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How do i flatten a board that has a bowed edge?

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Forum topic by KenBry posted 04-27-2012 03:41 AM 2446 views 0 times favorited 19 replies Add to Favorites Watch
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KenBry

470 posts in 1908 days


04-27-2012 03:41 AM

I am trying to straighten several boards that are rough cut. I am trying to flatten the narrow edge so i can square them up width wise. The narrow edge is bowed where the center part sticks out more than ends.

I am trying to feed them through my old jointer except i can’t seem to get them to flatten. As a matter of fact they just get worse.

My jointer doesn’t have exceptionally long in and out feed tables. You can see it in my shop pictures. For what it’s worth i managed to get 24 out of 30 boards straight edged. These last few are kicking my butt.

Added info: the boards in question are 6 feet long, 4 to 6 inches wide and 1 (4/4) thick. The edge I am refering to is the 1 inch (4/4) thickness part.
I tried riping on a table saw but using the fence just got me a board that was worse.

One option I was thinking was to try to sister a straight board and cut it on the table saw. Double sided tape?

I was hoping there was a way to do this on the jointer. I tried the method below to grasp both sides and just work on the center till it came down. I wasn’t real sussesful. Lol

Hehe, yes I mean a Jointer, not a planer. I have an older model 54 powermatic, it has shorter in and out feed tables compared to the new 54A on the market.

-- Ken, USAF MSgt, Ret.


19 replies so far

View Lee Barker's profile

Lee Barker

2170 posts in 2311 days


#1 posted 04-27-2012 04:17 AM

Do you have a table saw? That would be the tool to straightline all your material before it goes to the jointer.

Technically what you’re talking about, I think, is hook In other words, if the board lays flat on the table but has an arc to it, like it wants to be the letter C, that’s hook.

If you need some help figuring out straightlining, I could help you.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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harry1

520 posts in 1746 days


#2 posted 04-27-2012 08:34 AM

When passing the board over the jointer Ken, grip the board firmly with both hands and with the centre high part resting on the table with each end off the table, several shallow cuts will bring it so that the full length is flat on the table, or am I missing something?

-- Harry, Western Australia

View David Craig's profile

David Craig

2136 posts in 2570 days


#3 posted 04-27-2012 08:55 AM

I think what he is trying to do is put a flat edge on the board. The problem is that, with a cupped board, he is not going to be able to use the jointer fence to put a keen edge on it because of the bow. What is going to happen is he is going to end up with a beveled edge instead.

Ken, I would flatten the face first. You might want to rip the board into several pieces so that the majority of the cup will be gone before using the jointer, then, flatten, edge, and then edge glue them back into a wider board.

-- There is little that is simple when it comes to making a simple box.

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harry1

520 posts in 1746 days


#4 posted 04-27-2012 10:28 AM

Ken says that he is trying to flatten the NARROW edge. When Ken mentioned “through my old jointer” could he be refering to a thickness planer I wonder, if so and it is in fact a cupped board, then feeding it through the planer with the hump uppermost, a flat reference side will be produced. Your further thoughts please David.

-- Harry, Western Australia

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David Craig

2136 posts in 2570 days


#5 posted 04-27-2012 10:40 AM

Ken will have to produce more details, some of what I gathered that he was edge jointing first was from the sentence – “For what it’s worth i managed to get 24 out of 30 boards straight edged. These last few are kicking my butt.” So I took that as edge jointing. You are right, his other references also indicate he could be face planing.

The problem I see with using a thickness planer is that by the time the hump was gone, there would be nothing left of the board. I learned the hard way that too much stock gets lost when trying to joint or plane a cupped piece. When ran through the thickness planer, the feeder will press the board flat, will take off some material, and then the board will spring back to a cupped position after it completes the pass. It will pretty much take the same amount of material uniformly leaving you with a thinner, but still cupped piece. If the board is ripped where the board curves, in multiple sections, most of the cup will be gone, and less material will have to be taken off to make each piece flat.

-- There is little that is simple when it comes to making a simple box.

