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Forum topic by Safetyboy posted 05-30-2008 12:08 AM 1155 views 0 times favorited 10 replies Add to Favorites Watch
View Safetyboy's profile


119 posts in 3936 days

05-30-2008 12:08 AM

Topic tags/keywords: router

I was routing mortises for some doors I was making for a shop cabinet (figured it was good practice). Using a spiral upcut bit, I plunge the ends, then route away the middle about a 1/4” at a time. Halfway through the first 1/4” cut, my bit snaps in half!

Don’t think that’s supposed to happen! Guess it’s back to knocking them out by hand:

I’m terribly slow by hand, but I guess it’s good practice until I can pick up another bit. I do not really love my router – but it’s so much faster than I can do things by hand at the moment, I still use it.

-- -- Kevin in Mentor, Ohio

10 replies so far

View GaryK's profile


10262 posts in 4165 days

#1 posted 05-30-2008 12:16 AM

Solid carbide is very brittle. It happens.

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

View Taigert's profile


593 posts in 4018 days

#2 posted 05-30-2008 12:34 AM

Try drilling the worst part out, foristner bits work really well. As close to end as it looks its hard to not blow out the end without a backing block if your chopping them by hand.

-- Taigert - Milan, IN

View motthunter's profile


2141 posts in 3976 days

#3 posted 05-30-2008 01:06 AM

this happens. what speed were you using on the router? were you forcing your speed or letting the machine do the cutting?

-- making sawdust....

View Lee A. Jesberger's profile

Lee A. Jesberger

6866 posts in 4157 days

#4 posted 05-30-2008 01:26 AM

Your quite lucky you weren’t hurt!

There are a number of other way to cut mortises. This method you used is normally not a problem. Maybe the bit was faulty, or maybe you were forcing it, as opposed to letting the tool do the work.

My guess is a faulty bit.


-- by Lee A. Jesberger

View Mario's profile


902 posts in 4228 days

#5 posted 05-30-2008 02:52 PM

WOW that is not good, but as long as you did not get hurt it is not all bad.

-- Hope Never fails

View Joey's profile


276 posts in 3992 days

#6 posted 05-30-2008 07:40 PM

solid carbide is not good to use while cutting deep or heavy cuts. i found out the hard way too.
i’ve gone back to straight bits or shear cutters when i can find them. a shear bit is like a straight bit but the flutes are set at an angle.

-- Joey, Magee, Ms

View Grumpy's profile


24541 posts in 4028 days

#7 posted 06-03-2008 07:51 AM

Lucky for you Kevin, no injury. I had a similar thing happen, the bit broke, hit the floor inches from my left foot. They are a great tool but need to be treated with a lot of respect.

-- Grumpy - "Always look on the bright side of life"- Monty Python

View Douglas Bordner's profile

Douglas Bordner

4029 posts in 4241 days

#8 posted 06-03-2008 06:06 PM

I use HSS spirals for this type of work, not so brittle.

-- "Bordnerizing" perfectly good lumber for over a decade.

View Grumpy's profile


24541 posts in 4028 days

#9 posted 06-03-2008 11:32 PM

Yes Douglas, me too.

-- Grumpy - "Always look on the bright side of life"- Monty Python

View Loren's profile


10477 posts in 3825 days

#10 posted 06-06-2008 05:27 AM

With a plunge router it is more difficult to “feel” the cut.
I always disliked mortising with a plunger. When I got
a horizontal mortiser it was a very different experience -
all my energy was going into guiding and feeling the
cut – much more relaxing and you can feel when you
are cutting too much at a time.

I have never broken a 1/2” spiral flute bit but I have
snapped 1 or 2 1/4” bits in half – they are quite fragile.

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