# Bit Shank Length



## Ruthy (Dec 11, 2011)

Hi,Mike here,
I'm a "newbie",so excuse the ignorance.I just got a Milwaukee 5616-24 router.I also got 3 undersized plywood bits from Infinity because I planned on making dados.The collet depth on the router is around 2 1/16". The Milwaukee instructions say insert all the way then back the bit out slightly which leaves very little sticking out.
I've read several posts on this forum & they range from using bit extentions, to inserting at least 80% of the shank in the collet.Is this collet depth a trait of Milwaukee routers?
I don't want to try anything that's not safe,thank you for any help I can get,
Mike


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## Quillman (Aug 16, 2010)

Engineering standards, minimum:

1/4" shanks: 5/8" insertion
3/8": 3/4"
1/2": 3/4"
Whence there is more shank than collet: Center the shank length on the long center line of the collet. Avoid bottoming the shank; the axial vibration of the armature can hammer it (the cutter) off the floor of the seat!


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## Ruthy (Dec 11, 2011)

Thanks for the quick reply,Quillman.I had not seen the engineering standard before(because of being a newbie).
Appreciate the help,
Mike


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## Mike (Nov 22, 2004)

Mike, it would be nice if router manufacturers would standardize the depth inside the shaft. Some actually require a dowel to be inserted to make it easy to install a bit for table mounted use. On many routers you can push an 1/8" rubber O ring into the shaft so you can just drop your bit in until it stops and lock it in position. This prevents the bit from bottoming out; the O ring will compress and allow the collet to tighten properly. It also prevents heat transfer between the bit and motor as well as the hammering effect Pat mentioned. If you remove your collet from the router and insert a bit so it is slightly through the collet you will see the maximum safe height that bit can be installed; this varies from one bit to another.


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## bobj3 (Jan 17, 2006)

Hi


Some of the better bits come with marks on them to help

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/kathome.htm
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/katana_bits9.htm

http://www.sommerfeldtools.com/sommerfelds/catalog/page03.pdf
==========


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## Ruthy (Dec 11, 2011)

Thanks,Mike-
I was confused with "shaft depth" vs. collet depth.Really feel like a dummy.At least I can proceed now.
Congrats on the new Forum Liaison position,
Mike


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## Cherryville Chuck (Sep 28, 2010)

You might want to take the collet out of the router and see how long the collet is. It may be that you are extending the bit shank thru the collet and out the other side which serves no useful purpose.


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## Kensway (Nov 28, 2011)

MikeD I too am a newbie and did not realize router bits have different shank lengths.I had to install rubber grommett into router then a 1/2 oak dowel in order to use my router bits.Thanks to this forum we can all learn something as I have.


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## Ruthy (Dec 11, 2011)

Thanks,Ken.I now have heard the 1/2" "o-ring" trick several times & I'm going to the hardware store today.I must assume that the o-ring goes to the bottom of the shaft and the dowel then is cut to the proper length for the bit you are using (meaning enough to let the shank pass through the collet).


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## Ruthy (Dec 11, 2011)

Sorry,Ken. I went back to Mike's reply and realized it's a 1/8" o-ring.(It's hard being a newbie),
Mike


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## Mike (Nov 22, 2004)

Let me clarify this. The O ring cord/material diameter is 1/8" and the O ring should be a diameter which fits snug inside the routers shaft.


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## bobj3 (Jan 17, 2006)

Hi

The rubber O-Ring is not the best way  glued to a dowel plug or not.

see below

===



Mike said:


> Let me clarify this. The O ring cord/material diameter is 1/8" and the O ring should be a diameter which fits snug inside the routers shaft.


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## Kensway (Nov 28, 2011)

I should clarify my post.I have sommerfeld bits using pc 7518 router.In order to utilize matched bit height advantage of sommerfeld bits I first installed sommerfeld gromett which is 7/32 thick 1/2 in in circumference then I installed 1/2 oak dowel which measures 1 1/32 in length.The dowel will go into the colett slightly.Now I am able to set bit height once then install other sommerfeld bits of a given set as needed.Some routers will not need dowel but mine did.Hope this makes sense


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## bobj3 (Jan 17, 2006)

HI Ken

The easy way to get around the error of the deep hole under the bit is to use a rubber faucet washer, they just just fit right into the collet (press fit), it that way you don't need a wood dowel in the hole..and yes they work better than a O-Ring or grommet.. I now use it in all my routers big and small..and you can get them from any hardware stores for peanuts..the norm is in a repair faucet washer kits..hand full for about 2.oo dollars 

Just a note ====all the holding power of the collet is in the first 1/3 part of the collet,see below..

====



Kensway said:


> I should clarify my post.I have sommerfeld bits using pc 7518 router.In order to utilize matched bit height advantage of sommerfeld bits I first installed sommerfeld gromett which is 7/32 thick 1/2 in in circumference then I installed 1/2 oak dowel which measures 1 1/32 in length.The dowel will go into the colett slightly.Now I am able to set bit height once then install other sommerfeld bits of a given set as needed.Some routers will not need dowel but mine did.Hope this makes sense


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## Mark (Aug 4, 2004)

bobj3 said:


> Hi
> 
> The rubber O-Ring is not the best way  glued to a dowel plug or not.
> 
> ...


There are multiple ways to do things, instead why not say "This is how I prefer to do it".


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## mstraw0001 (Apr 3, 2012)

I agree. Standards would be nice. I do like that "O" ring tip. I'll give that a try.
Thanks


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## mstraw0001 (Apr 3, 2012)

it sure is


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