You probably think I meant taking out the bow lengthwise. I actually meant I wanted to take out the bow across it's width on both sides.unless you build a sled a planer will not take the bow out of a board it will only make the two sides parallel. What are you building that you want to use construction lumber and why does it need to be flat?
What is cup warp?A small planer will work fine if you don't have to run too many at one time. They will overheat if you run it continiously. The little planers will work better for taking out a cup warp. Some of the larger ones the feed rollers are under so much pressure sometimes the rollers will flatten the wood and it comes out the other side will warp back where the little planers with the rubber rollers will just surface the high places.
I think any of those portable planers would do it but all I could swear to is mine. It's a Delta 22-560. Most of the experience I have had with planers is with professional grade powermatic planers. They have steel infeed and outfeed rollers that have considerable pressure on them. When you run a board through the rollers tend to flatten the board out while it is being surfaced and when it comes out the other side will bow again so on those planers it's not possible. The planer I have has rubber rollers with barely enough pressure on them to pull the board through. If you run the crown side up it will take the crown off. Depending on how much of a crown it has may take more passes but will flatten that side. Then once you have that side flat turn it over and flatten the other side. On a 2x6 you might end up with a board that is 1 3/16 to 1 1/4 thick before you get it cleaned up. Now if you were trying to flatten a 1x12 that probably wouldn't work. The board is too soft, too thin and too wide to do this.OK yeah, cup warp is exactly what I was referring to.
Steve, are you saying that a small planer is capable of taking the cup warp off both sides?
If I understood Ryan's post correctly, he's saying it's not possible.
Yes a jointer is commonly used for this purpose. Sometimes when I'm making an entry door I would purchase the wood rough sawn for the stiles because the boards may be bowed lengthwise as well as have a cup warp. You can run one face of a board cutting just the middle of the board or the ends so you can get it straight as well as flat. Then send the wood through a planer for the final thickness.You can take the cup warp off with a jointer?
I thought a jointer was only for the sides of the board...