Advice for Fret at knot in yew?

[AH]

I'm currently working on a yew warbow, the stave of which I got from Carson at Echoarchery. The stave is roughed out and floor tillered, and I am tillering it on the long string. It's still bending only about 6-8 inches, I'm taking my time on this stave and carefully exercising it every inch I pull. But when I took it off, I noticed a chrysal on the belly of two knots--the large one in the picture is about 1/2" diameter, and the small one is a little less than 5/16" diameter. The knot seems sound. It was rather surprising that this fret showed up. They are'nt very deep. I have left the area around the knot almost 2" wide to compensate for it.
By the way, Del, I noticed that on your MR copy, the big 90 lb'er, there was a fret at an area where you filled a knot, if I remember correctly. is that the same sort of situation here? If the frets are detrimental to the bow, I think I may drill out the knots and insert a plug. I was thinking about filling the fret with superglue and yew dust, would this work?

[George Tsoukalas]

First, if I were making a 90# bow I'd want a relatively clean piece of yew with no knots. Second, I always tiller knotted areas to not bend as much as the rest of the limb.

But that does not help you with this stave. Eventually, if not fixed the bow will fold on itself like  a book closing. Been there.

All you can do is remove wood from above and below the fret so it is not bending  as much as it is.  You could also do a rawhide patch directly on it.

Honestly, I would not try to get a 90# bow from that stave but that's my cautios nature.

Jawge

[Weylin]

I'm knot saying this is the best advice but I have a couple of yew long bows that have cracks though knots like that and they haven't given me any trouble. I filled them with superglue. My bows are in the 55-65# range so it might be a different story if you're trying to coax 90# outta that stave.  That being said, if some of our resident yew experts think you should do something more about it I'd listen to them. Good luck.

[Hamish]

That's not a fret. Its just a drying check in the knot. You could drill it out and patch  a plug in there but I don't think it would be necessary( use a heat resistant, gap filling glue if you do). The compensatory swell should be fine.
                                                    Hamish

[Joec123able]

That's not a fret. Its just a drying check in the knot. You could drill it out and patch  a plug in there but I don't think it would be necessary( use a heat resistant, gap filling glue if you do). The compensatory swell should be fine.
                                                    Hamish

I agree it looks like cracks from drying if that's the case then it's nothing to worry about I have an Osage bow with knots like that that have cracks in them and thousands of shot haven't affected them

[AH]

That's not a fret. Its just a drying check in the knot. You could drill it out and patch  a plug in there but I don't think it would be necessary( use a heat resistant, gap filling glue if you do). The compensatory swell should be fine.
                                                    Hamish

I guess then that it is just a coincidence that both checks are perpendicular to the grain, as frets would be? The lower check is sort of at an angle though...are frets always perfectly perpendicular to the grain and length of the bow?

[Pat B]

Those are drying cracks(checks) and not frets. Frets are breaks in the fibers across the grain do to overstressing in a specific area; compression fractures. Checks split along a grain line like these are doing, like checks in the end of a log and these knots are small logs.   I would fill them with super glue and keep tillering. I've only built one bow that heavy(95#@30" yew) but I couldn't pull it to shoot so I can't speek to how this will work for a 90# bow.

[adb]

I agree... those are not frets. Knots in yew tend to crack, because knots are hard. The good news... no big deal for yew. Fill it with CA glue if you want, but it's no big deal. You can easily get your weight from that stave. Very difficult getting a yew stave without at least one knot! If you do, cherish it.

To answer your question about frets... generally, yes. Not always, but usually. Frets are a sign of overstressed wood, that is very close to failing, and they will usually run across the grain.

[AH]

Ok...thank you all...that's a relief!

[Gordon]

I agree with what has been said. Those will likely not give you any trouble.

[mikekeswick]

+1 to whats been said. They are not chrysals.
I would say though that if you are making an elb then it doesn't need to be 2 inches wide around the knots.  Work them down soon. My advice is to not leave the knotty bits stiff just keep them a little wider. Any stiff area in a limb puts too much stress on the handle side of the stiff spots. Stiff spots are the cause of chrysals.

[Del the cat]

+1. Them's just drying cracks in the core of the knot.
Those knots look pretty sound.
I only dig 'em out if there is a thin black line of manky stuff round 'em.
Some low viscosity super glue will fill/stabilise those checks.
Don't worry too much about the belly.
The big Q is do those knots appear on the back???
If they don't appear on the back, what is going on inside the wood???
Is there a pocket of rot where the sapwood has grown over?
A good clean solid layer of sapwood is the vital thing. It doesn't necessarilly have to follow a ring, but it needs to be pretty clean and even thickness.
Del

[Josh B]

First off let me preface this with the fact that I have no experience with yew.  Those aren't frets, but they are crush damage.  As you pointed out the direction of the opening indicates that. It has to do with crush strength and compression strength.  Compression strength is resistance to pressure in line with the grain.  Which is much stronger than crush strength which is resistance to pressure diagonal to the grain.  I've had this happen on knots in erc, elm and hackberry and in every case it remained isolated to the knot never spreading into the surrounding wood.  I agree its a good idea to leave it wider but not stiffer.  Basically your knot got crushed and cant swell back up once the pressure is relieved so it split along the grain.  This is the reason you done want a knot running diagonally across the belly of sapling bows.  They will crush like this creating a hinge and ultimately limb failure.  Josh

[George Tsoukalas]

Drying cracks on the belly generally go with the grain. Cracks in a knot usually stop in the knot.  Be careful with that stave though for a heavy bow. Jawge