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Thread: Advantage to 1/2" Shank Router Bits?

  1. #1
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    Advantage to 1/2" Shank Router Bits?

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

  2. #2
    You get a good hold on the bit without using so much over tightening.

  3. #3
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    Stability...

  4. #4
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    Yes, as mentioned, stability. The half inch shank will provide a cleaner result than the quarter inch shank.
    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

  5. #5
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    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

  6. #6
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    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, " to " becomes a flex point leading to premature breakage. So a " bit with a " shank is stronger than a " bit with a " shank.

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

    LMT.jpg

    Obviously for profile cutting tools with larger bodies the larger shank is stronger. The above holds true for straight cutters, tapered tools, etc.
    Last edited by Mick Simon; 04-27-2021 at 7:49 AM.

  7. #7
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    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.

  8. #8
    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.

  9. #9
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    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...

  10. #10
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    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.

  11. #11
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    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.
    --Certainty is the refuge of a small mind--

  12. #12
    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
    Go into the world and do well. But more importantly, go into the world and do good.

  13. #13
    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.

  14. #14
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    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.
    Andrew Gibson
    Program Manger and Resident Instructor
    Florida School Of Woodwork

  15. #15
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    1/2" less chatter. More rotational mass,more clamping surface, harder to break

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