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Boards warping quickly after milling

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Forum topic by lblankenship posted 03-16-2019 03:11 AM 418 views 0 times favorited 16 replies Add to Favorites Watch
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lblankenship

19 posts in 576 days


03-16-2019 03:11 AM

Topic tags/keywords: pine joining milling question movement warp bow twist

Hey everyone,

I was working on milling some 2×8 boards for a shelf as well as some dividers. The boards had been in my shop for almost a week prior to milling. I started by running flattening one face on the jointer, then planing down to final thickness. However, when I went back to the jointer to square up one edge almost all the boards had some sort of twist, bow or cup in them. Also to note, prior to moving to the planer I had checked each board for flatness using the bed on my jointer and they were very flat so I know they were flat when I started at the planer. I try to mill over multiple days but I was planning on gluing up the panels today as well so I figured I could get it in clamps before they decided to move but I guess I was wrong. Is it common for wood to shift this quickly? If so, is this common for all species or does the fact I’m using construction grade lumber have anything to do with it? Is there any solution or tips you could recommend to eliminate/prevent this drastic movement after milling? I understand wood is going to move regardless but just trying to cut it down to a minimum.

Thanks in advance!


16 replies so far

View Jared_S's profile

Jared_S

134 posts in 262 days


#1 posted 03-16-2019 03:24 AM

If its construction lumber it needs about 6 months to acclimate/dry, and will still likely warp somewhat from case hardening.

View GrantA's profile

GrantA

1350 posts in 1710 days


#2 posted 03-16-2019 03:36 AM

construction lumber is only going to frustrate you here. It’s probably got twice if not more the moisture content you want and it’s just going to move a lot more on you. I like poplar for an inexpensive lumber choice (assuming you buy it from a mill or specialty shop, or even a cabinet shop). Nothing wrong with southern yellow pine either, you want it dried though.

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lblankenship

19 posts in 576 days


#3 posted 03-16-2019 04:12 AM

Thanks guys. After this project finishes up I’ll steer clear of construction lumber from now on. So is moisture content the main difference in 2-by material and Southern Yellow Pine I would get from my local lumber yard? Also in using poplar how do you typically go about finishing it? I’ve used it before but only really for painting projects, have you had any success staining or just adding a clear coat to it?

View AlaskaGuy's profile (online now)

AlaskaGuy

5133 posts in 2611 days


#4 posted 03-16-2019 04:40 AM

Any lumber you mill should have the same amount of material removed from both sides and left in manner that it get air around all sides. until you are ready to use it. .................................................................................................................................

I’m milling for an important project or expensive wood I’ll take 3 day to get to finial thickness.

There nothing quite as satisfying as taking some ruff cut lumber and milling it yourself. I like being in control of milling process. You don’t pre mill your project wood and set it aside for later use . You mill it after you have a project plan. You cut your pieces to lenght + couple inches before any thing else. Once that is done you can proceed with milling.

I flatten one face on the jointer, just enough to make it flat, then run them through the planer just enough to make that side flat and parallel to the first face. Once the faces are done I move on to the edges. That’s for the first day. At this point the stock is over size.

The next day I take some off each side but still leave it a bit over sized. Let that rest over night to see what moves. Don’t laugh I have stock move over night. Third and final day I mill it to finial size. All this time being careful as possible to remove the same amount of wood from each side of the stock.

No way the lumber yard can do what I described. They are just going to run it through a planer a time or two in full lengths and send it on it way. If you don’t use it right a way there still a good chance it can move on you.

I remember when I dind’t have a jointer and planer and have to use s4s stock from the lumber yard. Not many pieces were truly flat and many a time Id’ make a face frame the one piece would be thicker than the outer when butt together.

Here’s a table full of stock get ready for the last pass. Oh one other very important thing. Once you start the milling don’t lay the sock flat. Keep it so it get air to both sides of the stock.

I’ve milled a lot of wood over the years and my process has givens me great wood to work with. That’s a load of ruff cut cherry 4/4 lumber in that back ground.

That being said, “different strokes for different folks.

—Alaskan’s for Global warming!

-- Alaskan's for Global warming!

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Kirk650

598 posts in 1051 days


#5 posted 03-16-2019 02:29 PM

Alaskaguy has given excellent advice, and presented it well. I milled up some 2×12 pine yesterday, and rather than let it sit overnight (and maybe move a bit), I went ahead and did the assembly. Too many times I’ve put off till tomorrow or next week the assembly, and had it wiggle into a slightly different shape.

I’ve got some old dry walnut and cherry, and it won’t move noticeably after milling. Recently I bought a bunch of hard maple to use to build a large cabinet for my sister. I did not expect it to move much in the short term, but I was wrong. Had to mill it a touch oversize and then later mill it to the exact size as using it in the build. And even then the darn cabinet itself did a bit of shape-changing over the 2 weeks before my sister came to get it. Actually, looking back, it was good that I had it for a time after the build. I was able to avoid having her deal with sticking doors and such.

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tomsteve

919 posts in 1522 days


#6 posted 03-16-2019 02:54 PM

even with properly dried lumber what you experienced can occur. some lumber is cut from trees that were leaning and there are internal stresses in the lumber. those stresses can be relieved as the lumber is processed resulting in cups,bows,twists.

View jonah's profile

jonah

2038 posts in 3601 days


#7 posted 03-16-2019 03:46 PM

Most construction lumber has the pith of the tree in it (the very center). That will cause you no end of problems, because it will warp like crazy.

If you absolutely have to use construction lumber, you need to let it dry from the ~25% moisture content it comes with (even “kiln dried” is absurdly wet) down to under 10%. Waiting that long likely means most of the boards you have will warp some before you touch them.

