Router Bit Depth Setting In Collet

14013 Views 18 Replies 11 Participants Last post by gdonham1, Dec 7, 2018

Gaia

Discussion Starter · Nov 22, 2018 (Edited)

I've been reading about O rings etc.
I got a Musclechuck type 2 for Dewalt 625 yesterday but am having to return as router bit hardly above router table fully wound up.
I then read the following at,

Router bit shank install depth

"As a matter of fact, it is virtually impossible to bottom out a router bit in a Festool OF1400 or OF2200 router. The OF1400 has a spindle depth of 2.25" and the OF2200 has a spindle depth of 3.5". So it will be very rare that you will find a router bit with a shank long enough to bottom out in these routers.
The bottom line is that there is no reason to ever fully insert a router bit into a any router. Once the bit extends into the collet enough to be fully gripped by the collet, inserting it any deeper will not make it grip any better.
So the only decision a woodworker needs to make regarding how deep to insert the bit, is how much of the shank they need/want exposed above the collet. This relates to the stability of the bit, not about the gripping power of the collet."

The following is what I'd like to know?

" For a 1/2" shank bit, it hardly matters how much shank is exposed. It will be very stable at any depth as long as the collet clamping surfaces are fully engaged. (For Festool collets, this is 1" insertion.) 1/4" shanks are a little less rigid, but then the cutting heads are also smaller.

So the really simple answer is, stop inserting your bits so deep! Base your insertion depth on how big the cutter is and how thick the shank is.

For most router bits, 1" insertion is sufficient. For large panel raisers and profile cutters, leave enough shank exposed to not cause you other problems. "

I don't have a Festool collet I have an Axminster Collet extension, so rather than fathing about with O rings at bottom of collet or on shaft. Will I be OK with just 1 inch of router shank inserted into the collet. This approach seems much simpler than 1/16, 1/8 or 1/4 inch gap trying to use O rings.
Obviously I don't want the bit working loose.
Thanks.

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harrysin

· #2 · Nov 22, 2018 (Edited)

Some time ago I carried out a lot of research concerning insertion depth of router bits. During this research I contacted all major router manufacturers and examined as many routers as I could get my hands on and the definitive answer "beyond 1" serves no purpose at all" 1" was the length of all the collets that I examined. The armature shaft of the Makita 3612/C has a VERY deep hole and so a plastic rod is supplied so the bits don't get lost inside!
This simple jig makes it easy to fit "O" rings on each bit so no guesswork is involved.

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Stick486

· #3 · Nov 22, 2018 (Edited)

what does the manufacturer say???
better bits have a depth set mark/line on the shank...
insert the bit slightly more than the collet is long..

Cherryville Chuck

· #4 · Nov 22, 2018

Once you have the bit to the bottom of the collet there is nothing more to be gained. So if you remove the collet and measure it's length then that is the minimum insertion length for the bit shaft. It will be somewhere between about 19 and 25mm (my DeWalt 610 collet is only .7 something of an inch long). That's a clever little jig Harry made for keeping small straight bits from falling through.

JFPNCM

· #5 · Nov 22, 2018

As a point of reference, I just checked a Musclechuck collet and it is 1 5/16” from the top rim to the bottom of the collet. Assume then that the shank should be inserted accordingly. To follow Stick’s suggestion that would be at least 1 3/8”.

Stick486

· #6 · Nov 22, 2018

correct...

Gaia

Discussion Starter · #7 · Nov 22, 2018

Stick486 said:
what does the manufacturer say???
better bits have a depth set mark/line on the shank...
insert the bit slightly more than the collet is long..

Looking at their web site, no info but there is a mark on shank which I take to be the depth.
Thanks.

Gaia

Discussion Starter · #8 · Nov 22, 2018

OK thanks everyone.

JOAT

· #9 · Nov 22, 2018

Way back I found out my bits climbed because they bottomed out - real old Ryobi router. Was told if I raised my bit about 1/8" they would not climb, which proved to be true. So, now I just let the bits go as deep as they can go, raise them up about 1/8" or so, tighten the collet, and no problems.

