Wood drying ovens

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simso
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Wood drying ovens

Post by simso » Sun Mar 23, 2014 5:13 pm

Does anyone have there own wood dryer / kiln etc

Need to accelerate my drying times from air drying of months to maybe days or even hrs if possible
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Crafty Fox
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Re: Wood drying ovens

Post by Crafty Fox » Sun Mar 23, 2014 7:44 pm

How about building a solar kiln?
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Kim
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Re: Wood drying ovens

Post by Kim » Sun Mar 23, 2014 7:48 pm

Resaw your wood into back and side sets while it's still 'wet'. Then sticker it out in a press with 19mm sticks running an oscillating fan on low over the stacks. At first you need to unpack the stacks to move and rotate the stickers every couple of days to prevent mold growing between them and the wood below. But they do dry out pretty fast that way.
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Re: Wood drying ovens

Post by simso » Sun Mar 23, 2014 8:37 pm

Thanks Kim, not for guitar wood, but would come in handy

It's for solid cored tree trunks for drum shells, and 2inch square lengths of Aussie woods thinned out to make clarinets flutes and recorders, enterprise I'm embarking on at the moment

Solar. Kiln sounds good, any info

Thanks

Steve
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auscab
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Re: Wood drying ovens

Post by auscab » Sun Mar 23, 2014 9:17 pm

I was down in Geelong a few months back , I was picking up a mortiser off a nice married couple who had got rid of there staff , closed the doors and stopped dealing with the public ,and only quoted commercial work doing big winery fit outs of doors and Tables using second hand wood. All very impressive .

The Owner had a 20 ft shipping container hooked up to a household wood fired heater that ran off the wood offcuts from the work shop, he loaded it up and ran it for three or four weeks with the warm air circulating through it to get the moisture content down and was telling me how good it worked . I'm pretty sure he got the info to build it off the internet . I'm not sure where though . I can ask him about it if I can find his contact details and let you know.

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simso
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Re: Wood drying ovens

Post by simso » Sun Mar 23, 2014 9:33 pm

Thanks rob,

My goal is small scale stuff, doing a lot of reading at the moment on the topic

Would like inside to be 600 by 600 by a metre high,

Allows 3 drum shells at a time, and room for small long bits

Steve
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auscab
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Re: Wood drying ovens

Post by auscab » Sun Mar 23, 2014 9:36 pm

I did a little search , plenty here on solar and wood fired drying.

Your sizes sound close to a 44 gallon drum .

http://www.woodweb.com/KnowledgeBase/KB ... ction.html


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Re: Wood drying ovens

Post by tippie53 » Sun Mar 23, 2014 11:45 pm

Drying wood takes time. I can tell you from running a wood kiln it takes about 30 days to run a cycle.
The first part to drying is not to do it too fast , you can cause a lot of cracking and warping. Some kilns use a steam process to get the wood wet , then slowing remove the water.
The kilns we used were solar and oil heated. Both worked on the same basic principal , first you stack the wood for good air flow and a dehumidifier started once the air pulled the moisture down out of the wood to about 18%. This took about 5 to7 days. Once the dehumidifiers kicked in , they pulled the moisture down to 15% and then the heat kicked in. All this time there was forced air on the wood. The heat started up and took the temp up to about 95% in 3 days. Then it went up to 110 and held that till the wood was tested at under 8% and over 6%. This was for cabinet grade , if we did pattern grade we took it down to 6%.
once we hit the mark we held it there for 3 days and allowed a 2 day cool down cycle.

Don't think you can dry wood in a few hours. Even thin wood under 1/8 in will take about a week to dry and longer than that just to stabilize. The more stable you make it the better off you are.
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curly
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Re: Wood drying ovens

Post by curly » Mon Mar 24, 2014 8:58 pm

As commercial sawmillers we use the full range of technologies available , including gas fired , RH controlled kilns . Our own gas kilns have been decommissioned as not economical to run and maintain so we simply contract dry stock we need to get done quick . We have paid anywhere from $80 to $500 a cube for the service . The real issue is that high temperatures are not appropriate for many final applications , for instance we have experienced higher breakages of sides off high temperature kiln dried stock .

