I have a planer question!

[MichaelA Cooper]

I have a 2" thick board that is slightly bowed. Can my planer clean up the bow if I cut away very small amounts on each pass? I'd use a jointer but I don't have one yet!
Thanks for checking out my thread and any help you can give me!!!

[Cody Colston]

Maybe, since it's 2" thick but the passes would need to be very light so that the rollers don't force the bow straight as it passes through the planer.

[Prashun Patel]

Conventional wisdom is that planers remove thickness - not cup or warp. The rollers will push stock flat; and it'll spring back when it gets out.

That being said, I have been able to do what you're trying to do. Try flipping the board upside down on each pass - taking very light cuts.

A cleaner way to do this is to make a planer sled. Make a sacrificial sled that supports the length of the board. Hot melt glue it or double face tape it - with STRONG TAPE onto the sled. Then place tiny shims under the outside edges to support the wood so it's not pressed flat thru the planer.

Once the one side is flat, flip and plane the other side normally.

[Darius Ferlas]

+1 for planer sled

[Jeff Monson]

Yes you can do that with a planer...but you need some type of sled to hold the board. The pressure from the rollers will flatten the board and the cup will not be removed. So you need to be able to support the cup from below...thus a planer sled. Once the top side of the board is flat, then plane away as normal. Hope this makes sense, you can also do a search for "planer sled" and you will get loads of information.

[Darius Ferlas]

Jeff, I wouldn't bet my life on a planer exerting enough pressure on a 2" thick board to flatten the cup. I think you could park an average sized sedan on the cup and it would not flatten, not in the short run anyway.

I thought the support under the material is meant to prevent it from rocking rather than from being temporarily flattened as is passes under the rollers.

In fact, if the board is perfectly straight otherwise and the sole issue is the cupping then I wouldn't even use a sled.

[glenn bradley]

Planer sled: http://www.sawmillcreek.org/showthread.php?t=58735

[Mike Cutler]

I agree that a planer probably wouldn't flatten a bowed 2" board much. A lot depends on width of the board and the species of wood.
The larger issue is that unless the material is very short, the board will use the infeed and outfeed table edges, or rollers if installed, as the reference.
As the OP stated that the board was bowed, not cupped. This means that the height of the material under the cutter head will be continually changing. I've done it, but it's a rough go for a planer, and I have a 3HP, Jet 15".
When the board is finally flipped the leading edge is likely to get caught in the chip breaker and cause problems initially.
A thick piece of MDF, or plywood longer than the board, to act as the reference, would be a good way to do it. No need for fancy. It may take some temporary support to keep the reference material from sagging going into and out of the planer.

[Peter Quinn]

bowed[/B], not cupped. .

Well, I have so rarely seen much of one without at least a little of the other, and sometimes they dance to make a little twist too! My short answer would be ISH. You might make the bowed board flatish, or perhaps flatter, with a series of light careful passes shaving off the crown. This is particularly effective if our friends cup and twist aren't invited to the party. Sometimes, particularly with flat sawn boards, you can relieve a bit of tension and the board will appear to find its new equilibrium in a relatively flatter plane that that with which you started. So mostly you will achieve at best flatish.

The choice to use a planer sled for me depends on how much defect must be removed, how flat I actually need the stock (not everything in wood working requires extreme flatness). Certainly an alternative to a jointer.

[Ron Citerone]

I would try to flatten the worst with a hand plane first, nothing fancy just get one side as flat as possible and then plane it with the flat side dwon, light cuts.

[Mike Cutler]

Well, I have so rarely seen much of one without at least a little of the other, and sometimes they dance to make a little twist too! My short answer would be ISH. You might make the bowed board flatish, or perhaps flatter, with a series of light careful passes shaving off the crown. This is particularly effective if our friends cup and twist aren't invited to the party. Sometimes, particularly with flat sawn boards, you can relieve a bit of tension and the board will appear to find its new equilibrium in a relatively flatter plane that that with which you started. So mostly you will achieve at best flatish.

The choice to use a planer sled for me depends on how much defect must be removed, how flat I actually need the stock (not everything in wood working requires extreme flatness). Certainly an alternative to a jointer.

Peter

Yeah, I've rarely seen one issue that wasn't accompanied by the others.

How's the weather up there in Litchfield County this morning. It got a little brisk in the Northeast corner of CT this morniing. Still, as they say,,,, "No heat 'til trick-or-treat".

[Lee Schierer]

The only way a planer can remove bow on a board longer than the bed of the planer is on a sled. You would need a stiff sled as long as the board and then you would need to shim under the high point to prevent the rollers from pressing the wood down as it passes under the cutter head.

Without a sled you can smooth the surfaces, but will end up with the same amount of bow when you are done.

Unless you need a board that long that is flat, cut the pieces to length and flatten the shorter pieces either by hand or on a large jointer.

Please note that bowing is an indicator of internal stresses in the board. You might be able to take the material off the convex side and the bow will reduce. It can also indicate uneven drying. Try laying the board on a paved driveway in the sun so the convex side is up. Drying the long side of the bow may shorten that side slightly and eliminate the bow. You can also dampen the concave side of the board and then sticker it on a flat surface and hold it flat with weights while the dampened side dries. Make sure you put plastic under the stickers if you are using a concrete or blacktop floor as your flat surface.

[Frank Drew]

Bow, probably not, but cup in a 2" board, yes; as Darius notes, a board that thick will in all likelihood resist the downward force of the pressure bars if you take light passes at first. [Cupped face down until you get a good enough flat on top.]

On the other hand, if a board is bowed I'd straighten it on the jointer (can you use a friend's?) and save a ton of time over rigging up a sled for the planer, IMO.

[Wayne Hendrix]

You can make a very simple sled with only a flat sheet such as mdf and some shims. Hot glue the necessary shims in place to support the board on the sheet and hot glue the board to the shims. Then take really light (1/32") cuts. That will keep the board being planned from rocking and being flattened by the rollers and wont take much time or money to make.

[MichaelA Cooper]

I tried the sled and it didn't work!
I'm just gonna have to find the money for a jointer I guess!
Thanks guys!!!