# DIY Kiln Drying Wood



## Dehn0045 (Dec 22, 2017)

My project list usually has quite a bit of turnover, so I'm not sure this idea will ever find it's way into reality, but I'm really intrigued by kilns for drying wood.  I considered a solar kiln, but don't really make big projects often and a small solar kiln may be difficult to control.  Then I found the insulated cabinet type, using a light bulb as heat.  This would obviously be easier to control and probably big enough for my needs.  Then I stumbled upon the vacuum kiln, now that looks neat.  The speed of drying looks awesome, less than a week.  Also, since the drying is done at or near ambient temperature the result is less cracking and more stable woods.  Obviously this would be good for burls and difficult to dry stuff.  I found a book that is basically a plan for a hobbyist DIY version, looks pretty neat.  Anyway, do any of y'all have experience with either a vacuum kiln or one of the heated cabinet style kilns?  I am looking to up my game a bit with stabilization, but figured I should get drying right first...  Any nuggets of wisdom will be appreciated.


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## Wildman (Dec 22, 2017)

Light bulb versus DIY vaccuum kiln, I would go with the light bulb kiln.  

Light bulb kilns only require a box, light bulb (heat source) and either natural circulation or simple fan.  

Vacuum kilns, require much more expense to build and operate, and technical knowledge required.  Lot of good information online so do check into it before deciding. 

Neither light bulb nor vaccum kiln is a set it and forget it proposition.  While both will exceed at drying pen blanks,  when move into thicker wood different story.  When talking about bowls and hollow forms your talking rought turned items, not just sticking parts of a tree in a the kiln.

Tried to find DIY You Tube video but all I found were small commercial units. You may have better luck than I did.

Vacuum Kiln or Atomic Bomb -- You Decide: 8 Steps (with Pictures)
Vacuum Kiln Drying - Vacuum Kiln Drying for Woodworkers -- How to build and use a vacuum kiln for drying wood

Here is the basic idea behind a light bulb kiln.  We have had guys here use different boxes like beer coolers computer fan and light bulb, to all kinds of old appliances, and assorted boxes. 

https://www.youtube.com/watch?v=u-vpg1iyB4c

To get basic principle on drying wood various chapters of this reference will get you started.  

https://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p


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## Talltim (Dec 22, 2017)

Would like to see pics of other’s kilns. I have been pondering making one as well.


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## leehljp (Dec 22, 2017)

This is a good thread! Like it.

1. Bill, what is your recommendation for bowl blank wood? I don't like the "year in the attic" time line but accept it.

2. the vacuum tank looks interesting and simple enough. I have built more complicated things through the years! (I built my own stereo amplifiers and radios in the 60's and '70's from schematics only.) I also have access to large PVC pieces from the local town.

Now if I can only get the time. Looks like maybe a late next year project for me.


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## Dehn0045 (Dec 22, 2017)

Thanks for your input Bill.  Great links, thanks for passing them along.  My most pressing concern is that since I’m in Houston and EMC is probably in the neighborhood of 13%, I worry that if I don’t dry blanks out prior to stabilization I’ll have troubles.  I have done the microwave trick, but the extremely high temperatures worry me a little, especially with the higher density oily woods (only a concern for drying, not stabilization).  This morning I had an epiphany, why not use a food dehydrator?  This would probably be too fast for freshly cut wood, but just zapping stuff that is already at EMC it might not be too aggressive.  I still like the idea of vacuum drying, but maybe that is something I’ll tackle when I have more time, money and space.


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## MRDucks2 (Dec 22, 2017)

I am early in consideration of an electric smoker. You can get stable control, low heat,ventilation and moisture control. Those things are now badly priced. 


Sent from my iPhone using Penturners.org mobile app


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## JPW062 (Dec 22, 2017)

Don't waste energy heating a closed box.

An electric food dehydrator is not cheap to run and bleeds a ton of heat.  My wife and I only run ours when is is frigid outside to supplement the heat as we dry.


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## Wildman (Dec 23, 2017)

Folks please forget the 1” per year to dry wood that is nonsense.  That so called rule of thumb only good for some pines but not all.  

