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Collets or collet chucks are an excellent way to hold small pieces and with good tools the work can be removed from the collet and reinstalled with little loss of concentricity.
The split wire chuck was developed by US watch manufactures in the mid-19th century and is quite accurate but requires the work piece to fit the collet very closely. If the object to be turned is of a larger diameter or more than a few thousands smaller than the collet ID then the collet can be damaged and accuracy suffers.
So as result, you need a bunch of them. This set is in increments of 1/64” (0.016”) in an ideal world with an unlimited tool budget I would also have the metric set with increments of 0.5 mm. The collets for my watchmaker’s lathes are in increments of 0.1mm or 0.2 mm.
ER collets are a more modern design and have greater ability to handle differences between collet diameter and the diameter of the work piece. Once again the work piece should be able to slide freely into the collet but they have a greater clamping range. One manufacturer lists a clamping range of 0.039” this much mismatch on a split wire chuck would never be acceptable.
I’m not sure if one type is inherently more accurate than the other. However, I have seen that as a rule collet sets sold to metal workers have less runout than those sold to woodworkers. As a woodworker do you really need all that accuracy? I guess this depends on what you are making and if you need to remove the piece from the chuck during the turning process.
For a small but silly project, the world’s smallest wooden box:
http://lumberjocks.com/projects/50720
The error in the chuck would have made it impossible to successfully remove and replace the box into the chuck while working on this one.
The three sets I tested are all made in China and for the most part are of surprisingly good quality for the cost.
As a control I placed a piece of
Collet chuck comparison with good news for Shopsmith owners.
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