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RESAWING Again, moisture content?
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Author:  uncledave [ Tue Jul 03, 2007 2:03 am ]
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What moisture content in the wood being considered for resaw works best?  Fresh cut lumber, aged wood?  In between? 


I understand that some resawers glue lumber to be sliced thin to a stabilzing substrate, MDF or something.  Any experience with this?


Thanks ya'll


Dave


Flower Mound Tx
Author:  WaddyThomson [ Tue Jul 03, 2007 2:47 am ]
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Dave, have you been welcomed to OLF?  If not, Welcome!  You joined on my Birthday, so it was a good day.  I don't have a clue about moisture content for resawing, but I know there has been some discussion in the past couple of months on drying certain types of wood, and whether to resaw first or dry first.  Check the archives.
Author:  uncledave [ Tue Jul 03, 2007 3:12 am ]
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Thanks for the welcome, Waddy.  Yep, I'm another newb, come to bother you guys and hopefully learn somethin.  I'm in the process of setting up a shop, not quite all together yet, but getting antsy for sure.


My background is in metalworking, welding, prototyping and a little boatbuilding thrown in, mostly houses tho. 


I want to work on something small enough to not hurt me.  Gettin too old for big stuff.


Thanks again, I'll check the archives more thoroughly


Dave 


 
Author:  WaddyThomson [ Tue Jul 03, 2007 3:37 am ]
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As I recall the thread, there weren't many conclusions.  There were, however, many opinions.  Some say let it dry before cutting, some say cut first then dry, because it drys faster.  Then, again, there were some who said cut large, dry, then resaw for sides, backs and tops.
Author:  KenH [ Tue Jul 03, 2007 7:35 am ]
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Sawing wood thin while it is green is a real challenge because the wood wants to end check, check in the middle of the board, warp and twist. It can be done, but you have to have some strict humidity controls to keep the wood from drying out too quickly or you will end up with kindling wood.


Sawing dried wood is much more stable, but it has some challenges also. Some woods will dry in thick form strait and unchecked. As soon as you start to resaw it, tension in the wood will literally tear the wood apart.


The bottom line is that it is generally better to dry the boards in thicknesses of around an inch thick and down to at least 10% moisture before you try to resaw it into thinner boards. You stand much more of a chance of getting good wood this way than you do sawing green wood and trying to saw it thin.
Author:  stewalden [ Tue Jul 03, 2007 9:57 am ]
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Welcome Dave!  From one "newb" Texan to another.


I'm also setting up shop and really appreciate the question.  Hodge is definitely correct.  Wet wood will loose proportionately more width (across the grain) than length as it dries.  This will set up stress in the wood that will relieve itself when cut.  Metal machinists will tell you that you should mill to within 105% of finished dimension and let the part sit for a few days to stress relieve before cutting to finished dimensions in order to hold size and shape tolerances.  This applies to wood even more.  And always work in a humidity (45-55% RH) controlled environment. 


I went through the Taylor Guitar factory several years ago.  They store their new wood outside but weather protected (San Diego) where the RH is very constant and low.  Before it is worked it is brought inside and acclimated (I don't remember how long) to the indoor environment.  They keep the shops at 45% RH.


The resawing should be done when the wood is stable and dry.  Warping after resaw is a function of run-out in the wood.  If it is quartersawn and stored with stickers and air dried it should not warp very much, if at all, when cut.
Author:  Arnt Rian [ Tue Jul 03, 2007 10:28 am ]
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Shane Niefer had a thread, actually 3 threads, about the harvesting and processing of spruce that he does a while back. He resaws guitar tops from green wood and then dries it. These were some great threads, they should be put on the "tutorials" index page if they are not there already. Here's the one with the resawing part:

Shane Niefer's "Harvesting (Part 3) Lots of Pics" thread
Author:  fryovanni [ Tue Jul 03, 2007 10:58 am ]
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   It really depends on the type of wood you are dealing with. Ideal is well dried for resawing. However if you are dealing with large pieces(such as Spruce bolts) you need to ease up the tension that the wood creates as it shrinks(and it will) or else it has to release that by pulling itself apart(checking and cracking) and making the wood pretty much useless. Speed in drying is not the only reason why people mill lumber to smaller dimensions, and there is a good reason why thicker lumber costs more.

   Your losses go up when it dries in thicker form(as well as taking longer to dry). In the case of Spruce bolts(for example)you will do well to cut it thin so the wood can dry and shrink with the ability to move slightly(that is better than a crack or split). If you buy 8/4, 4/4, or what have you lumber, you should at least buy it and cut it below 12%. If you buy "green" wood do not pay full price(you will have losses, and the seller has not had to spend time or money drying or accepting those losses). Another thought for the informed buyer, if you buy green wood and have it shipped you are likely increasing your shipping cost 30-50%(which can add more dollars per. bd. ft. than you would think ).Green wood is tuffer on blades(not that that should stop you if you are trying to prevent losses, but something to be aware of).

   Personally, Hardwoods(dimenioned) and 1" or thinner softwoods lumber are sawn dry, thicker dimensioned and split lumber is sawn to thinner dimesions for drying(to reduce loss).

Peace,Rich

Author:  uncledave [ Tue Jul 03, 2007 2:55 pm ]
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Thanks!  Tho I was not clear on type of lumber, being in Texas, there is little or no chance of finding wood for tops, however, there are several woods that will make backs and sides.


A friend cut some walnut off his Daddy's place probably 20 yrs ago, and I believe I could talk him out of at least some of it.  I also believe it is in 4/4 form at this time.  Probably dry as it will get in this life.  I haven't seen the rough wood, but doubt that it is quartersawn, but some could be.  This is my goal.


One problem with beginning lutherie, is where to get wood that is dry and stable to work with.  Where do you purchase wood that is ready to build instruments without storage, waiting, drying, etc. 


Hell, I'm gettin  old. 


Great replys tho.  Thanks a lot.  And Shane's info on topwood is some interesting reading.  I'd like to go up there!
Author:  ckpung [ Tue Jul 03, 2007 4:10 pm ]
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[QUOTE=WaddyT]Dave, have you been welcomed to OLF?  If not, Welcome!  You joined on my Birthday, so it was a good day.  I don't have a clue about moisture content for resawing, but I know there has been some discussion in the past couple of months on drying certain types of wood, and whether to resaw first or dry first.  Check the archives. [/QUOTE]
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