New game, new chance, new problem...[NEW PROBLEM + 1]

[simk]

Hi Folks

May I bother you again?

This is another stave im currently working on - it will be a bow for my wife - about 64" long and 30# strong/weak

Theres a knot...nicely centered and healthy wood it seems. I think the knot can take the compression and the grain on the back is nicely going around it on both sides.That's why I decided to more or less ignore it.

Was that a good idea or do I have to...

A) take out the knot an fill it with epoxy?

B) let this spot a bit stiffer?

Thanx for your advice.

Cheers and have a nice day!

 

[Del the cat]

In the pic with the bark on it looks just fine. I'd have left the flow of sapwood round it just as nature had done. (If you needed to de-crown, maybe take the sapwood down a tad but try and maintain the flow).
Just pic out any many wood and use varnish or wax to stop moisture getting in. No point plugging it on the back as tension will just open it up round the plug, unless you do it for cosmetic reasons. If you want to strengthen it, you need to over lay a patch say about 3-4" long over the area... just like backing a bow.
Del

[simk]

Hi Del, thanx for you relaxed statement - i had only slight concerns about the belly, the back sure is strong enough for a mum's yew 

but what exactely does this knot in the back physically cause? does it make the belly stiffer? does it affect the ability to bend in a negative way? can I completly tiller it away? or will it overstress the back if i let it bend like the rest? ist the knot-wood harder and has less compression ability than the surrounding wood? questions over questions...cheers

PS: no need to decrown this one thickness of sapwood is just fine...

[Del the cat]

The sapwood back is just there to stop it breaking. If you have a sufficient width of clean sapwood it's fine. Excess thickness will make it stiff there.
My pet hate is people who leave a knot proud on the back and then make it proud on the belly too, the end up with a series of stiff spots with weak spots in between.
I'd rather add extra width than extra thickness.
(On the belly side I try to make sure there is no weak material which will compress and cause a pinch.)
Del

[simk]

thanx for your guidelines - that helps a lot. i will keep it slightly wider in the process and let it just bend...love you all!

[DC]

I try and measure the width of the knot and add that to the width of the bow. If you look at the first picture you can see on the left hand side that you've cut off a bit of the wood that was swelling around the knot. If you are going to narrow the limb, narrow everywhere but around the knot. I soak the knot with the thinnest CA I can get. And be liberal with the glue. If you can get a little bubble of glue over the area it will stay liquid longer and hopefully soak in more. If you just put a little on it will harden right away and then no more will soak in.

[simk]

thanx for your sharp eye DC! the interesting thing is, that this is the stave from the very first pic of this thread; after narrowing to 1 1/4 and thinnening the ugly knot completely fell away - and yes, once again worked a bit too fast - just wanted to take another look at the stave to ensure if it's really a crappy one - therefore worked a bit careless and almost ruined it myself - good for my wife, she is getting a new bow now. cheers

Last question, assistance please: i've got my other yew stave prepared for steaming recurves. is 5/8" (14/15 mm) a reasonable thickness for bending? i never steamed yew before..

[DC]

Yew bends reasonably easy. If you have some scrap pieces it's probably a good idea to do some practice bends. 1/2" would be easier than 5/8". Round off any sharp corners to about pea size, steam for at least 30 min. 45 would be better.

[simk]

So, the knot-situation turned to a hole-situation (-; ialready had prepared the epoxy when remarked that it didn't change tiller despite the hole. So im not sure anymore if I should fill it. Filled with epoxy it would maybe safer and easier to tiller, Thoughts?
The bending job on the other project was easy and successful.
cheers

[DC]

Some people would kill for a bow with a hole in it. Need some measurements
Width at the knot and width 2" above and 2" below the knot.

[Hawkdancer]

Not any expertise, but a "hole in the bow" would be neat!  The other guys can give the expertise, but at 30-35#, it shouldn't cause any problems.  Keep posting, I'm curious how it turns out!
Hawkdancer

[simk]

Yeah, a hole in the bow would be nice. But: I cannot follow anymore the rule, that the bow in that spot has to be wider the diameter of the hole...alredy narrowed it to much at the hole
I still could do it - thicker - with an uneven thickness taper - in that spot. But: Del's pet wouldn't like that!
Will post measurmets for DC tonight, after work!
Cheers 

[Del the cat]

Dig out all the black manky stuff. clean up the knot (or shape a Yew peg) and glue it back in with the surrounding gap filled with epoxy/Yew dust mix. (Mix it with plenty of Yew dust, a bit drier than you think, as it gets wetter when compacted in.
If you make a peg you can have a nice rounded end protruding through the back if you want that sort of look
You do have some extra width there, so you don't need to go mad with extra thickness.
Del
(BTW.. when you run out of problems, that's when the bow is finished )

[simk]

So, my unfinished bows are still causing problems 

Bow no 1 measurments for DC are (width/thickness in mm): 2" before knot: 38/21, @ knot 37/22, 2" after knot 35/18.
On the following pic you clearly see the extra wood @ the knot - obviously didn't follow the grain there...
As far as I understood Del's pet would go for a yew-plug. My decision-making is not clear at the moment but I still think it would be easier and safer to tiller with the hole filled (with a steady thickness taper). Therefore I feel a slight tendency to follow Del's advice. Altough I like the idea of a bow with a hole. Thoughts?

On bow no 2 I've remarked 2 bad pressure marks from the leather gloves I used as cushions between wood and clamps while steaming (pic 2). Next time I have to take clean leather pads without stitches and folds...Can I make them dissappear with steaming again?

And a basic quastion about bow no 2: I'm a little concerned because it seems to have become a rather stressed design with these recurves and with a bow length of 63". Do I have to worry about it(Edit: If I aim for 50"@27)? It's a perfect piece of yew, wide and flat, planned slightly working recurves... (pic 3 - with my coppices in the background  )

Cheers, thanks and have a very nice day!

[DC]

I've made lots of 40# yew bows with 30mm wide limbs so I was thinking you could narrow the rest of the bow and leave the knot as is but now I see how short your working limb is it's making me re-think a bit. Del has way, way more experience than me.