Best way to recurve tips?

dvarela934
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dvarela934
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March 7th, 2018, 12:49 am #1

Hi all.
I have reflexed tips on about 5 bows with some success. Just want to ask what’s the best angle/ radius length etc to make a form

I have not yet used a form I have just freehanded it but most end up settling with less recurve than intended or crack and splinter when I try to go too far. I have used a heat gun before but have had more success steaming for about 20 mins.

Here is my most successful recurve





Last edited by dvarela934 on March 7th, 2018, 12:49 am, edited 1 time in total.
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Dark Factor
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March 13th, 2018, 6:04 pm #2

I have never had good results with dry heat methods (heat gun...) , except to correct some small curves. I advice you dry heat methods, I've had better results with steam (for several hours on a pipe/chimney), but for important angles I always put the tips on hot water (on a high cooking pot) for some hours too. I've only made this 6-7 times, so someone has maybe better expereience.
I have had good efficiency with about a 45° angle on tips about 20cm on the tip of the limbs, but you need a form (easy to make with a wooden beam)
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dvarela934
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March 13th, 2018, 10:19 pm #3

Dark Factor wrote:I have never had good results with dry heat methods (heat gun...) , except to correct some small curves. I advice you dry heat methods, I've had better results with steam (for several hours on a pipe/chimney), but for important angles I always put the tips on hot water (on a high cooking pot) for some hours too. I've only made this 6-7 times, so someone has maybe better expereience.
I have had good efficiency with about a 45° angle on tips about 20cm on the tip of the limbs, but you need a form (easy to make with a wooden beam)

Yes I have had my best luck with steam but have never tried cooking it for such a long time. I thought a half hour of steam for tips was on the safe side



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Dark Factor
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March 14th, 2018, 5:28 pm #4

Wood is an insulation material, so you need time before it become hot inside (more for big cross section). Water alone isn't enough, you need heat and the more it enter into the wood, the better, I think.

I generally put tips on hot water (a bit under 100°c) for 2-3 hours and then it becomes really more flexible. you put on a wooden shape to give the recurve (with ropes around not to move)  and then you let the bow drying for some days. you can take it away from the shape after 1 or 2 days (it will come back a bit to the initial situation, but no more than 20% ), then that's better you let it dry some more days on a dry room of your home.
That's how I do but other solutions are maybe good too.

Good luck for cooking you bow if you try ! you don't have to add vegetables on the soup... and please don't drink the soup after and clean the pot.
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Patrick St M
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March 17th, 2018, 12:18 am #5

Those bows barely have any recurve to them.  It depends on the wood you are bending when it comes to heating methods.  Soaking and boiling actually works really well.
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dvarela934
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March 17th, 2018, 1:10 am #6

Yes I know it’s not much reflex in the bow shown but that’s the best I’ve gotten without cracking or splintering


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dvarela934
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April 1st, 2018, 1:12 pm #7

Here’s an update after another layer of sinew



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Beadman
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April 15th, 2018, 12:58 pm #8

dvarela934 wrote: Here’s an update after another layer of sinew



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This all depends on what you call a true recurve.Pictured will be a working recurve.A true recurve is one where the string rests on the belly of the recurve at least a couple of inches at brace.That takes a static type sharper bent recurve tip to do that.
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dvarela934
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April 15th, 2018, 1:18 pm #9

Beadman wrote:
dvarela934 wrote: Here’s an update after another layer of sinew



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This all depends on what you call a true recurve.Pictured will be a working recurve.A true recurve is one where the string rests on the belly of the recurve at least a couple of inches at brace.That takes a static type sharper bent recurve tip to do that.
Correction. Best ways to reflex tips


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Beadman
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April 15th, 2018, 1:35 pm #10

I use forms and it requires a good half hour of steaming per 1/2" of thickness of wood for it to bend good.Starting out with around 5/8" thickness first and that wide too.Filing and sanding it to final shape after tillering.Rounding the belly's sharp edges before bending to negate splintering is needed also.Leaving a single ring on the belly also helps.Some incorporate a metal strap onto the belly while bending too to hold down splinters.This is black locust wood.Practice on spare pieces helps.

