Way back when I was researching my first router and router bit purchases, a common piece of advice stood out – 1/2″ shank router bits are better than 1/4″.
What much more experienced woodworkers have said about 1/4″ router bits is somewhat true, but I let their experience-based advice too strongly influence my budding preferences, and so it became an ingrained idea over the years.
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Their advice made sense – a thicker shank is indeed stronger. In the 1/2″ vs 1/4″ router bit debate, larger shank bits provide for greater stability, better collet grip thanks to greater surface area, and less deflection, with all of this translating into better cut quality and user experiences.
With a full-size woodworking router, you don’t ever want to use smaller 1/4″ router bits, or so I had been led to believe over the years, even though they often ship with 1/2″ and 1/4″ collets.
Meanwhile, compact routers and laminate trimmers are ubiquitous among carpenters, contractors, installers, and others in the construction and remodeling industry.
A 1/4″ router bit in a compact router? I hardly give it much thought, and have had great experiences over the years. But, I also use compact and full-size routers for different things. I might use a compact router for shallow edge treatment or to cut small slots and grooves, and a full-size router for large dadoes and edge treatments.
This past weekend I needed a top-bearing flush-trimming router bit, and all I could find at the local home center was a Freud 1/4″ shank bit – and at $5 more than I could get it for online.
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I was hesitant – using a 1/4″ shank bit in my full-size router? Blasphemy! The router bit had a 1″ cutting length, which is also a bit shorter than I needed. Okay, I could adjust the cutting depth a couple extra times to compensate.
In truth, a 1/2″ shank bit with 1-1/2″ or 2″ cutting length would have been perfect, but I didn’t want to put everything on hold for a few days.
In hindsight, there are ways I could – or should – have improvised with a typical bottom-bearing flush-trimming router bit, but I lacked the vision of how to do so at the time.
So, how did things work out with my router’s 1/4″ collet seeing use for maybe the first or second time ever? Terribly! Okay, that’s a bit of an exaggeration. But, the results were less than ideal.
Instead of a smooth cut as I am used to, there were hints of chatter and deflection. I gave myself extra material to work with, and so it wasn’t the end of the world for me to do things over with two more “finishing cuts.”
The truth is that the “internet community” advice is right. I’ve parroted it over the years, that 1/2″ shank router bits are better than 1/4″ where possible, but to the point where I let myself believe larger shank router bits were the only option in a full-size router.
I built up a barrier. 1/4″ shank router bits in my 1/2″ router? No way!
But, I have also grown accustomed to using compact routers with 1/4″ router bits for certain tasks and operations. For part of my project, I had to cut (12) grooves 1/2″ wide by 3/4″ deep x 13/16″ long. This was a cinch for the compact router and 1/2″ cutter x 1/4″ shank straight cutting bit I was using, although there were a couple of insignificant miscuts due to the straightedge I was using.
After this, I still prefer 1/2″ shank router bits, and I still don’t plan to use 1/4″ router bits in my full-size router unless it’s the only option.
But, the experience made me a little more open to the idea that 1/4″ shank router bits aren’t all that bad. If I had been open to the notion before, I would have gained more experience earlier, allowing me to better plan for how to counter some of the issues that could arise when using 1/4″ router bits with wider cutting edges.
Once I realized I was seeing evidence of chatter and bit deflection in my cut, I took shallower do-over passes, and that helped a little bit. Maybe there could have been ways to make the process more controllable, and it was with that thinking that I realized I could have created an entirely different template to take advantage of more popular trimming bit styles and sizes.
Part of the problem with my recent experience, aside from a less than ideal cutter size for what I was doing, is that I was using a 1/4″ router bit in a full-size router as I would have a 1/2″ bit. In hindsight, I know I would have been a lot more delicate if I were using a compact router instead of a full-size model, but possibly also because a compact tool would have been starved for power.
I am having trouble thinking of a good analogy, but perhaps it could work to think about fastening tools. Use a drill or impact tool to drive a smaller screw in the same way you would a larger one, and you could shear the head right off if you’re not careful.
I used that 1/4″ router bit in the same manner as I would have a 1/2″ router bit. Of course I experienced chatter and deflection, giving me an imperfect edge quality!
