Since that would be at it max clamping size should we go up one size to get into the "mid" range of the collet?
Never had put much thought into this before but since we have a mess to buy I thought I would ask what is the best practice.
hoil Captain
27/64 = ~10.7mm
you may use a er20, er25 or er32 size collet ; i recomand the er32
regardless of the collet size, thus regarding of clamping the tool in a smaller or bigger collet, use collets with clamping domain of [ -1 .. 0 ] or [ -0.5 .. 0 ]
i say this because 10.7 is not a standard metric value, but it may be a standard inch value
if you clamp non-standard shanks than use collets with a wider clamping domain
if you clamp standard shanks than use collets with a h7 clamping domain
about using through coolant tools, thus sealing methods :
... rubber, from
Kintek - Home
... sealing disk over a standard collet ( pretty comon ) :
...... advantage : you may use through-coolant-tools inside normal collets
...... advantage : less chips will enter inside the collet ; rubber seal will also block chips
...... disadvantage : means more parts, and more weight, and sealdisk are usually for collets with wider clamping domain, and this means collet deformation, and/or less contact between collet and chuck
... metalic sealed : less elastic behaviour inside the collet, thus same torque aplied on such a collet compared to another, will lead to a smaller grip on the tool
i use kintek precision, rubber sealed, for standard shanks
i use whatever for non-standard shanks
i try to avoid non-standard shanks, because ( compared to when clamping normal shanks ) :
... collet deformation is higher
... collet is out of the chuck a bit more
... in time you may ruin the cone surface inside the holder
so :
... standard shank - h7 clamping range collet - good holder, only for such collets
... non standard shank - wider clamping range collet - whatever holder, only such collets
