# Tenon cutting Router bit



## iamwelty2 (Dec 27, 2008)

Does anyone have any experience with this bit for cutting tenons?

Tenon Cutting CMT Router Bit #800.627, Routers, Bits & Accessories - McFeely's


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## allthunbs (Jun 22, 2008)

iamwelty2 said:


> Does anyone have any experience with this bit for cutting tenons?
> 
> Tenon Cutting CMT Router Bit #800.627, Routers, Bits & Accessories - McFeely's


Make sure you have a feed block to reduce tearout. I just use a flat bottomed bit, run one side, flip the board and run the other side.


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## bobj3 (Jan 17, 2006)

Hi Terry

I have ,it's great bit but it is a Big one, I must be a bit slow they said on the DVD I could use it for making 3/16" wide tenons but I can't see how with this bit in one pass (all the cutters are 1/4" thick) but other than that it works well, I did make a hold down/push block all in one for this spec.bit. (2" x 6" type)


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iamwelty2 said:


> Does anyone have any experience with this bit for cutting tenons?
> 
> Tenon Cutting CMT Router Bit #800.627, Routers, Bits & Accessories - McFeely's


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## jlord (Nov 16, 2009)

bobj3 said:


> Hi Terry
> 
> I have ,it's great bit but it is a Big one, I must be a bit slow they said on the DVD I could use it for making 3/16" wide tenons but I can't see how with this bit in one pass (all the cutters are 1/4" thick) but other than that it works well, I did make a hold down/push block all in one for this spec.bit. (2" x 6" type)
> 
> ...


Hi Bob,
Can't you take the bit apart & change the spacers to get your 3/16"? There are supposed to be different spacers with the bit.


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## jlord (Nov 16, 2009)

jlord said:


> Hi Bob,
> Can't you take the bit apart & change the spacers to get your 3/16"? There are supposed to be different spacers with the bit.


I see what you might be saying on one pass as 1/4" + 1/4" + 3/16" = 11/16". That would make it at least 1/16" short for 3/4" material & thicker. It should work ok for most 3/4" ply as it comes under size closer to 11/16" anyways.


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## bobj3 (Jan 17, 2006)

Hi James

Yes it can be done that way but you lose the control of the bearing, it's true you can use the router table fence for the bearing, but because the bit is so big ,in diam. it's hard to keep it out of the black hole behind the bit in the fence.
I now have a new bearing for the set ,that's 5mm thick that works great for the smaller tenons.

The whole key in using the one bit for both jobs, it can't be done with a cutter that is 1/4" wide cutter..I now have a 3/16" and 1/8" wide saw blades that fits the arbor just right for the female slot...but that been said the CMT bit should be use for the normal way with out all the modifications to keep it simple. 


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jlord said:


> Hi Bob,
> Can't you take the bit apart & change the spacers to get your 3/16"? There are supposed to be different spacers with the bit.


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## jlord (Nov 16, 2009)

Hi Bob,
Who carries the other cutters that fit the CMT bit?


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## bobj3 (Jan 17, 2006)

Hi James

From Grizzly and Amazon...are the best price..but you must make your own adapter washer for the arbor shaft...

Amazon.com: HSS Plain Slitting Saw 3 Inch Diameter, 1/8 Inch Width, 1 Inch Hole, 30 Teeth: Home Improvement

Amazon.com: HSS Plain Slitting Saw 3 Inch Diameter, 3/16 Inch Width, 1 Inch Hole, 30 Teeth: Home Improvement

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jlord said:


> Hi Bob,
> Who carries the other cutters that fit the CMT bit?


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## jlord (Nov 16, 2009)

bobj3 said:


> Hi James
> 
> From Grizzly and Amazon...are the best price..but you must make your own adapter washer for the arbor shaft...
> 
> ...


Thanks Bob!


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## Hamlin (Dec 25, 2005)

Having an adjustable finger joint bit is one thing, having a adjustable tenon cutter... IMHO is pushing boundaries for safety. I've always preferred having the correct size of tenon cutter for the size I'm after or, I make them on the TS. Anymore, for me atleast, it's faster and easier to cut them on the TS.


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## malb (Sep 15, 2008)

bobj3 said:


> Hi James
> 
> From Grizzly and Amazon...are the best price..but you must make your own adapter washer for the arbor shaft...
> 
> Original links deleted newbie cannot use them even when quoting. MB======


Hi Bob, I am a newbie here and probably shouldn't question experienced people but have you considered what the RPM rating for these blades is? 

As slitting saw blades, they are designed/manufactured for use in milling machines with top speeds in the order of 3-4000RPM. I haven't come accross any routers that can slow down to that degree, with the exception of the drill/router drive on the back of RAS motors. Can't say that I have ever seen a slitting saw with a speed limit printed on it like a circular saw blade has, but I see that as a warning rather than a approval.

My other concern is heat build up. Although designed to cut metal in shallow cuts (less than half tooth depth), they are normally supplied with copious quantities of coolant. Because they have minimal set and clearance in the kerf I suspect that they might get too hot at high speed when deeply immersed in wood to cut a tenon.

Could be wrong, but prefer to raise the issue than discover later that someone was injured because a blade failed doing something it was never designed to.


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## BigJimAK (Mar 13, 2009)

Malb,

Being new should never keep you from questioning the safety of an action. If it doesn't feel safe, don't do it, no matter what it is.

There's an ongoing "detante" here between those of us who believe as you do, that a bit should not be run at a speed significantly higher than it was designed for and those who "poo-poo" that idea. One of the things that make this forum such a valuable source of information is that you can get many ideas from a wide range of people telling you what they've successfully done in the past. 

The engineer in my cannot ascribe to the philosophy of "I've done it for years and it hasn't maimed me yet" as any predictor of future safety.

The forces on a bit go up with the *square* of the speed. As you can probably tell, I'm in your court and only use cutters designed to work at the high speed a router spins.

You can tell which side of the "detante" I'm on.. <g>


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