nev":3qeux1o6 said:
what puzzles me is theyve machined the individual jaws to match the individual sections of jaw, why dont they just machine them to all be the same size in the first place? surely its 4 times as much work making the individual ones fit?
The rear of the 4 jaws or Jaw carriers are different as they have scroll pitch spacing matched to the actuating scroll behind them.
This is done as a set in production with the partially machined jaws aligned in a jig.
In use the jaws/jaw carriers need to be assembled in the same sequence as they were in the jig.
Likewise accessory jaws are turned in the round as a complete disc, and the location holes drilled to an accurate PCD and circumferential pitch.
They have to be machined on back and front and this requires a move of jigs/holding methods
The jaws are then split into four sections using yet another separate jig or holding method.
If production controls are very good then they will be identical, but any slight miss alignment for this second and third process may result in a discrepancy, hence the need to mark them and assemble them in the original order that they were machined in the round.
Individual accessory jaws are not machined to match specific jaw carriers, but by careful control of the quality of jigs etc. by maintaining a known reference, (the numbers) there is the likelihood that any discrepancies are kept to a minimum and one that is acceptable for wood working.
On a metal lathe requiring increased precision jaws are ground in situ on the lathe.
