Board cupping

[richard b miller]

i have pine 1x4's that i plan to use as long (42") drawers. they have a slight cup (~1/8") to them.
in your opinion, should i:
a. slightly plane out the cup and just thin the drawers all around
b. put them together and not worry about the cup
c. replace the cupped boards

any comments appreciated.
thanks
rich

[Bryan Lisowski]

I would go choice A, but I would rough cut to dimension first. If that doesn't work, I would go buy poplar instead of pine.

[Ted Derryberry]

Better yet, plywood. I work with a lot of yellow pine because that's what a steady customer specifies. It's nothing but a moving target. I can mill something one day and the next you'd think it came out of the bin of construction lumber at the big box. This is after having it in a relatively stable shop for a couple of weeks. If I have to pick up material and work on it immediately it's even worse. I try to mill and assemble with as little time as possible in between and hope it all works against each other in the long run. When I glue up panels that aren't going into frames for a while I clamp them all together to try to keep them flat. In short, no matter what you do to your pine today, your drawers might not work well tomorrow.

[Tom Trees]

How fancy do you plan these drawers to be ...
You could rip those boards and orientate the boards in a way to counter the cupping..
As in looking at end grain, you would see smiley, sad, smiley grain...
This way you would get a wavey board instead of a big cupped one

[Andrew Hughes]

I'm found the thinner a board gets the more it cups. So I pick C.

[David Eisenhauer]

In my experience, Ted and Andrew have called it right. Mill then immediately do the joinery as quick as possible. A drawer at a time only and not worry about efficient work methods like doing all of each step on all of the boards before going to the next step. If you have some pre milled material left over at the end of the day, then clamp it all flat with cauls or something similar to your bench overnight. Wait till you have some stuff planed down to 1/4" for the drawer bottom and see how it resembles a potato chip the next day if left "free ranging". Better yet, if it is possible, do what Bryan says and go to poplar or as Ted said - go to ply.

[Wayne Lomman]

Dress it flat. If it's cupped again next day, use it for firewood and buy something better. Whatever you do, don't just proceed and hope for the best because the best will not be pretty. Cheers

[Ted Derryberry]

Good point, the thinner it is the more likely it is to cup, bow, warp, twist, crawl across the workbench, etc.

[Rick Alexander]

This is why I've had to go to a policy of making my dovetails the same day as I mill my lumber to size. Even poplar wants to misbehave when I plane it to 5/8 but once it's assembled it seems to stay straight. I dovetail all 4 corners because of t his as well.

[Ted Derryberry]

I also bundle small stock that's milled but I can't get to for a couple of days with stretch wrap. I ship a lot so I buy it by the case and it's just over $3 each for 80 gauge 5" x 3000' rolls. I keep one handy with all my "go to" hand tools. I think the borg has individual rolls if you don't need much.

[lowell holmes]

Lumber core plywood makes good drawer sides.

I prefer drawer side material from the BORG if you can find it.

1X6 jointed and thickness planed in the shop if you have seasoned dry wood.

[Lee Schierer]

I frequently use 1/2" kiln dried yellow poplar from a local supplier for drawer sides and I don't think I've ever had a piece that came to me milled to 1/2" cupped. I have several short pieces of left stock over that are currently in my shop and after reading this thread, I went out and checked them for flatness and they are still flat. The moisture meter I have reads 6% and these pieces have been in my shop for a year or more and are unfinished, not stickered or weighted down.

[Art Mann]

I don't use it for furniture but I use a lot of SYP for jigs and shop cabinets and structures. I normally keep a stock of it drying in the hot second story of my shop. I leave it for 2 or 3 months in the summer even though it is already supposed to be kiln dried. Then, I joint and plane it down exactly as if it were rough sawn lumber. For example, a 2X4 will become 1-3/8" X 3-3/8". Lumber that cups or twists is often recoverable. I have to cut it into short and/or narrow pieces first to reduce the amount of material removed on the jointer. In your case, a 1X4 would machine down to 7/16" or 5/8" by 3-7/16" or 3-3/8". After it is milled this second time, it usually won't cup or twist again.

[Ted Derryberry]

In my experience it might be relatively stable if you're only milling a little off of each face. If you're cutting it down significantly there's no telling what it's going to do. Just this week I was making door stop material. The size is 7/16" x 1-1/2" and the most cost effective way to get that is to buy rough sawn 2x (8 in this case), mill it down to 1-1/2" and then rip it to 5/8" or so strips and make two passes through the planer to get to 7/16". I've had good luck with that method in the past, but this time when I ripped down one of the boards the small pieces took off in all kinds of weird directions. Pretty much turned to kindling before my eyes. The 2x had been in my shop well over a month, probably 2 or 3. In the future I'm just going to use any 1x6 that I can't get 3/4" thick jambs out of and keep milling it down to 7/16" and hopefully get 3 decent pieces out of it. I did the calculations on the board footage and it's more expensive that way, but in the long run will probably save me money and certainly time and headache.

I've made the mistake of making jigs and fixtures out of pine in the past. Never again. Plywood, MDF, or hard maple for me. I will use it for shop tables on occasion.

[richard b miller]

when i saw how much the pieces were cupped, i got pissed off and threw them outside in the rain, destined for the burn pile.
this morning, i picked them up and low and behold, they were almost perfectly flat, almost 0 cupping!
the moral of the story... getting pissed off makes you feel better and sometimes it even resolves the issues :-)

[Tom Trees]

It is not unheard of, to dampen the cupped side, as that's the shrunken side.
Makes a case for standing your boards on edge, or some other means of mamimum air exposure