# Router Bit Shaft Size



## Selwyn Senior (Jan 11, 2014)

My fixed base router, which is table mounted, handles both 1/4 and 1/2 inch bits. Why would I purchase 1/2 inch over 1/4 or vice versa? Are there bits which only come in the larger size?


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## BrianS (Nov 7, 2004)

Hi Peter. Welcome to our little corner of the 'net.


1/2" shank bits are normally stronger than the 1/4" bits. With the 1/4" bits sometimes you can experience some deflection of the cutting head, especially with larger bits. I buy 1/2' shank whenever possible, altho I DO have an assortment of 1/4" bits that I use. It doesn't happen often, but 1/4" shank bits have been known to bend, or even break outright, if too much sideways force is exerted on them, which can happen when too deep a cut is attempted. 

Where it becomes really important, imho, is with large cutters. I would not feel comfortable spinning a raised panel bit, (3-3.5' dia) on a 1/4" shank. Just too much metal moving at too high a speed...


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## Cherryville Chuck (Sep 28, 2010)

I'm not sure if you can find bits over about 1 3/8 or 1 1/2 in 1/4" shank. Just too much toque on a shaft that size.


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## fire65 (Oct 29, 2008)

Because routers spin around 20,000 rpms. So stronger is better, less flex and safer, won't break as easy. I still use 1/4" in some of my smaller routers. Also think of it like this, 1/2" is about 4x as big as 1/4".


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## JOAT (Apr 9, 2010)

All of my routers only take 1/4" shank bits. They work just fine for what I do, so I'm quite content. However, if I ever buy another router my choice of shank will be 1/2".


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## rwl7532 (Sep 8, 2011)

Buy 1/2.
Look out for smaller at a good price at garage and estate sales.


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## Selwyn Senior (Jan 11, 2014)

*Many Thanks*

Thanks to Brian and others for your resposes. It certainlly makes sense to buy 1/2 inch bits since I have that option. I have snapped a 1/4 inch shank but a big part of that was my asking it to do too much too soon.



BrianS said:


> Hi Peter. Welcome to our little corner of the 'net.
> 
> 
> 1/2" shank bits are normally stronger than the 1/4" bits. With the 1/4" bits sometimes you can experience some deflection of the cutting head, especially with larger bits. I buy 1/2' shank whenever possible, altho I DO have an assortment of 1/4" bits that I use. It doesn't happen often, but 1/4" shank bits have been known to bend, or even break outright, if too much sideways force is exerted on them, which can happen when too deep a cut is attempted.
> ...


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## Daikusan (Apr 12, 2013)

I’ve used a 1 ½ in tongue and grove bit with a ¼ shaft in my old no variable speed router. I cut over 200 linear feet with it. Dumb!! I wouldn’t recommend doing that. 

I wouldn’t hesitate to us it for a similar project in my variable speed router now: though with that big of a cutter the ½ in shaft would be much better. Since I now have the option for ½ bits I have bough any ¼ inch


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## Dejure (Jul 27, 2009)

With exception of my trim routers and my Trend router, all mine take 1/2 and 1/4 bits. Wouldn't have it any other way - I can always go down, but I can't go up if the receiver for the collect won't allow it.

If nothing else, 1/2" shank makes a better heat sink, but the points made elsewhere here are even more important.




Selwyn Senior said:


> My fixed base router, which is table mounted, handles both 1/4 and 1/2 inch bits. Why would I purchase 1/2 inch over 1/4 or vice versa? Are there bits which only come in the larger size?


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