‘odd’ sized R8 Collets

[Tony RayParticipant @tonyray65007]

Given that endmills & slot drills have standardised shank diameters -either imperial or metric what is the purpose of R8 collets that fall between these sizes ?

As R8 only seem to be used in milling machines for tool holding I can't work ot why they would be needed – but there will be a reason.

Tony

[Tony RayParticipant @tonyray65007]

[JasonBModerator @jasonb]

The 1/32nd and 1mm increments on R8 collets let you hold drills etc which can be handy if the job in tall and ther eis not enough room to get a chuck in, typical example here where I had to use a stub drill in a collet and only just had room with the head right up.

Obviously you can't grip sizes between the increments but it gives a better range than just the standard 1/4, 3/8, 1/2" etc mill shank sizes.

J

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Tony ,

In industry R8 collets are often used to hold parallel shank drills , taps , odd size cutters and special tooling so a full range of bore sizes is useful .

Some parallel shank drills in larger sizes are very long and fitting them directly in collets in the machine spindle allows maximum headroom for the workpiece and fixtures on machine table .

R8 collets are very cheap compared with collet chucks and QC tooling systems and for the semi permanent types of machine set up common in industry there is a useful economy in using one R8 collet instead of pointlessly using more expensive toolholding equipment .

MikeW

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