This jig will not only do centred dowelling, but it will dowel boards of different thicknesses to one reference face; the assembly is perfectly flat on one side and all thickness variations are on the other side. This saves a lot of planing and scraping time. Using a dial, each micrometer clamp head can be set from 6mm(1/4") to 13mm(1/2") from the centre line to handle work from 13mm(1/2") to 25mm(1") thick. The setting is positive and accurate to a few thousandths of an inch. The movable clamp heads will grip work as small as 13mm(1/2") x 35mm(1.3/8"). With boards of constant thickness, you can set the jig for centred dowelling. For boards of uneven thickness, you set the heads for a constant set back from the reference face.
By using the tapered pin to register off the last hole drilled, you can quickly chain drill dowel holes for tabletops or panels. The movable bush carrier comes with 3 hardened steel bushings: 1/4", 8mm( 5/16"), and 3/8". Other sizes are available. All turnings are solid brass. Machined parts are anodised aluminium.