I’m cutting out some square balusters out of 5/4 poplar. First I joint one face of a piece several inches wide, then the edge, then the other face so it is the desired thickness (I may have to settle for 1 1/8). Then I rip to 1 1/4 with a view to planing it to the final thickness. As I rip, some of the strips spring as if interior stresses are being relieved. So far, one out of four are this way. I haven’t bought all of the wood yet. What to do?
One thought is to rip to release the interior stresses, then joint flat and plane. This would require many more steps.
Replies
This is a common occurence when ripping wider boards into narrow ones, often happens when resawing, too. Some pieces warp, others don't. Folks give a number of different reasons why it happens, often improper kiln drying but it happens with air dried lumber. Boards can go whacky when sawing from the log. The only thing you can do is rip while in the rough and cut over size, then dress each piece as an individual. There will be times when a piece warps so badly, it can't be corrected or used as intended.
I think stress relief is a good description. It can cause safety issues when ripping. The board may pinch on the blade and it can go the opposite way. Larger shops use a specialized rip saw that has no fence and an auto feed. Those of us using a standard table saw may have to stop during a cut when things go awry. At times, you can see that a board has warped or you can read the grain characteristics, other times there are no warning signs. You can't do much about it other than using the experience of your eye when selecting stock, and hoping. I have to rip some 2" x 10" x 6' hard maple today and I'm worried and thinking it over. I cleaned out all my suppliers, can't get anymore and this job needs to move forward. I would have prefered to buy all 4" wide stock for my job but there wasn't enough. When you need small pieces, as you do, you have no choice but to rip wider pieces. Unfortunately, there can be a waste factor and it can be significant.
Reaction wood.
Fine Woodworking #26 has a great piece on flaws in wood and they cover reaction wood in both hardwood and conifers. Go to the home page, log in and search for reaction wood. The problem stems from trees that grow at an angle to the ground other than 90 degrees and involves compression of cell walls and other events. There are many other problems with reaction wood besides the danger of kickbacks and blade pinch. For one finishing can be a major problem, but better to read the piece. I think you have to be a member of FWW to get the whole file, unless your collection of the mags goes back to #26. Good luck.
Penobscot,
there are several reasons the stock can be moving while you are machining it.
As has been mentioned, reaction wood (from trees growing crookedly, or from limbs) or uneven/improper drying setting up internal stresses are the most often blamed. In addition, severe grain variations within a board, like proximity to a large knot or crotch can set up internal stress during drying. Wild, sudden swings in humidity can also temporarily change moisture gradient from the inside to the outside of a dried or drying piece of stock than can cause movement after stock is opened up.
At any rate, it is standard procedure to rip stock 1/4" or so oversize and let it re-acclimate for a day or two before planing and jointing. This may seem like extra work/wasteful of mat'l above surfacing a wide board in one operation, and ripping to final width, but if you then have to re-true the squares, or discard some of them after jointing, planing and ripping, you haven't saved any time or material.
Ray
there are times
when one is cutting squares like that and out of straight grain, that as i cut them , i stack them back into the same order and run some clamps across them to pull them together. then I run a good strong tape around them to hold them in thaty position, remove clamps and put them aside till they relax. it lets the inner moisture escape more slowly, redu7cing much of the warpage. it may take a few weeks. I learned years ago to be patient with nature. don't let anyone or anything ever pressure you into rushing a job, as it usually comes back to haunting you. time your jobs to compensate for this
ron
But of Course
After all it IS . . .
Spring Time
: )
A poplar time of year.
The problem can be reaction wood but generally your problem is caused by the wood not being at the same equilibrium moisture content throughout the board. How dry is the wood? Did you allow it to acclimate to your shop for a couple or three weeks? Acclimating it is important when you plan to resaw it.
At this point, you may be able to stack and sticker the boards you sawed. Put them in an area where air can easily get to all surfaces. Give them a couple of weeks as see if you get flatter boards.
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