Replies

1. 
   PlaneWood | Sep 11, 2005 04:33am | #1

   Buy a moisture meter.

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)
   PlaneWood

2. 
   JeffHeath | Sep 11, 2005 04:54am | #2

   johnny

   ditto on the moisture meter.  Unless you're using reaction wood, as long as the poplar is in equilibrium with your shop MC, you shouldn't experience too much movement.  I make a lot of mouldings for some local custom builders out of poplar, that I mill and air dry myself.  After the initial milling, I sticker it and let it set for a while.  Once I know it's at the same MC as my shop, I run the mouldings.  I have had very few pieces out of thousands of feet brought back.

   Jeff

   BTW to avoid confusion, I only use the poplar after it has dried for about a year (4/4 stock)

1. 
   johnny | Sep 12, 2005 03:31pm | #5

   Thanks, though I'm not sure what you mean by "reaction wood". I should start an inventory of dressed down lumber to dry before I use it. My problem is lack of space. Is outdoor storage an option? Covered, ofcourse. I live on the coast of Maine, so the weather is not too forgiving.

3. 
   hammer1 | Sep 11, 2005 05:03am | #3

   The problem is most likely the resawing. When milling lumber it is best to take equal amounts off both sides. The molding operation will also take a fair quantity off one side more than the other unless you have a foursider. Resawing the 8/4 will release the dynamic tension that is inherent in the stock. Is there a reason you don't buy 4/4? Are you trying to do all the milling with your molder and not flattening and planing with the jointer and planer to save time? I think the best way to ensure that your stock comes out straight and flat is to mill it in the traditional way. I don't think a change in species will make much difference, particularly, if you are resawing 8/4. The same thing can be common when ripping wide stock in half. It may not happen with every piece but it does have a high frequency rate.

   Beat it to fit / Paint it to match
1. 
   johnny | Sep 12, 2005 03:23pm | #4

   Thanks for the reply, My procedure usually is jointing one edge,then ripping 3 inch sticks down to run through the planer (both sides).Then back to the jointer to get a good square edge for the resawing. Then run through the moulder. Is that traditional? I'm self taught. I notice alot of stresses in the poplar as soon as I start ripping. Either it binds down on the saw (even with splitter),or it starts to look like I should be making skis.

1. 
   hammer1 | Sep 13, 2005 03:46am | #10

   It sounds like you are making 1x3 out of 2x6 or something like that. In my experience, this is a recipe for disaster. Call it what you will, reaction, dynamic tension, severing the integrity. It all amounts to the pieces taking off as you have described. Your chances that the pieces will bow, twist or warp are high. If you want 1x3, then start with that in the rough. Usually, thicker lumber is more expensive and the added labor has to be figured in, add the fact that you are going to lose a certain percentage to warping and it doesn't make sense. You may be able to cut up short stock like this, oversize, and let it sit, but I've had problems wih 6" long pieces so I wouldn't count on a high rate of success, unless you have plenty of thickness to work with. Unfortunately, this is just the way lumber reacts, you get lucky once in a while but not very often.Beat it to fit / Paint it to match

1. 
   johnny | Sep 13, 2005 04:02am | #11

   I just looked at some comercial stretchers. Maybe 1 by three inch or so. But they were fingered joined every 8 inches or so. Perhaps a long run of moulding put together with finger joints will be more stable than a long stick?

1. 
   hammer1 | Sep 13, 2005 04:34am | #12

   They are just making use of some, otherwise, unusable scrap. In time, the finger joints will fail. Each individual piece will move at it's own rate and break the glue line. Someday, someone will be cursing those stretchers and it won't be too long.Beat it to fit / Paint it to match

2. 
   cherryjohn | Sep 19, 2005 02:10am | #23

   damn, Hammer, you remind me of someone who knows what he is talking about..........  when are we getting together anyway?

    Wicked Decent Woodworks

   (oldest woodworking shop in NH)

   Rochester NH

   " If the women dont find you handsome, they should at least find you handy........yessa!"

4. 
   jimmy | Sep 12, 2005 07:02pm | #6

   Basswood is the preferred wood for stretchers.  Conservation issues...Jimmy

5. 
   CharlieStanford | Sep 12, 2005 07:45pm | #7

   Newsflash: Resawn lumber moves like crazy.  Mill it thick to allow for movement and give it plenty of time to settle down.

1. 
   johnny | Sep 13, 2005 03:23am | #8

   I think I'm begining to get it... so I need to buy my lumber a year or so in advance? Even when told from the seller that it is close to 6%? I buy my lumber from a person that I've done business with for 5 or6 years now. I enjoy his company and advice. I can't imagine to pull out a meter on his wood as if I don't trust him.

1. 
   JohnWW | Sep 13, 2005 06:08pm | #14

   There's a misunderstanding here, the wood should be stickered  in your shop to readjust to the humidity levels in your shop once the wood is taken out of the seller's barn or warehouse.  This usually only takes a few days to a few weeks, it depends on how much more or less humid your shop is compared to the previous storage conditions.  