I made my workbench from construction lumber, but I’d never use it for any kind of fine furniture. It’s just too unpredictable.

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lblankenship

19 posts in 576 days


#8 posted 03-16-2019 04:05 PM

Thanks guys, even more great advice. I really appreciate it. However, I have a couple more questions.

When you mill over multiple days on the second/third day do you flatten the same face on the jointer that you originally did day one, or do you just go with the most stable face at that point?

When you addressing the edges of the board in the first day, are you just running both edges over the jointer to remove as little material as possible? Or do you still rip the second edge on the table saw?

When aiming to remove the same amount from both faces do you just flatten one face on the jointer then get a parallel face on the planer then flip the boad back and forth when running through the planer to achieve that result?

Thanks again guys this is all really going to help me out in the future.

View AlaskaGuy's profile (online now)

AlaskaGuy

5133 posts in 2611 days


#9 posted 03-16-2019 06:11 PM

lblankenship
Time for more information on you part.

What was your 2×8 stock? (species)

What jointer do your have.

How long is the stock you are jointing?

How long are your combined jointer tables?

How much experience do you have using a jointer?

-- Alaskan's for Global warming!

View Kelster58's profile

Kelster58

717 posts in 842 days


#10 posted 03-16-2019 09:10 PM

I’m in the don’t use construction lumber group. I hesitate to run construction lumber through my equipment. You never know where those darn staples are hiding. I am buying clear kiln dried 8/4 poplar wood for $1.80 per board ft. $1.60 per board foot for 4/4. I know it’s twice the cost of construction grade lumber but it really is worth it. The wood I get from this mill is very stable. I usually just run it through my planer, no jointing required. Once in a while I’ll get a board that cups a bit. Then I do have to joint the face but usually I just run it through my planer. Good luck to you !

-- K. Stone “Tell me and I forget, teach me and I may remember, involve me and I learn.” ― Benjamin Franklin

View lblankenship's profile

lblankenship

19 posts in 576 days


#11 posted 03-17-2019 04:27 AM



lblankenship
Time for more information on you part.

What was your 2×8 stock? (species)

What jointer do your have.

How long is the stock you are jointing?

How long are your combined jointer tables?

How much experience do you have using a jointer?

- AlaskaGuy

Southern Yellow Pine

Powermatic PJ-882HH

66” is the longest board. Final length after milling is 60”.

82” total for both beds.

I started with a small 8” benchtop jointer and recently upgraded to my current machine. I’ve watched countless videos on techniques as well as gotten some pointers from a local professional woodworker near me. I’m pretty comfortable with it.


I m in the don t use construction lumber group. I hesitate to run construction lumber through my equipment. You never know where those darn staples are hiding. I am buying clear kiln dried 8/4 poplar wood for $1.80 per board ft. $1.60 per board foot for 4/4. I know it s twice the cost of construction grade lumber but it really is worth it. The wood I get from this mill is very stable. I usually just run it through my planer, no jointing required. Once in a while I ll get a board that cups a bit. Then I do have to joint the face but usually I just run it through my planer. Good luck to you !

- Kelster58

Good to know! What do you typically do to finish the poplar? I’ve always seen it recommended for painted projects due to the greenish tint not being as appealing. Have you had any luck staining or a natural finish with it?

View BlueRidgeDog's profile (online now)

BlueRidgeDog

330 posts in 82 days


#12 posted 03-17-2019 11:47 AM

As to re-milling, you have to work on the concave side regardless of what side you previously flattened.

Even bone dry wood can move some, as milling often relieves or exposes existing stress. I have been burned twice this year milling stock to final dimensions in one sitting…only to find the next day that some of my drawer sides or a cabinet stretcher had a bow to it.

View Dave Polaschek's profile (online now)

Dave Polaschek

3477 posts in 885 days


#13 posted 03-17-2019 12:14 PM

Good to know! What do you typically do to finish the poplar? I’ve always seen it recommended for painted projects due to the greenish tint not being as appealing. Have you had any luck staining or a natural finish with it?

I finish poplar (and all my shop furniture) with oil and shellac. Some of it is more greenish, but I can often pick boards that are more brown than green. I use either poplar or pine for most of my shop cabinets, and the greenest poplar goes to interior bits, backs, etc. But as I’m the only person who has to look at it, a little greenish tint doesn’t bother me too much. And if it does bother me, orange shellac will turn it brown.

-- Dave - Minneapolis

View Carlos510's profile

Carlos510

39 posts in 674 days


#14 posted 03-17-2019 05:15 PM

Wet construction grade lumber is hard to work with, it is normally kiln dried to 22-25% MC and things like heart wood and stressed lumber are not taken into consideration as long as it can be sold. I agree with some of the other posters, to get the movement you indicated it is probably stressed wood. Ideally for fine projects you want straight grain, quarter sawn and 7-10% MC, 8% is perfect. Crooked grain may indicate stressed wood, it may look ok but internal stresses created in the trees growth will move the wood every time you change its dimension. The best use for such wood is the wood stove.

-- From popular rap:"If time is money, then I need a loan." Carlos B., http://www.hobbyworkshopprojects.blogspot.com/

View OSU55's profile (online now)

OSU55

2159 posts in 2292 days


#15 posted 03-17-2019 05:39 PM

You can always add some color with dye or pigment stain to get rid of the greenish poplar color. Poplar is about the worst blotching wood there is and benefits a great deal being properly conditioned first. Its fine for shop stuff but I wont use it for any parts that show for furniture except if it is painted.

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