Hank Lee, can only tell you what works for me and where I live.  Harvest my own wood for turning, for bowl blanks simply rough turn store them on floor back of my  unheated or air condition shop.  I shoot for a uniform thickness which does vary by size & design of bowl rough turning.  Normally those blanks ready to go in two to six months but may not get to all of them in one year.   I shoot for uniform ¼” thickness on hollow forms which just started turning couple years ago.  This long leaf pine lamp developed developped couple cracks at the base which filled.  Can only see one of those on bottom lower right.  

Another Pine Lamp - by Wildwood @ LumberJocks.com ~ woodworking community

This pine vase has pith crack on one side but not the other. 

Pine Vase - by Wildwood @ LumberJocks.com ~ woodworking community

Did live in Mc Comb and Jackson for brief period so no expert on weather or relative humidty there.  My introduction to weather in MC Comb was a “Tornato,” back in mid 1970’s.  While loved MS and many fine folks I met, had to leave or be fired for non-productivity.  Mobile Al, was my salvation on that tour of duty. 

At one time there were many great articles on light bulb kilns on the internet sadly not as many today.  Met a man at a turning symposium in Stateville NC in early 1990’s that built one and got an outstanding class on how to build and operate one. 

Nice article: Please pay attention when Cindy tells just because wood has been cycled thru a kiln doesn’t mean will stay at same MC. 

http://www.cindydrozda.com/handouts_Pdfs/handouts/demo handouts/drying_kiln.pdf

different aproach:
https://www.youtube.com/watch?v=jNKlD6fTPVI

Cardboard box kiln. Listen to what gentleman says about heat.  
https://www.youtube.com/watch?v=KYogSkXQgEw

Do I see vacuum kilns as a viable solution to drying wood?  Yes I do for those folks that have the skills, money, and not afraid to fail and give it a try.


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## Herb G (Dec 23, 2017)

FWIW, I saw a show on TV where a guy made chairs. All kinds of chairs.
He had a drying oven made from 2" thick foil faced foam board.
He dried out his rungs and spindles in it using a 60 watt light bulb.
It was plain & simple, but it worked well for him.


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## JPW062 (Dec 23, 2017)

I wrote heating, but meant lighting in my post above.


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## tonylumps (Dec 24, 2017)

An old undercounter Refrigerator.A 60 or 100 Watt bulb Keep the door cracked open about 1\2 " Works great .And also kept my Welding rods dry.I got the Fridge out of the trash


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## tonylumps (Dec 24, 2017)

An old under counter Fridge from the trash .A 60 Or 100 Watt bulb .Keep The Door open 1\2".Works Good And Keeps my welding Rods Dry  Tip .Do Not Use led Bulbs LOL


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## tonylumps (Dec 24, 2017)

Double post sorry


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## Wildman (Dec 25, 2017)

If you buy your wood to turn, and not sure of MC, a small incandescent  light bulb kiln will serve you well.  Components entirely up to you concerning size, vent, racks, light bulb wattage, size fan,  and timers if desired.  You don’t really need much heat just want cycle of heat and air circulations.  If took a look at DIY solar & commercial kiln’s operation in Wood Handbook or other references will see need to operate a kiln in on & off cycles.  Well your cycling schedule entirely up to you.  Procastanation has kept me from building one for years!  Besides have had pretty good luck air drying and turning thin bowls, which don’t turn any more.

Monitoring results probably easier with a scale and weighing items before and after you determined a decent period of time.  Yes moisture meters will also get you in the ball park too. 

Food dehydrator look interesting some come with digital temperture settings other come with adjustable temperture thermostats and timers.  Could not find any with lower temperature setting less than 90 degrees. Unless did a lot of food items would not buy one to try but I am sure other turners have tried. I tried microwave and pretty much gave up on that idea.

Still like to read more about vacuum driers not sure that useful if buy or harvest small quanities of wood.  Know both carvers and woodturners have been kicking around the idea since early 2000’s. 

Once undertand few basics of drying wood pretty easy to find which method is for you.  Wood dries from the outside in!  Drying wood simply a water removal process thru evaporation.  You don’t want to stop this, just slow it down a little.  Wood shrinks a it dries, but will always contain some moisture even after turning and fnishing.


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