Router Bit Extensions: How Safe?

[Grady Cowardin]

Instead of buying a 1/4" collet I can get an extension for use in a 1/2" router that holds 1/4" shanks for $5 more. MLCS has both the 1/2" and 1/4" Extensions as a package for $40, not a bad deal or one for $25. I know extending the distance away from the motor shaft adds torque to the router's output shaft/bearings etc but what about the possible extra vibration added? What are the disadvantages to these extensions? I am sure they are safer than not seating the bit completely in the collet to gain extra height but I've never used one so please fill me in.

If I order from them I may also pick up a Dovetail bit set. They sell a standard 14 degree kit but it doesn't include and straight bits. There is also an Incra kit that includes the straights but they are odd angles and I assume you need their templates etc. Trying to avoid buying crappy bits off ebay so bare with me here. Thanks!

[David DeCristoforo]

IMMHO, these are best reserved for situations in which you must have the extra "reach". For general routing, the 1/4" collet will be better. You have already pointed out most of the reasons.

[Greg Funk]

Do you need the extra length? If you just want to use 1/4" bits in a 1/2" collet you can also buy a collet reducer that fits inside the 1/2" collet. These should cost less than $6.

I would never use an extension. I believe it will result in more vibration and a rougher cut. If I needed extra length I would look for a longer bit. If longer bits weren't available I would assume there was a reason for this...

Greg

[Grady Cowardin]

Thanks guys. Greg, I saw that universal insert and figured that was the cheapest route and the OD of it should be the same as a standard bit with matching standard tolerances and should work in any 1/2" router. Most collets are locked in from axial travel by the threaded surround piece so there is a possibilty of movement but I imagine if tightened properly nothing will budge.