Small Kiln for Turning Blanks

First advice - don't dry blanks unless you're talking about pen blanks. The vagaries of thickness versus length of turning pieces are a tough nut to crack. Rough turnings of things like containers - my word to encompass plates, bowls and "forms" of all sorts - can benefit.

Second, all you need is something large enough to hold your materials which is relatively air-tight. I used an old FM transmitter box back in the days when I thought there was some sort of magic in drying wood. About the size of a closet, made of the cheapest 1/4 plywood and spruce 1x3. Nice pallet underneath, though.

Third, think humidistat. You'll get some "rule of thumb" advice from those who just warmed the air with light bulbs inside old refrigerators, but it isn't going to be anything you can duplicate with assurance. Water removal by humidity reduction, and control of drying degrade by keeping a schedule of RH reduction is the way things have been done for a long time. Best place to start all this is at

where searches for kiln construction and schedules will come up with all kinds of things. Now, given that about a 1" thick bowl will reach equilibrium with its surroundings in a couple months, tops, what's your hurry?

Check out this guys homemade kiln. The web address keeps changing, but I have followed it for a couple of years. I am going to build one asap (I.E. in the next three to five years :-). I have some of the matierial already laid back in the barn. Good Luck Lyndell P.S. I strongly recommend you read William H. Brown's Conversion & Seasoning of Wood and take a look at Ron Kent & Leif O. Thorvaldson's info on using liquid dishwashing detergent to prevent cracking at

I am interested in their technique.........but they say use kirkland LDD ( costco's house brand) but my closest costco is 2 hours away oneway plus $45 membership which will never get used. I also am exploring options. Word is not yet in as to whether or not other brands of LDD will. I wore out google and yahoo trying to establish who make kirkland and what it has in it. No luck so far.

Greg I built my Small Kiln about 5 years ago and it is in constant use and I hope to add details to my hints and tips section of my Web Site in the future.

I built it under my Bench by forming a box which I then lined with Polystyrene Insulation faced with Hardboard covered in Aluminium Foil [Kitchen Type will prevent moisture penetrating through wall of Kiln] made sure that all joints are Vapour Sealed [Important] by using Good Quality Waterproof Sealant Mastic.

Formed a small Duct across the top with an opening at each end, at one end I fitted a small Fan [Ex-A/C Unit] and then used a 80 Watt Tube Heater upstream of the Fan.

Fit a drain to allow Water to run away.

Door is a Insulated Plug Door that Bolts onto the Front of the Kiln again lined with the Foil and a Rubber Gasket to form a Seal.

Fitted a Thermostat to switch the Heater on/off.

Start the process at 35°C for 1 month then 40°C for next month and then upto

45°C for final month.

Purists will say this is all wrong.

But I have now had something like 20 loads [upto 100 mixed Blanks] go through the Kiln and I always have mixed Timber and mixed Sizes from Small Blanks upto much larger bits at 14" x 14" x 4" and Logs.

I have dried and eventually Turned successfully:-

Oak Cherry Beech Ash Holly Burr Oak Laburnum Yew Beech Spalted Beech Walnut Pear Apple Horse Chestnut Eucalyptus Elm Maple Plus others I cant remember.

I would say success rate is about 90/95% but what the heck it is nearly always free wood.

It took me along time to get round to building this because all the Myth's put about on drying timber, which I'm sure are true if you wish to Dry Furniture Quality Planks by the Ton?

But when I got my first Free Tree [A Pear Tree of about 30ft³] I thought it was about time I tried my luck and I have never regretted it.

Have ago it is not that difficult.

Lyndell, Thanks for the references. I don't have any problem with cracking, because most of what I work with is English Walnut trunk wood and Black Walnut root burl and I have learned how to prepare the wood properly for air drying before and after roughing out. I do roughout a limited number of pieces, but store most until I (or someone else) may decide what they want to be.

The only wood I have experience with and have found challenging to keep together is Apricot. I do rough turn it and love it. I have tried the LDD process on Apricot over a period of a couple of years and many pieces some in the pot and some cured more conventionally. I have noticed no difference in results with this wood. Results may vary with other types of wood, and I know there is a group of believers out there in this process. So, it undoubtedly has some merit, at least for them. I have also used PEG with good results, but it is a long process and one that has consequences I choose to avoid.

Our rule of thumb here in the desert (Albuquerque, NM) for air drying most hardwoods to EMC is one inch per year plus a year. Tracking the change in weight tends to confirm that this is a pretty good guide for this climate, at least for the wood I get. I'm just interested in reducing this time to reduce storage space. Thanks again for the references.

Greg

Richard, I was hoping to hear from a few folks with actual experience rather than just those with opinions and thoughts. Thanks for this information and I'll try to check your site in the future for additional tips and tricks.

Greg

Well, that rule of thumb is for planks drying in outdoors New England. Also assumes spring saw. Winter produces no drying. FPL experimental data shows a summer's dry as adequate for most domestics. My rule of reality in Michigan is to take 4/4 planks of local hardwoods (hard maple, cherry, birch) sawed in June after the crops are in, sticker and stack for the summer. Bring indoors in October when the nights get cold. Sticker, stack in basement, and by January the stuff's at 6% by meter and oven dry.

Of course, you're not drying planks, and end grain dries at 10-15 times the rate of face grain. Scientific and valid. That's the bad news. With solid pieces short relative to their thickness, accommodating the drying schedule to the end grain while waiting out the slower lateral (inverse square rule) transfer from cell to cell takes special effort. It's the good news when you speak of roughed containers with any depth, because no place is more than an inch or so from open air through end grain.

