Primitive Archer
Main Discussion Area => Bows => Topic started by: Crogacht on April 06, 2014, 08:08:23 pm
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Hi guys,
I'm working on my first bow at the moment, an elm stave. It was cut about 12 years ago, with the bark left on, unsplit. I split it 6 months ago and yesterday I started removing the bark. The bark was still very firmly attached, aside from a small section at one end which peeled off leaving a thin layer of cambium behind.
I've been using a very sharp chisel for the job, just gently with my hands, no hammers or anything. It's working pretty well as I am able to use very little force to make shavings, and can get a lot of control out of it, but I wondered about violating the back of the stave.
I take the bark off, then I hit the cambium layer, which seems to be pretty thick, then I get down to the sapwood. It seems very difficult to take the cambium off without taking off ANY sapwood at all. In places I have gone a little deeper than I would like, but it's VERY minor, maybe 1/16th of an inch as most (I'm being VERY careful.)
When people talk about violating the back, are we talking about going though growth rings, or are we talking about the wood fibres themselves?
If we're talking growth rings, then I'm fine, the rings are quite thick and I'm nowhere remotely near going through a growth ring, but if we're talking cutting through fibres, I've probably cut through some in a couple of places.
How forgiving is a whitewood like elm in this situation with very small wood fibre violations like this? Am I better off trying to go down to the next ring? Like I said the nicks are very very small.
I'm not too worried about "wasting" the wood, more interested in learning what it's got to teach me.
Ben
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If you leave a damp towel over the back of the stave overnight, the cambium will soften up and it'll be much easier to remove, especially if you thin it first. I haven't worked elm personally, but apparently its one of the better woods in taking back violations
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It's hard to say without seeing the piece, but you should be ok. I'm curious about the stave. Was it sealed good and where has it been stored?
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Yeah, I think I would probably take 90% off with the chisel next time and then maybe move to a scraper of some kind.
I cut it when I was about 15, it wasn't sealed and it got put in a woodshed for a decade. It had minor checking on the end, but survived quite well actually, I guess because it was left as a whole log with bark on, and it was relatively small diameter.
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Scrapers are good for that part of working the back down. I would smooth up the nicks with sand paper or a scraper before I started bending the wood.
Since it was not sealed and spent time in a shed, checks and insect invasion might be a problem.
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Thanks,
I think leaving the bark on has mostly saved it. I did have a smaller diameter piece (the top of the tree) which I stripped some bark off not long after it was cut, it checked badly and had insect damage so it went to the firewood pile 6 months ago when I went to split them.
The two pieces were quite a good example of the importance of sealing wood if you decide to strip the bark off while green.
All the staves I have collected recently have all been sealed religiously with white glue and they seem to be drying alright.
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To put it quite blunt: a chisel is not the right tool for removing bark. The tool is not made to do that job, and you don't have so much control. Because it is really sharp, it is also easy to cut through the bark into the sapwood. Myself, I use a sharp drawknife to remove about 75% of the bark. The two handles on the drawknife give me a great deal of control and no possibility for slipping. The remaining 25% of bark is removed with a variety of scrapers. You can vary the amount of pressure you apply on a scraper and thus regulate the amount of bark you remove at once. You can also really feel the wood underneath. The scraper has a lot more difficulty with the wood, while the soft bark and cambium is easily removed with the scraper.
Elm is very forgiving for small nicks in the outermost ring on the back. Don't go through the first ring and make sure you sand the nicks flat before you start bending the wood. Then you'll be fine.
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Yeah, you're right about the chisel :P, I'm still building a decent set of tools though so sometimes I don't have the perfect tool for the job.
I will definitely get some scrapers for that last 25%, seems like they would work really well.
Thanks for the advice, I'll post some pictures at some point.
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Look at flea markets and antique shops for old hand tools. I picked up a vintage mint Boker draw knife from an antique dealer for $5! Also, a good set if scrapers is <$15 new. Ditch the chisel, as advised. There's the right tool for every job...
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Things are a bit different around here, but I'll certainly keep an eye out. We have one secondhand tool shop, so you just have to check back as often as you can.
For example, it's cheaper for me to buy and import a 25kg vice from USA than it is to ship one from another city in my own country :P
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I got a drawknife of trade me, one of the most important tools for bow building. The first couple of bows I made I used a paua ( abalone) knife that my brother made me as a chilsel. That second hand shop in blenheim sometimes has drawknives if your over that way.
