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Bird's-Mouth Router Bits for 1/4" or 8 mm shank

11K views 24 replies 7 participants last post by  Are Qvale 
#1 ·
I´m a novice in routing. Got my first router only months ago. I´m planning to create a hollow spear for my boat and need Bird's-Mouth Router Bits.
I have a Bosch POF 1400 that that I only can find support 6mm, 8mm and 1/4" shanks.
Does anyone know of birdmouth bits that will fit, I only find 1/2" shank online. Or does anyone know if it´s possible to fit a 1/2" collet on my router.
 
#3 · (Edited)
#6 ·
Hi Are and welcome. I did a quick search and all I was able to find were half inch shafts. I'm not familiar with the hollow spear you refer to. Can you describe what you want to do? There may be other methods open to you.
 
#8 ·
Hi Chuck

I see I had a typo. Not spear, but spar.
I´m not allowed to poste url´s here yet, but if you google: "Building Masts and Spars by the Bird‘s Mouth Method" and look at first hit you´ll see what I mean.



I need to create a new hallow topsail spar for my boat. It should be about 6,5 m long and have a diameter of 8cm in the midle and about 6 cm in the ends. To do this I was thinking of using 6 staves of spruce about 2x3cm and thinning them in the end. I think this should be able to do this even tough I am not very familiar with routers. I only need my bird moth.
If you have other suggestions...
 
#9 ·
Are we still don't know much about you or what tools and skills you have but at least we know where you are now. I don't think you will find those bits in a small shaft size to fit your router. What you might be able to find is a 30* bevel bit though. If the edges of each board were beveled at that angle then that should equal 360* total and you would have a full circle. In order to get a taper you would need to taper the boards first and without knowing more about you I can't suggest how you should do that.
 
#17 ·
a bevel will do him no good... the spar will never stay together...
birdsmouth is made to order and has been in use a zillion years and flex has to be taken into consideration......
if he used thickened material a spline can be added to mix... just saying...
is your Kebony wood an option/consideration???
 
#12 ·
Welcome Are, to the forum. You will like it here. I came by some years ago to ascertain the natives, and never left. I shall follow your sparmaking project with great interest. Will you be using Spruce ? How big a spar is it to be ? I don't think I need to renew any of my boat's spars ( Cornish Crabber ) but you never know.
 
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#15 ·
Yes, I think this is a great forum. Plenty of knowledgeable and active members. And yes, I´ll be using spruce. It´s light and strong only problem as I can see it is that i rottens from inside. I was thinking of using oregon pine, like rest of the spares on the boat are made of, but that is heavier and not so easy obtainable in Norway. Since this spare is to be hoisted to the top of the mast it´s important that is as light as possible. The topsail is for light winds so it will be only used in light breeze.

The spar will consist of 8 staves. It will be about 6,2 m long with a diameter of 8 cm on the middle and 6 cm in the ends. I will poste some on the making on my boat facebook page: not allowed to poste links yet, see my profile for link to the page or search s/y venus on facebook.
 
#14 · (Edited)
DaninVan: Thanks for info, Lee Valley was very expensive on shipping.

I´ve spoken with a boatbuilder about the dimensions. That was his recomondations. Today we have a topsail spar that is about 8 meter in oregon pine that is not hollow. I think that one also is about 8 cm in diameter. I´ve used that one in gale without any problem.
 
#16 ·
here's a handy chart...

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#20 ·
Straight grain, clear, 18'+ lengths of lumber...yikes! Good luck finding that, Are. I can see it being cut from smaller trees or from local mills, but shipped from N. America? You're probably right at thinking splices will be needed.
Have you tried boatyards? They may in fact get long lengths custom milled for planking.
Perhaps take a square timber, rip it lengthwise, hollow it, then glue it back together...
 
#23 ·
I tried building arch rafters for a while for the buildings that have a tarpaulin cover. On 3/4" material I was required to make a tapered 9" (about 250mm) long splice. There were only 2 glues I was allowed to use. Either polyurethane or resourcinol, both of which are 100% waterproof. I suppose I could have used epoxy too but that would have been too expensive.

I thought about adding splines but not knowing what he has to work with that could be tricky because you have to cut the slots at 30*. I suppose a biscuit cutter could do it. It's easily set to 30* and once you start it I imagine it shouldn't be too hard to slide it along the board to make a continuous groove.
 
#24 ·
to add a spline to a birdsmouth joint you cut the slot before cut the joint on the TS...
 
#25 ·
I´ve just got my birdmouth bit and will start playing around with it soon. I know it might be easier just to split some timber and hollow it, and then glue it together. I just did that for a jackyard spar. But for this spar I want try another way.
This is a great way for me to learn a lot of different techniques. Like mentioned here earlier it´s almost impossible to get material that is 6,5 m. So now I´m learning and testing different ways to splice staves.
I will probably do a lot of mistakes, but it will be fun (I think... )

I´ll get a lot of timber for my fireplace.
 
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