Greg, as an alternative, have you looked a microwaving the blanks (one at a time). The reading I done suggests that it works well, the usual warning of not rushing (ie setting the wood on firre). I'm going to try it, once I have some wet wood.

George, And your point is...? I am happy for you that you know how to dry 4/4 planks of local hardwoods in Michigan. I'm also impressed that you know where the rule of thumb some of us here use came from. And as I mentioned, it tends to correlate well with observed weight loss in my circumstances. I should probably acknowledge that the blanks I cut from English tend to range from 12 inches square by 4" thick to 20" square x 4" thick. The Black Walnut burl varies in dimensions up to 12" x 12" x 20" and I can cut it much larger if I choose to.

But if you re-read my original post, I was seeking information from those with experience with small kilns on materials and operating conditions. Perhaps the other information you have provided will be of interest to other readers, but for me it is OT. Nevertheless, thanks for your effort.

Ralph, Yes I have used my microwave for small pieces on occasions, but most of my stuff is too large to fit in my kitchen unit. Thanks for your thoughts.

Greg

Lyndell Thompson wrote: > ...

I've heard that Kirkland is mainly water. I use SunLight (stick with Yellow, not Green) but have used other cheep store brands before. They all seem very concentrated - since I have not tried Kirkland I can't compare, but they all seem to work, at concentrations about 1 or 2 bottles for one 6-gallon bucket (maybe 4 gallons of water).

mike

Thanks Mike I will give it a shot. You use all the other methods mentioned I suppose? TIA Lyndell

They must be large... my old kitchen unit (which is what I will use) would handle a 20 by 12 by 8 inch block. But then it's a ~25 year old unit and the old microwave's were much bigger then the current units

I've used both, and there is also no difference. Kirkland tends to separate more, but a good shake takes care of that

As one who has made it a tenet his personal religion to avoid Costco, Home Depot, and other behemoths of retail, I have had very good success with Sunlight brand -- yellow as Mike recommended.

:-o

I just pulled a small Filbert (Hazelnut) bowl out of the "soup" after forgetting about it since January of '03. Wiped it off and set it on the shelf to "off-gas". The thing certainly feels dry - weight wise - after only a couple weeks. It also doesn't appear to have distorted anywhere near as much as the other Filbert bowls I made back in '03 from the same wood haul. I lost probably 80-90% of the other pieces due to major cracking while brown bagging them for 6 months or so in my basement.

(I know how to brown bag and usually have excellent results with the other woods I use like Black Walnut, Big Leaf Maple and the like.)

BTW, that bright sunny yellow Sunlight dish soap is now a motor oil colored witches brew.

I've not turned apricot but love it whenever I get ahold of some plum. About the only way I've been successful with plum is by boiling. Some folks have commented that the color of their plum has diminished markedly over a short time, but my boiled pieces appear as gorgeous as they did years ago. (They are in an interior bookcase and not subject to direct sunlight, so maybe that is a major factor compared to the folks offering their comments. I believe some of it tho is a factor of boiling.)

AAMOF, here's a pic of one of them:

Put in a pot of cold tap water, bring the heat up, let sit in a roiling boil for at least an hour, cut the heat and allow to cool in the water. Then wipe dry and air dry for an hour or so and paper bag for several weeks to two months. Haven't lost one yet doing it this way.

That if you start with poor information, your outcome is likely to be the same. The inch per year is folklore, and your invocation of it indicates that you haven't really done much information-gathering about drying wood.

If you don't understand what's happening as wood dries, then any kiln is just a magic hat, and you may spend much frustrating time pursuing the combination that finally reveals the rabbit.

George, George, George, Once again I think you have missed the point. My original post was seeking information from anyone with experience in "building and operating" a small kiln for drying turning blanks. If you have any, it is not apparent from your posts. So why did you even chime in? I don't doubt that you are quite an expert when it comes to wood - an expert being someone who doesn't know what he doesn't know and is afraid to learn because it would threaten his self image. Having said that, however, I want to encourage you to continue posting your little rants, because it is reassuring to me to know that every minute you spend typing is one less minute you have to be hurting wood in your shop or studio assuming you have one.

Have a great life, George, and by all means continue to enlighten us with your prophetic knowledge! Type on George!

Greg

Thanks, Owen. Next time I get some Apricot, I try this.

Greg

Greg, Here's an idea used by a club member Joe Ruminski. I'll try to remember it correctly. At least it's about your question.

Build a rectangular plywood box, well sealed and insulated with that hard foam stuff at Home Depot, with a long side facing you and hinged to open upward for loading. Include shelves that allow air circulation. Install a dehumidifier (mine from Grainger's - BASEMENT variety) with drain tube to a bucket outside (to monitor rate of drying). It's plugged into a simple programmable timer (to control rate of dehumidification better than just the control on some dehumidifiers). He even uses a small squirrel-cage fan for interior circulation.

He's developed a plan for timing it's operation; something like all the time at first, then so many minutes per day for X days. He puts rough turned bowls in and then uses a moisture meter to verify progress, and then finish turns.

Joe's a commercial turner and a great guy, not a BS artist. This system works well for him to accelerate production. While I haven't all the specifics it should give you a start point. To me, the keys are the bucket measuring the rate of moisture removal without intrusion and a dehumidifier instead of just heat. I just ordered one of the moisture meters from Harbor Freight. Be sure to use the "online catalog" since the price becomes 19.95 vs 29.95 simply online.

TomNie