Advantage to 1/2" Shank Router Bits?

[Dennis McDonaugh]

Is there an advantage to 1/2" shanks in smaller size bits like 1/4 or 3/8"?

[Mel Fulks]

You get a good hold on the bit without using so much over tightening.

[Ed Aumiller]

Stability...

[glenn bradley]

Yes, as mentioned, stability. The half inch shank will provide a cleaner result than the quarter inch shank.

[Tom Bender]

I always forget . . . Is it the letter "S" or the letter "C" that is silent in the word scent?
- Glenn (the second "N" is silent) Bradley

Rhymes with Perth

[Mick Simon]

I'll go against the grain here. I was fortunate enough to attend the Onsrud Cutter Tooling School twice before I retired. One of the biggest takeaways for me was that a tool with the same shank diameter as the cutting diameter is usually stronger than one with the cutting diameter ground down from a larger shank diameter. The transition point from say, ½" to ¼" becomes a flex point leading to premature breakage. So a ¼" bit with a ¼" shank is stronger than a ¼" bit with a ½" shank.

This is an excerpt from their Routing Guide. Note the Cutting Edge Diameter:

456734

Obviously for profile cutting tools with larger bodies the larger shank is stronger. The above holds true for straight cutters, tapered tools, etc.

[mreza Salav]

Not always. If we are talking about very small bits (say a 3/16" round over or a 1/4" straight cut) I prefer a 1/4" shank as it there is very little benefit in thicker shank and instead it allows me to use the bit in palm routers.

[Jim Dwight]

Fractures at the change in shank diameter are not unusual in inexpensive bits in my experience. I do not buy "cheap" dovetail bits for my half blind dovetail jig, for instance, because they break quickly while a quality brand lasts a long time. But of most bits, this is not an issue.

1/4 inch bits will slip in the collet and ruin your work. There is not enough surface area. It happens less often with good collets but it's best to just use 1/2 inch bits. Little bits are fine in 1/4 but anything serious you want 1/2 inch shanks. Something like a cope and stick bit should not even be offered in 1/4 shank in my opinion. It is going to bend and when it does, it is a real hazard. 1/2 inch shank bits work fine.

[Ed Aumiller]

It may be that 1/4 shank is best for 1/4 cutter.... I am no expert.. just giving my experience...

But in my opinion (and we all have one)... I believe a 1/4 on a 1/2 shank is more stable and will be stronger against breakage...

You just have to remember it is a 1/4" cutter and you cannot push it past it's limits or it will break...

[Zachary Hoyt]

I buy whichever is cheapest, of a given brand. Sometimes the 1/2" are less for the same profile, on eBay. I mostly buy Whiteside bits.

[Paul F Franklin]

Another, admittedly small, advantage of 1/2" shank bits is that they likely run a little cooler; more mass to absorb the heat generated at the cutting edge and more surface area to transfer the heat to the collet. Cooler bits stay sharp longer and burn the work less.

[Mike Henderson]

I used to be a 1/2 inch shank bit only worker. But with the new trim routers, I find that I'm using them in a lot of places where I used to use my big routers. Unfortunately they only take 1/4 inch shank bits.

But so far, I haven't had any problems with bits breaking or slipping in the collet. I have a couple of DeWalt cordless routers and those are my go-to for a lot of work.

Most of what I use them for is not heavy work, however: edge profiles, hinge mortise, and a few other things that are too difficult to describe.

Mike

[johnny means]

I've burned through thousands of bits. I've never seen a bit break at the step down, I'm pretty sure I've never seen one machined as to create a stress riser. I've broken a couple of half inch shanks, but dozens of 1/4". 1/4" shanks also tend to spin in the collet. I only use them for trim router type tasks in which they are the only choice.

[Andrew Gibson]

In small diameter bits I would not get hung up on the shank size. Choose the shank that best suits your intended use. If you are likely to want to use the bit in your trim router, go 1/4". You can still use that bit in your larger routers or router table if you have a 1/4" collet. The time to jump to 1/2" shank for me comes around 3/4" cutting diameter. 3/4" hinge mortising bits, 1/2" standard straight bits, round over bits larger than 3/8" or 1/2" radius. This is the gray area where I let application make the call. A good quality bit, if used properly, should wear out before fatigue causes a problem.

[George Yetka]

1/2" less chatter. More rotational mass,more clamping surface, harder to break

[Jim Dwight]

I don't remember any ruined projects from it but my Bosch Colt has had a bit slip some in it's collet. That's why I don't think it is all in the quality of the collet, I think some of the blame is on the shank area being too small. But I still use my Colt and like it. I just have to remember to only take light cuts with it. The motor is stronger than the collet can grip.

On the other side, even my big 3.5 hp Porter Cable router motor in my router table does not slip bits with half inch shanks.

For any cut where you are removing a serious amount of wood, my opinion is you want a half inch shank. For a 1/8 roundover or a small chamfer or something it doesn't matter. But for nearly any dado cut, using a 1/4 inch shank bit is asking for a damaged project.

[Dennis McDonaugh]

The reason for the question — I was standing there looking at a bunch of worn out 1/4” straight router bits with 1/2” shanks and wondered if I could save a couple of dollars by buying 1/4” to replace them.

I don’t know I’ve ever experienced a bit slipping. Does it stop spinning for an instant?

[Mike Henderson]

The reason for the question — I was standing there looking at a bunch of worn out 1/4” straight router bits with 1/2” shanks and wondered if I could save a couple of dollars by buying 1/4” to replace them.

I don’t know I’ve ever experienced a bit slipping. Does it stop spinning for an instant?

What most people refer to is that the bit moves up or down in the collet when it "slips" and what you're using the router on gets messed up.

Mike

[Wes Billups]

I'm one of those that started with exclusively 1/4" shank router bits because my Craftsman router only took that size. Over the years I got a larger router that accepted 1/2" bits and began collecting some of the larger sizes.

It wasn't until I was trying to dovetail baltic birch plywood with a dovetailing jig that I learned the advantage of 1/2" shank. I just could not route the tails without tear out, I even bought a new 1/4" shaft dovetail bit thinking my original was too dull. I then tried a 1/2" dovetail bit and the chip out disappeared. Only thing I can figure is the 1/4" shank allowed too much chatter causing the chip out. Ever since then I've used a 1/2" shank for anything that'll allow it and only use the 1/4" or 8mm when required.

[Mel Fulks]

The slipping is most often caused by not having the bottom of bit 1/8th off the bottom of the collet.

[Andrew Seemann]

I tend to prefer 1/2" shank bits solely so I don't need to swap out the collet on my routers. I know that is a lame excuse, but the extra 5 minutes to change a bit really does irritate me. I do have a fair number of 1/4" shank bits for my trim router which I use, and some additional ones I inherited. In general, I rarely buy new 1/4" shank bits unless specifically for my trim router.

On a side note, I have always wondered why bottoming out a router bit would cause it to slide out. Is it from heat? That seems like it would maybe total to a couple thousandths of an inch, assuming expansion of the bit at one millionth of an inch per degree per inch, and no expansion of the collet.

[Ed Aumiller]

Slipping ....

When you tighten the collet on most routers, the bit will move slightly further into the collet... if it is bottomed out before tightening, it cannot move and will not be as tight as it should. Leave a small gap to allow it to move...