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Newbie question; how can I prevent beam checking ?

Started by Jimbob, January 03, 2006, 08:38:11 AM

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Jimbob

I want to use a chainsaw mill to make 6x6 beams by slabbing off small southern pine logs.
Even if I paint the ends of the logs after I fell them, is there anything I can do to prevent the beams from checking (full length cracks nearly to the center) as they air dry ?

Ianab

If the pith is in the beam.. then basically there is no practical way to prevent it checking  :(

What some people do though is to run a saw kerf down one face of the beam, usually the top where it cant be seen. Make it a couple of inches deep. This acts as a controlled check, the kerf opens up a bit as the wood dries and relieves the stress that would otherwise cause a split at some random location.

End coating will help prevent excess cracking on the end 6" of the beam, but wont help with those big cracks around the pith.

Cheers

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Tom

Jimbob.

It's just my opinion, but:

Painting the ends of Pine doesn't hurt but seldom helps.  The sap in most species will seal the end of the log fairly efficiently.

The cracks in the sides of the beams are something else again.  You will probably not be able to stop them without a lot of luck, expensive equipment and controlled drying schedules.

If you have created a pith-centered beam, you still have the equivalent of whole log.  The outside will dry faster than the inside.  When the outside dries, it shrinks.  The water can't get out of the inside until it gets out of the outside, so, when the outside shrinks and the inside doesn't, something has to give.

I have had 4 x 4 posts of lessor dense species stay intact but not to the point that I could say that was the reason.

If you saw a beam from the outside edges of a log and leave the pith and immature wood out, sometimes you can avoid the checking (splitting).

If you dry the outside surface quickly to avoid mold and then slowly dry the beam, under cover, sometimes you can avoid checking.

Checking in the sides of a product isn't as related to sealing the ends as 'end-splits'.  Sealing the ends is mostly and 'end-split' remedy.

Ianab already said it, but, I spent so  much time typing this fool thing that I'm going to post it anyway.  :D :D :D

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