# Big bits can really vibrate



## kp91 (Sep 10, 2004)

Was surface planing with a 1-1/4 surface planing router bit from Magnate. I've had this bit for at least 12 years, it was a great bit. That is until it threw a chunk of carbide off at 18,000 rpm. I didn't hear anything, but the router started shaking a little bit.

Just a gentle reminder to give your bits a good looking over before you use them. I hadn't seen anything wrong with this one before I started, and the walnut I was turning didn't have any metal in it, so I guess it just finally had enough.


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## Marco (Feb 21, 2009)

Glad you missed the shrapnel. Plus 1 on inspecting the bits prior to using them.

When I chucked up my new HF slot cutters the other month lets just say I would have put on a face shield if I had had one.


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## Rebelwork Woodworking (Sep 11, 2004)

Its typical for a fractured bit


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## sreilly (May 22, 2018)

Not something that you'll want happening but sometimes really hard to tell before hand. Glad it wasn't anything more than a bad bit and no bloodshed to deal with.


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## TenGees (Sep 12, 2012)

The break looks all fresh so I have my doubts you would see any problem with it ahead of time.


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## papasombre (Sep 22, 2011)

I had the same problem with a brand new router bit from Rockler.
I kept it in its original package for several years.
When I wanted to use it, I found a small piece of carbide inside the envelope.
I never used the bit.


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## kywoodchopper (Jul 18, 2013)

kp91 said:


> Was surface planing with a 1-1/4 surface planing router bit from Magnate. I've had this bit for at least 12 years, it was a great bit. That is until it threw a chunk of carbide off at 18,000 rpm. I didn't hear anything, but the router started shaking a little bit.
> 
> Just a gentle reminder to give your bits a good looking over before you use them. I hadn't seen anything wrong with this one before I started, and the walnut I was turning didn't have any metal in it, so I guess it just finally had enough.
> 
> View attachment 397271


You were running a large bit at 18,000 RPM. NEVER! I alway run large bits at the slowest speed the router will run. I had a woodworking friend that did the same as you, but it blew his fingers off with it.


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## sreilly (May 22, 2018)

*kywoodchopper*

_I _get the impression from the picture that the bit isn't very large at all. But it is a good reminder to slow the speed down based on size of the bit. A reference that can be used is:

From Rockler's website

*Router Bit Diameter* *Maximum Speed* 



Up to 1" 22,000 - 24,000 rpm

1" to 2" 18,000 - 22,000 rpm

2" to 2-1/2" 12,000 - 16,000 rpm

2-1/2" to 3-1/2" 8,000 - 12,000 rpm

Remember, that's just a reference; Always follow manufacturers recommendations and the sage advice that if something doesn't feel like it's working right, there's a good chance that it isn't. Better yet, pick up a Router Book and get to know your router inside and out.


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## kp91 (Sep 10, 2004)

It's an inch and a quarter bit, not too big.


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## difalkner (Jan 3, 2012)

I run my 1 1/2" flat bottom cutter at 18k rpm every time I surface the spoilboard on my CNC. 18k rpm is within the range specified by the manufacturer. It definitely 'sings' at that speed but it works just fine and is very smooth.

David


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## kywoodchopper (Jul 18, 2013)

kp91 said:


> It's an inch and a quarter bit, not too big.


I would also add I never use inexpensive tools. If I'm thinking of saving a few bucks by buying inexpensive I would first go to the nearest emergency room and ask for a rough price a reattaching 3-fingers. Whether it is a router bit, tablesaw or any equipment.


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