Router bit breakage

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Forum topic by 404 - Not Found posted 11-09-2011 04:34 PM 2969 views 0 times favorited 15 replies Add to Favorites Watch
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404 - Not Found

2544 posts in 2966 days

11-09-2011 04:34 PM

Everyone knows a swan can break your arm, but I have never met anyone who HAS had their arm broken by a swan.

I’ve read a couple of posts over the last few days cautioning about router bit breakage and the danger of cutter tips flying around like shrapnel in the workshop.

I just wondered, has anyone ever had this misfortune? Or is the flying cutter head like the story of the swan?

I have had a few router cutters fail on me (1/4” shank straights 6.35mm → 9.5mm) that have all broken in the same place – where the top of the cutter meets the shaft. I have never encountered bits of spinning metal go flying about the place. The broken cutter head simply drops onto the workpiece and the router picks up revs.

I’m not being blasé about router safety, I was just curious, that’s all.

15 replies so far

View mikema's profile


180 posts in 2583 days

#1 posted 11-09-2011 04:43 PM

I have had a couple bits break while using them. Both times this happened while they were buried in the work piece, so I did not experience fly shrapnel. I suppose it would be possible that a bit that is mostly exposed, like one doing an edge profile, to send shrapnel flying, but I have not experienced that.

-- Mike ---- Visit my woodworking blog:

View Bill White's profile

Bill White

4929 posts in 3957 days

#2 posted 11-09-2011 05:00 PM

I dealt with enough shrapnel while I was wearing olive drab fatigues.


View GaryK's profile


10262 posts in 3985 days

#3 posted 11-09-2011 05:19 PM

I have been using routers a long time and I have never even know that a bit has broken until I just happened to look at it and noticed. It’s usually just one of the carbide teeth that chipped and I never even noticed it in the cut because the other tooth cut it.

Never had anything fly off that I have noticed.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Brandon's profile


4152 posts in 2948 days

#4 posted 11-09-2011 05:24 PM

I’ve never broken the cutting edge or the shank of a router bit. I use both 1/4 and 1/2 shanks and use them pretty well (borderline abuse them). Maybe it’s the quality of bits (generally Freud bits) or just luck, but I’ve yet to have a problem.

-- "hold fast to that which is good"

View jackass's profile


350 posts in 3710 days

#5 posted 11-09-2011 05:40 PM

Hi Renners,
I have had a few router bits break over the years, usually at the point where the shaft meets the cutter head. If I remember correctly they were “V” notch being used to simulate wainscotting. They broke and just dribbled to a stop, with no danger to me. Hope this helps, but you do have to have a healthy respect for anything with a high RPM. I always wear a face mask.

-- Jack Keefe Shediac NB Canada

View Jeff's profile


433 posts in 3191 days

#6 posted 11-09-2011 06:01 PM

I’ve had a few break off, but like others have said only the shaft not the actual carbide cutter. And it was while I was putting too much stress by feeding too fast. My fault not the bit.

View 1yeldud1's profile


301 posts in 3039 days

#7 posted 11-09-2011 06:08 PM

A router bit that has the carbide silver soldered to the steel shank probably wont just shatter but small pieces of the carbide can chip off. A solid carbide cutter when stressed will shatter into 2 larger p[ieces and it could have small slivers also fly out of the “break area” As a 36 yera plus toolmaker who has had lots of experience with carbide endmills (both solid and laminated) it is a very wise move to wear glasses with side shields. Just remember eye injuries are almost premanent. Always errior on the side of good judgement if possible !!! Thanks

View NiteWalker's profile


2737 posts in 2574 days

#8 posted 11-09-2011 06:27 PM

I had two bits break; the first was a 1/4” cutter; 1/2 of the tip broke off, steel and all. It was during a circle cutting operation. The other was recently; it was a rockler 3/8” straight bit and one of the carbide cutting edges broke clean off the body. I was template routing with a bushing in that case.

In either case, no carbide went flying. Both broke parts were in the workpiece.

-- He who dies with the most tools... dies with the emptiest wallet.

