Black Cherry for core lathe

I tried bending the pieces that I had cut for siyahs and they both broke. I guess that answers that question.

Prunus avium works when it's green. Green wood is definately the way to go for me.

How long did you dip and how long did you cook (while boiling)?

I think you need to dip 2 days and cook over and hour with maple.

I steamed for about 45 minutes. No presoak.
I have identified some young Norway Maple trees on my property. Is this a suitable wood for making a composite bow? I know sugar maple (hard maple) is considered good, but I don't recall anyone talking about Norway maple.

I also have some black locust which I know is good for making self bows and it steam bends easily and is even stronger than sugar maple in sheer, compression and tension but I have heard that it does not glue well. Has anyone had experience in building a horn bow with black locust?

On further investigation, I have discovered that Black Locust isn't as difficult to glue as I first thought. In the boat building forums, black locust is always lumped in with White Oak as being difficult to glue, but I think this must be because the glue they refer to is epoxy which isn't the same as real glue. In general woodworking forums Black Locust has a moderate to good gluing rating.
I think I will be using the Black locust for my bow project - unless someone else has something to add?

Tapsnap wrote:

On further investigation, I have discovered that Black Locust isn't as difficult to glue as I first thought. In the boat building forums, black locust is always lumped in with White Oak as being difficult to glue, but I think this must be because the glue they refer to is epoxy which isn't the same as real glue. In general woodworking forums Black Locust has a moderate to good gluing rating.
I think I will be using the Black locust for my bow project - unless someone else has something to add?

NO!
Use a difuse porous wood.
Black locust is no good for various reasons. Keep it for self bows :)

Tapsnap wrote:

I steamed for about 45 minutes. No presoak.

Steaming is no substitute for boiling. That being said, I know others have succeeded with steaming. I have not.

I suggest dip for 2 days or so and then boil for 2 hours. That should make nearly anything bending.

Tapsnap wrote:

I have identified some young Norway Maple trees on my property. Is this a suitable wood for making a composite bow?

Yes.

mikekeswick,
Can you expand on why Black Locust is no good for this type of bow. Here is the link to the article and a passage that led me to rethink gluing Black Locust.

http://www.bfafh.de/inst4/41/411/
EU INCO-COPERNICUS Project No. PL 96-4114
Technology for High Quality Products from Black Locust
(Robinia pseudoacacia)
In this particular study glue bond strength was determined as a function of surface preparation and adhesive system. Seven different means of physical and/or chemical modification of the substrate (Black Locust wood) surface were tested in conjunction with six adhesive sytems (exterior use) selected for gluing tests. The results indicate that, with polyurethane based adhesive systems, individual surface treatments (steaming, sanding) can be expected to enhance glueline strength. PU systems appear more sensitive to the physical properties of Black Locust than the jointly tested resorcinol, PVAc, and melamin adhesives. These results give rise to the hypothesis that the particular chemistry of the wood surface has no or little bearing on glue bond quality. Rather, the gluing problems reported earlier by industry and previous studies must be attributed to the high internal stresses built up during drying and the subsequent slight to noticible deformations (cupping, warp) in conjunction with the considerable stiffness of the material.
Subsequent exploratory tests with two PU systems indicate that glue bond strength increases slightly with an increase in contact area (surface roughness).


14.
Gluing for exterior applications
J.A.M. Kickken, B.D. van Etten (DELFT)
Summary
Black Locust wood was bonded with five D4-quality adhesives destined for exterior applications, i.e. one thermosetting resorcinol glue, one reinforced PVAc glue, and three polyurethane glues. The slow setting (long pressure times) PU glue (I) failed in the delamination test and cannot be recommended for exterior applications. All other tested glues gave for the most part satisfactory to good results for surface gluing, yet highly variable as a function of the wood type (factors "origin" and "treatment") and process parameter "pressure". For finger jointing, only one PU (III) and the resorcinol glue performed reasonably well but failed to meet the standard requirements. In general terms, the production of finger joints with polyurethane glues requires modification of processing parameters (pressure, time) as compared to those presently in use for the more common exterior glues.


jkekoni,
Boiling, to my understanding, weakens the wood more than steaming. This is why most furniture manufacturers steam bend their bent parts as they are usually under great stress, especially in chairs. It is true that boiling the heck out of a piece of wood will allow you to bend it easily, but it will greatly diminish it's strength. It is heat, not water, that allows wood to bend and steam is actually hotter than boiling water.. Over steaming will have the same results - it will also weaken the wood. The general rule is one hour of steam for every inch thickness of wood. But you are right, my piece of cherry was too dry and pre-soaking would have been a good idea.

Black locust is ring porous. It has a distinct difference in the properties of the latewood and the earlywood. A hornbow core has to withstand sheer more than anything and the hard/soft/hard/soft nature of ring porous woods means they aren't ideal. Also when it comes to making the grooves for the core/horn joint you will find that you will bite into the softer earlywood. Black locust would be a good wood to use for the tips in a five piece core as it is very stiff for it's thickness and not too dense.
The short answer is to use your norway maple!
Great bending properties, great gluing, diffuse porous and it's just coming into spring so it will be full of moisture which will help greatly with bending.
I now fully submerge my cores in boiling water for around 1 hour to bend them. Steam just isn't as effective in my eyes. I also boil my tips when doing selfbow recurves and can get 90 deg bends with a tight radius - I can't with just steam.

Also reports of gluing with modern glues should be taken with a pinch of salt. Remember that you will be using collogen based glues which act differently.

