Let me just add that in my opinion the MUSCLECHUCK is one of the greatest improvements in router technology probably since routers were invented. All three of my 1/2" routers have MUSCLECHUCKS. Their grip is several times that of a standard collet chuck and only requires a half turn of a 4mm, preferably ball ended Allen key to secure and release the bit.
Bob according to what I've read you'll need one for every size that isn't 1/2" but I could be wrong. With any other router you usually get a 1/4 and/or 1/2 (in North America) and any other size requires a bushing.
whats confusing me is when I buy a 1/2" (12 mm) router, I dont need to buy a 1/2" (12 mm) collet.
That page seems to suggest that I would.
So if the chuck comes with one collet, will the 12 mm fit straight in and I can have a 6 mm as the one collet?
Bob, a Musclechuck adds 5/8" and there is an extended version of the Type 1 that is longer. 1/2" is not 12 mm and you need a bushing to use 12 mm bits in the Musclechuck; this bushing is high precision and made in the USA.
Bushings are available in a wide range of sizes both Imperial and metric.
To be specific, if your Makita router comes with a 12mm chuck then when you replace it with a MUSCLECHUCK which only accepts 1/2" bits you will require a reducer sleeve 1/2" to 12mm available from the web site:
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