1/2″ shank router bits are better than 1/4″ shank router bits, that’s undeniable. But if you must use 1/4″ shank bits where you might prefer to use 1/2″, compensate for it, to mitigate the factors that could negatively impact cut quality. Take shallower cuts. Go slower. Pretend that full-size (typically 2+HP) woodworking router is a compact trim router. That’s what I should have done.
But hey, at least I finally got over my imprinted aversion to using 1/4″ router bits in anything but compact routers, although only to replace it with a slightly more experiential-based aversion.
You don’t learn if you don’t try.
Finally, smaller shank router bits also dissipate heat slower than larger shank router bits. I wasn’t burning the wood, but this is another aspect to consider when using smaller bits in a more powerful router.
Despite what I learned with this, I don’t feel the need to reexamine all of the professional, expert, and experienced advice I read, learned about, or was given over the years. But perhaps on a case by case basis I won’t let others’ experiences fully dictate my own decisions and preferences.
Nathan
Interesting I’ve always been of the midset to only use small bit 1/4 router bits in compact routers. Their size and inertia weight come into their own with a smaller motor spinning fast. but aren’t meant to do heavy work (light passes)
where 1/2 bits and their inertia weight require power – or more specifically torque and are meant to be used to do more work. Likewise any cutter with more than 2 cutting faces – needs more power.
I route only occasionally though.
JoeM
Wow… Ummm… This begs a question about the Dremel series 1/8″ router bits… They only fit in Rotary Tools, and are meant to be used with Router Base attachments… Considering they’re meant to be used at somewhere around 15K-35K RPM, and are most definitely meant to be used only lightly… I wonder how it holds up to the full-sized router bits? Does the massive speed difference help the tiny bits in ANY way?
I’ve got some cheaper Mastercraft rotary router bits, but I’ve been nervous about taking the plunge (no pun intended) on the full Dremel set for a while. I genuinely don’t route that often, so it’s a question I rarely ask myself.
Stuart
How it holds up in what way?
Different materials require different cutting speeds.
You have two wheels that need to cover a set speed, say 100 feet per minute. One wheel is 4 inches in diameter, the other is 8 inches in diameter.
The distance a wheel travels per one rotation is roughly equivalent to its circumference. Correct?
So, one rotation corresponds to a linear travel speed based on the diameter of the wheel. Do you agree?
Now, will the 4” wheel cover the same distance as the 8” wheel if it spins at the same rotational speed? No.
So how do you get the smaller wheel to cover the same linear speed as the larger one?
Faster RPMs. To cover the same linear speed, the rotational speed has to be faster for a smaller diameter cutter.
With respect to router bits, you also have tool-dependent considerations such as cutting depth per pass and optimal feed speed. Push the tool too hard, and even if your smaller diameter bit doesn’t yield, your rotary tool and limited power will be the weak link.
That’s why this experience has been somewhat embarrassing, something there was a complete disconnect between theory and practice, and I screwed up.
Rotary tools are suited for intricate and small. Sure, you can approximate some results of larger tools used with larger bits, it’ll just take a lot longer.
fred
For small box making and inlay work, I use many 1/8 inch shank bits held in a Foredom Handpiece . I use a base for that setup that I bought from William Ng about 7 years ago. His newer base is nicer – but almost double the price I paid in 2013.
https://wnwoodworkingschool.com/product/new-router-base-for-foredom/
I find that the Dremel brand router bits are lacking – but better 1/8 inch shank bits are available from Amana, Lee Valley and MLCS.
For most inlay work you are taking very shallow cuts with small bits – so you are not pushing the limits of the 1/8 inch shaft.
Stuart
When faced with similar needs/wants, I went with Lee Valley’s rotary tool router base, figuring I could use my imported Bosch cordless rotary tool with it, but then went with the StewMac threaded Foredom handpiece – https://14cyiuhvcgv.com/custom-foredom-handpiece-for-dremel-compatible-router-base/%3C/a%3E . That requires considerably investment since you need the flex-shaft motor and what-not, but there are fewer power compromises than with a Dremel-style rotary tool.
JoeM
I will say I am not particularly fond of the Dremel router base. I have it, it “Functions”, but it’s flimsy. I want to bite the bullet and go with the Lee Valley cast iron kit for the stability, it’s just… Hard to justify. “You already have a plunge router base! It was $30! It’s so rare you even use the routing function, why go to a device that will cost you $300?”
