I don't bother with spotting drills. If that sort of thing is needed I use a centre drill in the drilling machine. They are available in a variety of sizes. I don't believe in throwing money on things that in practice aren't needed.
2 turns down is way too much – as I have mentioned before even 1/2 turn down before reversing to break the chip is to much really and that gets more and more important on finer taps. This is likely to be why you are raising a burr – the tap back cutting. But carry on abusing your tools if you like.
While a drill can be used to remove burrs an hss countersink will make a much better job of it.
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I use 2 types. One is the usual fluted one the other is the cone with a hole in it more for use on the lathe on larger holes. The fluted one is what you need. I have one size but it's extremely pointed and for some reason 16.5mm dia but will do all diameters I am likely to need. You could make a handle for one if needed. I usually stick it in a small morse taper drill chuck that I have kicking about when and if I need to use it by hand. If it has to be significant and super neat I use the depth stop on the drill. – Countersunk headed screws etc.
Drill size – measure the drills and the tap and adjust the 1.6mm accordingly erring on being over size. You should have picked up from other posts that it's not that critical providing that the roots of the tap are clear. Zeiss ain't too good in that respect. Number drills add a whole host of different sizes few of which are needed but if say a No50 was bought the actual size may not be exactly as it should be. I shouldn't have mentioned it really as metric by 0.1mm offers similar accuracy at this size.
John
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