Tapping Essentials from Hass Automation Good info for manual and CNC machinists

**Floradawg** · Jul 4, 2021, 08:07 PM

He didn't go into thread forming taps. They are used in aluminum (and possibly other soft metals) and don't remove any metal. You start with a larger hole and the tap displaces the material rather than removes it. It is suitable for automated tapping but I'm not sure when it is a proper method. I have use them with CNC machining but why the engineer specified that, I don't know.

**NeiljohnUK** · Jul 5, 2021, 04:51 AM

Originally Posted by old kodger

If you are looking at very old equipment, it's possible that you've run across BA(i think it stands for British Association) taps and dies 9and 10 BA would be about 40 thou dia.or so, and insane tpi.

Indeed BA stands for British Association (named after the British Association for Advancement of Science), often found on electrical equipment in the UK and only going out of regular use after the adoption of metric thread and measurement standards, 16BA 0.0310" 133.3 tpi being the smallest.

**Floradawg** · Jul 4, 2021, 08:34 PM

He didn't go into thread forming taps. They displace metal rather than remove it. You drill a larger diameter hole and then run the tap in. It is for soft metals like aluminum and is useful for automated machining. I've used them for CNC machining but why the engineer specified it, I don't know. Maybe when lower strength is permissible.