Zugul.
As for heat treatment I would clamp the bow to a form to a slight reflex and slow bake over coals using a pit method. You can achieve very similar results using a heat gun too. I’ve done this myself a number of times in the winter months when my fire pit was covered in snow. I build a stand for my heat gun that positions the gun over top of the belly of the bow about 3-4”. I usually start at the fade of one side and just move the gun along every 4-5 mins on high setting. It may vary in time depending on your gun and heat output. I think mines a dewalt make it it helps. This gets you a deep heat treatment and jay move it along 2” or so. Try a build your gun support to trap most of the heat to the belly and avoid the heat getting around to the back. I go about 4 mins or so check it for depth then move it couple inches and this gives me a cook that goes little over half way thru the limb. I do prefer to use the hot coals method as I can do 4 bows at once and don’t have to move the gun every 4-5 mins. I’ve also done this repeated 2 times on bows with good results if I felt it didn’t go as deep as I liked. I also applied pine pitch while still hot on one of my bow once as demonstrated by Marc St. Louis. He has a good video showing this. I found that It seals and locks in the hydrophobic nature of heat treated white wood. Just food for thought. Here’s a pic of my gun support I used if it helps.
If I'll heat treat it I'm going to go with the heat gun method, and will for sure build a stand for it since it's pretty boring to keep it by hand, ahah. I will also cut some long, very thin wood strips to clamp to the sides of the bow, as "heat shields", in this way the sides and the back of the stave should be fine. I could go for a touch of teflex, between one and two inches if I think the bow is bending very well and I'm feeling brave
. I don't have pine pitch, could some bees wax do the trick?
Wood source?
I have never worked with black locust but I hear it frets easy. Is this stave from the same source as those other bows you "screwed up"? Sometimes you simply hit a bad tree and make staves from it and then they all cause the same problem..
This stave came from a different tree harvested from the same property of the ones that fretted, but it has a very different colour and "texture": the previous ones responded in a very strange way at being scraped or sanded, leaving thread-like fibers when worked upon with a scraper or sandpaper. They had a very light colour and some dark streaks too. I do still have one stave from that tree, but I decided to leave it even if it was already roughed out.
here's a comparison pic of the woods
20221017_173852 by
Mattia Zuccolo, su Flickr
Tillering method.
If you made a few attempts previously and they all fret in similar ways you need to change something in what you are doing.
If there are knots or minor bumps on the back I usually leave the belly flat and let the back compensate with extra thickness. That works with elm at least.
When I am working a stave I really don´t want to mess up, I go very slow. In between rasping and checking the tiller, I sand it or scrape every part of the limbs smooth and make it look like a nice bow at all times. It might sound stupid but it helps me to stay focused and go slow. After floor tillering to a VERY nice bend at what seems like a good draw weight (compare flexing the limbs against the floor with other bows) and sand it I pull it to brace height 20-30 times on a long string and check the reflection in a window. When that is perfect I let it sit braced for a while to see if it takes any set at all. If I go this slow and careful to brace height I usually won´t have much more work to do to get it to full draw. This is really key in my experience, to get it to perfect brace height with no set. Good luck!
In my previous attempts I layed out the front profile, roughed it out, thinned the stave without taking measurements or spending some time feeling with my fingers for a good thickness taper and I just started floor tillering it. Now I reckon only people with a lot of experience can eyeball the thickness taper and get it right from the get go, so mine was an error dictated by inexperience and impatience. I will leave the belly flat through out the tillering process and to be extra safe I won't use rasps or drawknives on the limbs from this point, so I'll take it very slowly to complensate my inexperience. for the tillering method I'm going to use the long string until I reach at least 18" of effective draw, then I'll think about shortening it to brace the bow. for that time I should be able to get the limbs bending evenly, I hope!
Lot of good info from Superdave and Askel. So Ill try and not repeat all they said ... Its not practical for me to heat treat with a fire pit so I have used a heat gun for eavery bl bow I have posted here. I mark the limb off in 6" lenghts. Then work each 6" section for about 5 min to get the color I want, heavier(better) locust maybe a bit longer, lighter wood a bit shorter time. This is about half the time I would do for white woods such as hickory or elm. The color Superdave has is about my goal. My new heat gun has digital settings, so I set it at 850 deg F. Its discussed in older topics but I believe the heat treatment workes deeper than the color change, just my thoughts on that. But you could do that at 24" inches on the tiller. Because you already have tip overlays glued on I'd stay away from the tips about 8" or so to not degrade the glue joint. Just my thoughts if you decided to heat treat.
I think the problem most encounter fretting with bl is because they use dimensions too short or too narrow or both. I think at 68.5"x2" is good for what your after, to be successful. I also try and keep the belly flat as I go when its on the tiller tree. Make yourself a tillering gizmo, helped me alot to find the stiff spots. Although it will not work well around that 1 area your questioning.
Take your time. Sounds like you have learned from your past experiences and are going to make this one work. and best of luck.
Mike
Normally how close to the belly do you get with the heatgun? mine only has 2 settings, 660 F° and 1020 F° so I think I should put it on high and keep it further away then you to get a similar result. I do have a tillering gizmo, but this stave is not as straight as it seems so I'm scared to screw it up if I use it... To help me see the bend I'm using aaron's method, from this topic:
http://www.primitivearcher.com/smf/index.php?topic=36145.0 maybe it won't be as precise, but it should allow me to see a hinge forming way before my untrained eye. in this way I should also be able to monitor set as it developes and avoid scraping those areas too much.
Like any other wood not all Bl is equal. I failed with the first 4 attempts with one Bl log that I cut. Bad wood. Either the back would crack ,or the belly would fret. Last 4 bows was a good thick ringed log, and all were successful bows that are still shooting fine using the same method. I chased a good heart wood ring, and trapped the back. Floor tillered it. Put it on a 4 inch reflex form, and heat treated the belly. Got every thing lined up. Then tillered carefully. I sinew backed a couple as they were 48 to 50 inch horse bows with 25 and 26 inch draw. All the bows were in the 40 to 50 lb range, and from 48 to 62 inches long. That is my limited experience with Bl. Like any other bow it all starts with at least a decent piece of wood. Guys who sale bows on the Primtive forum use primo staves, and the cost goes to the buyer. Good building, and hunting.
in my very limited BL experience, the thick ringed wood I harvested was the bad one, while the thin ringed behaved better! Wood is some strange stuff!
thanks again for all your advice, you guys are awesome!
