Flattening Long Boards


Keggers
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Hello Fellow Woodworkers,

I need some advice on SAFELY flattening long boards. I'm talking about boards that are 7 to 8 feet long. Much too long for my jointer. I'm making my own chair rail molding and I have several hundred bf of rough cherry. None of the boards are perfectly flat and I'm sure there is some degree of cupping on each board. I'm thinking that if I just run them through my planer - alternating sides - I won't get sides parallel to each other. The finished thickness needs to be 1/2 inch. Any help will be greatly appreciated.

If I can't find a good solution I'll just have to buy pre-made cherry molding.

Thanks!

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Hello Fellow Woodworkers,

I need some advice on SAFELY flattening long boards. I'm talking about boards that are 7 to 8 feet long. Much too long for my jointer. I'm making my own chair rail molding and I have several hundred bf of rough cherry. None of the boards are perfectly flat and I'm sure there is some degree of cupping on each board. I'm thinking that if I just run them through my planer - alternating sides - I won't get sides parallel to each other. The finished thickness needs to be 1/2 inch. Any help will be greatly appreciated.

If I can't find a good solution I'll just have to buy pre-made cherry molding.

Thanks!

Have you tried to use some sort of infeed support? you might be able to make a MacGyver'd version of an accessory table extension..

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If the boards are pretty flat to begin with, you can always try skip planing. Basically, try taking alternating light passes on each side with the planer. If there are major issues with the board like excessive cupping or twisting, this won't work. But I have used this technique many times on long boards that are already pretty flat. And don't forget, a little bow over a 7-8' span is really nothing to worry about as long as you have a consistent thickness.

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If the boards are pretty flat to begin with, you can always try skip planing. Basically, try taking alternating light passes on each side with the planer. If there are major issues with the board like excessive cupping or twisting, this won't work. But I have used this technique many times on long boards that are already pretty flat. And don't forget, a little bow over a 7-8' span is really nothing to worry about as long as you have a consistent thickness.

Skip planing was what I was going to try if I couldn't find a better method.

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I've made a long sled out of two pieces of 3/4 MDF glued and screwed together for the planer. Lay the rough stock on the sled and wait for it......hot glue the board on the edge down to the sled. If you have a corner or section not laying flat, slide a door shim under it and glue it in. Let the glue set and send it through. I've had great success with this method.

Once you get one side planed down, you can take it off the sled and run it through the planer without the sled.

Just set up a few roller stands to help support the whole thing while running it, or get a helper. :D

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For chair rail, it doesn't need to be flat. Just plane both sides even. The edges need to be parallel and it will nail on to the wall flat.

lol..true Rick...always the voice of reason. I didn't think about what the wood was for. As long as the twist, bow or cupping isn't drastic, it will nail down flat.

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None of the boards are perfectly flat and I'm sure there is some degree of cupping on each board.

Just to be sure, are they cupped or bowed...or both? Cup is across the face whereas bow runs the length of the board.

I'm thinking that if I just run them through my planer - alternating sides - I won't get sides parallel to each other.

Actually, that's precisely what you'll get. The planer will also take out any cup across the width of the board. The only problem to watch out for is that the feed rollers can squash a cupped board flat as it goes through. The board is artificially flat as it hits the knives, but then the cup springs back as it exits the machine. This phenomenon gets worse as the stock gets thinner. A few transverse passes with a scrub plane will give you a ballpark flat side prepped for the machine,

The planer is not capable of taking out a bow along the length of the board. (Excepting a planer sled as other folks have mentioned.) But this isn't strictly necessary for your purposes. Millwork isn't furniture. Even if you owned a battleship scale jointer and trued these boards dead straight over the entire 96" of their length, you'll put them in and discover that the wall is wandering all over creation.

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Hey I have had very good results with the "Planer Sled" that I believe Fine Woodworking has made and show cased.I have attached the link to their site for it. It's easy to build and Believe me when I say this, "It Works Great".I have planed down rough White Oak and Pine to a very smooth ,cup free, twist free board, then removed the sled and finish planing the board. I hope that you build it and see for yourself. Good Luck. & "Keep Makin That Sawdust,"

Lance

http://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesArticle.aspx?id=5245

Just to be sure, are they cupped or bowed...or both? Cup is across the face whereas bow runs the length of the board.

Actually, that's precisely what you'll get. The planer will also take out any cup across the width of the board. The only problem to watch out for is that the feed rollers can squash a cupped board flat as it goes through. The board is artificially flat as it hits the knives, but then the cup springs back as it exits the machine. This phenomenon gets worse as the stock gets thinner. A few transverse passes with a scrub plane will give you a ballpark flat side prepped for the machine,

The planer is not capable of taking out a bow along the length of the board. (Excepting a planer sled as other folks have mentioned.) But this isn't strictly necessary for your purposes. Millwork isn't furniture. Even if you owned a battleship scale jointer and trued these boards dead straight over the entire 96" of their length, you'll put them in and discover that the wall is wandering all over creation.

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