Primitive Archer
Main Discussion Area => Bows => Topic started by: animus_divinus on February 07, 2011, 05:17:55 pm
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im thinking of building a small, simple apparatus for drying out bowstaves rather than waiting two years... this way i can go select tree limbs of a variety of hardwoods for making my bows...
wood drying kilns generate something around 150-180 degrees of heat... too much and its just a charcoal machine
my idea was to take something like a 7 foot length of tube steel of adequate diameter with an inexpensive heating element running the length of it, a strip of steel mesh could be cut and places inside for the stave to sit on so its not in contact with the element.. and a simple electric themostat can be used to regulate heat... open up one end, slide a stave in, close it, and dehydrate it for a few days
another option would be to lay the tube upright... and inside the cap you could install an electric stove burner element to generate the heat
to make this work, youd need some means for removing the humidity and moisture that evaporates from the log itself... and what size pipe would be neccessary?
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so basically like a hot box?
use a few incandescent light bulbs in a small insulated enclosure and you should get there pretty easily.
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Think about making board bows until your wood is dry. Rough out the stave and floor tiller bending the limbs an inch or so. Place it near a heat source. It will be ready in about a month. Leave the handle full width and the nocks an inch wide for adjustments later. You young'uns sure are in a hurry. :) Jawge
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yeah.. good idea.. ill get like an 8x4 sheet of plywood, cut it into strips, and make a 1x1x8 foot box i can set some bow staves into.. power it with a couple 100w bulbs set up with a potentiometer so i can tune down the voltage, and regulate tempature to the heat i need
i should install hinges and a latch for the top piece... and who knows, maybe when im not drying out bowstaves i could use this to make jerkey in large quantities
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hey... i bet i could line this box with foil... get a couple LED grow lights to go with it and tune the temperature to use it as a hydroponic box for starting seeds for this years garden :-D... i can easily justify the costs now
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Mines a plywood box,with the inside lined with "low-e" foil backed insulation. Three light sockets spaced evenly. wired in hot water thermostat,and thermometer/hydrometer.
Very simple.
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what is the temperature range your hot water thermostat allows you to set the box for?.. and your lights, are those 100w or 60?
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A small fan to move the air around will also speed up the drying process.
David
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Here is one like I built back when i first got started 4yrs ago. It worked pretty well and adding a fan really helped with moving the air. I have enough in the shed thats cured now so I don't need to speed it up anymore but if I did it would get the job done.
http://poorfolkbows.com/hotbox.htm
Hope this helps. Danny
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ill get quarter inch plywood.. cut out 1x1x7 foot piece.. with two 1 foot pieces for the ends... get a single board of insulation, cut and glue them to the inside of the plywood (the plywood makes it a lot more durable so it wont chip or break if it gets hit)... get those cheap $1 light sockets and mount 3 in the top section.. which will be attached to the box with hinges, use a 110-170 degree hot water thermostat turned all the way up
then when im not drying wood i could use a home heating thermostat with LED grow lights and use the box to start my plants for the year too
i have relatives with land that will let me select a few branches that i could use to dry out and make bows... my goal is to make my bows with just a tomahawk to do the shaping, planing, and scraping into shape
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I made my hot box from Bingham instructions to build an unsuccessful glass bow. It has 4 light bulb sockets and a thermostat that maxsout at 168 deg(F). I rarely get it over 100 to 110 deg for drying wood. I controll the temp by unscrewing light bulbs when it gets too hot. I also have a small fan inside which speeds up drying. I put a 1" hole at the top of one end and another at the bottom of the other end for fresh air circulation and a place for any moisture to escape.
A few sheets of foil backed foam board and a roll of duct tape will make a fine hot box...and cheap!
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why do you need to unscrew bulbs if it gets too hot? isnt that the purpose of a thermostat?.. or did you mean a thermometer?
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My thermostat cuts it off at 168deg. That is way to hot for drying wood. Generally 2, 100w bulbs is plenty to get it to 100degs or so. That's all the heat it needs. The fan, circulating the air, probably does as much as the heat.
