Tools and Tool Buying

[dbltap2]

I need to know why ther are different size shanks for router bits?  Is it because there are different size routers.

1/4" for routers and 1/2" for some routers and shapers?

Thanks

[John Courtland]

You will have two different size collets to accommodate both sizes, your router should be able to use both.

IN some cases it is just a matter of personal preference which size shank to buy. 

But in other cases, it is just plain ol design.  If you have  a rather large cutter on your bit, it will most likely come with a 1/2" shank to handle the stresses put on the cutters.  1/4" shanks usually are associated with smaller cutters.

Sometimes I have seen cutters that have no business being on a 1/4" shank, just too much stress.

I try my hardest to just simply purchase 1/2" shank whenever I can.  I believe the cutters last longer as there is more steel to dissipate the heat.  And the 1/2" shanks are just safer IMHO.

[Dave in Md]

I'm with John, get the 1/2 in shank when you can, less deflection particuarly on deeper cutting and stronger. some of the smaller cutters are only avail in 1/4 so you do need to have both collets

[knotscott]

When possible use 1/2" shank...it has every advantage in most cases.

[Zox]

Be aware that trim routers only take 1/4" shanks. So you may want to get the bits you're likely to use in a trim router (flush cutters, small roundovers, etc.) with 1/4" shanks, even if you choose 1/2" shanks for your larger bits.

[sweensdv]

Let me jump on the bandwagon and say that I also agree that whenever possible go with a ½" shank router bit.

[dbltap2]

That's what I needed to know.  Thanks all.

[Howard Acheson]

Just a little history.  When routers first came out, they were generally low powered.  1/2 to 1 HP was normal.  They all were manufactured with 1/4" collets.  As higher horsepower routers and larger diameter router bits were designed, a 1/4" shaft was not strong enough.  Hence 1/2" diameter bits became standard for 2 - 3 1/4 HP routers. 

With an adaptor, or an accessory 1/4" collet, 1/4" bits can be used in a 1/2 collet machine.  However, 1/2" diameter  bits can only be used in a 1/2" collet router.

[handyman john]

WOOD did a test of router bits a year ago (or so) and this was one of the things discussed. 1/2" shanks are more STABILE than 1/4" with larger diameter bits. 1/4" shank allows some "wobble" when you are routing heavily in especially HARD WOOD or making deep cuts.

I use both sizes but limit 1/4" to small diameter and trim bits. More robust bits like coves and round-overs I try to use 1/2" bits.

Oh, and I learned the HARD WAY to never bottom out a routerbit. Always bring it back UP at least 1/4" from the bottom of the collet hole. (don't ask how many things I've ruined to learn that lesson). 

[Old Woodie]

Some jigs will not take a 1/2" shaft. I just discovered this with a Porter Cable dovetail jig. I had purchased a 1/2" top of the line dovetail bit, but the shaft is too large for the jig.