Primitive Archer
Main Discussion Area => Bows => Topic started by: Mac43560 on April 12, 2016, 02:54:10 pm
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I have an osage stave I acquired that was cut from stump to stave last month and I checked my MC and the machine said 13%. My spider sense tingled so I measured it and weighed it and my rough calculations were way different. So I need an upgrade/ replace my moisture meter as I can't trust this one anymore. What kind do you all use? What's my price range for some dependability?
I still going to measure it the hard way when I can but I don't always have the luxury.
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I don't use a moisture meter any more(I gave it away) but I don't build bows from wood that hasn't been off the stump for at least a year, preferably more.
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I bought a $10 kitchen scale. Weight it every day or so until it stops losing weight.
http://www.csgnetwork.com/emctablecalc.html is handy.
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I am also experimenting with drying staves in months instead of years without heat by manipulating the RH with a dehumidifier only during moisture recovery periods like night time. The way I see it, at least 8 hours a night the RH is too high to have a suitable equilibrium MC. That's a third of a year. Plus if your climate is like mine, two months out of the year it rains too much to lower the EMC. It might raise the MC. By manipulating RH during those times alone just to what's normal on average, I figure that's five months less for every year.
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Build a box and put a lightbulb in it but be careful if you try to dry too fast it'll check. The moisture can only move through the wood so fast and each wood is different. You would be better off using this time to collect wood. By the time you have a stave ready to work you will have a stockpile of wood that is drying faster than you're using it. Then the drying time is a non-issue. Getting past the first few is tough. My first ones took too much set because they weren't dry. I just looked in my warm box yesterday and there are at least ten staves in there ready to go. All I have to do now is collect a new stave for every bow I make and I will always have a stave ready to go. I also have a few extra for giving to people that can't wait to get going :) :)
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Sounds about right for a surface reading, Mac.
Keep checking the belly wood as you work the stave into a bow.
Stop when you get a reading above 10% and let it "dry".
Be sure you seal the back of the bow, which to my mind should be heartwood, to prevent drying cracks.
I use the Mini Ligno.
Jawge
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Weigh your staves. When they stop losing weight for at least a week or so they are good to go.
A scale doesn't lie, a moisture meter isn't telling you the whole story.
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Thanks George. I'll keep weighing and shop around for the meter. I just don't want to use heat over normal Temps. Using my dehumidifier and kestrel I can keep the EMC constant instead of constantly chasing it.
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I stopped using my moisture meter, likewise, and just weigh it every day on a digital gram scale, and pencil the date and reading on the belly side. Pretty simple, and always works for me -- unlike the moisture meter.
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I have a humidifier to keep the moisture content up to a level that I don't fear it will explode on me. According to the charts, I would be sitting at 6-7% max moisture content if I don't try to add water. Anyone have some hickory you want to send me? >:D
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I have one I bought for $30 at the local box store.
Its see a lot of use and works well till it drops close to 5% that low it won't pick up anymore.
I have some staves 3 years old that will read 13% once I open them up. I just don't bend them till until checking moister.
It's always near by and I keep checking any time I work on one or before shooting sometimes. I consider mine to be as handy as a shop rag.
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you can weigh your stave, but if the relative humidity is too high, it still may have too much moisture to make a good bow,, and would need to be placed in a dryer location,, and the opposite as well, if the relative humidity where the stave is stored is way to low,, the bow could break,, so a moisture meter can help in that way,, I had a bow explode this winter, I had it in a heated room,, of course it was not loosing any weight, but the moisture content of the bow was 6% or lower,, my meter will only go that low,, so my moisture meter gave me a clue not to keep bows in that room,, :) it is not a necessary tool for sure,, but at times can be very helpful,, when you are roughing out a stave, the meter will give you a clue as to if the bow might check or not,, etc etc etc,,
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Moisture meter are notoriously inaccurate. Look at the price range available...why do the expensive ones cost so much? Also we need to know what the wood is doing in its center not the surface.
Feel will get you there. I only need to take a few shavings now to get a good idea on mc.
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RH being kept low will only get you so far, I kept the kiln the other day at 140 Fahrenheit and an RH of 15 that's with fans on em too and 2 out of 7 samples lost no moisture and the others lost 1% at most. Granted i was down to 7-10%, on the lower ones but it's just hard for me to imagine it fluctuating within a piece of wood very quickly with out some significant heat and humidity both being involved
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Yeah I have no delusions about that last 5% of the moisture leaving the wood quickly or easily. But the bulk of it, you'd be surprised. Around half the wood moisture is unbound in the wood anyway. It's how nature cures wood and if you live out west, it does it exceptionally even in places with temperate climate and temperatures. And that's with diurnal changes in RH and some overnight recovery. But I am taking weeks not days.
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I feel ya man, I have to make effort to keep the bulk of it from leaving too quickly, once you are down past 20 though it becomes tricky, obviously varying with species of tree. Although.. You are using a surface moisture meter so breathing heavily on it probably changes the apparent mc
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if you are roughing out a stave you have access to wood under the surface,, sometimes cutting off a belly cut etc, you can get a good idea what the wood is going inside, when I lived in Tenn and Texas, moisture content was difficult to manage, the moisture meter helped, I live in New Mexico now,, I hardly ever use the meter,, unless I am curious about that state a new stave is in,, I am not advocating using one,, many bows for 1000,s of years made with out one,,,, i found it useful in the humid climates,,
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I quit using my moisture meter. I have to make bows from green staves a lot more often than I really care to. I usually rough them out green then let them air dry for a couple of months and then put them in a hot car for several days before I really start bending. If the bow has a lot of mass weight but a relativley low draw weight compared to its mass it is a good indicator that moisture is high. If I have a bow close to target mass weight and the draw weight is where I want it at that stage I feel like I am good to go.