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aah.. so you dont have an adjustable thermostat then.. all the thermostats i was looking at were adjustable from about 110-170 degrees
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aah.. so you dont have an adjustable thermostat then.. all the thermostats i was looking at were adjustable from about 110-170 degrees
Mind letting me know where you are looking at the adjustable thermostates? I think I would be interested in one of those myself.
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Just my two cents,I'm a hvac plumber 32 years I do a couple self bows a year I can get green wood boards easy what I do is I have a small closet in the basement, and I put a 30 pint 'Dehumidifier' in the closet it's about moisture control i have dried wood in there in a few weeks those units have some kind of control on them and if you get good air circulation you'll have good results I have lot to say but this is my job, and I do well, and take what you want it's not rocket science good luck and it's nice to see your thoughts grow JeffW
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i let my wood cure naturally
any staves i get i leave sit for a year atleast,i got a sweet osage from sawfiler a year ago
he said it was seasoned and ready to be worked
i wont start on that one till the end of this month
but i do have a hot box,its made from that foill backed insulation
has 3 125 watt bulbs,each has their own switch,all of which are also controlled by a rheostat(a light dimmer switch)
i can run one ,two or all three bulbs at one time and adjust the rheostat to controll them
i have had that sucker up to 180* f,and that wasnt even with all thre bulbs crancked up all the way
i built it for glue ups,never even tried to dry a piece of wood in it
i took one of my AC thermometers from work and just poked it right thru the side of the box
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hot water thermostats allow you to adjust temperature for the most part, and theyre not expensive
i wish there were a variety of thermostats available to the hobby market, but unfortunately it seems central heating, water heater, or applicance thermostats is all we can find
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My lowest setting is 90 degrees. I set it there and it will range from 85 to 108.Most of my wood is perty dry before I put it in,so I don't need high temps. ALthough......I have done some serious checking. ::)
I also run a humidity check.20 to 30 % seems to work just fine for my local. Three 100 watt bulbs is plenty of heat.
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i have a 3/4 inch sheet of MDF laying around... need to find something useful for it... would this be suitable for a hot box? or is the heat not going to go well with the chemicals used to bind the MDF?.. i know its nasty stuff to inhale if youre cutting it
second, IF i can use MDF, would it be a suitable insulator as well? i ask these questions because this is what i already have
if not, ill just make a frame with construction grade pine, route a lip around the inside of the frame to cut sections of thin plywood for aesthetics, and then line the interior with the foam insulation which im thinking ill attach with double-back tape
one idea, which seems to be a common one is using light fixtures to hold 100w or 125w bulbs... is this the most efficient way to go?, or would using an inexpensive heating coil, perhaps even the screw in type heating coil a hot water heater uses which is inexpensive, and less energy is used to actually convert into light, so more wattage will go into making heat
also what i plan to do is use one of those dial-face thermometers with the stem... drill a hole into the front of the box, press this thermometer in so i can get an accurate reading on the inside of the box without opening it, and these thermometers are like $5
lastly, reading humidity in the air, tells you what the humidity in the air is, the only accurate way to tell how much has actually been removed from the wood is to weigh it before and after, so one idea i had as maybe a future add-on of this box was to mount a pressure-plate inside, to that would be bolted a light sheet of plywood to match the floor of the box... that way when you put your wood in you can take a reading, calculate what it should weigh when its done, then check the weight periodically until it matches that figure
those are my ideas so far.. and i should mention that i have an otherwise fully equipped woodshop that i use for a variety of tasks, a major use is building musical instruments, so having such detailed control over the wood would be worth the little extra cost to do something like add something to the inside to weigh the wood as it dries
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check this out
http://www.amazon.com/Pound-Capacity-Digital-Shipping-Scale/dp/B000R4HRGO/ref=sr_1_22?ie=UTF8&qid=1297244060&sr=8-22
imagine having that on the bottom of the box.. 1/4 or maybe even 1/8 inch sheet of plywood bolted to the top and the scale is re-zeroed.. then the remote display can be mounted to the outside front of the box with the wire passing through a small hole... and with a 330lb capacity you could dry and measure a lot of staves
and this is the thermometer i mentioned id use, just drill a hole for the stem to fit into the box and leave it mounted outside
http://www.amazon.com/Taylor-Classic-Instant-Read-Pocket-Thermometer/dp/B00004XSC4/ref=sr_1_11?ie=UTF8&qid=1297244257&sr=8-11
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might just be better, and a lot easier to measure the humidity in the box afterall.. when that stops dropping the wood SHOULD be finished.. i guess im just a bit of a perfectionist
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A D now your thinking !!!!! air flow+ low humidity over time= cured wood! wood will loose it's moisture at a certain rate, too fast or hot = checking, . just control the humidity above freezing and you'll have good results, for instance what happens to a slice of baloney in your fridge un wrapped? jerky,,,,, put it in the crisper drawer (where the air movement is restricted ) it last longer! I think you are on to something!! keep at it good job Jeff W
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The secret to having dry wood is to have a stockpile of wood on hand. ::) After a year or two all of your wood is dry and in a few more years it is seasoned.
