Boiling cores or dy heating??

[Jake Levi]

I am preparing a couple of maple cores to soon add horn to, but need to put in the recurve first.

I have used a LOT of dry heat to remove string follow and add reflex, and to recurve self bows that I then sinewed.

I have Adams book and reading and rereading it, great book! But, I have never boiled any bow wood, although I have soaked some. So I am asking the pros and cons of boiling versus dry heating.

I can soak them easily. And then dry heat, just looking for the better ways to go, if there is a better over an alternative method.

These are for two long Manchu style bows, not as severely recurved as a Turkish bow.

[KenH]

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.

[Jake Levi]

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.

[Arry]

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.

[Jake Levi]

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.

[bheggeseth]

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.

[Pat Menzies]

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.

[Jake Levi]

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.

[mikekeswick]

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.

[jkekoni]

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.

[jkekoni]

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.

[bheggeseth]

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.

[bheggeseth]

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.

[Jake Levi]

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.

[bheggeseth]

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.