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Cherryville Chuck

· #10 · Nov 22, 2018

Peter if you look at the MC you'll notice that the screw that clamps it to the bit is near the top end of the MC. This is different than the slotted collet in a forcing cone type design that is the norm for standard collets. One of the reasons for making sure the bit is at least to the lower end of a standard collet is to ensure you don't damage it by having it squeeze together with nothing to restrain it from going too far. As long as a bit is past the tightening screw on the MC a little ways then it shouldn't damage the MC. Certainly the more shaft inserted, the better the holding power would be but if you stopped at the 1 inch insertion mark that should be good enough.

sreilly

· #11 · Nov 23, 2018

I don't think I've ever installed a bit that I didn't bottom out and then just slightly raise before tightening. If you have a straight bit that won't cut deep enough this way I've always felt you have the wrong bit. At the speeds these bits are turning you really want a firm grip on them. I've never had an uissue using this method.

harrysin

· #12 · Nov 23, 2018

JFPNCM said:
As a point of reference, I just checked a Musclechuck collet and it is 1 5/16” from the top rim to the bottom of the collet. Assume then that the shank should be inserted accordingly. To follow Stick’s suggestion that would be at least 1 3/8”.

Not at all, study the photograph and you will see that only approx. the top 3/8" grips the bit close to 360° but to avoid run-out insert the bit 1".

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mgmine

· #13 · Nov 23, 2018

Did you have this problem with your old router or is this the first one used on your table? How thick is your table? Is it possible to recess your router more into the table?

harrysin

· #14 · Nov 23, 2018

sreilly said:
I don't think I've ever installed a bit that I didn't bottom out and then just slightly raise before tightening. If you have a straight bit that won't cut deep enough this way I've always felt you have the wrong bit. At the speeds these bits are turning you really want a firm grip on them. I've never had an uissue using this method.

Even two of the manufacturers, one who's instructions stated to FULLY insert the bit and the other that stated to fully insert then withdraw slightly agreed with me when I pointed out that below the depth of the collet, nothing was achieved.

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chessnut2

· #15 · Nov 23, 2018

Great idea for the jig, Harry. I use O-rings too, and have been wondering if I should cement them into place once located. Do you do that, and if so, what type of adhesive do you use? Thanks.

TenGees

· #16 · Nov 23, 2018

I believe the biggest issues are:
- Having the bit too far in. In that case, some chucks will grab only near the bottom of the bit. A buddy did this and launched a whirling, bouncing bit.
- Not in far enough to be held properly.

The whole O-ring trick is to keep the bit from bottoming out because when the router is upside down it's hard to hold the bit above bottom while tightening.

I think all the replies are right... nothing to be gained beyond a certain depth but keep it off the bottom.

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chessnut2

· #17 · Nov 23, 2018

TenGees said:
I believe the biggest issues are:
- Having the bit too far in. In that case, some chucks will grab only near the bottom of the bit. A buddy did this and launched a whirling, bouncing bit.
- Not in far enough to be held properly.

The whole O-ring trick is to keep the bit from bottoming out because when the router is upside down it's hard to hold the bit above bottom while tightening.

I think all the replies are right... nothing to be gained beyond a certain depth but keep it off the bottom.

Thanks for the warning about the bit being too far in.

Reactions: 1

JFPNCM

· #18 · Nov 23, 2018

harrysin said:
Not at all, study the photograph and you will see that only approx. the top 3/8" grips the bit close to 360° but to avoid run-out insert the bit 1".

Thanks Harry. Charles described that point earlier and I agree with both of you.

gdonham1

· #19 · Dec 7, 2018

On Porter Cable type collets you do not want the bit bottomed out because the bit will chatter. The collet is cut in a W pattern and the router motor shaft hole is inclined slightly. When you tighten the collet nut you are squeezing the W together holding the bit slightly pulling the bit down. The bottom of the hole can be not perfectly smooth causing the bit to spin slightly of center introducing chatter. Look at the collet you are using and insert the bit at least below the clamping jaws. But do not bottom out the bit. If your bit is too low in relation to the table move your router up in the mounting of the lift. If you are using a regular router base then you may need a bit extender. Just remember the further your bit is above the router can introduce chatter with the bit turning out of round. Most routers are turning 16000 to 20000 rpms. Small errors turn into vibration and make a rough cut.

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