Need help: Straightening a crown

[Matt Day]

I've got some 5/4 Maple (rough) that's got a decent size crown in it. It's about 1/4" at the max over 8', when layed down with the crown up (obviously it's much more noticeable sighting down the edge).

Are there any techniques to getting this out? I don't want to just keep passing through the planer until I have a 1/2" board left.

Luckily it's just a crown and it's not twisted. I'm thinking of cleaning up the board with the crown in it, through the planer, but not taking all of it out. Then I'll let it sit with some weight on it until I'm ready to put it together for my table top.

Thanks,
Matt

[Andy Hoyt]

Look to your jointer

[Fred Voorhees]

Matt, at a 1/4" over 8', that really isn't much. What final thickness are you looking at getting down to? I would pass it over the jointer with the crown up and with just a few passes, knocking thickness off of the ends, it should bring it down to flat without compromising much thickness at the ends.

[Matt Day]

I don't have a jointer, and have been using the sled technique through the planer to give me a flat face.

It's a 1/4", but that's measuring the rough cut. This is my last board for a table top, and the thinest board I have after planing in 1.1". I suppose I'll take that crown out as much as possible and stop at a thickness of 1.1". The remaining crown I think can be worked out when gluing up the top. Would you all agree?

[Mark Singer]

You can steam it out with an iron a wet towel and so weight....on the concave side

[Per Swenson]

Pretty sure what you are referring to is called cup.

A crown is bent longitudely (sp).

So, what Mr. Singer recommends will work wonders.

Add heat and moisture to the inside of the C.

Per

[Stu Ablett in Tokyo Japan]

I just reach up and tip mine right or left to make it straight...... ;):D

I'd be happy to have only that much cup on a board, really it is not a lot. I'd be a bit careful of the steam and heat method, it surely works, but it will also come back to a certain point once cool and dry.

Is there no one around with a jointer you can borrow, rent for 10 minutes?

Cheers!

[Kirk (KC) Constable]

What's the orientation of this board in the tabletop glueup? Obviously, we'd like to have ALL the boards flat...but practically, you could reasonably expect that a straight board on either side of this one will take care of it. Been my experience, anyway...

KC

[Matt Day]

I'm sorry for my err in terminology; to clarify, the face of the board is not flat. The edge doesn't have a crown, but the face is cupped.

I think Kirk is right. I'll put the board that's cupped in the middle of two flat boards and use them to keep it in line.