly square. At this point, you can round over the comers slightly so that the piece recesses easily into the 4" jig. To secure the insert, run a couple of wood screws in from each side which are just long enough to hold the insert in place. You can also use your existing four hold downs by relocating them from the larger jig.

To make the 2-1/2" x 2-1/2" cube, prepare the stock as you did for the larger cube and size it appropriately. You will need 2", 1", and 1/4"-Pia. Forstner bits, Place the smaller cube into the insert in the jig and bore the holes as follows:

2"-Pia. bit—15/32" deep 1"-Pia. bit—13/32" deep 1/4"-Pia, bit—thru three surfaces

This will produce the smaller cube shown in the photograph.

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