Recurve cracks

[DC]

Have you ever had a recurve crack after it's been bent? I bent some Cascara with about a 5" radius. I used a strap and let it sit for an hour or so. Then I took the strap off and left it clamped for another hour or so. It was fine, no cracks. So I hit it with some heat to lock it in and got two tension like cracks across the belly. I know it sounds like I was too impatient but I remembered Marc saying he steams them, lets them cool for 20 min then locks them in with dry heat, waits another 20 min. and they're done. Unless I dreamt that

[Marc St Louis]

That is weird.

[upstatenybowyer]

Never had that happen. I can't think of why it did. 

[DC]

Hopefully I can fix it with underlays. One of them looks pretty deep. I'll go slower on the next. I flooded them with CA.

[DC]

I posted this over on Upstates thread but thought it was hijacking so I moved it here.

-Buckthorn is more dense than yew and ERC. I'd say it works more like BL, plum or mulberry. It's hard to make comparisons though cause it's kinda got a feel all it's own. I know it sounds weird, but the grain seems fibrous to me, almost like bamboo. 

Sure doesn't sound like Buckthorn and Cascara are related. This piece of Cascara I've got works really nice with a block plane or spoke shave. It kinda crumbles with a scraper. Anyone out there worked them both?

[PatM]

I would consider this pretty nor al if your steam time is a bit long and the recurve is kept under full tension for the heat treat after steaming.

 I've done some experimenting and you can watch the cooked wood separate when the dry heat hits it.

[DC]

So I should release a bit of tension off before I heat treat. What does the excess steam time do?

[BowEd]

I've had that happen before with hickory while the other tip bent nice with no cracks showing from tempering.From what I remember the one with no cracks was bent a bit quicker on the form after steaming than the cracked one was after steaming.In other words the cracked one had just a little too much time to cool before bending while the other did'nt.I assumed that was the reason.Unseen stress was there and revealed from tempering.

[junseld84]

DC,

I just had this happen on a piece of osage I was heat treating. Of course this was my first bow and I have no idea what i'm doing but I didn't think to put the bow back on the form to heat treat it so I lost a lot of my reflex. When I tried to bend the tips again, a horizontal crack formed in the belly. I also filled with thin super glue but you can see it's bulging out after shooting it.

[DC]

I just bent the other. The first one I steamed for an hour, this one forty minutes. I'm going to delay the heat treat a little. I'm wondering if Cascara sucks up more water and needs a bit more drying time. I did a test with an offcut, it was thinner but I bent it tighter. It crushed the inside of the bend so I figured with the bigger radius I would be OK.

[DC]

DC,

I just had this happen on a piece of osage I was heat treating. Of course this was my first bow and I have no idea what i'm doing but I didn't think to put the bow back on the form to heat treat it so I lost a lot of my reflex. When I tried to bend the tips again, a horizontal crack formed in the belly. I also filled with thin super glue but you can see it's bulging out after shooting it.

It can get really tricky if you heat straighten a wonky stave and then try to reflex it. You have to remember where the bends used to be so you can restrain it in the right direction. I saw your other post and thought that you probably didn't apply enough heat when you tried to re-bend your tips.

[Marc St Louis]

I would consider this pretty nor al if your steam time is a bit long and the recurve is kept under full tension for the heat treat after steaming.

I've set the recurves with dry-heat both ways and never had that happen.  Personally I suspect that particular piece of wood

[DC]

We'll see how the heat treating goes on the other end. So far the bend is good.

[DC]

Second half went fine. Everything is heat treated. Planed away 99% of the cracks and still have just under 3/8" thick recurves. Add 1/8" or so of Hard Maple backing to that and I think I'm golden. Might not need underlays but they're starting to sound attractive.