[Woodcarver] drying a 10" log

[Lynn Diel]

Phill and others
If you haven't perused the back issues of the eZine
that was started by our fearless leader (Bill) and
later handed over to Matt, who, in my humble opinion
who has done exceptionally well by continuing the fine
eZine, you are missing good stuff. (A shorter version
of the previous statement - Check it out!)

Thanks
Lynn


 fine --- Phill Pittman <phill at masterwerkes.com>
wrote:
> To make a DONATION to the Mailing List using PayPal
> OR regular mail, click this link:
> http://wwwoodcarver.com/WWWList/WWWList.html
> 
> 
> 
> Thanks Lynn, I hadn't seen that either,  Phill
> 
> 
> ----- Original Message ----- 
> From: "Lynn Diel" <carvers_creek at yahoo.com>
> To: "[Woodcarver]" <woodcarver at six.pairlist.net>
> Sent: Tuesday, June 22, 2004 6:49 AM
> Subject: Re: [Woodcarver] drying a 10" log
> 
> 
> > To make a DONATION to the Mailing List using
> PayPal OR regular mail, click
> this link:
> http://wwwoodcarver.com/WWWList/WWWList.html
> >
> > Ray
> > To follow up on what Phill wrote, there is an
> article
> > in the woodcarver ezine located at the following
> url;
> >
>
http://carverscompanion.com/Ezine/Vol2Issue4/Vol2Issue4TOC.html
> > it talks about how you can build your own vacuum
> kiln.
> > If you have any questions, let me know.
> > Good luck Lynn
> >
> >
> > --- Phill Pittman <phill at masterwerkes.com> wrote:
> > > To make a DONATION to the Mailing List using
> PayPal
> > > OR regular mail, click this link:
> > > http://wwwoodcarver.com/WWWList/WWWList.html
> > >
> > > Hi Ray.  there is no simple way ( if drying the
> wood
> > > ) to prevent splitting
> > > without involving an environment with a partial
> > > vacuum in it. We carve large
> > > ( and small )green wood regularly and anything
> you
> > > do that accelerates air
> > > flow past it will cause cracking where the air
> > > crosses the surface. (
> > > aromatic cedar and a few imported oil laden
> woods
> > > are some of the only
> > > exception ). drilling holes will help if
> naturally
> > > drying, but hurt if you
> > > force air with the vacuum.
> > >
> > >  Making a vacuum chamber for a log is not as
> > > difficult as it seems.Large
> > > schedule 80 pvc ( the kind you will see around
> > > public sewer projects ) will
> > > work in a pinch, but if it is something you
> might
> > > want to repeat later, a
> > > section of iron pipe that the log will fit
> inside of
> > > will do it. I got mine
> > > from a local scrap metal place and had enough
> left
> > > over for the " shop"
> > > smoker/bar-b-q). Welding a plate over one end
> and
> > > fashioning a removable
> > > plate for the other end will work for the
> vacuum.
> > > remember a vacuum is self
> > > sealing and getting an airtight seal is more
> > > important than fasteners or
> > > bolts etc. It is also much easier to do. If your
> > > project allows, remove any
> > > surface of the wood that you can before drying,
> but
> > > keep the fresh cuts wet
> > > until you are putting it in the tube.
> > > The fluids inside the log will gasify at near
> room
> > > temperature in a 25"
> > > vacuum. If you are lucky enough to score a good
> > > vacuum pump, it will work at
> > > room temperature.
> > > As I am sure you know, wood splits when drying
> as
> > > air removes moisture from
> > > one location more than the rest. Usually this is
> the
> > > exterior of the wood.
> > > The resulting shrinkage from the loss of
> moisture is
> > > unable to occur because
> > > the interior wood still contains it moisture and
> > > it's original size. When
> > > using a true ( partial) vacuum to remove
> moisture,
> > > the wood is not drying
> > > from the outside in. As the pressure drops the
> > > moisture, in a pretty uniform
> > > sequence, aspirates the moisture into gas which
> > > escapes the wood.
> > >
> > > This process is accelerated by heated wood. This
> is
> > > the only difficult part.
> > > There are expensive heating blanket made
> > > specifically for vacuum kilns, but
> > > they represent a significant invest in the
> make-up
> > > of the chamber and the
> > > heater itself. Any heat source has to be contact
> > > only. Remember that a
> > > vacuum insulates and normal convection does not
> > > convey heat. Radiant heat
> > > ( light in various forms ) heats only the
> exterior
> > > and may cause uneven
> > > drying. All we do is pre-heat it just like an
> oven
> > > and try to get the vacuum
> > > pulled down while there is still some heat in
> the
> > > log. It will not cool down
> > > much after the vacuum has removed the air.(
> think
> > > about a thermos jug ) When
> > > you heat it up you have to let it remain heated
> for
> > > several hours to insure
> > > that the interior of the log is the same
> temperature
> > > as the exterior.
> > >
> > > You can get serviceable vacuum pumps off eBay
> for
> > > $50 bucks if you are only
> > > going to do it a time or two. The actual
> original
> > > purpose of the vacuum pump
> > > is inconsequential, only that it will pull a 22"
> or
> > > better vacuum and run as
> > > required for several days. the drying time will
> > > depend on species, size, and
> > > too many other factors to name. But the
> thumbnail
> > > measuring method of choice
> > > is to weigh your entire contraption. If your log
> is
> > > of any size there will
> > > be a drastic weight change ( usually a hundred
> or
> > > two pounds) as it loses
> > > moisture. When your assembly stops losing
> weight,
> > > your done. At lest as far
> > > as you can go without mortgaging the house.
> > > Commercial kilns dry 8/4 white
> > > oak for about 48 hours at 22" vacuum. Almost
> zero
> > > checking /splitting and a
> > > very uniform 6% moisture content.
> > >
> > > Woodmizer ( the same folks that make the saw
> mill)
> > > used to sell some light
> > > commercial vacuum kilns and are a great source
> for
> > > technical info.
> > >
> > > All that being said, if you can find it,
> aromatic
> > > cedar is real forgiving
> > > the same day it is cut. We are in the middle of
> a
> > > 2000 piece run of
> > > "spirits" about 20" tall and 4" thick through
> the
> > > nose area. We produce
> > > about 50 a day out of aromatic cedar that is
> often
> > > sawmilled on the same day
> > > we mount it on the machines. We have an
> occasional
> > > loss from internal
> > > checks, but they seldom to appear to be from
> drying
> > > in the wind of the
> > > router motors, more like internal stress cracks
> with
> > > some resins visible.
> > >
> > > I also have a friend that is about to try Vacuum
> 
=== message truncated ===


=====
Lynn E. Diel
Columbia, MO
Website: http://carvers-creek.com