Heat treating yew, another pair of tiller eyes please.

[dwardo]

Hi All,

I have a yew stave, 60ntn, 1.5 inch fades with a taper to the tips.
This is a very dense bit of wood and i am looking / hoping to get abotu 55lbs or a tad more if possible. I flipped the tips and have  alow brace and 55 out to 16 inches.

Problem is due to it being relatively thin it is starting to take set already which is unusual for me at this stage. I am pretty sure its dry and i know i am pushing my luck length width stiff handle and tips but i was wondering what heat is like with yew? Set at the minute is about an inch and half and with any other white wood at this point i would have it braced into reflex and be happily heating the belly.

Problem is I have never used heat on yew before and i dont particulaly want to ruin the nice heart wood and sap wood colour. The other thing is this bow is mostly sapwood with a thin`ish heartwood belly.

The set is being taken evenly across the inner limbs and i have a fair old way to go yet, about 12 inches.

So whats your experience with heat and yew?

thanks.

[Badger]

Hi, Dwardo. You may get different opinios here but I never heat treat yew. You may have braced the bow a bit too soon. I do use dry heat for correcting yew but I keep the heat gun moving and don't allow any color change to take place,

[dwardo]

Hi, Dwardo. You may get different opinios here but I never heat treat yew. You may have braced the bow a bit too soon. I do use dry heat for correcting yew but I keep the heat gun moving and don't allow any color change to take place,

I guess this was one of those questions that I knew the answer too but didnt want to hear it. Its a lumpy bit of wood with lots of character. I think as you say that i got carried away with its density in the hand then rushed the early brace, even though it looked ok it was too much.
Forgot that had a pic i took with my phone.



Could you not just lie to me? Cheers Badger.

[Del the cat]

I've heat bent Yew with bothe steam and dry heat successfully, I've also heat tempered the belly on a Yew longbow which I'd got to floor tillered stage. I clamped it up with abaout 1.5" reflex and heated the belly slow and steady wafting it about until I just got a slight darkening of the heart wood.
I protected the sapwood with a couple of layers of cloth duct tape wrapped slightly onto the sides.
Here's a copy of my heat treating notes, using a temperature controlled hot air gun from Screwfix (which I subsequently wrecked bu not leaving it nozzle up yo cool )

Heat treating/bending  temperatures.   27/3/11

250 for bending won’t scorch the wood, but it will brown it slightly when kept in with aluminium foil (Yew)… maybe 210-220 would be better (yes that’s safer , be carefull not to forget it and leave it cooking for an hour!).
 I protect the sapwood back with masking tape and duct tape, rub a bit of beeswax on the belly to help spread the heat/stop scorching.  30/04/11
350-400 for heat treating. (anything over 250 will brown)
Currently using 310-330 on the  Yew longbow I’m doing for myself, heating in a bit of reflex and tempering the belly all at once on the roughed out bow. Aiming for a fast  50 pounder which is what I’ve now got, 99% of the reflex has pulled out leaving a straight fast bow.

Hope it's some help
Del
PS Give it 3 days to re-aclimatize...

[dwardo]

Thanks Dell,

Notes are something I always mean to do and soon regret not making them.
Think it might be best to lighten the outer limbs a bunch and see if I can avoid any more set. Maybe set the handle back a bit? anyone?
Then if the set increases i think its going to get a gentle but long heating....

[DarkSoul]

Yew sapwood is generally pretty bad in compression. The heartwood can take a lot of compression, but the sapwood is only designed for tension, not compression. As soon as the sapwood is under compression, it will start to take set. It certainly won't necessarily break the bow, but set just starts to kick in. Since I don't see any heartwood in your bow (but I could be wrong), I guess this is the reason for your unexpected set. Try to keep the belly flat and the back crowned. That should keep compression on the belly low.
Due to the lower SG of sapwood, the bow can still perform real good. Don't let 2 or even 2½  inches of set scare you off!

I'm not sure how yew will take heat treating, so I'm following this thread But since I haven't seen or heard of any belly tempered yew bows, I'm slightly inclined to say that yew doesn't take it very well...

editted to modify typo.

[dwardo]

Yew sapwood is generally pretty bad in compression. The heartwood can take a lot of compression, but the sapwood is only designed for tension, not compression. As soon as the sapwood is under compression, it will start to take set. It certainly won't necessarily break the bow, but set just starts to kick in. Since I don't see any heartwood in your bow (but I could be wrong), I guess this is the reason for your unexpected set. Try to keep the belly flat and the back crowned. That should keep compression on the belly low.
Due to the lower SG of sapwood, the bow can still perform real good. Don't let 2 or even 2½  inches of set scare you off!

I'm not sure how yew will take heat treating, so I'm following this threat But since I haven't seen or heard of any belly tempered yew bows, I'm slightly inclined to say that yew doesn't take it very well...

Hmm. There is a relatively thin layer of heartwood coverign the whole belly which is flat`ish. Would have been nice to reduce the sapwood earlier on but with the lumpy bumpy back i whimped out

[Badger]

  After seeing the picture I think I will change my response, I would heat trea the belly as described by Del, I believe Dark Sould nailed it with the sap wood characteristics. When I said I didn't get any color change when I heated I should have said I get a deepening of the wood grain color but no change from toasting.

[Gordon]

I've had mixed results heat tempering. It's worked well a few times and spectacularly poorly a couple of other times. Unfortunately I don't know the cause of the difference. Given those results, I don't risk it on good yew anymore.

[1000000volts]

hello ive heat treated yew before,the way i did it was with a kettle of boiling water, steaming hot with towells and things to hold the steam around the area for bending ,also i had to tape the switch on cos i kept turning off lol.. the wood went very soft and bendy,i braced it left it for about two days,and it was fine,its up to yew,dont blame me if it fails though,i take no responsibility for your actions.

[dragonman]

looks like too much sapwood to make a decent bow to me.....without the heart wood on the belly yew isnt so special, in my opinion....explains the set

[dwardo]

hello ive heat treated yew before,the way i did it was with a kettle of boiling water, steaming hot with towells and things to hold the steam around the area for bending ,also i had to tape the switch on cos i kept turning off lol.. the wood went very soft and bendy,i braced it left it for about two days,and it was fine,its up to yew,dont blame me if it fails though,i take no responsibility for your actions.

That might be a bit dangerous ye mad man! 
My question was more aimed at tempering the belly rather than making it soft enough to bend.

[dwardo]

I've had mixed results heat tempering. It's worked well a few times and spectacularly poorly a couple of other times. Unfortunately I don't know the cause of the difference. Given those results, I don't risk it on good yew anymore.

Thanks Gordon, when you say "spectacularly poorly" do you mean damage or just no difference at all and just pulls out?
I tillered it out some more yesterday and its still at about and inch and a half of set, no follow due to the flipped tips yet. It feels so dense in the hand and has that dry "ring" to it so i can only guess its not too happy with compression so heat may be the only way to go..

[Gordon]

when you say "spectacularly poorly" do you mean damage or just no difference at all and just pulls out?

The belly would crack badly across the grain rendering the bow useless.

[dwardo]

when you say "spectacularly poorly" do you mean damage or just no difference at all and just pulls out?

The belly would crack badly across the grain rendering the bow useless.

Thanks for the info Gordon and i now see what you mean by "spectacularly poorly"