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dvarela934
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April 15th, 2018, 1:37 pm #11

Beadman wrote:I use forms and it requires a good half hour of steaming per 1/2" of thickness of wood for it to bend good.Starting out with around 5/8" thickness first and that wide too.Filing and sanding it to final shape after tillering.Rounding the belly's sharp edges before bending to negate splintering is needed also.Leaving a single ring on the belly also helps.Some incorporate a metal strap onto the belly while bending too to hold down splinters.This is black locust wood.Practice on spare pieces helps.

That is an impressive curve!


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Docmann
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April 15th, 2018, 9:30 pm #12

That’s about the same amount of reflex I prefer.
I typically build with Osage, and while I’ve used a heat gun, I prefer steam. I use a big kettle and get creative with foil. Wrapping it carefully, it’s probably not much different than boiling. The steam saturates the wood, and the temperature is going to be about 212’ F (100’ C).
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beardedhorse
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April 15th, 2018, 10:27 pm #13

Docmann wrote: That’s about the same amount of reflex I prefer.
I typically build with Osage, and while I’ve used a heat gun, I prefer steam. I use a big kettle and get creative with foil. Wrapping it carefully, it’s probably not much different than boiling. The steam saturates the wood, and the temperature is going to be about 212’ F (100’ C).
Some good replies and pictures.   Some woods like hickory will want to have the recurve pull out unless laminated with another wood or made very thick which negates any gains in speed you might try to achieve.   Why do you want a recurve to begin with?  Shortening the bow by bending the tips adds more mass there and if the wood has a higher density you might not improve velocity.  We need to distinguish between reflex and recurve, too.  They are not the same.  If you are at a higher altitude, boiling water is not as hot as a sea level so doesn't soften the cellulose and lignin as much.  I also use holes drilled in the form and c-clamps but add an aluminum straight edge on the belly.   More sophisitcated shops use the fire hose and air to compress the stave to a form.  I know a lot of bowyers who like heat guns with a caul.    Overcooking and over heating will ruin a good stave so watch the heat and steaming times.   Boiling does leach out some of the minerals.    Have you ever tried "training" green wood with weights (example is tying an anvil to the middle of a stave resting on two sawhorses to induce a reflex.    The Martin style bow that Laubin learned from another bowyer, Nelson Hoffman  recurves two separate limbs (maybe using the same form) before  splicing them together at the handle with the tips and limbs leaning forward.   This design puts a lot of strain on the wood.   Stan Honour who knew Laubin's teacher had his tips working and not static.  
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Beadman
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April 16th, 2018, 12:02 am #14

Some of what you say can be true apparently to someone not doing it the right way.Statements of what a recurve definition is and using a metal strip have already been addressed.I dry heat temper steamed in recurves after they cool and dry.They don't pull out.Even hickory.My statics are no wider than a regular bow tip so no extra mass.Speeds on them are higher than a regular straight tipped bow with a fatter fdc,All this I know through my own making and testing.True recurves are twice the trouble to make than a straight tipped bow but everyone with the bow making bug should try at least one.
PS...Drying a roughed out bow into reflex by weights or a form and clamps is really not the most substantial stay put way of keeping reflex.Most all of it will pull out while tillering.Natural/laminated in/or heated in are the best ways to get the best sustained reflex.Starting with the best to worst.
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Beadman
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April 18th, 2018, 8:04 pm #15

dvarela934....The type of recurve on your bows will make fine shooting bows.Working recurves that is.Easier to tiller than more extreme type recurved tips.Although they are not all a walk in the park that's for sure.Reflexing more with more sinew after the bow is in tiller well helps things immensely as far as tillering them goes and should really remain in tiller for you if sinew is put on evenly on both limbs.I would feather that sinew out 6" below your tips as sinew on the tips does nothing for performance.
The more extreme the reflex with sharper recurved tips the more troubles can occur like string alignment of tips,touchier to tiller because of more energy stored etc.I never put any sinew on the static tips of mine.It's not needed.
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