- Joined
- Jan 20, 2016
- Messages
- 602
That decision will be made by a number of different factors such as:Out of curiosity, why would one choose the various collet types over the others? I see why you want collets, just not sure why you want 5C/ER40/etc..
-Intended use
-Cost
-Clamping range
-Clamping machanism
-Size requirements
ER collets (if I am not mistaken, and I could be) were originally made as a tool holding solution rather than a work holding solution. They also clamp at the front and back of the collet which means if you put something in only half way or less, the back will clamp tighter than the front which can lead to poor support and distortion.
5C collets (note that there are also 4C, 3C, 2C etc) are work holding collets and typically have an external thread. That allows better access to the front of the work due to the lack of a clamping nut. They can also be easier to use because of the thread. They can use a mechanism similar to the scroll of a 3 jaw chuck to tighten and release the collet. You can also clamp small portions of the part securely. However, they also need to be keyed which can cause problems in certain applications. It is also possible to use a pneumatic chuck to secure them where thats not possible with an ER collet. ER collets can clamp a larger range than the 5Cs which means in theory, you need fewer ER collets to get a full clamping range (though in practice, trying to clamp too far down doesn't work out as well.
There is also cost and space requirements when picking size. You aren't going to want to stick an ER50 collet on an ISO20 tool holder, but you also don't want to stick an ER8 collet on a 14x40 lathe spindle (I suppose you could, but I don't see why you would). With increased size also comes increased cost. Maritool sells ER20s for $19 vs ER50s at $42.
So for work holding, a 5C collet is probably the better way to go, but I know for a fact that ER collets will do the job just fine, especially for hobby work.