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Steve do you ever have problems with your staves checking when you put them in a hot car?
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Aaron, I don't have problems with osage. Woods like Elm, plum and quite a few others I slow dry over a longer period. With osage I usually rough it out once the stave has set for about 2 months. From that point on I have not had trouble with checking. I only use the hot car when I am down abut 12% or so I am guessing. The roughed out stave has usually sat in my house for about 2 months by that time.
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I think it depends on what wood you are using. for osage, yeah, it might not be necessary to have a meter but I work with hickory a lot and for me, its a necessity. using a scale means nothing for hickory. its weight loss could stabilize and the wood will still be at 12% which is way to high for hickory. Hickory needs to be under %8 preferably 6% and in my opinion, you need a meter for that. I have had guys tell me they could tell by listening to the 'ping' sound when they drop it on concrete...maybe with osage but not with hickory. I've had hickory bow blanks sit outside my box for a day and gain %6 moisture reading. you wouldn't be able to tell that from a kitchen scale. But like I said earlier this is for hickory and not for all bow woods.
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Thats one of the reasons I quit working with hickory, I have a similar issue but not as bad with elm. I don't like to have to worry about maintaining a RH, If I lived in a drier climate I would likley use hickory a lot more often.
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You guys are just stubborn. :)
I don't have trouble with any wood as long as I have my trusty not so dusty moisture meter.
I just keep using to several inches before full draw.
You can't beat it.
Jawge
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Build a box and put a lightbulb in it but be careful if you try to dry too fast it'll check. The moisture can only move through the wood so fast and each wood is different. You would be better off using this time to collect wood. By the time you have a stave ready to work you will have a stockpile of wood that is drying faster than you're using it. Then the drying time is a non-issue. Getting past the first few is tough. My first ones took too much set because they weren't dry. I just looked in my warm box yesterday and there are at least ten staves in there ready to go. All I have to do now is collect a new stave for every bow I make and I will always have a stave ready to go. I also have a few extra for giving to people that can't wait to get going :) :)
What temps do you have in the box, have u any fans ?
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My box is in my one of my workbenches. The box on the end(picture) is a heating tube with a 4" computer fan between the two(Black arrow). There is a 300 watt incandescent bulb in the tube(Red arrow). The bulb and fan are controlled by a humidistat set at 50-55% RH. I also have an old waterbed heater in the bottom of the box to make sure the temp stays around 70 degrees. It's not a hot box it's a warm box. I keep about 10-15 staves in it to make sure that I always have a stave ready.
Excuse the wiring :-[
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What is the gadget with the little white roller on top??
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Nice!
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My box is in my one of my workbenches. The box on the end(picture) is a heating tube with a 4" computer fan between the two(Black arrow). There is a 300 watt incandescent bulb in the tube(Red arrow). The bulb and fan are controlled by a humidistat set at 50-55% RH. I also have an old waterbed heater in the bottom of the box to make sure the temp stays around 70 degrees. It's not a hot box it's a warm box. I keep about 10-15 staves in it to make sure that I always have a stave ready.
Excuse the wiring :-[
Realy nice build, need some like it as my storage is too damp:(. Have u tried without any heating, using only gentle breeze?
/Jonas
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Badger, that's half of my recurve stringer(the other half is the same :D). I got tired of fighting with a bracing string when tillering the ends of a recurve. This gadjet makes it easy(er).
Freke A gentle breeze would speed the drying a bit but it wouldn't lower the RH. So the EMC wouldn't be any different than if you just stood the stave in the corner. If your spot is too moist you need the heat to lower the RH. 70 degrees@ 50-55RH will give you roughly 10% MC. With no heat around here (average RH 70-100%) the best I could hope for would be 13-14% MC. A recipe for set. I store my staves outside, under cover and open to the wind for minimum 6 months for yew and maple and the like and a year for Ocean Spray. Then I put a selected few in the box and start weighing daily. Even when the weight stabilizes they should stay in there for a couple of weeks. When they have "stabilized" I can still see the weight go up and down daily as the RH changes. Going from a nice couple of days to rain a 600 gram stave will change 5-10 grams. This is with a $10(on sale) kitchen scale. Canadian Tire if you're a Canuck. All this time waiting becomes a non-issue once you get a store of wood built up.
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I quit using my moisture meter. I have to make bows from green staves a lot more often than I really care to. I usually rough them out green then let them air dry for a couple of months and then put them in a hot car for several days before I really start bending. If the bow has a lot of mass weight but a relativley low draw weight compared to its mass it is a good indicator that moisture is high. If I have a bow close to target mass weight and the draw weight is where I want it at that stage I feel like I am good to go.
I have cut thousands of board feet of wood, sanded it, planed it, drilled it what have you. When I feel that a piece of wood it is ready to work I cut a chunk off and roll the sawdust between my fingers, if it makes nasty clumps its to damp. Its works for me. :)