How to install and change router bits
Installing a router bit is very simple.
The first step is to unplug the router, even if you have an auxiliary switch. This often overlooked steep prevents the router from accidentally being started should the switch inadvertently be brushed. For helical adjusting routers, it is often simpler to remove the motor from the base to change bits, especially if two wrenches are involved.
If the shank of the router bit does not slide easily into the collet, check for manufacturing problems, such as insufficient radius at the end the shank, rough finish grinding or a burr. Other times, the problem is a roughened interior on the collet or scratched shank on the bit, which can be caused by the bit spinning in the collet. These problems can be alleviated, if not prevented by breaking the edge on a bench grinder and then buffing the shank.
Changing router bits
The bit should not bottom out in the collet, for this could prevent the collet from being fully tightened. If the bit shank bottoms out, pull it back out of the collet about 1/16 in. before tightening the locking nut. You should pay attention to the bit shank, it needs to be inserted to sufficient depth to be gripped securely by the collet. Otherwise, the bit may cock sideways and even spin loose.
Once the bit is engaged, the collet is tightened. Many people tend to overtighten collets, turning the wrenches with the strength of a superman. This is not a good technique. Overtightening won’t really hurt anything but it puts an unneccesary strain on the collet and makes router bit removal much more difficult.
When using an adapter bushing, however, more torque is generally necessary so some extra force should be used.