View knotscott's profile


8012 posts in 3373 days

#9 posted 11-09-2011 06:30 PM

Several years ago I was present when a friend’s router bit shed a carbide tip and imbedded itself in the wall…it was dumb luck that it didn’t pierce one of us. For that I reason I try to talk people out of the lowest grade no-name imports…it’s too risky, and there are good quality, well proven, reasonably priced bits available from brands like MLCS, Woodline, Grizzly, Holbren, Price Cutter, Woodcraft, to name a few.

I’ve broken a few of router bits…mostly 1/4” shaft, or very small diameter straight bits. MLCS, Freud, Woodcraft…doesn’t seem to matter, and I don’t think poor quality is the issue there….just a matter of pressure on a thin shaft.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View skunkeye's profile


7 posts in 2391 days

#10 posted 11-10-2011 02:34 AM

I haven’t broken a bit, but a few weeks ago I was flush trimming some edge banding and had the bearing fall off. The little screw just came loose. Led to a big gouge. May have cussed a bit.

View robscastle's profile


4989 posts in 2201 days

#11 posted 02-23-2017 05:57 AM

comment deleted usual reason

-- Regards Robert

View papadan's profile


3584 posts in 3365 days

#12 posted 02-23-2017 06:07 AM

A long time ago I had Craftsman bits that were not carbide tipped. I hit a knot in Walnut and the round over bit snapped off a corner that cut my arm. About ten years ago I had another bit break a wing off but it went the other way. I wont say why it happened, but it did. I really hate it when a bearing comes off and screws up a good piece of wood.

View Mikesawdust's profile


325 posts in 3036 days

#13 posted 02-23-2017 09:02 AM

I’ve broken several in mostly due to poor practices on my parts, never had pieces fly at me but I’m not sure where they ended up. The only time I was worried was using the router table at our hobby shop (not mine) and it had a bad collet, which allowed the bit to loosen and climb through the piece I was working. Seeing a 3” bit swinging wildly around in the router table, I hit the ground and the off switch. Luckily the bit spun down without coming loose. I did see one guy that broke one off on the table by doing a climbing cut between the fence and bit, even that didn’t launch the bit, the board got good distance to the nearest wall though.

-- You never cut a piece to short, you are just prepping that piece for a future project

View smeyer's profile


7 posts in 1286 days

#14 posted 02-23-2017 01:28 PM

When taking a class at the local WoodCraft store, we had a big panel router bit break on us. I guess we were lucky because the pieces fell under the table instead of being shot into the classroom.

As to the swans breaking your arm… When I was growing up there were swans near us and one of the neighbor girls got to close and they broke her arm. I think she was only about 5 years old when it happened, so I don’t know if an adult would be in any danger of getting a broken arm. Swans look pretty but they can be really mean.

View bc4393's profile


65 posts in 1140 days

#15 posted 02-23-2017 02:51 PM

I broke a rabbiting bit on a quarter inch rabbit. A big chunk (bigger than a 1/4 inch) of the carbide actually separated from the weld and took a chunk out of the aluminum throat plate (big kick and spark btw) on its way out of dodge. I won’t say what kind of bit it was but needless to say it’s in the top tier. I called them and after being dismissed of of hitting a nail, they said if I wanted I could send it back to them with a details description of what I was using and how it happened. If it was actually a failure they would send me a new bit. They analyzed it and sent a new bit in the mail without notice or apology. Which is good for my wallet, but I just didn’t want someone else actually getting hurt if they had a problem with a batch of bits. I had to stay in the garage for a bit to make sure that hot piece of carbide didn’t fly into a can of paint or thinner in the shelving next to me and catch my house on fire. I never did find it but I’m glad it didn’t go into me. Every once in a great while shit happens, but companies normally take these things seriously. My dad had a Delta table saw blade come apart in his class years ago and Delta wanted the pieces sent back immediately so they could figure out what happened. This company wasn’t as professional about the process but they did make it right. And a couldn’t find a “better” router bit company to take my business too instead, so I have to just move forward and bet that it won’t happen a 2nd time.

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