My own preference , and the system we use for all final drying of high value stock is a coupling of low heat (max 35 degrees or so ) from whatever source you prefer , air movement and dehumidification . I have dried a good amount of high density timbers for woodwind spindles this way with no degrade to speak of , and this is how we dry all our acoustic timbers . We always prefer where time permits , to air dry to fibre saturation point first . The real key is to match drying conditions to the species and it's moisture content . That is a whole art unto itself ! This is where the movement statistics you find in good guides such as Bootle find their true relevance , the higher the numbers , the more difficult to dry . Basically . The numbers mean nothing in how long they will take to dry , just how much they will move . Incidentally plenty of timbers that are hard to dry are very stable in service as is evidenced by the fact that R and T movement statistics are often totally different to unit shrinkage stats for the same species .

In a box as small as is being suggested I would recommend an electric blanket for heat , two flat household fans (placed so that air flow runs between the stickers ) and a dehumidifier inside the box with it's drain tube running outside . For these type kilns we build on a custom heavy pallet base so it can be forked around with the box itself built out of coolroom panel . They are cheap as to make , cheap to run and you can customise the drying conditions to suit the charge . One of our little boxes like this just dried Gidgee fingerboards from wet to 8% in 3 weeks , zero drying degrade . That is stunningly fast for such high density stock .

All the best
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simso
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Re: Wood drying ovens

Post by simso » Mon Mar 24, 2014 9:48 pm

I buy a lot of stuff from china, because simply I cannot make it as cheap as they can or more importantly do not have the time to setup a machine / jig or process.

So china suppliers got back to me today, they can supply me to my door in 3 weeks one of the following, also the inside of the dryer is big enough to hang a guitar inside (may be handy for repairs)

Machine one, humidity controlled cabinet 1-20 percent relative 40 watts an hr power consumption

or

Machine two, humidity controlled cabinet 20-60 percent relative, 20 watts an hr power consumption

Both cabinets can display the temperature but are not temperature controlled.

or if I get a temperature controlled unit, the price triples, so I am thinking maybe I could rig up some heat lamps inside or just light globes to warm the air up for drying

I like the 20-60 percent unit because I can use that for rehumidifyng guitars in a controlled environment, we are always rehumidifying guitars 2-5 a week in an uncontrolled environment at the momment just via tricks of the trade, but would it be suitable for removing moisture from the rough machined wood. ??, or should I go the 1-20 percent unit
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Re: Wood drying ovens

Post by tippie53 » Tue Mar 25, 2014 9:53 pm

For a small unit you can make what gunsmiths use here in the states. Old chest freezers work well as they seal tight , are insulated and you can control the inside environment.
You need to control air flow , RH and temp. They use dessicant beads. ( Salt will also work ) a small fan and a light bulb. The salt absorbs the water in the air , the small fan circulates the air to pull the water off the wood , the light bulb supplies the heat. You can experiment a bit till you find a process .
http://dnr.wi.gov/topic/ForestBusinesses/kiln.html
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simso
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Re: Wood drying ovens

Post by simso » Sat Mar 29, 2014 9:40 pm

Thanks everyone for the replys

One of the issues with commercial business with employees is work safe Australia, so everything has to be built to a code and wired to a code.

So for this reason I bought a medium humidity cabinet from overseas, it's big enough to hold a guitar and controls humidity between 20-60 percent dependant on what you select

I just have to be able to raise the heat in the cabinet, so hoping when it arrives, that I'll just be able to fit some heat bulbs to achieve this, fingers crossed

But thanks to all the comments

Steve
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simso
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Re: Wood drying ovens

Post by simso » Fri May 09, 2014 7:37 pm

Newest arrival, Humidity controlled enviroment, put a guitar in for a test run, I just need to put a heating circuit in, Im guessing a light bulb controlled by a temp control unit

Then it can become a small style dryer for tree trunks for making drum shells and hopefully clarinets
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Steve
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