Router bit breakage

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Forum topic by 404 - Not Found posted 11-09-2011 04:34 PM 2372 views 0 times favorited 10 replies Add to Favorites Watch
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404 - Not Found

2544 posts in 2479 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.

10 replies so far

View mikema's profile


180 posts in 2096 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

4492 posts in 3471 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 3499 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


4151 posts in 2462 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 3223 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 in Huntersville's profile

Jeff in Huntersville

404 posts in 2705 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 2552 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


2735 posts in 2087 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


7355 posts in 2886 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 1904 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.

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