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Good advice from DarkSoul,you can use a knife blade/I used a fillet knife for several years when I first started ,worked fine and easy on the wood. :)
Pappy
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When your tool poor, sometimes you just have to make do with what you got. When I first started, an old huntin knife was one of my main tools. One of the best bowyers I ever met only used a hatchet and an old butcher knife from the stave to finished bow. That would be Joe Mattingly. He's gone on to bow heaven, but I'm sure some of the old timers remember him.
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Just looked on Flea-bay, there are over a thousand draw knives listed. You can get a sorry looking one that will do the job for $10 or a really nice one for around $25. I would suggest one with a wider, straight blade about a foot long with handles that are on the same plane as the blade, not tilted up or down.
Here are some examples; From top, my favorite, a huge, heavy, debarking draw knife and my primary tool. Next is a Greenlee, $20 at a flea market, a perfect size and looks like it hasn't been used, third one down a Pine knot, OK but a little thin on the blade, and last a Swedish 8" with a very thin, sharp blade. I don't use this one much but it does have it's applications when working around knot clusters.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/fourdrawknives.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/fourdrawknives.jpg.html)
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If the log was in your wood shed for 10 years, whole, with the bark still on I'd do a bend test to be sure the wood is sound. With the bark left on the log released its moisture very slowly and if you live in a warm, humid climate there is a chance it got infected with fungi which thrives in warm moist environments.
An example...a friend gave me a 12"x6' hickory log that was cut fresh and squared off(still had some bark left on) to be used as a mantle in his new house. It sat protected off the floor in his garage for 2 years then he decided to use another wood for his mantle and gave it to me. I took it to another friend with a portable bandsaw and we spent hours sawing it into backing strips and a few staves. The first piece of backing I used on a bow broke across the grain shortly after bending the bow. While we were sawing the log I noticed the wood wasn't as hard to the touch as I thought it should be. It felt too dry and surface felt "fuzzy". Needles to say I had a years supply of kindling but no good staves or backing strips. :(
I know I always harp on this (fungi etc.) but it should be a consideration on any wood that was not stored properly from the stump.
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Thanks for the advice guys,
The secondhand tool place here is pretty small, has some nice things, but the best stuff goes reaaal fast. I should be able to grab some cheap tools though.
I found a nice looking 10" greenlee on the website, it looks very nice, and only $15 bucks, unfortunately shipping is about $42, haha. It looks real nice though, I'll talk to the boss ;)
Pat B, now you mention it, where the bark had come free (about 4-6 inches at one end) the sapwood has kind of a grey tinge to it, whereas the rest of the sapwood is a creamy yellowish colour, maybe it got a bit of fungus or something in it where it had no bark protection. I guess I can either cut it down (but its already short) or I could go down and attempt to chase a ring.... at least the rings are quite thick on this one :D but I'd definitely need a drawknife for that.
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A good trick is to remove the bark but leave the cambium on.
It has no real strength and will pop off once the bow starts bending on the tiller. OK it will scare the cr4p out of you but you'll have a perfect pristine back.
It also acts like a strain gauge, it will start cracking and popping where there is most bend, thus giving you a timely heads up.
It will still need some bits taking off, but I find an old pallette knife type scraper gets under the loose edge and pops it off.
Final bit of work with scraper or wire wool dampened with white spirit and you have a pristine back.
Del
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I like the sound of that Del. I have 3 other staves from the same log, I might try that technique on those. I still need to pickup a heatgun, as these staves definitely need a bit of straightening before I can even string them up, so I'll probably get all 4 staves to a debarked, "bow-blank" kind of stage while I work on getting a heatgun.
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Sometimes the bark comes off quite easily on Elm that has been stored for a long time. All you need to do is get a sharp instrument in between the wood and the cambium and it comes off in big long strips with just a slight pull. It best to do this from an end
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Well, I picked up a cabinet scraper, a cheap heatgun and managed to buy a decent looking 10inch marples drawknife online, should be making some progress in the very near future!
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Your hooked!!! ;^)
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Hehe I think so ;)
I had a go with the scraper, didn't like it too much, so I grabbed a nice sharp knife from the kitchen to use instead and I like it much better as a scraper, I seem to have much more control around the bumps, knots and dips with it. I might pick up a nicer one at some point, but this will do great for now.
But the stave has a nice smooth clean back now, and I have reduced it down to 2 inches wide with the hatchet.
The stave is only 60 inches, so I think I'll aim for a lowish draw weight and keep it fairly wide.
I REALLY need to post some pics soon lol.
In fact, I'm not even sure I like the workbench/vice setup I've got. It seems a little awkward for the work I've been doing. One of those nifty shaving horse/bow bench things that you sit on seems to make much more sense now... I'll give it a while yet, but I may sell what I've got and build one of those instead. Seems like it would be pretty sweet for the drawknife/scraper etc.