How deep do I set the #201 into the collet?
I think the ideal fit is to match the top of the tool with the top of the collet, about 1" of tool into the collet. Before inserting the collet, insert the tool into the collet & mark the tool with a piece of tape or just grab with your fingers at the bottom of the collet. Insert the collet then insert to tool to that mark.
However, there are situations where you need more tool for cut depth, or want less tool protruding to make the tool more rigid. You can also insert the tool all the way, then back it off about 1/8". Or if you need a bit more cutting length, mark the tool at the desired cutting length plus a bit of clearance & insert it to that line. If you can’t get at least 1/2", or better 3/4" of the tool shaft into the collet, it’s best to find a longer tool.
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This has been my go to. IDC Woodworks has a great chart showing all the things to consider. I’ll take a pic when I get home.
| Step | What to Do |
|---|---|
| 1 | Insert bit deep, then pull back ~1/16“ to 1/8" |
| 2 | Ensure ~80% collet engagement, no flutes inside |
| 3 | Hand-tighten, then snug with wrench |
| 4 | Optionally use depth rings for consistency |
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Welcome to the forum.
The tooling should be engaged with the collet’s full length. The design of the collet is for full engagement of the tooling shaft which means no cutter or flute geometry other than a complete full diameter of smooth shaft should be in contact with the collet. You can adjust the tool length as mentioned above as needed while maintaining full collet engagement, different length tooling may be needed based on your needs. The top of the tool should not be inserted into the router/spindle shaft so that it “bottoms out” in the shaft. There should be 1/16” to 1/8” clearance so the collet can compress for full engagement and holding of the tool as the collet will actually travel up into the shaft while being compressed with the collet nut. A trick used in table top router configurations is to use a small grommet in the shaft fully seated, that way when the bit is installed it rests on the grommet and then when tightened the grommet will compress while not allowing the bit to bottom out in the shaft.
It is preferable to use shorter tooling for the specific projects to minimize tool deflection (impacts accuracy) and the ability to use faster feed rates.
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Not sure about other routers but the C3D router has a hole through the shaft above the collet nut threads. I insert my endmills so that I can just see the tool shaft through that hole.
Another way I’ve used is to have the flutes of the tool down from the collet nut the same distance as the thickness of the tool. So for example the flutes of a 1/4 "endmill would be 1/4 " below the collet nut
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Usual preface, I’m with PreciseBits so while I try to only post general information take everything I say with the understanding that I have a bias.
I have a somewhat different outlook on this from working with a lot of microtools and things that have high failure rates for minor issues.
The bare minimum would be to have smooth shank through the collet gripping surfaces. However, as Redlander indicated you have more deflection with the more tool stickout you have. So the best result would be as much tool as you can get into the collet and still not bottom out or have any ground portion of the tool in the collet.
To give a rough idea, using millalyzer, the rigidity on an 1/8" shank, 1/8" cutting diameter, 0.25" LOC tool. The force required to deflect (bend) the tool 0.001" goes like this for the stickout (amount of tool sticking out of the collet):
1.0" - 3lbf
0.8" - 5.7lbf
0.6" - 12.4lbf
0.4" - 31.54lbf
For a 1/4" shank, 1/4" diameter, 0.50" LOC:
2.0" - 6lbf
1.6" - 11.4lbs
1.2" - 24.8lbs
0.8" - 63.1lbs
The easier it is to deflect the more you are going to get potential dimensional accuracy issues as well as vibration and forces issues. So choking up a tool is an easy way to minimize potential issues from at least one source.
I intentionally made these short tools to show a greater range. However, it more or less applies across the board, or at least until you get to very small diameters vs shank size. I also didn’t convert these as it’s more to make the general point.
Hope that’s useful.
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Thanks for providing more precise detailed industry related info to the forum. That’s excellent info to know.
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