Boiling cores or dy heating??

Personally I wouldn't "boil" wood at all. It's really difficult to get a long large container and enough heat together. I would hot water soak it for a few hours or days (I use my girlfriend's hot tub - 105F). Or I would steam wood. But not boil it. You can make a simple steamer rig using a (rented) carpet steamer some flex tubing and a length of PVC pipe.

The actual technique doesn't matter as long as the wood will bend to shape on your form.

Hi Ken

Adam uses that phrase so I did. I have bent some pretty sharp bends with dry heat, that have held, but, I am a novice with hornbows, so I do want to get the best results that I can.

Yes, steaming isnot hard to do, I have used a large PVC pipe and a couple fittings and it worked, but the dry heat worked just as well, and was faster even with slow heating it.

As I posted, I am open to all's suggestions.

Boiling worked perfectly for me. I tried steaming, and it worked, too. But my subjective impression is that wood is harder to bend then. I have moved back to boiling, having bought a cheap pot for big fish.

Thanks Arry

I'd have to get a really big pot, or do one end at a time as its a one piece core, I could make a steamer, but wanted to check with guys here on the dry heat.

I found boiling to work the best, but have found a few tricks are needed. I start by using fresh green cut hard sugar maple, I then soak the core strips for up to one week. Before boiling I notch under the sharp bend to take some pressure off the side of the cores that are under tension. for the boiling I had a metal fabrication shop weld me a steel tray and utilize two camp stoves. I try to keep a real good rolling boil for the full hour. After trial and error and coming to the above steps I have been quite successful at bending 5/8" thick cores.

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Are you attempting to have a one piece core and recurved portions?
It is considerably easier to use a wood with better steam bending properties to form the knee and v-splice them into the extremities.

Nice working setup for bending .I do like those forms.

Pat yes, one piece cores. I have dry heat bent maple and oak self bows with good lasting recurves in them, basically like Jim Hamm discribes in TBB 1. Heat it and bend around the knee.

But all of the discussion here is on the hot water treatments so examining them. I am going to soak one of them for a couple weeks and see what I can do with it. I have a number of good pieces of hard maple, fall cut. So with inside storage the Moisture Content is down pretty good.

The moisture content wants to be up not down!
Wood bends easier at a higher m.c.
It all depends on how much reflex and in what shape. We are guessing until you show your plans.
For severe bends - green wood - soak for a few days - rolling boil for 1 hour or so. Using a form and steel strap.
For shallow bends steam or dry heat.
Of course you can only use dry heat on a fully seasoned piece of wood or else it will check.Hence the use of water as a heat carrier.
I suggest you just humbly follow every word in Adam's book - don't think 'oh I know a simpler/easier/etc way!' There are reasons why and it all becomes apparent after a few bows.

KenH wrote:

It's really difficult to get a long large container and enough heat together.

It is not. I used 1m ventilation duct and attached an end with silicone and plumming hemp and used 2kW immersion heater, I extended the cord with "Heat-shrink_tubing". I used a sock with stone inside and wire to pull the wood from boiling water. I detach the heater before pulling wood out.

Takes about 1h to for water to boil, and much less for constructing the rig.

I would recommend usage of horisontal container, since they are easier to use, but require much more energy since more heat escaping.

I however have newer any success with steaming.

Anyhow 3 piece requires boling, but for 5 piece hot air gun and steaming are likely to succeed. Also not bending is an option.

bheggeseth, what is the container you are using. Did you make it yourself or is it for other purpose ?

3 day soaking seems to be ok, for commercial kiln dried mapple.

The metal tray was made by a local metal fabrication shop; friend of a friend so no cost for me, I would guess $50 would cover the steel and the labor. The sheet metal was simply bent in a U shape with welded end caps.

If I ever needed to make a second tray I would go with slightly higher sides as currently some water boils over. The material is regular carbon steel, I make a point to dry the tray right after using and so far no rust, I would guess after some time there will be a bit of surface rust but it should not harm the process. If you made sure to never run the tray dry a person could try make the tray out of aluminum.

Also note: I would agree that the best path forward would be to buy Adam's book and follow his directions word for word.

One more note: my first cores were bent using aluminum flashing for the boil tray, cheap but it worked. Be very careful when bending the corners as if the aluminum kinks it will leak. I believe I used some aluminum foil duct tape to hold the corners from opening up when the water is added, The tray was long enough to where the taped corners didn't sit under the camp stove burners. Also make sure that the try is supported well underneath as the whole setup is a bit wobbly.

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Another possibility for a container is aluminum eaves troughs.

A consideration I have is my cores are almost 2 meters. So its either boil and end at a time, or something like an eavestrough. Still thinking on this.

My end goal is a Manchu or Mongol style bow, not a shorter ME flight bow. So far I am not finding a whole lot of information on the actual building process of the Chinese bows, not as in such detail as the Turkish and Ottoman bows.

