DH & thick hardwood

Den Socling · April 12, 2004, 07:19:52 AM

F.A.O. Don Lewis

Don,

A Nyle salesrep told a forum member that a L200 would do well at drying bowl blanks. Would you agree? What would you say are the limits of thickness in a DH kiln for the common hardwoods like Cherry, Oak and Walnut? How long would the kiln charge take?

Den

old3dogg · April 12, 2004, 04:47:44 PM

Den.
I have had the chance to "work" with some 8/4 RO dried in a DH kiln.60% of it went to the boiler.
I heard that it took 3.5 months to "dry"
Oven samples said the final MC was at 12%.
A long way from dry!
Dont know a lot about DH drying but............
Mike.

sawwood · April 12, 2004, 06:18:08 PM

I had Larry dry some 2" thick oak in his solar kiln. it was
just a few boards and the rest was 4/4 oak. Seem like it
took 3 months to dry and it didn't do to good. I still used it
but there was a lot of waste. Most bowl turners i know use
a old icebox with a light bulb and fan to dry there rough out
bowls.

Sawwood

WoodChucker · April 13, 2004, 10:45:31 AM

So are you guys suggesting that a DH kiln can't dry 2" lumber? I'm getting ready to build one and this is disappointing news if thats the case. Thanks!

R.T.

old3dogg · April 13, 2004, 11:58:28 AM

WC.
You can dry 2" lumber in a DH kiln.Its just a slow process.
What species are you going to dry?
Mike.

WoodChucker · April 13, 2004, 01:52:20 PM

It's mostly red oak, ash , maple and some poplar. I'd say about 75% is red oak. So lets say 1" red oak took 45 days to dry (I'm guessing) , how long would it take for 2" to dry? Thanks!

R.T.

Don_Lewis · April 13, 2004, 03:38:32 PM

Nyle has a number of customers drying bowl stock. Some do softwoods and some hardwoods. There is a substantial risk with drying bowl stock. Much depends on how it is sawn, or shaped and then dried and how much the person doing it really understands about what happens to wood as it dries. . Factors that are out of the control of the kiln operator can create lots of problems. I don't think one method of drying is significantly better than others.

Den Socling · April 13, 2004, 03:48:44 PM

Don,

When I think about bowl blanks, I'm thinking 4" or more square. Can a DH kiln do 4" or more (hardwoods)?

The question drifted to 8/4. I know a DH kiln can dry some 8/4. Give us some basic times for the common species. WoodChucker, for one, needs this info.

Den

Don_Lewis · April 14, 2004, 04:00:43 PM

Yes, a dh kiln can dry 4" squares. We had one customer that filled two kilns with 50,000 BF each of 4" Red Oak Squares. Big bucks at risk and it took 6 months to dry. He did two loads a year, 200,000 BF which sold at a substantial premium.

Den Socling · April 14, 2004, 04:06:13 PM

6 months is considerably longer than the 14 days that the 4" squares would take in a vac kiln but forget that thick stuff. What can the average guy with a little DH kiln expect when drying 8/4 Red Oak, White Oak, Cherry, Soft Maple, Hard Maple, etc.

WoodChucker · April 14, 2004, 04:27:52 PM

Holly jingles, 6 months just to dry 4" squares? I sure hope it doesn't mean it takes half that time (3 months) to dry 8/4 red oak? I thought maybe at tops it would be 45 to 60 days.

Den how much does a small vac kiln cost? Say something that would do around 1500 to 2000bf of 12 foot lumber? Is it even something a small fry like me would even consider? :-/

R.T.

old3dogg · April 14, 2004, 04:54:38 PM

WC.
But Don said the guy dried 100,000BFT of 4" Red Oak in 6 months.Thats a lot of wood.
Could a small fry like yourself use 2000BFT of 8/4 RO every 2 weeks?This is the question you need to ask yourself when considering a vac kiln.

