Wood threads -- redux
Mark Harrison -- in Sydney, Australia
>I have bought a couple of wood thread cutters made by the Lion Tool Company in England on Ebay. One is 1" and the other is 5/8". I don't know how good the modern reproductions are but these are unbelievably good and incredibly easy. I just took a 25mm dowel in Tasmanian Oak and cut an absolutely perfect thread using the die.
The tap requires a little more work to get right. I sharpened the tap using wet and dry paper and a profile water stone. It's not what I would call brilliantly sharp but it still cut a perfect thread in Tasmanian Oak.
One down side is that it is difficult to get started. I partially solved this by using a 7/8" bit to start the hole instead of the stated 3/4" requirement. I also did this on the reverse side to minimise the blow out. Of course, a large countersink would also be helpful but I don't have one that large.
The total solution was to create a starting threaded hole in another piece of Tasmanian Oak that I clamp to the piece that is to be tapped. There is an upside to this though and that is if you were creating multiple nuts say for a dual screw front vise the threads will be started at the same point in the circle.
Another interesting feature is that the outbound hole in the thread box (die) is wood. Not aluminium like the current Taiwanese made dies.
When you look at the thread box the construction is really very simple. The only hard thing to get that is needed to create one of these is the tap of a suitable size and appropriate TPI for woodworkers. In this case, 5 TPI for the 1".
So there I was thinking that perhaps all that we need to create our sets is to buy the tap and make the rest. As I am not a machinest I have no idea how difficult to make these in larger sizes. Or perhaps these are made in these sizes. I would be interested to hear the experience of others with a machine tool background.
This makes me wonder what the point of the Beall wood threader was. The easy part is making the die. The tap is the hardest part. But then, I haven't tried their tools so I may be judging them too harshly.
As to what I am going to do with these, well the uber-bench is not that far off from being started... especially as I now have way too much time on my hands, but I'll leave that story to another time.
