Collect extension and 12 mm collet.

CMT 12mm router collet extension selection

As I explained in the previous post about CMT 8mm router collet extensions, if the largest router bit shank that your router will accept is 8mm then you cannot use 12mm or 12.7mm (1/2″) router bits. And there is no collet extension for 12mm routers that you can put in your 8mm router. If we have a router machine installed on the router table that accepts a 12 and a 12.7mm collet, we can buy a collet extension like the one in the picture, with the shank and the chuck made of a single piece of metal. This type of collet extension accepts 12 or 12.7 mm collets. The problem is that with it we can only use the 12 and 12.7 mm collets since the 6, 6.35 and 8 mm collets are too small to be used in its chuck.

You can also buy this type of collet extension, with 12 or 12.7mm shaft, but for use with 6.35 and 8mm collets, to get your 1/4″ and 8mm router cutters to protrude far enough above the table top. But with these collet extenders you won’t be able to use the 12″ and 1/2″ collets.

Collet extension for 12 mm wood router machines.

The product references for these one-piece collet extensions are:

Prices are from 2014 and are outdated.

For use with the large collets:

Collet extension with S=12mm shaft, for 12mm collet -> 796.002.00 -> 32,71€

Collet extension with S=12.7mm shaft, for 12.7mm collet -> 796.001.00 -> 32,71€

For use with the small collets:

Collet extension with S=12mm shaft, for 8mm collet -> 796.002.01 -> 32,71€

Collet extension with S=12.7mm shaft, for 6.35mm collet -> 796.001.01 -> 32,71€.

In the catalog it says that they come without collet, but the collet extension that I bought of this type did have it. I got confused here and also in the video. If you look at the CMT catalog, this particular model (the one-piece one) DOES have the corresponding collet that it says in the catalog. The two-piece ones are the ones that come without collet.

The references of the collets and prices (outdated) can be found below.

I have the S=12.7mm and it allows to use the 12 and 12.7mm collets. So I think that the collet extensions for the large collets accept the two large diameter collets (12mm and 12,7mm). And the collet extensions for the small collets accept the two small diameter collets (8mm and 6,35mm). [[ Notice that 12,7mm are 1/2″ ; while 6,35mm are 1/4″ ]].

For the case where the router machine accepts collets for router bits with a shaft of 10mm, 12mm or 12.7mm:
CMT router collet extensions catalog.

In this case the best option may be to buy a chuck like the ones we saw for the case of router machines that admit at most an 8mm collet. But in this case the chuck must be bought together with a reduction shaft with a slightly larger diameter.

What we do is to choose only one of the following reduction shafts, the one you are interested in depending on the collets you have for your router:

Prices are from 2014 and are outdated.

Reduction shaft diameter S=10mm and metric M12 -> 797.100.00 -> 11,18€.

Reduction shaft diameter S=12mm and metric M12 -> 797.120.00 -> 11,18€.

Reduction shaft diameter S=12.7mm and metric M12 -> 797.127.00 -> 11,18€.

With any one of those reductions you can use any of the following chucks, so if you buy both chucks you can use all the collets:

Chuck with metric M12 -> 796.000.00 -> 18,97€

(For use with 6, 6.35, 8 and 9.5mm collets only)

Chuck with metric M12 -> 796.121.00 -> 20,40€

(For use only with 10, 12 and 12.7mm clamps)

So, if you have a wood router that accepts at least 10mm collets, if you buy only one shaft reduction and two chucks, you will have a collet extension for all collets and therefore for all router bit shafts diameters between 6 and 12.7mm (well, you have to buy all the collets, too). The set of shaft reduction plus chuck would be similar to the one shown in the picture above.

As you can see in the picture below, the collets that come with the wood router machine and the collets that are used into the chuck of the collet extensions are different, so there is no choice but to buy the collets as well:

Collets for collet extension chuck and for the built in router chuck.

Prices are from 2014 and are outdated.

6mm -> 796.560.00 -> 6,15€.

6.35mm (1/4″) -> 796.564.00 -> 6,15€.

9.5mm (3/8″) -> 796.595.00 -> 6,15€.

10mm -> 796.600.00 -> 6,15€.

12mm -> 796.620.00 -> 6,15€.

12.7mm (1/2″) -> 796.627.00 -> 6,15€.

How to choose the router collet extension and the collets.

> See collet extensions for 8mm routers.

Scroll to Top