Hi all,
There are two problem areas associated with making Wood Threading tools for those of us with limited metal working facilities. Obviously these are making the tooth of the die, male threading part, and making the tap, for the female part. The Beal system uses a router with a 'V' cutter to form the male thread, and a purchased Tap to form the female thread.
Fortunately Axminster offer the Tooth of thier dies, thread box, as a spare. This has a maximum gap at the top of the 'V' of about 5mm. Of course, this means that the coarsest pitch can only be 5 tpi. I have idly wondered if a carving 'V' gouge could be used. Setting this cutter in a suitable block is fiddly but not terribly difficult. It is essential to remember that the outer diameter of the wood should be cut before the inner.
The tap is an altogether different problem, but the Beal system could be used of course.
A little while ago I successfully made a tap from a suitable flat bit. I started with the assumption that I was basically filing a saw tooth. The tooth angle, although not exactly the same as the die cutter, came straight off the saw file. Worst bit here was organising sufficient light, and visual magnification, to accurately mark out the teeth. The image shows the tap I made. In use it worked well, but any movement off-axis ruined the thread. Hence the nails, these are glued on with super glue and filed to the core diameter of the tapped hole. This tap is for 10mm threads and works suprisingly well on the gauges I used it on.
Smaller taps would be difficult using this method as the 6mm shank would come into play. Larger ones, well 1 1/4" flat bits are available, perhaps one day I may try one.
http://www.rdgtools.co.uk/acatalog/WOOD ... _TAPS.html are offering taps for headstock sized threads. I see amongst them is one at 1 1/2" at 6tpi.
xy