   The 6% level quoted was the MC of the wood only at the moment it came out of a kiln or the drying shed, what it is at the moment you buy it, or when you use it, is entirely dependent on the humidity in the air around the stock, and how long it has had to adjust to the new environment.

   Any thick board, no matter how carefully dried, can have stresses in it that will cause the resawn pieces to warp.  The best approach is to buy knot free, straight grained stock, that has been properly dried, preferably in dimensions close to the final dimensions you are planning to use.  After resawing give the stock a few days to react to the changes in stress and then joint and plane to final size.

   John W.  

   Edited 9/13/2005 11:11 am ET by JohnWW

   Edited 9/13/2005 11:13 am ET by JohnWW

1. 
   johnny | Sep 14, 2005 03:07am | #17

   That sounds like good advice. I'll give it a shot.

1. 
   JohnWW | Sep 14, 2005 04:47pm | #18

   Buying a kiln won't help, even the most carefully dried wood will still move with seasonal moisture swings.  Some woods are especially stable, such as the cedars but the extractives in the wood might affect the canvas.  Basswood is quite stable and would seem to be extractive free.

   I also make stretchers and have given up on using solid wood on larger sizes because of the same problems you are having.  I now build stretcher frames out of good quality plywood and then apply a shop made poplar molding, similar to a corner molding for house trim, around the outside edge of the plywood frame to create the rim that the canvas is attached to.

   John W. 

2. 
   acornw | Sep 14, 2005 11:23pm | #20

   The wood does not move because it is Poplar, it moves because it is casehardened. This happens in the kiln as it is being finished off.  Remember several things, drying is both science and art, 6% MC is only a small component of the picture, and just as Sara Lee doesn't pick the cherries for pies, your lumber seller has zero control over the wood he is buying for resale.  If he dries it himself, then he is to blame and needs to learn how to avoid casehardening.

   Good wood, properly dried, can be resawn any number of ways without problems.  Drying lumber requires energy and careful know how.  Both are in increasingly shorter supply.

   Make a square cut off the end of an 8/4 plank - about 6" or so. Then cut off a 1 inch piece.  Take this 1" pc to your band saw, set it so the long grain (1") runs up and down, and cut out a "U" shape with walls about 1/4" thick. Your goal is to preserve the outer U - you can waste out the center.  As you saw, or after you saw, the two ends of the U will bend towards each other if it is casehardened. Try this with several boards to see how consistent it is.  Take the worst one to your lumber dealer and see what he can do.  Most will just shrug their shoulders and mumble something about wood moves, so "what are you gonna do?"

   Hoadley explains all this in his Understanding Wood.

   Dave S

2. 
   johnny | Sep 13, 2005 03:29am | #9

   I don't know what you mean by settle down. From my experience, lumber that has moved badly only either stays that way or gets worse. I built a boat a few years back, not a bad way to use curved wood. But unfortunatly i'm making picture frames now and stretchers, which must be straight.

1. 
   Crunk | Sep 13, 2005 12:58pm | #13

   Johnny, resawn lumber almost always moves.

   Edited 9/13/2005 6:00 am ET by BossCrunk

6. 
   john | Sep 13, 2005 07:58pm | #15

   Wood that was originally sawn 8/4, then dried, by whatever means, and then resawn is going to move. It's got little to do with the M/C or the drying technique. Trees are under quite a bit of stress, and as they get sliced up so those stresses are released. Rather than resawing, buy 4/4 stock.

   John

   If my baby don't love me no more, I know her sister will.
1. 
   johnny | Sep 14, 2005 03:03am | #16

   OK- I understand the stuff is gonna move- but I'm making picture frames. I mill it down to 3/8 and 1/2 inch. Sort of like making trim. I don't have too much trouble with the frames since I glue them up. But the stretchers are single sticks-and they MUST be straight. Oh man....do I need to buy a klin?

1. 
   K1500 | Sep 14, 2005 10:15pm | #19

   Could it be case hardened.  I did a little work with poplar a while back and it would curl away from the sawblade like crazy during a rip.  Even if you took a 1x4 and turned it into a 1x3 by taking 1/2 of both edges, it would twist like craze.  I have had no such problem with the white oak from the same place, while my father had a devil of a time with some white oak from a different mill/kiln.  At the time I attributed it to case hardened wood.  I don't know if poplar is prone to that, but I have heard oak is.

7. 
   WillGeorge | Sep 17, 2005 05:25pm | #21

   My Mom has many streatchers of various sizes.. Even some LONG ones for lace curtains.

   ALL are mahogany but old so maybe 'good' wood... They must be 60 years old or so.. Not one is warped..

1. 
   johnny | Sep 18, 2005 12:21am | #22

   That's interesting. I'm sure they must still be sound. I don't know what mahogany sold for back then, but I know it would be cost prohibitive to use it now . It's wonderful wood. I use it for some picture frames-sparingly.