What is the difference between Nylon 6/6 and 6/12. I found them on MSC. How do they machine and which one is softer? I am looking for something that holds shape well. I would like to make some collets to mount in the back of the spindle (of a mini lathe) to hold a wooden shaft centered while it is being machined. Also need someting to cover the jaws with so that it would not mar/damage wood shafts while holding in the chuck. Any other suggestions Other than Delrin? Since Delrin is too hard. I need material with more flexibillity. Thanks for any advise.