depends on thread length ; not needed if holder has compensation to "traction & compresion "
(the term used is.....Extension & Compression)
by the way, nice trick : it works like a charm on pitch:2
holder may contain none, or at least 1 of these atributes :
( has to have at least one )
... radial comensation = float
( static/hand adjusting to reduce radial play, or dynaminc/while moving )
... length compensation ( short/for syncro machining - long )
... angular compensation (
nah, not this one..... who'd want to tap a crooked hole )
... and others
( there are no others)
"float or solid" are more used for the machine parameters, so to syncro at it's best or not
ps : some producers reffer to "length compensation" as "float" or "syncro tapping" ... from this point if view, is same thing