OK. I will use the Norway maple and I will boil the bend but I have to say I am a little confused. Take a look at the shear strengths in this table. http://www.woodworkweb.com/woodwork-top ... ngths.html

Black Locust performs better than hard maple in all aspects of strength including shear.
By the way, that is a beautiful Cathedral you have in Durham. I visited Durham in my early 20s

Tapsnap wrote:

OK. I will use the Norway maple and I will boil the bend but I have to say I am a little confused. Take a look at the shear strengths in this table. http://www.woodworkweb.com/woodwork-top ... ngths.html

Black Locust performs better than hard maple in all aspects of strength including shear.
By the way, that is a beautiful Cathedral you have in Durham. I visited Durham in my early 20s

Yes but the most important bit by far is that b.locust is ring porous. Maple is diffuse porous. B. locust is in my eyes the premier self bow wood but it is not suitable for this application.
Have you got Adam's book yet? It explains all this better than I can.

Boiling ... weakens the wood more than steaming.

I do not comment about that.

Boiling works. It is the traditional way of bending composite bows, so I would say it does weaken too much. I would assume the furniture industry is more conserned about the process speed than the damage to wood.

If you can bend well enough with steaming then it is enough. Because you could not, I would suggest boiling.

You can also bend wood with hot air gun. I would suggest it for making smallish bends for self bows, because you can bend dry wood and heat the belly at the same time.

BL

Ring porous woods have also been used. You must use wood with vertical grain ((((( . I do not comment if BL is ok or not. Most people use maple as it is easy to get known to work well.

Hazel also work well, but must not be green for checking reasons.

I would think that wood from the Sorbus family should work well, like Aucuparia or Intermedial. It is diffuse porous and a tough strong wood and not too heavy. Besides it is easy to come by both in Europe and North America.

I should correct myself. Sorbus is a genus of about 100-200 species of trees and shrubs in the Rose family ( Rosaceae)

OK, well I saw that the electric company was cutting down tree limbs on the side of the road and noticed they were working on a sugar maple, so I picked up a few branches. My question now is, how important is it to stay within the growth rings. When making a self bow, one must never cut through a growth ring when dressing the back of the bow or you need to go to the next ring and get a perfect complete growth layer the entire length of the stave. Secondly, how far beneath the bark do I need to cut. With self bows this varies. Working with yew, the sapwood is kept on the back, working with osage orange, the sapwood is removed. What is the story with composite bows?

Here are the hard Maple logs I found.

Here are some staves I have cut so far. As you can see the hard maple stave is a little lumpy and the Norway maple is a little smoother but the black locust staves are the straightest. All staves cut within one growth ring.

In a composite core you should have the outer growth ring in the belly of the bow. That way, when you bend the ears, or core, forward you have the single ring on the outside of the bend. After the core is bent I don't think it's as important as on a unbacked selfbow to keep the ring intact. You will work that side before you glue on the horn anyway. With maple I just remove the bark.

Well , that makes no sense to me at all. The tension is going to be on the back not the belly and you want a single growth ring to prevent the grain lifting as the bow is brought into tension. The belly, being in compression, can withstand breaks in the growth ring because there is no danger of the one growth ring splitting off the next. Don't you have this backwards?

Think about it which sides are under tension/compression when you wedge them into the forms.

When the bow is done, things are different as the sinew and horn does each it's job. Wood is the medium between these materials. Everything you need to know is in Adam's book.

Sidenote: You can see korean bowyers doing the same thing with the bamboo laths. The outside of the bamboo lath, where the nodules were is glued to the horn. I belive there was a discussion about this here somewhere. Anyway, you can see that the bowyer in Thomas Duvernay's video does it that way.

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" I belive there was a discussion about this here somewhere. "

I was looking for for it but can't find it. Do you remember in which forum it was asked or who asked it or what the title was?

I would very much like to read it.

I don't recall much of it. It might have come up in a few posts in a thread about something else entirely. It was about the video that I mentioned most likely or korean bows.

You can buy it at 3riversarchery. It's invaluable to have the whole process documented so well.

No they aren't wrong. It will all become aparent when you try making one!
I cannot recommend you to buy Adam's book strongly enough.
I wouldn't use any of the wood you have. Not straight enough. As I said before b.locust is heavily ring porous = not good.

When the bow is finished the sinew takes (most of) the tension. Just as horn takes most of the compression.
You need the single growth ring on the outside of the bend when you bend the core over forms, to avoid breaking.

And as mikekeswick and Bj?rn said, get Adam's book. Lots of trouble reinventing the wheel. I know, I tried. :)

I also thought this was backwards, but will bow to your guidance. If I had read this I would be doing it as Taproot says, I havent received Adam's bok yet but will read it thoroughly before I start. Right now I am collecting material.

Just think - how on earth do you expect to bend the cores into shape without unbroken fibers on the outside of the bend! It's hard enough as it is!

So here is my first attempt at making a composite bow. There are quite a few things that are bothersome about it to me. Firstly the crack in the horn which began as hairline crack and has grown to be about 1mm since putting on the sinew. Secondly the horn really was not wide enough to cover the belly as far up as I would have liked it to go. I don't have much expectation for this one but I have learned a lot building it. We shall see in October whether it makes a decent bow.

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I've never tried bending or boiling but have used a heat gun often for setting recurves and putting in reflex.

Is there a good reason to boil rather then to dry heat bend? I have clamped the bent pcs and then sinewed them when clamped, so far none have returned to a straight piece.