Note 1 : These prints are somewhat experimental in that I have only used them a short time, so I do not know how they will hold up in regular use. Based on my initial tests, I expect them to withstand typical home shop use.

Note 2 : I made these print to fit the #4 to #8 taps in my tap set. However, based on other taps that I have in my shop, there does not appear to be a standard size for the non-cutting shaft of a tap, so it will take test fitting to see if this fits your taps. These should also work for any small metric taps that fit the handles, but I have not tested this.

Note 3 : When tapping the holes for the set screws, I recommend tapping only about 5mm (¼") at a time, and then fully removing the tap and clearing out all “chips” before tapping the hole fully. Otherwise, I have found that the plastic chips get packed up in the tap flutes and damage the already cut threads.

This “tap handle” is based on an ideas by Joe Pie :

• Make your own Small Tap Handle !!
• Tapping Small Holes - Not a Problem

The idea is that because very little torque is needed for small taps, it is easy to apply the necessary tapping force with a simple disk or small handle. The disk “handle” also provides better feedback on the application of force, resulting in fewer broken taps.

The Joe Pie metal version uses a set screw in a round hole to hold the tap in place. However, because it is easy to create a square hole with 3D printing, I added a square corner at the top of the handles for better “grip”.

The tap handles are in two different sizes; the smaller size handles taps #4 - #6, and the larger size handles for tap #8 (but can also be used for sizes #4 - #8). Note that the tap handles will work for any size tap that fits in the hole; although smaller diameter taps will be slightly off center, this does not effect their operation.

The tap handles will require that the side holes be tapped for a #8-32 set screw (or M4 for metric equivalent - see Note 2 above). The round handles use a #8-32 X 1/2" set screw, and the “bar” handles use a #8-32 X 1" set screw. In general, use as long a set screw as possible to reduce the possibility of the threads stripping out in the plastic.

Assembly and Use

Thread each handle fully (see Note 3 above), and insert the appropriate size set screw, leaving the center hole for the tap clear.

Note that the tap handles have a top and bottom - the square is on the top of the handle. Insert a tap from underneath so that the square end of the tap is aligned with the square on the top of the tap handle. Push the tap in until the square end is protruding from the top - this makes it possible to use a tap follower. Remove the tap handles in reverse (that is, always insert and remove from the bottom).

Tighten the set screw to hold the tap in place. Do not over-tighten the set screw. Tighten the set screw on enough to keep the tap from rotating when it is is use;; otherwise you may strip the threads in the handle.

Print Instructions

Print in PETG in two colors using the 3mf files provided; otherwise :

• 0.2mm layer height
• 5 perimeters
• 25% grid infill

Note that I printed in two colors using filament switching. This makes the top of the handle more obvious, and also shows the orientation of the corner. I also printed the base colors for the two different size taps in different colors to make them easy to distinguish.

CAD

The OnShape CAD files for this are here :

https://cad.onshape.com/documents/160c930f5348d21df3f0f25c/w/3e2efa46df8ffd4889d78a11/e/1b94bb00952e10a9f438a2f0?renderMode=0&uiState=656f8362977bd40463b0207d