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I made a router table out of pretty thick plywood.

Router table

Because of this I need to stick the router bit at the top of the collet to get it to clear the table.

Is that ok or must I stick the router bit as far down the chuck shaft as possible?

  • 1
    There is essentially one correct placement for a router bit in its collet. This isn't it. – Graphus Aug 30 '17 at 22:05
  • I did this a few years ago, and had a 2" long straight bit eject itself from the collet at VERY high speed. Fortunately no one was hurt. I'd route out some of the plywood on the bottom of your table to give the router room to move up the necessary distance. – 3Dave Sep 3 '17 at 1:16
  • Yes thats the plan @DavidLively. – Justin Dearing Sep 3 '17 at 2:58
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A router bit shaft flexes more than you might think, especially one like you show with a big heavy body and relatively large diameter. Because they spin at high speed, that head carries a very large amount of energy https://en.wikipedia.org/wiki/Rotational_energy (note the energy increases with the square of the angular velocity (RPM roughly, probably radians per second in that formula).

The net of it is you don't want that thing working its way out or breaking off because it could do some serious damage if it hit you. Very much like a bullet I would expect.

So best to keep the extended length as short as possible and definitely not cheat the collet by not having the shaft going all the way through it. In a pinch, I'd run at lower speed when the bit is not fully inserted (bottomed and then pulled out 1/16" or so to accommodate shaft lengthening with heat).

I would recommend replacing the top with something thinner so your tool doesn't encourage bad habits. This sort of thing is easy to forget over time and you don't want it biting you one day when you're not thinking about it.

Also note that collets wear over time. Especially in this case you'll need to make sure it's fitting closely to both the shaft and the spindle taper. In particular, you'll want to ensure the collet has not become "bell-mouthed", and that the entire internal collet surface is bearing on the shaft, to maximize the friction that keeps it in place and support the shaft over the entire length of the collet.

  • This router was manufactured before I was born. Can I get a new collet for it? Is there a way to test it? Dial calipers with the arms for inside measurements? – Justin Dearing Aug 31 '17 at 1:43
  • @JustinDearing A quick search on Google for "black and decker router collet" shows several available. You'll need to do your research to find the right part number. I'd start with adding the router model number to the search. On assessing its condition, I would start with a visual inspection of the fit and the inside surface. A worn section will look different, maybe shiny or peened (dented). If the shaft rocks in the collet, like fits tight at the bottom but not at the top, that's not a good sign. You'll have to use some judgement on that though. – scanny Aug 31 '17 at 4:32
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    Instead of replacing the entire table with something thinner you can cut out the part where the router sits and make a thin insert so you can get access to the collet while the router is installed – ratchet freak Aug 31 '17 at 10:56
  • @ratchetfreak I make a bottom base of mdf for drawing compass holes in. I plan on doing just that. – Justin Dearing Aug 31 '17 at 13:15
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As an addition to the accepted answer, the instructions in both my routers mentioned that the bit should be placed 1/16" off the base of the collet.

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