This is a way of tapping blind holes in order to fit legs to the Multiple Height Press that is described on the website.
A large Multiple Height Press clamped in the bottoming tap frame. Tipping the tap 45 degrees makes it easier to use and the shavings can still fall out of the hole being tapped.
In the original post (starting below) the tap was positioned vertically (90 degrees instead of 45). There is a little more information on the Making Wooden Screws page of the website.
The 5 TPI bottoming tap installed in the tapping frame. The wooden part is the frame. The metal parts are (top to bottom): the TAP (bronze), the SHAFT COUPLING which connects the tap to the MASTER THREAD which passes through the NUT (brass). The nut screws into a FLANGE which is bolted to the wooden base of the frame. The tap has been made from bronze rod. All of the other parts are ‘off the shelf’, though the master screw has been cut to length.
This gauge is used to align the hole in the press jaw with the tap.
The press jaw is clamped in place and the alignment gauge has been removed.
The tap is driven by hand. This is slower than using the bit brace but I haven’t figured out a better way. Orienting the tap this way allows the shavings to fall out of the hole as it is being threaded. This makes it more awkward to drive the tap. I may try a hand wheel at the bottom of the master screw to see if that works any better.
A view of the tap as it is aligned to enter the hole from the bottom.
The tapped hole. A thread cannot be cut all the way to the shoulder of a wooden screw. Thus it is sometimes necessary to have a larger diameter hole adjacent to the tapped hole to accommodate the unthreaded part of the wooden screw. I would normally not use this very ‘buggy’ wood but this is a press made as an experiment to test an idea.