# Birdsouth bit what went wrong



## stripit (Oct 21, 2012)

Hi everyone. Anybody out there ever use a birdsmouth bit?? I'm using Yonico birdsmouth 3 bit set. I tried the octagon bit with no trouble. I tried what I thought was the hexagon bit, I measured the cutting edges. This is what I ended up with







as you can see it is closer to a pentagon, which is a 105 deg. hexagon is 120 degs.
What went wrong, this bit is not close to 6,8, or12 sided.

I'm trying to make a post for a lectern, and thought a hexagon would look more interestiing then just a square.

Thanks for any help you can give me.


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## MadMark (Jun 3, 2014)

You got a part # please?

M


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## Rayne (Mar 9, 2014)

Read some of the reviews that it would be best to get the instructions from Yonico first. It looks like a setup issue rather than the bit since the bit apparently can do both 6 and 12 sided object.


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## CaptainKlutz (Apr 23, 2014)

Like you I attempted to use a birdsmouth router bit. There is trick to setting the location of the intersection point of the two angles. If not perfect, your board widths are wrong and angles won't close. 
I found getting it right took lots of test passes, and finally gave up; switched to table saw.

IMHO it was really easy to use table saw for cutting birdsmouth joints?
Set the angle per one of the many online calculators with digital gauge; make 2 passes - one horizontal and one vertical on one edge of each board. 
Done.
Use a flat top ripping blade for perfect corner. But due the massive glue area, it's not a requirement unless the ends and joinery will be visible.

The boating folks use the birdsmouth joint for wooden masts. This 'howto' site has lots of different calculators to calculate the angles based in lumber thickness, diameters, and board width. It also has a full length article on the math involved for making tapered wooden masts using birdsmouth. it's fascinating reading if you want to learn nitty gritty math details.

YMMV


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## wapakfred (Jul 29, 2011)

They are not that hard to use, I've had good success with them. There are a number of internet guides one set up, and that's all your problem is.


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## Lazyman (Aug 8, 2014)

After modeling the bit and boards in Sketchup, the only way I can see that happening is if you tilted the board or router while cutting or the bit is faulty and the resulting angles on the sides of the cut are not 60 and 30 degrees. Non-flat and square stock could cause that too but it looks okay in your pictures. Measure the resulting angle of the external edge and make sure that it is 30°.

The only thing you can change about the setup is the height/depth of the bit and the only effect that has is whether the corners are flush from what I can tell.


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## Kazooman (Jan 20, 2013)

I do not have any personal experience with birdsmouth bits. I did look up the set of bits you are using. I think you might be using the wrong bit. Bit number 15137 is for 16 sided glue ups. Note that it cuts a 22.5 degree angle. Combining that with the 90 degree angle of the mating piece gives a total angle of 112.5 degrees. That is darn close to the result you get. I suspect that with an improper setup for the thickness of your stock you don't get the 16 sided result either.










Are you certain that you have used the correct bit? It should be 15139.


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## Lazyman (Aug 8, 2014)

Yup. That meshes with my theory. It didn't occur to me that he was not actually using the 6/12 sided bit. If you assemble boards cut with 16 side bit inside out, you will get a result like what he showed in the OP.


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## bondogaposis (Dec 18, 2011)

I have no experience with Yonico bits, but I have had excellent results with the Infinity birdsmouth bit for hexagons.


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## WoodenDreams (Aug 23, 2018)

Here a good video link "how to use the birds eye router bit" . The height set up in the video starts at about 4:15
https://www.bing.com/videos/search?q=how+to+use+birds+eye+router+bits&docid=607997777401348405&mid=1282FF1ED5992EDEA7921282FF1ED5992EDEA792&view=detail&FORM=VIREHT


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## wapakfred (Jul 29, 2011)

Stripit, did you use the wrong bit? I had not considered that as a possibility.


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## Lazyman (Aug 8, 2014)

This is what happens when you use a 16 side bit and assemble inside out. Looks pretty familiar. Results will vary slightly depending upon the height and depth settings.


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## wapakfred (Jul 29, 2011)

Yep, sure looks like the outcome above to me.


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## stripit (Oct 21, 2012)

Thank you to all who took the time to write.
I just checked the bit (lots of light and large magimify glass) your right Ihad the wrong bbit, I'll try the right one tonight.
I haave watched Dave henery many times, he is very good.

I'll let you know how it turns out.


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## stripit (Oct 21, 2012)

Hi. I'm back. It's amazing how well thing work out whenyou use the right bit.








Thanks again for the help. I'll post the lectern when it's done.


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## shipwright (Sep 27, 2010)

This is also a very easy joint to cut on a table saw.
Set the angle and height, run the board through on the flat, run it again on its edge, assemble.
The board thickness isn't limited by the bit size either, great way to make hollow masts.


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