At that point, you’re ready to place your tool into the collet and tighten things into the holder.
When properly seated, your collet face should be flush with the face of the nut - almost press fit into the nut. The key is to fully engage (clip in) the collet inside the nut before you tighten it onto the holder. This is designed into the collet nuts and without it you would not be able to insert the collet into the nut To a new machinist, these clamping nuts may even appear to be manufactured incorrectly, due to the offset lip inside the collet (sometimes this is a loose collar, rather than an offset). Overtightening the nut can cause damage to the collet, as well as poor tool runout.ĮR collets seem simple, but there are several ways to misinterpret the mechanical simplicity of these holders.
Goutensnug… But in practice the torque to which you tighten the nut ensures you have proper clamping on the tool. It’s a running joke that the torque spec was German. Other tools holders like the setscrew, heatshrink, or milling chucks can offer you an even higher level of rigidity and precision, but don’t offer this versatility since they are limited to a single size.Īnother important detail with ER collets that is commonly overlooked is how tight do you go. They are a very versatile holder offering a wide clamping range. Having a large array of ER collets in your arsenal is important. Runout is important in a drill situation, and having a collet as close to your drill size will help you keep your runout to a minimum. Keep in mind that the closer your tool is to the nominal collet size, the more accurately it will clamp it, so having those intermediate sizes can prove helpful, especially when you are using ER collets to hold drills.
SHOTBOT COLLETS SERIES
The real strength of ER collets is that they collapse down to fit whatever you’re trying to hold, but a single size can’t hold everything.īecause the diameter only collapses down from 0.5-2 mm (depending on the collet size), having a set sized in a variety of increments allows you to hold any tool in the collets series clamping range. The short answer to the question, “what size ER collet do I need?” is: the whole series. While the initial ER system is based in metric, there are ER collets available with imperial sizing as well. As you tighten the nut on your holder, the ER collet collapses together to hold round tools or stock from 0.5-2 mm (or 0.0197-0.0787 in., depending on collet size) smaller than the collet internal diameter. The numbers represent the opening diameter of the tapered receptacle in millimeters. These collets are usually found in a standard series as: ER-8, ER-11, ER-16, ER-20, ER-25, ER-32, ER-40, and ER-50. Whether you’re looking to hold tooling or even round stock, these collets are an industry-standard for machine work. Since their development in 1973, ER Collets have become an essential element of every machine shop.
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