Mandrel to lengthen the axis of the milling machine.

CMT router bit chuck extension 8 mm shank

If you have made a milling table (<- see in this link how to make one) or small homemade router with your column milling machine, or if you are thinking of making one, you will have realized (or you should know, as the case may be) that when you put the milling machine underneath For a board of about 18mm the cutter may not protrude far enough above the board. One possibility is to use a thinner board, about 10mm (which we may need to reinforce around the router so that it does not deform). Still the strawberries may not reach the desired height. We can always tighten the axis of the bur by inserting it into the collet of the bur holder slightly less than 3/4 of its length, which we see engraved as a recommendation on the axis of some burrs, although sometimes it may not be enough and it is not recommended to be too short with the length of the axis of the cutter that we put in the collet. The best solution we have to make the most of our homemade router is to use a drill chuck extension like the ones manufactured by CMT. Yes, it is a "small" expense more. Or rather a few more small expenses, since if we look at the CMT catalog we will need to buy several pieces.

At the moment I still did not need to use these drill chucks, since my strawberries always protruded enough above the board. I acknowledge that this is partly because the milling machine I use, a Power Plus X093, allows the use of milling cutters with a 12mm shaft (and had a set of such milling cutters) and these are somewhat longer than those of the cheap milling cutter sets with 8mm shaft that I have.

Pliers and milling nuts.

The milling machine that many of you will have, and also the first type of milling machine that I had, in many cases will be for strawberries with axis of 8mm at most. And surely you have the 6mm and 8mm calipers. With these milling machines you cannot use drills with a 12mm or 12.7mm (1/2 ″) shaft and There is no extension chuck for 12mm or 12.7mm drills that you can fit into the clamp of an 8mm router..

Cheap router bit sets.

These milling machines often bring a set of strawberries, and if they do not, I recommend buying at least one set of strawberries cheap. I have a pair, one is the typical one that is seen everywhere and that is usually the one that comes included with many milling machines and the other, that I do not remember where my father got it, is a more complete game that curiously brings strawberries something else long.

In the case that your milling machine supports a clamp of 8mm milling shafts at most:

To get the strawberries to reach the desired height on the home milling table, a solution, as I said above, is to use an extension drill chuck such as the one from CMT. These are made up of a reduction and the drill chuck itself. You can see in one of the photos the parts: reduction, chuck, clamp and chuck nut. In this type of chuck, the largest collet that can be used is 9.5mm (3/8 ″), and it is not possible to fit collars with a larger diameter. Neither the 12mm nor the 12.7mm goes into the chuck.

Combinations for 8 mm extension chucks.

I leave you below the necessary parts, references and prices that I found as of today (May 2014):
You need a reduction, a drill chuck and the calipers:

Shaft diameter reduction S = 8mm and metric M10 -> 797.580.00 -> € 11,18

M10 metric drill chuck -> 796.100.00 -> € 18,97

You can use the clamps for the following diameter of the cutter shaft:
Collet for CMT extension mandrel.

6mm -> 796.560.00 -> € 6,15

6.35mm (1/4 ″) -> 796.564.00 -> € 6,15

8mm -> 796.580.00 -> € 6,15

9.5mm (3/8 ″) -> 796.595.00 -> € 6,15

When I bought the calipers they did not have the 6.35mm one, but they gave me the option of buying a supplement that transforms the 8mm caliper into a 6.35mm one -> € 8,30


And in case you also wonder,

the clamps of your milling machine DO NOT They serve to fit these mandrels (nor those of the mandrel serve for the milling machine's milling cutter), so it is mandatory to also buy the necessary clamps according to the diameter of the milling cutter shaft that you have or that you think you will have in the future.

-> See CMT extension chucks for 12mm collet milling machine.

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3 comments on "8mm CMT drill chuck extension"

  1. Hi, I'm Fran .. Thank you very much for the information. I have a jcb milling machine for 6.35mm and 12.7mm drills but in all the DIY department stores they sell 8mm drills. I would like to know if there is any type of reduction for the clamping pliers to be able to place 8mm drills. Thank you. I follow you on YouTube.

    1. Enredando No Garaxe

      Hello Fran. Thank you for following my channel. There is also a 6mm to 6.35mm reducing bushing. But I don't know if there is from 12 to 8. Maybe there is from 12.7 to 8? (12.7: is that the size? I don't remember). You could put two reducing bushings 8.38-> 8.38-> 12.7, although I do not know if it is highly recommended. Your router does not have an 8.38mm collet?

      1. Thank you very much for your answer. I am from Valencia, you do not know how difficult it is to find strawberries for milling machine and if they are not 8 mm above it is impossible, you have to use the internet and the risk that this entails (that does not coincide, mistakes etc) in addition to those that come in Games usually bring different stem measurements, anyway, thank you very much.
        I have been taking a look at the catalog that you show in the video but there is no way to buy online, it is a very complete catalog. Regards.

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