iDRY Vacuum Kilns

Sponsors:

Douglas Fir 6x6 Posts

Started by westside, June 27, 2017, 02:38:19 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

westside

I have a ton of Incense Cedar and Douglas Fir along with Madrone and Oak on my property and have been milling some Incense cedar for siding my pump house (as seen in the image below).  I am now looking to cut down some fir trees to make (4) 6x6 Douglas fir posts that will hold up my 5 1/2 X 15" glulam beams for my porch.  My question is should I be looking for trees that will be so small to just cut basically the posts out or should I be trying to find some larger trees that will produce all 4 beams in the diameter of the log?  Also this is my first post on the forum.



Thank you

Chuck White

Welcome to the Forestry Forum, westside!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

Ianab

There are 2 ways to cut beams. Either centre the pith and cut one beam from the centre of a smaller log. Or cut your beams "free of heart". This means completely away from the heart.

Cutting 4 beams is probably bad because you will end up splitting the pith and having it on the corner of each beam. They are then likely to wrap.

If the log is big enough you should be able to cut 1 beam centred, and another 4 from around it. With D. Fir the wood should be stable enough for this to work OK.
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

ChugiakTinkerer

Welcome to the forum!  Satisfy our curiosity if you will, please, and update your profile to indicate whereabouts you call home.
Woodland Mills HM130

richhiway

If you have you have your pick of trees and just need the posts, cut trees big enough and cut your post from the center. Save the larger trees to make boards.
If you are cutting larger logs anyway and need posts cut boards and 2X until you get down to the center and then cut your post. you would need a huge log to cut four 6x6 posts and stay free of the center. Many logs have tension and those post will warp.
Woodmizer LT 40
New Holland 35 hp tractor
Stihl Chainsaws
Ford 340 Backhoe

Brucer

So, having actually cut several hundred thousand BF of Douglas-Fir ...

I hate 6x6's. You can cut one boxed heart 6x6 from a 9" log but that's from the top of the tree and will often have a lot of knots. Or you can cut one boxed heart beam from a large log (say 12") which will give you a very nice timber but also a lot of side lumber. Or you can jump up to a much larger log and cut 2 or more FOHC timbers.

Quote from: Ianab on June 27, 2017, 03:40:00 PM
... Cutting 4 beams is probably bad because you will end up splitting the pith and having it on the corner of each beam. They are then likely to wrap.

If the log is big enough you should be able to cut 1 beam centred, and another 4 from around it.  ...

There's another way, which I used all the time. Cut 2, 3, or 4 beams but stay 1" away from the pith. Bascially you're cutting a 2x or a couple of 1x's out of the centre and taking your 6x6's from the sides. Cut this way, you will get ...
  2 - 6x6 (full dimension) from a 16" log (top diameter), or
  3 - 6x6 from a 17-3/4" log, or
  4 - 6x6 from an 18-1/2" log.

To get 5 pieces from one log as Ian suggested, you'd have to go up to a 20" diameter top.

Quote from: richhiway on June 27, 2017, 09:43:26 PM
... you would need a huge log to cut four 6x6 posts and stay free of the center. Many logs have tension and those post will warp.

I wouldn't call a 16" or even an 18" top "huge" for a Douglas-Fir.

While cutting FOHC will cause most species to curve away from the centre, Douglas-Fir doesn't usually deflect that much. For 8' and 10' long posts, the curvature is negligible. At 16' you might get 1/4" of deflection, or even up to 3/8". If this was going to be a problem, I'd usually cut the posts a little oversize and then saw them down to 6" after they curved.




The deciding factor on whether to cut one or many from a log may be the size (and power) of your mill. An 18 HP engine will cut big D-Fir logs (slowly), but 24 HP makes it go much more quickly. Anything above that and you're laughing.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

mad murdock

Welcome westside! I would add also that raw log selection may differ from one situation to the next depending on the type of mill along with, as Bruce has said- HP! 
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

Ianab

QuoteI wouldn't call a 16" or even an 18" top "huge" for a Douglas-Fir.

That's what I was thinking. Judging by the picture and tree species (and user name) I was going with Pacific Nth West as the OP's location. That suggests some decent size trees, and a 20" log isn't "big" in my part of the world.

The 5 posts in a star pattern is of course not the only option, and would need a log around 20"+. Like Brucer says you can cut the pith out in a smaller (low grade) board and get 2 FOH posts, and some decent side boards, from maybe a 16" top.

Maths experiment. How many from a 48" log?  :D No idea, I'd just get a crayon and ruler and start drawing 6x6 boxes on the end of the log  ;D

My current mill maxes out at ~36", but can handle that with 12hp, because it only cuts 6" at a time. Start whittling at the top of the log, and stop when there is none left  ;)
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

50 Acre Jim

So if I understand correctly, a 6X6 post with the pith centered is structurally OK?
Go to work?  Probably Knott.  Because I cant.

WDH

It has to be in the center or the juvenile core containing the pith must be completely out of the timber for the straightest results.  The size of the juvenile core varies with species, but it is usually about the first 10 years of growth.  In fast growing species, it can be quite large, and conversely, quite small in slow growing species.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

50 Acre Jim

Would it be safe to say the pith should be avoided in any/all cuts if possible?
Go to work?  Probably Knott.  Because I cant.

redprospector

I just filled an order of 6x6x10's. Boxed heart, pith as centered as possible. They weren't all Doug Fir though. There was some Ponderosa, White Pine, and White Fir mixed in.
I try to cut 6x6's out of small logs if I can, and save the bigger logs for bigger timbers.
1996 Timber King B-20 with 14' extension, Morgan Mini Scragg Mill, Fastline Band Scragg Mill (project), 1973 JD 440-b skidder, 2008 Bobcat T-320 with buckets, grapple, auger, Tushogg mulching head, etc., 2006 Fecon FTX-90L with Bull Hog 74SS head, 1994 Vermeer 1250 BC Chipper. A bunch of chainsaws.

Ianab

Quote from: 50 Acre Jim on June 28, 2017, 08:06:26 AM
Would it be safe to say the pith should be avoided in any/all cuts if possible?

That's a good rule of thumb to work by.

Problem is the wood around the pith is "juvenile" wood from when the tree was a skinny little twig. It has a different cell structure, and can actually shrink in length as it dries, while normal wood doesn't. So if you have one edge of your beam or board with the pith in it, and the other side normal wood, as the beam dries, one side shrinks, and the beam bows. If the pith is centred, it has normal wood on both sides which keep it under control.

Other species will have serious defects in or around the pith. Walnut has that hollow channel up the centre, and the Monterey Cypress I often cut will almost always check in the 2" or so around the pith. May as well just cut that section out and throw it straight on the firewood pile, or cut a big post with the pith centred.
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Brucer

Structurally the wood in the centre of a post or a beam isn't subject to much stress, so it doesn't hurt to bury the pith. Strangely enough, there is no mention of where the pith should be in the grading manual.

If I'm going to box the heart, I try to keep the pith in the center 1/3 of the timber (an idea I picked up from Ian a while back). That's one thing my customers remarked on -- they'd get timbers from a competitor and have the pith popping out the side of a timber.

If I'm sawing FOHC I want the face nearest the pith to be at least 1" away from it. (That's for Douglas-Fir ... it may differ for other species).
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

Thank You Sponsors!