05-30-2014, 04:33 AM
Hello.Ron,
The D1 spec. is that there should be a few thou" gap between the flat faces until the cams lock and tighten, at which point the taper is in compression and the gap closes up - in practice strips of silver fag paper (0.0005") should indicate a closed up gap. I've tested hundreds of chuck/spindle fits, ones where the chuck taper's too small are sadly common, particularly from Wanko :-(
The formal spec for D1 taper fittings (and the DIN equivalent) is pretty tight, tolerances are a couple of ten-thousandths, as you can guess the name brands meet the spec., the Chinese factories approximate them....
Nicely documented fix though! I have the rare as rocking-horse droppings D1-5 on my lathe which more or less forces me to go name-brand, but some far-eastern backplates I have are pretty good (Taiwanese, not Chinese...)
The D1 spec. is that there should be a few thou" gap between the flat faces until the cams lock and tighten, at which point the taper is in compression and the gap closes up - in practice strips of silver fag paper (0.0005") should indicate a closed up gap. I've tested hundreds of chuck/spindle fits, ones where the chuck taper's too small are sadly common, particularly from Wanko :-(
The formal spec for D1 taper fittings (and the DIN equivalent) is pretty tight, tolerances are a couple of ten-thousandths, as you can guess the name brands meet the spec., the Chinese factories approximate them....
Nicely documented fix though! I have the rare as rocking-horse droppings D1-5 on my lathe which more or less forces me to go name-brand, but some far-eastern backplates I have are pretty good (Taiwanese, not Chinese...)