2017-04-28

More jaws for the 4th axis chuck on the CNC

Design intent

This is my 4th axis.
A "K11, 100mm, 3 jaw chuck".
I already made a custom steady-rest for it but still, the existing jaws are not very good at gripping soft, cylindrical blanks to mill.
So I want to have either cylindrical chuck-jaws or base jaws that I can bolt any kind of custom jaw-geometry onto.

Existing hardware

Thanks to Jeremy Parton on Google+, who pointed me to this website ,
I know that:
  • K11 is grouped into K11 (1 jaw), K11A (3 centering jaws) and K11C (3 independend jaws)
  • meaning we have K11A here
  • K11A are ISO3442 standard clutches.
 K11 100mm is defined as
  • D1=72mm
  • D2=84mm (diameter between mounting-bolt center-points)
  • D3=22mm  (shaft diameter)
  • H=74.5mm (thickness of chuck with jaws)
  • H1=55mm (thickness of chuck)
  • H2=n/a
  • h=3.5mm
  • Z-d=3-M8 (bolts mounting the chuck to the face plate)
(Without a copy of the DIN/ISO3442 standard, I found this catalog of chucks and jaws containing a reference drawing. It shows where these measurements apply.)

Options considered

I'm currently investigating these 95mm jaws for turning machines.
The  chuck they come with is not compatible because it uses a thread to attach to the shaft.
This doesn't work when changing direction. So I need to use them with the existing chuck.

This chinese seller seems to sell K11-100mm chucks and the chucks I want. So he should be able to answer if they fit together.

What I actually did
In the end I now meassured the existing jaws and created a parametric CAD design.
The single design has 3 configurations for labeled Jaw #1, #2 and #3 .
After getting a single Jaw #2 to fit properly....

...I'm now printing Jaw #1 and #3

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