If I am sent to a bad place when I die, I am certain it will be filled with bockety threadboxes.
Today I spent the entire afternoon preparing for a class at the Melbourne Guild of Fine Woodworking and prepared the stock so every student could make a Moxon vise. I started by making the blanks for the screws.
While I was turning these spindles, I threaded one with my generic “Made in Taiwan” threadbox that is available everywhere.
The spindle jammed in the tapped hole.
I adjusted the threadbox and made another spindle. It jammed in the hole. I made another. Jam. Alastair Boell, who owns the school, sensed my despair (it might have been the fact that I was screaming and peeing myself) so he came to take a look.
He made some adjustments. Jam.
Then he had the brilliant idea to cut open the threaded hole to see if we could diagnose the cause of the jamming. The problem was obvious. The tap and the thread box each cut different a tpi.
I had heard there was a batch of bad threadboxes last year. But the suppliers assured me that the problem had been resolved.
I don’t think it has been fixed entirely. There are still bad threadboxes in the pipeline. This was a new, unused threadbox I’d purchased recently with another threadbox (which worked perfectly). I brought the unused one to Australia to make sure I had a cutter that was in good shape.
If you buy a threadbox, keep your receipt. If the results from your threadbox won’t work, cut open a threaded hole you’ve made and check out the tpi.
— Christopher Schwarz