# shank depth



## pemdas86 (Nov 21, 2008)

Greetings.

General question having to do with instering the bit shank depth and in conjunction with the use of template guide bushings.

The issue I'm just finding out with my new template guide set is when the template guide bushing is installed into the base my 1/2" straight cut bit barely extends past the guide bushing itself, rendering any operation useless.

What is the minimum depth that the shank needs to be inserted into the collet/arbor considered for safety ? 

I have heard 5/8" to 3/4" depth. Of course, in normal operations the bit should be inserted almost fully, about 1/16" from fully inserted.

Is it OK to use a bit at different depths, or, do they make extra long shanks for use with bushings? 

So much to learn, and so much time.
Thanks.


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## Ghidrah (Oct 21, 2008)

This is a link to an older thread here at the site. I pull my bits back out an 1/8", depending on the shank length. 

Bear in mind the shank needs to be in deep enough to be thoroughly grabbed by the collet in the chuck. IMO long cutting lengths and shanks are more versatile because of their extended range of use.
Height debate


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## Charles M (Apr 10, 2006)

You will need to consult the bit manufacturer for this info. For Freud bits, at least 80% of the shank must be in the collet but you should never bottom it out or try to insert the any portion of the bit beyond the shank.


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## pemdas86 (Nov 21, 2008)

Yes. Thanks.
The more I'm reasearching and understanding is that the bit does NOT have to be inserted fully, if need be. The manufacturer recommendation on the bit I have says to insert at least 5/8". But I totally agree that is not the best of protocols on a regular basis. Correctly, a longer bit shank and wider diameter should be used. I did some scouting around last night and found a couple 1/2" shanks that were 3-1/2" and 4-1/8" long. This would appear to be sufficient to clear the bushing to achieve an adequate depth of cut. Luckily, my router has both 1/4" and 1/2' collets.
Thanks Charles for the info, I'm going to check out the Freud bits at my local H.Depot this afternoon, along with another wishful look at the 94T crosscut blade for my miter saw 
Otherwise, the alternative (which I'm not too keen on) has been mentioned to grind down or file down the template bushing itself enough to clear the bit. Probably easier just to buy the right bit in the first place.


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## pemdas86 (Nov 21, 2008)

Just yesterday looked at the Freud bits at Home Depot and they look real darn good ! 
Plus, the price difference between the 1-1/2" and 2" bits is less than $1. 
Very good deal, most likely will get out the gift cards today. I've also heard they got very good reviews in comparison tests, and well within my price range for future purchases. Thanks for the help. Now I should be able to get back to my exact-width dado jig from where I left off.


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## cbsjoez1935 (Mar 14, 2007)

Steve,

Guide bushings also come in different shaft lengths. I assume for different applications. I have two different sets with one set having all its shaft lengths 1/4", while the other set has all different lengths, depending on what diameter you use. Using a 1/4" shaft length guide bushing should pose no problem for your 1/2" bit. Other factors might be if you have mounted your router directly to a thick table base or plate and the router shaft does not have enough travel to it.

Joe Z.


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