I’m not sure if this was always the case, but when I put my 1/8 cutters in the collet and tighten it down, it has some play in it (I believe.) when I push / pull it, it’s making a clicking sort of sound and feels to me like it may be moving a little.
@Darren, on my Tormach I’m still using the ER collets that came with it 9 years ago and have seen extensive service. I wouldn’t consider them a consumable, rather permanent tooling and the only reason to replace one is if it was damaged in some way.
Make sure the collet is fully snapped into the nut before you tighten it. http://www.precisebits.com/tutorials/er_collet_system.asp has a good step-by-step explanation of ER collets. The one way I know of to damage an ER collet is to tighten the nut when the collet isn’t fully engaged on the extractor ring. That can spring the collet out of shape.
My precision collets were definitely consumables - over time the runout (wobbles from perfection in the spindle/collet system) was noticeably increasing - but, as Randy observes, this is a (very) slow process that may not be noticeable.
It really depends on how often one inserts/removes tools, how much you machine, what materials you machine, how you machine (machining techniques), how much you machine’s unique characteristics (very subtle) affect collect life, how your spindle ages with use, and how easily one can see affects in the finish.
Some tools CAN affect collet wear as well. For instance, a fly cutter can put quite a bit of stress on a spindle and/or collet. I wouldn’t expect these types of tools to be appropriate for the Nomad or Shapeoko. I did see a company selling 1/8 shaft fly cutters though…
Some types of machining - 4 and 5 axis continuous machining - and machining techniques (e.g hogging (RAPID roughing), high flute counts) CAN affect collet (and spindle) wear as well.
If you’re working in wood, where the material changes dimensionality with temperature and humidity, collet aging is much less likely to be noticeable than if you’re producing precision parts with near mirror finish in metals - is it noticeable to the human eye?
I found that I had to replace mine every 3 years or so. I know of production shops where they can see runout degradation and replace theirs once a year. It was definitely visible in the finish for some work. Their spindles needed to be refurbished every few years too! SERIOUS AMOUNTS OF COMPLEX MACHINING.
YMMV. I would expect that Nomad hobby type use one would see VERY long collet lives.
Cheap collets are crap when precision machining is desired. The Precision Bits WEB site Randy points to has some really good collets for the machines they support.
It is VERY IMPORTANT that one learns to insert tools in a collet properly and the collect is seated in the nut properly as well. Don’t just slap tools in and lock them down… monkey tight, not gorilla tight.