I created this two simple blocks to help me when tapping the threads for the Helicoil® repair inserts. It improves the quality of the final result by helping you to guide the tap perpendicular to the hole.

Taps are guided on the smooth part and not on the cutting edge, this makes the block last longer, as the cuting edge does not bite into the printed part.

The dimensions of the holes are OK on my machine (X1 Carbon) with no X-Y hole compensation. Could be that you will need to enable X-Y hole compensation. I suggest to cut the model and print only few mm of the top surface to check the tolerances.

If you end up with too small holes, you can still clean them out with the drill.