Sorry… AGAIN… My late Jewish Grandmother’s voice in the back of my head, always complicates things.
Stuart
Here are more options:
https://14cyiuhvcgv.com/rotary-tool-router-base-attachments/%3C/a%3E%3C/p%3E
fred
Aug 27, 2020
Here is another option:
https://www.lmii.com/rotary-plunge-tool/2820-rotary-tool-plunge-assembly-for-dremel.html
https://www.lmii.com/rotary-plunge-tool/2821-rotary-tool-plunge-assembly-for-foredom.html
JoeM
See… fred always has insight… Never fails… I can definitely see myself leaning toward the Lee Valley made router bits, rather than the Dremel ones now.
Never know when you just need to clamp something down and put a rail groove into it, or something similar.
JoeM
I suppose I mean cutting capacity. Scaled down from normal Router sizes, I genuinely wonder if the massive speed increase (adding at least one zero to the end of the speed of many regular routers, and often two zeroes in the cases of Dremel’s top line Rotary tools…) does for the 1/8″ (God I wish the switch to Metric was universal by now.) shanks, what stepping up to a 1/2″ shank would do for the 1/4″ shanks in a standard sized router.
I think this might just be curiosity, from a physics type of perspective… Is the scaled-down shank, at all, reinforced against chatter or vibration when sped up by a factor of 100? Obviously the cuts are going to be smaller, but if you can buy a decent third-party Carbide, Diamond Edged, or HSS Rotary sized Router bit… Are you wasting your time doing so, because the shaft and speed difference don’t scale properly to do the job?
I might be waxing philosophical at this point. I’m sorry, again… Some of these things are probably a total waste of time to ponder, my brain just… GOES there…
Stuart
I would say not.
Let’s say you have a 1/8″ straight cutting bit, a 1/4″ straight cutting bit, and a 1/2″ straight cutting bit.
1/8″: 0.3925″ circumference
1/4″: 0.785″ circumference
1/2″: 1.571″ circumference
Cutting speed (SFM) = circumference * rotational speed (RPM)
Let’s say you want a surface cutting speed of 500 SFM.
6000 inches per minute divided by circumference (inches per rotation) = rotations per minute.
So to get that 500 SFM:
1/8″: 15,287 RPM
1/4″: 7,643 RPM
1/2″: 3,819 RPM
Yes, the smaller bit is spinning much faster, but the cutter-material interface isn’t going to see that.
Things get really complicated when you start talking about cutters as material removal tools instead of wheels on a surface.
But, you generally need that speed for smaller tooling.
Rotary tool vs. compact router vs. full-size router vs. shaper are all about scaling to different needs and material removal capabilities.
I am perhaps not fully understanding your question.
If you want more to ponder, look into contour vs. “adaptive” cutting. =)
fred
This is akin to many other tool discussions and the old maxim about “horses for courses” applies. A teaspoon, garden trowel, laborer’s shovel, a backhoe an excavator and a dragline bucket can all move soil – but choice of tool sometimes comes down to speed and efficiency. An archaeologist might sometimes choose a teaspoon – but a strip miner goes with the dragline.
Shapers were once more commonplace in the home shop – but have mostly been replaced by router tables. When I replaced my home-shop shaper with a router table (was then using a 3.25Hp PC Router) – I immediately noticed several differences – and had to slow down and take more passes on some work.
In the commercial cabinet shop – we had power feeds on our rip saw and on our shaper. I would be very hesitant to try to power feed my current router table (with Bosch router).
Trying to cut long hardwood moldings on the router table is the place I most notice what’s probably some combination of runout and bit/shaft (1/2 inch naturally) deflection compared to my recollection of using the shaper.
Ben
If you get into Festool routers, you’ll soon find yourself using an 8mm collet. I use mine the most for an 8mm dovetail bit included with the Leigh Dovetail jig. Even though 8mm is only ~0.06inches bigger than 1/4, it makes a MASSIVE difference in cut quality. I’ve run 1000’s of dovetails with both bits and will never go back to the 1/4 if I have the 8mm option.
1/4 bits need to take a smaller cut and a *tiny* finish pass. They chatter; you just have to figure out how to deal with it.
