Threading Head Wrenches.

[Crusty]

It's only a ½ HP, 1725 rpm motor on the DP. I've got the belt set for the lowest rpm and with the Versatapper in the chuck it threads close to what I consider too fast (but not) so I think it's the ideal speed for threading. With correctly sized holes it threads a ½" thread in ¼" plate steel in seconds and the belt can always be left a little bit loose if I'm concerned about tap breakage. For me it's an inexpensive win since I got great deals on both the tapper and the DP. The chuck with tapper and tap takes up a lot of vertical space so it's more useful in a pedestal press than a benchtop press.

Do you know Joe Pie's easy way to determine the proper hole size? Subtract one thread pitch length from the nominal diameter and that will give you around 65% threads. For instance, a ¼"x20 thread has a thread pitch length of 1/20" so, ¼-1/20 = .250-.050 = .200 and the closest drill is a #7 (.201 - always choose a bit larger than the actual calculated number) which results in 75% thread engagement or go larger for less thread engagement in steel (7/32" equates to 50% which is adequate).

Due to the magic of gearing the Versatapper is also a torque multiplier. A replacement tap flex collet (J441 often missing on Ebay deals) can be purchased from McMaster-Carr).

TapDrillSizes.pdf

I use CRC True Tap fluid which is a low cost equivalent to TapMagic.

I exercise care and attention to detail when I thread holes because it's a huge disappointment to break a tap in a part that I've spent hours making.