sweet gum and tulip poplar

[DWM II]

I've been reading up here in the forum getting some pretty good ideas on where to start in this timber frameing stuff. I saw there is a book or two that I need to get but here are some simple questions for yall to chew on and spit out for me.
1. Is sweet gum good for use in timber frameing? It is very plentifull here in Louisiana and it is a scourge to most folks.
2. How about tulip poplar? There are plenty of these as well and they are normally pretty large. I q-sawed some the other day for my sawshed (used them for some 6x6 posts) they stayed straighter than any of the oak posts that I cut.
3. I was reading on some previous posts about wether to cut and dry all material or to work green. Seems that there is a mixed opinion on this. How about that question regarding these two species.
4. Are there any clinics planned anywhere in the gulf south anytime soon?
thanks,
Donnie

[Jim_Rogers]

I went to the timber framers guild site and did a search on sweet gum and there were only two threads on the subject. Both were timber framers asking if anyone has used it. No one responded. But I only searched all open forums, there maybe more info in the archives. You may need to do a search there for more answers.

I did a search of the site for tulip poplar, and here is one quote:

From personal experience, I would suggest that you stay away from tulip poplar. It twists and checks like crazy while drying. Oak is fine, and white pine appears to be even more forgiving.

There were 13 threads there with poplar in the post.

And this search may have included the archives.

Good luck on your research.

#4. We've been talking about one in LA sometime in the spring, maybe. Stay tuned....

Jim Rogers

[Raphael]

  Jack Sobon had some very nice thigs to say about working with tulip, it's strong for it's weight and cuts easily.  I'd guess from TFG quote that it's like working with spruce (without the splinters) in that you need to harvest the trees when the sap is down and get it cut and assembled before it moves.  Probably not the ideal timber for a solo project.
  From my experience with spruce timber, it will move for a couple of years while air drying.  Cutting your timbers and waiting for them to stabilize may be an option (if you aren't in a hurry) but you'll need a lot of extra timbers as some might twist beyond utility.
  I've no idea about sweet gum...  I've never seen engineering values  listed in the tables so you'll need to consult with someone who knows the character of the tree (is it prone to inclusinions, shake, etc.) and can derive timber engineering values from the forest services raw data.

[beenthere]

Tulip poplar has a reputation to be bad for growth stresses, meaning as the tree grows the outer layers of wood laid down are in tension, which adds up as the tree gets bigger, to the point that the center of the tree is left in compression.
When sawing the log of tulip poplar, balancing these stresses will be important to keep in mind. The three sided cant would probably result in a sweeping curve right off the saw for many poplar logs from trees of any larger size. Maybe become worse when dried. Sawing relieves the balanced stresses in the tree. Trying to tack it down when green might help some, but those stresses are quite powerful.

If sweetgum were a good structural wood, probably would be used more for that already.  :

[Qweaver]

I am building a post and beam cabin using poplar almost exclusivly. See my thread in the general forum. https://forestryforum.com/board/index.php?topic=19307.0  My posts are 7x7, sills 7x9 and girts/tie beams 6x7.  I cut most of my timbers last spring (2005) end coated them with anchorseal and air dried.  Most timbers were cut from logs that were just large enough to make the required size and so the heart was always boxed.  Any timbers that showed bow as I was cutting them, I just sawed into boards.  The timbers stayed very, very straight but there is some checking and cracking,  but really no more than what I have seen in many of the post and beam and timber frame structures that I have looked at.  I love this wood.  It dries fast, is easy to work and looks great when finished.  BUT...I have very little experience with other woods so take my words with a grain of salt.  I just know that it is working fine for me.  I would hate to think how hard it would have been to build as we have with a really heavy wood like oak.
Quinton

[Thomas-in-Kentucky]

Put one sweet gum timber (a jack rafter) in my timberframe just as an experiment... It has behaved very well so far.  Actually, I cut it as a railroad cross tie and never got around to taking it to the buyer.  Then when I observed that it had done nothing out of the ordinary (sitting exposed for a year), I resawed it from a 7x9 into a 6x8.  The lumber, at first glance, could be confused with oak or hickory, so it matches the predominantly-oak frame just fine.  Hasn't twisted, checked or bowed yet, but this is only one small data point.

Tulip (yellow) Poplar is nice to work with.  Cuts like butter with a chisel (compared to oak, maple, or just about any other hardwood).  Although it is not as strong as oak, it is very light, so you could just scale up the timber a bit if your design assumptions were based on oak.  Yes, it seems to check more than oak, but... that might not matter to you.  I haven't observed any of my poplar timbers twist badly when drying.  (have had a few beech and hard maple timbers twist to the point that I had to cull them)  I have about 12 poplar timbers in my frame and they're all behaving nicely so far.  They make really nice rafters - because once you get up to that height, you don't feel like wrestling oak rafters.    Although the wood is a green color when cut, the heartwood on tulip poplar will turn almost as dark brown (sometimes witha  reddish cast) as walnut, when treated with nothing but linseed oil (while the sapwood remains acreamy white).  A lot of people are hard pressed to identify the Tulip poplar in my frame - some guess walnut!

Echoing what "beenthere" said, I have had a bear of a time trying to cut long, straight 2x4's from poplar logs.  The internal stress in tulip poplar is a force to be recconned (sp?) with.  Turn the log often on the mill.  Most poplar trees around here grow about 8 feet up and then bend a few degrees one way or the other before taking off and growing straight for 40 feet or more.  I usually cut the butt log at 8 feet and then the remaining logs in the tree are long and true w/o much lopsided stress in them.

A timberframe exclusively of Yellow Poplar would be neat indeed.  Qweaver - nice frame! - thanks to the link to the old thread.