How to correctly tap hole by use both drill and tap bit

[abdulbadii]

TL;DR

How do we correctly tap hole by use a both drill and tap bit

How to correctly tap hole, i.e. make thread inside it, by use a usual drill with bit having 2 in 1 i.e. both bore/drill and tap bit once as in hole tap the rule is it must always go back and forth full cycle clockwise and half cycle counter-clockwise direction, so how can this rule in the former use ?

 

[Baluncore]

The combined drill and tap is for use in soft sheet materials such as plastics, aluminium or composites. It is not designed to be used for deep holes, or for hard materials. The hole is drilled and threaded in one pass, without backing the tap. A cordless handheld drill is often used, with some form of soap or cutting fluid to lubricate the tap.

 

[Lnewqban]

When drilling-tapping in metal, that type is to be used for limited thickness walls or sheetmetal.
The drill part should exit the opposite side of the wall prior to the tap part engages.
The reason is that drilling requires less advance and the tap, and the threading section can easily shear off is drilling and tapping happens simultaneously.