Router Collets

      The number one cause of router problems is a dirty or worn collet.  Symptoms include bit breakage, slippage and excessive run-out.  Excessive noise and or poor quality cuts are signs of possible problems.  Bit slippage is occurring if there are black or brown marks on the shank of the tool.  Use compressed air and a brass brush (plus pitch remover if necessary) to remove all sawdust, pitch and rust.  Clean the outside and inside of the collet, the collet arbor and the inside of the collet nut.  The brass brush will remove deposits that solvents and compressed air can’t.  Do not oil these surfaces unless the router is being stored and be sure to remove the oil before use.

      It’s important to periodically check the run-out of your routers collet, which shouldn’t be more than 5/1000 (.005”) of an inch, when measured 1" from the end of the collet.  To measure run out, insert a drill rod in the collet and tighten it.  While turning the router by hand, measure the run-out of the collet using either a dial indicator, or a feeler gauge and a block of wood clamped to your router base.  If the run-out is over .005”, check to see if your routers bearings are bad.  Turn the router slowly by hand while feeling for any rough spots in the bearings, plus try to wiggle the router arbor.  If the bearings seem OK and cleaning the collet doesn’t fix the run-out problem, try replacing the collet.

     Collets are a wear item and will eventually need to be replaced, usually because the become bellmouthed.  It’s similar to what happens when a fence post is put in the ground and then wiggled back and forth.  The fence post (router bit) is no longer held tightly and the post hole (collet) is now “bellmouthed”.  Bellmouthing can occur at one, or both, ends of a collet.  If the collet is bellmouthed, it will not be as apparent as a loose fence post, but it will cause the cutter to have excessive run-out which will be noticeable (greater vibration/noise & poor cut quality) while routing.