Wood, left alone will hit an equilibrium with the relative humidity(R/H). The rate(hygroscopic rate) at which wood changes moisture content(M/C) is quite slow. Wood will normally dry at a rate of 1" per year but will stop loosing moisture when it hits that point of equilibrium.
So, once your wood is at equilibrium it is only a few % of M/C that you have to change artificially. I understand your delima. You are relatively new so you don't have a stash of good bow wood...and you really want to build a bow.
With whitewoods you can have a stave ready to build a bow in a month or a little more if properly cared for. This time of year in most of the US the R/H is quite low. Any wood you have stored under shelter will be loosing moisture at it's max rate right now because of the naturally low R/H. Actually, under your bed is a very good place to cure bow wood. Just enough air flow and dry inside air surrounding the stave.
Take the time between now and when your wood is ready to build bows and prep all your staves to floor tiller stage. By the time you have completed your first bow you will have the beginning of a stash of dry bow wood. Try to think more long term when it comes to wood bow building. You can quick dry bow wood in a relatively short time and build a bow with it but once you build a bow with that same wood that is seasoned you will see the difference.
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well.. im quite skilled with woodworking, and using a variety of tools to carve, shape, and manipulate wood.. carving bows certainly isnt out of my range.. all my lumber consists of boards that are either carved into instrument necks, glued together for electric instrument bodies, or sliced up and planed for sides and backs of acoustics...
building the box is easy.. regulating it with a thermostat and heating it with bulbs, or even a screw in element is also easy.. just knowing when ive achieved equillibrium is what i need to determine.. and im just not sure if weighing the wood for moisture loss, or measuring the humidity in the box until it stabilizes is the best way to do that
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if you take a stave and tap the ebd of it ona concrete floor and it makes a ringing type sound
its dry
if it make a dull thud type noise
its still wet ;)
this is actually how i do mine,like i said i let my wood dry/season naturally
hotbox is for glue ups
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I do like Tim. I go by sound and feel. I bought a moisture meter years ago and never used it. I gave it to Justin Snyder so his wood wouldn't get too dry in Utah where he lives. If you build instruments you should be familiar with judging wood by feel and the sound tools make while working. I'm not trying to razz you. It doesn't have to be complicated and IMO shouldn't be complicated.
You can use a moisture meter to check the M/C of your staves or you can weigh your staves every other day until they quit loosing weight and you are at equalibrium.
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if you take a stave and tap the ebd of it ona concrete floor and it makes a ringing type sound
its dry
if it make a dull thud type noise
its still wet ;)
Is it because I'm still wet that I thud when I bounce on the concrete floor? :-\
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Bevan all i can say to that is
DEPENDS :D
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ok.. well, i have what i need then.. i wont use the MDF though since that crap tends to bow often, plywood tends to resist it better so ill make it from that
i plan to start learning how to make bows with hand tools, basic ones like a hand axe to give myself even more of a challenge
anyway, i know a guy willing to trade me a custom instrument for a bunch of osage orange branches i can cut into multiple bowstaves, i might take him up on that