RKA
In my eyes, the shank size has less (Or nothing) to do with the router you put it in and more to do with the work you’re trying to do. How much meat do you need to take off, how deep is the cut. 1/4” bits work fine if you’re doing slight round overs, chamfers or template routing with thinner materials where you only need to skim off 1/16”. I’ll use them for grooves for back panels or bottom panels on cabinets and drawers as well. For bigger work, taking multiple passes is a good idea unless you like the taste of carbide or just get the 1/2” bit.
Nothing wrong with making do as you did, sometimes you have to. As long as you’re aware of the limits of the bit. If I need to go 3/4” deep with a 1/4” bit, I’ll do that in 3 passes of 1/4” each.
Stuart
Part of the problem is that I needed longer bit extension than a larger bit with greater cutting length would have allowed. That made the deflection worse. The final passes were maybe 1/8″, and the results passable but imperfect.
For a critical application I would have waited for the appropriate bit or reworked my template.
For this, there are small gaps in the mating surfaces, but part of that is also due to the countertops having warped a little over time. There would always be a degree of imperfection. But, whereas I needed to use the router for the inside corner-cutting, I used a circular saw for the other corner, and with smoother results.
James
I use a ton of 3/8″ bits on my CNC and I usually run it at 800-1000 inches per min. It’s more about your chip load and moving that heat away. When your done routing the bit should still be around room temperature if it’s hot your moving to slow. Big router bits can be pushed harder and faster however you need more power to back that up.
Typically for me a good trim router with 1/4″ shank will do the bulk of any hand routing. If I am using 1/2″ shank I am usually using the 3 HP on a router table or the bulk of the time my shaper. The fun stuff is running big edges on thick wood tops, lots of passes, slow RPM’s and 3HP.
Hans
One of the biggest difference in quality of cut is the diameter of the the cutter, more so than the size of the shank.
(The others are feed rate, number of cutting surfaces and circumstance speed.)
Of course those two are somehow connected but I would take a 8mm shank, large diameter bit over a 12mm shank smaller diameter bit any time. This is also the biggest difference between a shaper and a router table. On a shaper you cutterhead is between 120 and 220mm diameter (sometimes even bigger).
The shavings you take off, start out thin and become thicker towards the end, this difference is smaller with large diameter heads, and thus there is a smaller change of chipout.
Hans
Doug N
Yes, 1/2” is the way to go unless you’re using a trim router which only takes 1/4” bits. Double the diameter = four times the mass.
Michael
I remember when 1/2″ shank bits or routers were not readily available.
Matt J.
I know this a year-old thread, but I remembered it when working with a 1/4″ shank bit the last few weekends.
I was “gifted” two 3″ by 12″ x 8′ rough-sawn red oak slabs that had been a friend’s work bench top before he rebuilt it. I was in need of some thick oak stock (ideally 8/4) for stair knee wall cap, and thought it was a great way to save some money (and hassle in trying to find some thicker stock that was already dry as this was). Problem was, they were both cupped and bowed pretty badly. So, I made a makeshift router sled with some jointed 2x4s. I couldn’t find any larger diameter flattening bits locally except for an Amana 3 flute 1-1/8″ diameter with a 1/4″ shank. Not ideal.
The amount of chatter and runout was crazy. Even taking shallow passes, way more than I would have normally used, you could see visible snipe from every single pass. I ended up borrowing a 2-1/2″ spoilboard bit from a friend for the second board (more for the increased diameter than caring about the chatter) and it was much cleaner and I was able to do the entire board (which was the worse of the two with almost 2″ removed at the ends to flatten) and it was done in 3 passes vs the 6 or so of the first.
Also, this project killed my vintage USA-made PC 690 router (cracked the cast aluminum upper motor housing where it holds the upper bearing), so I picked up the newer Skil variable speed kit as it is what was in stock. Very impressed so far. Hate to say it, but it it puts the 690 to shame (longevity remains to be seen, obviously…hard to knock a router that was nearly as old as I am).
Stuart
I’m glad you were able to borrow the spoilboard bit for the second board! 1-1/8″ is definitely more than I’d feel comfortable using with a 1/4″ shank, especially in something like oak. Maybe a CNC router or router table might have handled it more delicately, but I don’t think anyone would have great luck using that size bit in a handheld router.
Matt J.
Yeah, it was a bit sketchy. I probably should have just done it with my 3/4″ straight bit since it was getting run through a planer anyway, but I wanted to make it quicker. Should have known better…next time I’ll definitely plan ahead and order one.