A Bottoming Tap

A bottoming tap is needed to cut threads in a ‘blind’ hole.

Having the tap set at 45 degrees makes it easier to adjust and drive the tap and allows the scrapings to fall out of the hole.

The tap positioned to tap the ‘blind’ hole which is only 1-1/2″ deep.

Another view of the tap and wooden tapping frame. The metal parts from top to bottom are: the TAP (bronze), a SHAFT COUPLING (black steel) which connects the tap to the MASTER SCREW. The master screw passes through the NUT (brass) which is screwed into a FLANGE (also black steel) which is bolted to the wooden tap frame. At the bottom a second shaft coupling provides another hand grip to help drive the tap. This tap is driven with both hands only, it would be too awkward to use the bit brace. The same few couplings, nuts, flanges and master screws are used for other threading and tapping set-ups.

This plate aligns the press while it is clamped to the tapping frame and is then removed. This photo was taken before it occurred to me to tilt the tap 45 degrees.

A view of the tap from below.

The tapped hole. A thread cannot be cut all of the way to the shoulder of a wooden screw. Thus it is necessary to have a larger diameter hole adjacent to the threaded hole to accommodate the unthreaded part. This wood is very buggy. This was a an experiment and not a press to be sold.