[cyclestart]

Hand tapping is drudgery.

Even if the X2 motor could be reversed, it lacks the torque. What other solutions?

A former workmate was a big fan of tapping with an impact gun when the piece was inconvenient to move to a proper machine.

[Geof]

A reversible variable speed hand drill works fine up to 1/4" just hand held with a bit of practise. Get a 3/8" capacity one with a double reduction gearbox for best torque; you don't need high speed. The way to identify a double reduction gearbox is to turn the chuck and look at the cooling fan on the armature; if it turns in the opposite direction it is single reduction while same direction indicates double reduction. Triple reduction would give same direction but I have never come across this.

Some electric drills can drive up to 3/8" or even larger but hand holding the drill and work against the torque to keep the tap aligned is difficult. I have done it by making a little travelling cradle to carry the drill with a fixture to hold the work correctly aligned. This was back in the days when I couldn't even afford a tapping head and I was doing production work in my own shop.

[DareBee]

You can get auto-reversing tap heads starting at about $300 (China).
When the spindle pulls up the gears in the head disengage CW rotation and engage the CCW gears.
I have 1 permanently mounted in a drill press with a 3/8 tap in it.
Less than 5 seconds per hole in 3/4 CRS (100ish RPM).

We do a lot if site/install tapping with regular rechargeable drills. The low speed and torque makes this work extremely well.

[lvittori]

I have used the X2 to tap 10-32 in aluminum. I give the spindle a couple of turns by hand to start the tap then carefully advance the speed control. To back the tap out I put the gear shift in between positions and turn the spindle by hand. Not really any faster than doing it by hand but it keeps the tap straight. On smaller taps I turn the spindle by hand both tapping the hole and backing the tap out.

[hoss2006]

I used a stepper attached to the spindle and my own program to tap up to 1/2-13 in aluminum.
Read about it here.
Couple more videos here too.
Hoss

[cyclestart]

Ha! Checking your mega-thread should have been the first stop Who would have guessed you'd be the one to find a solution by standing the problem on it's head? Was this inspired by an existing design or did it come to you in a dream?

A little side note that probably belongs in PM or elsewhere. I found a more local solution to my import problems mentioned in another thread (sorry to lazy to link to it now). Thank you for the kind offer.