WoodChucker · April 14, 2004, 05:06:59 PM

Yeah your right, I didn't think about it that way. All I really need is a system thats going to dry wood in 4 to 8 weeks. Seems like a DH kiln should do that, wouldn't ya think? Thanks!

R.T.

woodhaven · April 14, 2004, 05:07:39 PM

Another thought to consider. When a DH unit fails you can run to your nearest air conditioner contractor and get a part. Can you do this with a specialty system?

old3dogg · April 14, 2004, 05:14:05 PM

Sounds like the "hardest" wood that you want to dry is the 8/4 RO.The Ash,Cherry,Maple and Poplar should be fairly quick and easy in a DH kiln.
Den is the only vac kiln company that I know of here in the USA and knowing Den,he can get you parts in a hurry.
Da Man got connections!

WoodChucker · April 14, 2004, 05:20:35 PM

woodhaven, I couldn't tell ya, I'm pretty stupid when it comes to kilns of any kind.

old3dogg, I think I got excited to quick, hey? lol.

Thanks guys!

R.T.

woodhaven · April 14, 2004, 05:29:28 PM

WoodChucker
So that sounds you need to dry 100,000 BF

Den Socling · April 14, 2004, 05:47:23 PM

I should add that we have customers who run Nyles and DryLines and they are drying 8/4 hardwood successfully. I just don't know how long it takes.

And six months IS half the time that it might take for 4" RO squares in a conventional kiln, I'm told. I can't imagine starting a year-long kiln charge.

old3dogg · April 14, 2004, 05:55:52 PM

I was told 10 weeks to dry 8/4 RO in our DH kilns but the results werent that good.A lot of honey comb.

Tom · April 14, 2004, 06:26:16 PM

I have an Ancsots kiln and every load I start will be a year or better. :P

Den Socling · April 14, 2004, 06:30:42 PM

WoodChucker,

I'm not selling vac kilns here and I'm not telling you how much they cost because I don't know how to do CPR through the internet. :D

Den

WoodChucker · April 14, 2004, 07:46:11 PM

QuoteWoodChucker,

I'm not selling vac kilns here and I'm not telling you how much they cost because I don't know how to do CPR through the internet. :D

Den

lol, that bad hey?

Well I'm getting more confused now then I was before. A few months ago just about everyone I talked to said a DH kiln was the way to go. I'm just about finished with my building site and getting ready to order insulation for the kiln. But now I don't know if I should or not.

Lets get back to basics here for a second, about how long would it take to kiln dry a load of 4/4 red oak that has been air dried for a few months? Say 2000 bf. I'll be using a Nyle L50 DH kiln and most of my lumber is 8 to 12 feet long.

And if anyone is drying 8/4 red oak under like condition, how long does that take you? Thanks! :-/

R.T.

Don_Lewis · April 15, 2004, 06:54:30 AM

8/4 Red Oak (and Maple etc) should ALWAYS be dried from green. Low temp (120F) kilns will take about 80-90 days and 160 F DH kilns will take about 65-75 days. Vacuum kilns will dry in about 1/10th the time, but loads are smaller so at the end of 2-3 months, for the same investment you will have about the same amount of wood dried. Operating costs are not much different and there is debate about the relative quality but we have had really good success with DH kilns and 8/4 Red Oak. When there are problems with quality, it has almost always been related to stock that was air dried first but that would be the same with both DH and vacuum

Den Socling · April 15, 2004, 07:10:23 AM

Thank you Don.

I created this discontinuous vacuum monster specifically for people who want to dry small quantities of heavy stock. I suppose it could be scaled to do some lumber but I never intended for it to be competition for DH. And the idea was for people who have a lot of do-it-yourself capability.

Den

DanG · April 15, 2004, 07:32:14 AM

Don, you said 8/4 RO should always be dried from green. I assume the same is true for 4/4 stock. Can you expand a bit on that? What sort of problems occur from pre-drying? Is there a known reason for it, or is it just a "statistical" rule?

I guess the other thread I started was redundant to this one. :