How to get the proper tightness for collets on router bits.

How do you know how tight to make the router collets so that the router bit wont slip, but the router collet is not too tight to where it is too hard to loosen when you need to remove the bit?


A good rule of thumb for knowing the right tightness for router collets on router bits and bit shanks is give it one last hand squeeze.  After you have slipped the router bit or bit shank into the collet and twisted the nut finger tightly, tighten it with the wrenches.

Once you have got it tight using the wrenches, you’ll want to arrange the wrenches sot that one is on the nut and the other on the spindle with the wrench handles offset.  Then, with one hand, squeeze the two handles together toward each other.  That final squeeze should ensure that the fit is tight, and you can reverse this last step to loosen the router bit when you need to.

This method may not work with some router models that only use one wrench.  For these models, you may need to try alternate methods.

The design of the collet can greatly affect the way you need to tighten the router collets.  The collet and socket are designed with precision so that when pressed into the socket the collet grips the router bit shank tightly.

Older style collets were shorter and had a steeper taper to them.  This created a need for a more considerable amount of force to drive the collet deep enough to get a proper grip.  Newer styles of routers use a longer collet with less of a taper that’s connected to the nut.  These routers grip nearly twice as much of the length of the shank as the older routers do.  The shallower taper requires more turns of the nut to get the bit tightly in place, but makes it so that it wont pop loose once it has been properly tightened.

Another method to achieving proper tightness from your collets, especially if you are using an older router, is to bottom out the router bit.  The reason this is important is that when you tighten the collet nut, the growing taper of the cone is being driven into the corresponding shallowing taper of spindle.  This grips the router bit, locking it into place and ensuring that it wont pull out.

If you bottom out the bit and pull back on it, the collet can take hold of the shank and bring the bit with it.  This will cause both the cone and the bit to get driven further into to spindle, locking tighter, but not over tightening it.

Also, Remember that it is important to change your collets regularly.  If a router cannot get a tight grip on the bit shank, then try to replace the collet.  If replacing the collet does not work, then it may be time to replace the router.  Also, remember to change your collets regularly.  By not replacing your collets when you need to, you may be greatly affecting the spindle life on your machine.


Information for this blog was taken from Woodworking journal and Ehow.

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