I have Thomas Duvarneys videos on Korean Bow making, which is more similar to the Ottoman building then any other Eastern Asia process. I have a couple very short videos of modern Mongolian bow making, which donot indicate any water treatment of the bows at all.

If anyone has any input on the Manchu bow building process I would appreciate seeing it.

Using a 1 piece core may prove difficult, I am not sure how I would attempt this. If you bend each side separately there is a risk the the first bend would open up when you go to boil the core for the second limb. If you try to bend both side at once you will have to work very quick before the wood cools down.

I would practice on some of the less than perfect cores first to make sure you have a good process down. I have a good friend who is a luthier and cabinet maker and after some thinking we had a plan for how to "best" bend the cores for my first turkish bow. After cracking every core we had prepared I went back and followed the steps outlined in Adams book.

I am not familiar if Manchu or Mongol style bows utilized a one piece core but I have been continually impressed with how easy the joints are to make and how strong the 3 piece core is, one benefit is that you can take out any twist and ensure that that tips are in alignment by properly fitting the joint.

Good luck.

There is an English translation of a report on the workshop of the last bowmaker in Chengdu in the 1940s. T'an Tan-Chiung, Investigative Report on Bow and Arrow Manufacture in Chengtu, a reprint from the Soochow University Journal of Chinese Art History, Vol. XI July 1981. It describes the working practices, had photographs and diagrams of tools and workmen in the shop plus many details of the processes and bows and arrows.

The basic bow core is made from a strip of bamboo with v-splices at each end for the ears. The handle is glued onto the back of the core. The ridged part of the ear (the "brain" in translation) is cut into a wedge to fit into the core fishtail splice and has a smaller v-splice at the other end for the tip. The brain is usually made from a naturally curved piece of wood. The tips are cut with a slight concavity on the back and a slight convexity on the belly.

Counting the glued on riser at the handle, there are six pieces in the core. There is a small amount of set back in the handle caused by the shape of the riser. The bamboo core is thinned where the riser is to be glued. It was not unusual to have an extra piece glued into the tip for the nock to be carved into. This was often horn and the joint was a fishtailed splice. All the wood was cut when green and seasoned when partially finished. The report notes that historical bows from North China had a wooden core instead of a bamboo one.

Your suggestion is what I am doing this week, I have two cores I amnot going to use except for pcs to make siyahs from. I am going to soak both in a stock tank for a couple of weeks, then let them dry for a day, then dry heat one end at a time and clamp into a form, then heat and clamp the other end, and leave in the form at least a week. After a week or two in the form I will unclamp and see how they are. To date I have never had a problem with dry heat bending, even without the soaking. So we shall see, I will post back on this as to how it works.

The form also allows for deflexing the handle an inch, and the tips reflexing about 3". The siyahs I will splice in after the reflexing. They are long after the Manchu style.

Adams book has been a great help to fill in anything I cant find on the Manchu/Mongol construction. I do have Thomas Duvarneys videos on building the Korean Bow, but in length they are much closer to the Turkish Bow. Wheras within the Mongol Bows I find both short horse bows and longer bows.

Adam's book is a great resource and generally the techniques he describes can be applied with little change to other types of composite bow. The order of constructing the core was to apply the riser to the central bamboo section and then add the tips, but the book is not clear about whether the two parts of the ear were glued together before being fitted to the core or were added one after the other. What is emphasised is that at each stage of construction the straightness of all the parts were checked and any deviation was corrected by heat.

There are also some problems with measurements; sometimes mm is written were cm is meant, but it is easy to spot the inconsistencies.

Could you post a picture of the bow you intend to make?

Mike the best photos online for the profile is on Justin Ma's Cinnabar Bow site, cinnabarbow.com, just google that, then click onto the Mariner Bows, and the Qing Bow #2, its the same overal length of mine.

Mine though composite, these are glass and bamboo. I put some pairs of test splices to soak yesterday, for different gluing tests, Titebond 3, two kinds of hide glue, and smooth-on. All same size and thickness, I will glue them and let each dry a couple of weeks and see how the two commercial glues do after then and the hide glues go for a month.

Meanwhile, I am working on one piece core forms, should have them done this week, and can heat treat each end separately and bend. Boiled or dry heated.

I am aiming for the profile of the Qing #2 bow. At least for the first 3 . I have the horn coming for the first 2 bows from Stivintiger. The forms will have sides for belly and back for putting on the horn then the sinew. Whitetail hind leg sinew from last seasons hunting. Ours and some from friends.

Adams book is a treasure chest of information, I refer back to it continually. I have had some suggestions from a couple bowyer friends who make composite bows also. I am in no hurry on these, I do hope to have one or two far enough along to take to the Chinese Archery workshop in Odom GA next March. For critque, not shooting, I will give then ample time to season as there will be a lot of sinew on them.