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harry1

520 posts in 1746 days


#6 posted 04-27-2012 11:06 AM

I was actually thinking of cupped across the board rather then length wise. I agree, that with the latter, it’s a case of feeding a banana into a thicknesser and you’ll get a thinner banana out! I’m sure that Ken will come back with a more detailed account of the problem, in the meantime we’ve discussed solutions to a number of problems which may help beginners reading this thread!

-- Harry, Western Australia

View lunn's profile

lunn

215 posts in 1769 days


#7 posted 04-27-2012 12:50 PM

If a board has a crown (board on it’s edge sighting down the edge) and you want to save the lenght. Chalk line either edge use a skill saw and saw it stright. Then run it through a table saw to strighten the other edge. Presto changeo stright board!

-- What started as a hobbie is now a full time JOB!

View Don W's profile

Don W

17958 posts in 2028 days


#8 posted 04-27-2012 12:58 PM

Ken, when dealing with rough lumber I start by snapping a line on one edge with a chaul line (as lunn stated), or if the board is short enough, use a skill saw with a straight edge. That gets you a reference point. Then joint it (either power or plane) and you should be good to go from there.

-- Master hand plane hoarder. - http://timetestedtools.net

View CharlieM1958's profile

CharlieM1958

16241 posts in 3679 days


#9 posted 04-27-2012 01:10 PM

If there is one thing this thread proves, it’s that a picture is worth 1,000 words. Obviously, there are many ways to interpret Ken’s question.

I took it the same was as Lee, meaning that his best bet is to rip his board to relative straightness on the table saw before bringing it to the jointer. You can buy jigs for holding the board, or you can easily make your own.

-- Charlie M. "Woodworking - patience = firewood"

View crank49's profile

crank49

3980 posts in 2432 days


#10 posted 04-27-2012 01:12 PM

I assume by narrow edge you mean like the 1” edge of a 1×6.
So, like Lee said, the board wants to look like a C.
You can’t do anything with this on a jointer but make it worse.

You need to attach this board to a known straight board of equal or greater length, in such a way as the bowed, or hooked high part of the arc is overhanging the edge of the carrier board.

Now, with the straight carrier board against the fence of the table saw, and the fence to blade distance set to just let you rip off the high part of the crook.

After you have one edge straight line ripped, then you can remove from the carrier and put the new straight edge against the fence and rip the other edge to be parallel.

What you are left with is a narrower straight board.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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KenBry

470 posts in 1908 days


#11 posted 04-27-2012 01:12 PM

Hi guys, i added more info to the original postt

-- Ken, USAF MSgt, Ret.

View Don W's profile

Don W

17958 posts in 2028 days


#12 posted 04-27-2012 01:15 PM

I don’t have a picture of this, but I have also added a long piece of angle iron to my fence if I had a stack of lumber to rip. it cants the board slightly, but the jointing takes that out, and I have a true straight board.

-- Master hand plane hoarder. - http://timetestedtools.net

View CharlieM1958's profile

CharlieM1958

16241 posts in 3679 days


#13 posted 04-27-2012 01:23 PM

Ken, you are on the right track with the “sister board” idea. The general principal is that you must attach your hooked board to something with a straight edge that can run along the fence. Once you get the first edge straight, of course, you can just put that edge against the fence to straighten the other side.

These are pretty basic, but they do the job.

-- Charlie M. "Woodworking - patience = firewood"

View harry1's profile

harry1

520 posts in 1746 days


#14 posted 04-27-2012 01:43 PM

I reckon that the straight edge and table saw is the best of the suggested methods. Rough sawn rules out double sided tape so probably a screw at each end is the answer.

-- Harry, Western Australia

View KenBry's profile

KenBry

470 posts in 1908 days


#15 posted 04-27-2012 02:42 PM

Harry, Yea, I was thinking a screw as an option as well. Just didn’t want to add a hole in the boards. I am working with. I don’t have allot of room for to much waste.

-- Ken, USAF MSgt, Ret.

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