Going deep with a router.

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Forum topic by richgreer posted 01-31-2012 06:47 PM 3777 views 0 times favorited 31 replies Add to Favorites Watch
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4541 posts in 2076 days

01-31-2012 06:47 PM

I need to go deep with a router bit. The question is my mind is how shallow can one go in the collet without taking any inappropriate risk.

My intuition says that I need to go at least 1” into the collet. I’ve never heard any “official” rule about this.

It is probably germane to say that I will be making multiple passes and only lowering the bit about 1/4” with each pass to minimize the stress on the bit.

Any thoughts?

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

31 replies so far

View Don "Dances with Wood" Butler's profile

Don "Dances with Wood" Butler

1051 posts in 2397 days

#1 posted 01-31-2012 07:03 PM

In my experience, the cost of a long shank bit is well worth the price.

-- Will trade wife's yarn for wood.

View KnickKnack's profile


1017 posts in 2568 days

#2 posted 01-31-2012 07:06 PM

Interesting question – I’ve wondered this myself whenever I’ve needed to not push all the shank in, which is usually.
For what it may be worth, Trend, my supplier of bits, has this to say...

Always insert as much of the Shank as possible into the collet, and at least three quarters of the shank length as a minimum, to decrease the chances of deflection of cutter when under load.

Ummm, I often don’t get them much in.

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."

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404 - Not Found

2544 posts in 1971 days

#3 posted 01-31-2012 07:12 PM

Rich, maybe you should think about a collet extension. It’s one of those things “that you think you’ll never use but now can’t live without”.
Especially useful on a router table.

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1406 posts in 1861 days

#4 posted 01-31-2012 07:13 PM

You could invest in a collet extension…


-- Herb, Florida - Here's why I close most messages with "Be Careful!"

View Bobsboxes's profile


798 posts in 1666 days

#5 posted 01-31-2012 07:13 PM

Rich, I have had a bit come out from not being deep enough in collet. It came up under my featherboad and scared me, Iwas lucky I had the feather board on or It may have got me. I got on computer that night and ordered some longer bits, and of those i have used all but one. I saw a picture in a mag. awhill back of a fellow with a ding in his forehead from a loose bit. So be careful. I have seen the bit extenders, they scare me also, if bit grabs as it has to most of us.

-- Bob, Lewistown, Montana. Kindness is the Language the blind can see and deaf can hear. - Mark Twain

View richgreer's profile


4541 posts in 2076 days

#6 posted 01-31-2012 07:15 PM

Don’s point is well taken. My problem is that I am working on a project that I must complete by Friday, which means I need a router bit today and I already own the longest bit available locally.

I cannot afford to wait even a day for a longer bit to be sent to me.

Did I tell you how much I hate deadlines?

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View S4S's profile


2119 posts in 1683 days

#7 posted 01-31-2012 07:16 PM

I would suggest not cutting more than 1/8 inch depth per pass if you are using a 1 1/2 horse power router or less horsepower than 1 1/2 h.p. . The less increased depth per pass equals less tear-out and burning and maybe worse .

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404 - Not Found

2544 posts in 1971 days

#8 posted 01-31-2012 07:18 PM

What is it exactly you are routing so deep? If you tell us what it is we should be able help you…

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682 posts in 1371 days

#9 posted 01-31-2012 07:40 PM

The collet of my PC has jaws that are about 1-1/4”, I can push the bit further than that to bottom it out, but the end would be past the jaws. As the collet grips by wedging the leading edge of the collet onto the shaft, thus pinching the collet around the bit, I would be hesitant to insert the bit less than 1-1/4”. You could probably run it out slightly (say an 1/8”) but too far and tightening the collet would tend to close the gap in the collet fully before actually tightening down on the shaft. It may seem hand tight, but under load it could slip, or worse, come out.

As Renners asked, what’s the application, maybe someone can come up with a work around?

-- John

View Loren's profile


7967 posts in 2650 days

#10 posted 01-31-2012 08:38 PM

What happens if the collet releases is the bit falls out and doesn’t
do much damage. I have had it happen a few times. In the
milliseconds as the bit comes out the end of the cutter may
wobble and mess up the work.

In terms of breaking your router or wrecking the bit, the
danger isn’t too great. I would look at the collet and make
a mark on your bit shank and leave the bit 100% inserted
in the collet proper. What happens if the bit is pulled
farther out, I believe, is the collet can get distorted.


View richgreer's profile


4541 posts in 2076 days

#11 posted 01-31-2012 09:21 PM

In response to “What is it exactly you are routing so deep?”

I’m routing mortises for a critical joint on some chairs. The mortise pal jig takes some depth away and I feel I need to get at least an inch of depth in the mortise. My horizontal travel is only about an inch. To avoid too much horizontal stress on the collet, I am doing more up and down motion that wide ways morion and only going sideways to clean up.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View DrDirt's profile


3377 posts in 2744 days

#12 posted 01-31-2012 10:12 PM

I use a 3/8 HSS mill.
I had to get an adaptor for my 1/2 inch router from Lee Valley – but it has the length.
Stay away from a 4 flute mill as those cannot plunge cut.

I got this set-up when Michael Fortune gave a weekend seminar at the Tulsa Woodworking guild meeting 2 years ago. He shared the plans for his mortising set up (also in FWW 197)

Best prices are at wholesale tool – hss bits are ~5 bucks.

-- β€œThe kind of man who wants the government to adopt and enforce his ideas is always the kind of man whose ideas are idiotic.” ― H.L. Mencken, Minority Report

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404 - Not Found

2544 posts in 1971 days

#13 posted 01-31-2012 10:22 PM

If you are using a plunging motion to nibble the waste out instead of pushing the router, I think you are ok leaving just 1/2” in the collet, you could even clean up with a chisel. Is the router used on the jig with the pheonolic base on? Could you gain a couple of mm by taking the router base off? (Plunge router I’m thinking off).
Can you use your mortise jig to get as much depth as possible, take router off and then go deeper using the fence for alignment/take more out with mortiser? What width mortise are we talking here and are you using a 1/4” router?
How many mortises, if it’s only 1 chair could you do it by hand? What about shallower mortises but pinning/fox wedging the tenon.

View Loren's profile


7967 posts in 2650 days

#14 posted 01-31-2012 10:32 PM

If you have mortise chisels, I’d recommend establishing the
geometry with your router jig and then having at it with chisels.

Even if you don’t have mortise chisels, the sides of a shallow
plunged mortise can act as a guide for drilling with forstner
or brad point bits. Then clean out with regular bench
chisels. Goes pretty quick.


View TheDane's profile


4379 posts in 2665 days

#15 posted 01-31-2012 10:55 PM

Rich—Without a collet extension, I wouldn’t do this with a router. I would either go to the drill press and waste out as much as I could then finish with a chisel, or find a buddy with a hollow chisel mortiser.


-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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