Anyone try dring 8/4 in with multiple loads of 4/4?

[Kelvin]

Howdy all,
Just wondering about drying 8/4 in my nyle kiln.  don't have enough for a full load, and can't imagine letting it sit long enough to dry from green to 6% anyhow.  Has anyone tried leaving some pieces in for multiple kiln runs?  I can see the trouble with putting a new load in and having the air RH go way up again, but maybe that would just wet the surface and continue to dry the core near the end of the cycle?  I have requests for thicker stuff but its not much.  I have lots of nooks and crannies in my kiln design to stash things.  What has been the accumulated wisdom so far?  No good?  The classic complaint of customers is this...  The surface was dry, but when i ripped it, the interior was sopping wet.  I imagine it would take a couple of months in the kiln?  Mostly walnut and cherry which both seem to have similar dry times.  What do you guys think?

Another interesting note.  I spent so much time sealing my kiln that now its always overtemp and i'm having to leave the door open!  Its getting 30 degrees out at night but still the compressor shuts off when i have all that stuff running in there.   Compressor shuts off at 132 degrees i guess.   Nyle says its typical to have to install vent openings in a highly insulated kiln.  the motors make quite a bit of heat.  Hmmmm.  Seems like i spent too much on insulation if i now have to just open the doors to let heat out.  I guess that makes for not worrying about door gaskets either.  Interesting.  Come summer time i'm going to have to just leave the door off!
KP

[scsmith42]

Kelvin, have you considered AD your 8/4 stock until it's down to 25% - 30% MC, and then adding it to whatever load you have in the kiln?

Scott

[oakiemac]

My experiences are that mixing 8/4 and 4/4 is not a good idea. It does take along time to dry 8/4 oak. I have a load in the Ebac that has been in there forever it seems.  You might get away with mixing some 5/4 in with 4/4 but not 8/4.

The problem you are having is exactly why I have a small 1000bf kiln and a 3000bf kiln. I use the small one for small loads like the 8/4 stuff or a customer who brings over 800bf of hackberry.

[Larry]

I have requests for thicker stuff but its not much.

Me to...I always threw in 50 to 80 board foot of 6 to 8/4 walnut with a load of 4/4.  Most times it would go through two cycles in both the solar and Ebac kiln with no problems.

My Ebac would constantly shut down from overtemp.  The solution was to power vent before it hit overtemp and bring the temperature down about 3 degrees.  I found power venting actually gave shorter drying times.

[MikeH]

 I have dried 8/4 walnut with 4/4 oak fresh off saw with no problems except when the oak was done the walnut was still about 12%. Then on the next load of 4/4 when the rh got down under 70% I threw the 8/4 walnut back on top of load and it come out real nice.
I also have to dump hot air all the time and finally put in nyle automatic fan and it works great. No more babysitting the kiln all the time.

[Kelvin]

Thanks for the ideas guys. 
Scott, Yeah, i like to air dry everything before putting in the kiln but its for people who want things NOW!  I'll give it a try and see what happens.  letting the second load dry a bit before adding sounds like a good compromise.  Yeah, two kilns sounds good to me too.  I'm thinking of building a small thing to chuck things in when people want things NOW!
Thanks
kelvin

[David Freed]

   If someone comes to me wanting lumber dried in a hurry I tell them to go to the big company 40 miles away that has 400,000 bf of kilns and I tell them what to expect. Your 1 or 2 bundles gets thrown in with 50,000 bf of their lumber. The kiln schedule (aggressive) is set for their lumber. If yours comes out okay good, if not, tough teabags. They charge 1/2 of what I charge and they dry it "fast" (read that as way too fast as far as I'm concerned). Several people that took their lumber to that plant got it cooked into firewood. >:(  That company does custom planing also for 1/2 my price and the finish is just one step above using an adze. :-\  I have since dried and planed lumber for some of these people. When they see what hurrying does to wood they change their attitude. I don't mix thicknesses of the same species in the same kiln load and I won't dry something in a hurry. Good luck.     David

[Brad_S.]

Drying 8/4 lumber with a 4/4 schedule would be way too aggressive for the thicker stock. You would dry the shell out while the core is still at a high MC (case hardening) during the first run. The internal stresses would cause honeycombing. I'm certainly no drying know-it-all, but I do know that if you absolutely have to mix species and/or thickness, the drying schedule should be the one that accomodates the slowest drying stock.

[fencerowphil (Phil L.)]

That's the "catch," isn't it, Brad.

When you match your schedule to the slowest requirement, you often lose efficiency overall.
You end up drying some stock slower than necessary.

For those who "want it now,"  that actually means more time to wait, not less.

Kelvin could always check with Den and get one of those high-falootin  vac jobs.   That's
"almost instant gratification"  in Den's words, that is.

Phil L.

[MikeH]

Drying oak on a 4/4 schedule has the same schedule as 8/4 walnut. From Nyle manual.

[beenthere]

Maybe the same schedule, but aren't the steps between changes based on the moisture content of the kiln samples?  and if so, would that be the mc of the 8/4 walnut samples, and not the 4/4 oak? 

Or... are these schedules only changed by time passed? prolly not..

[Brad_S.]

Mostly walnut and cherry which both seem to have similar dry times. 

Mike,
I was responding to Kelvin's original question. An 8/4 and a 4/4 of same/similar species put in the same kiln run and using a schedule for the thinner stock stands a high probability of ruining the thicker stock.

[MikeH]

Beenthere, you are correct. When I put in 8/4 walnut and 4/4 oak in, the oak dryed out sooner. Therefore I put the 8/4 in second load when mc was down enough. Maybe not perfect but I do have some nice 8/4 walnut now at 6%.

[Furby]

Maybe not perfect but I do have some nice 8/4 walnut now at 6%.

6% core or 6% case?