flattening wide boards

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Forum topic by brianlsu43 posted 12-22-2010 04:13 PM 3536 views 0 times favorited 15 replies Add to Favorites Watch
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18 posts in 3256 days

12-22-2010 04:13 PM

I am curious to know how most LJ’s flatten boards which are wider than their jointers.

I have seen several creative ideas using a planer (planer sled, glue rails, routed bottom rails, etc.)

I have some 13” wide hard maple with some minor cupping.

For the project I am working I will need a 11.25” wide board.

I was thinking of ripping the board into 6” wide pieces and jointing the faces. Then I would glue up to the desired width.

Is there any reason why this wouldn’t be a good idea?

15 replies so far

View Dan's profile


3630 posts in 3083 days

#1 posted 12-22-2010 04:32 PM

Have you considered using a hand plane? IMO it would be a lot easier to do that then rip them, joint them and glue them back up…

-- Dan - "Collector of Hand Planes"

View ajosephg's profile


1880 posts in 3764 days

#2 posted 12-22-2010 04:35 PM

I think ripping and gluing them back together is the best bet because it will minimize future cupping.

-- Joe

View live4ever's profile


983 posts in 3213 days

#3 posted 12-22-2010 05:00 PM

Ripping, jointing, gluing is fine so long as the amount of cupping is not severe enough to cause problems on the TS.

-- Optimists are usually disappointed. Pessimists are either right or pleasantly surprised. I tend to be a disappointed pessimist.

View PurpLev's profile


8547 posts in 3851 days

#4 posted 12-22-2010 05:38 PM

rough facing with a hand plane then use the planer to true the opposite face, flip and use the planer to finish off the first face. at least that’s how I do it -see my latest project blog where I milled 8” boards here:

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View TheDane's profile


5552 posts in 3866 days

#5 posted 12-22-2010 06:01 PM

Depends on how bad the cup is.

If it is minor, then do as PurpLev suggested … I have done that quite a few times at it works like a charm. I have a #5 that is setup to work as a scrub plane to do the rough work. Some LJ’s also use a planer sled, but I have never done that.

If it is bad, you could either rip/flatten and glue (which I have done on the top of a table project I am working on now), or you could cut a 2/3 or 3/4 depth kerf into the cupped side, put pressure on it to flatten it, fill the kerf with wood filler or glue in a spline, then plane to thickness. I have not done the latter, but just last night, I saw Norm pull this off in one of the old NYW shows on the Create TV channel.


-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View Gregn's profile


1642 posts in 3186 days

#6 posted 12-22-2010 06:14 PM

Ripping and alternating the growth rings and gluing up panels has been a pretty common practice for a long time, alternating the growth rings has proven to minimize cupping and splitting.
The only reason you may not want to use this method would be to preserve the grain pattern of the board that would be difficult to match up the grain pattern, or accentuate the project being used on.
As stated, rough jointing with a hand plane then cleaning up on the planer is a quick method and one I have used myself.

-- I don't make mistakes, I have great learning lessons, Greg

View JPNpro's profile


39 posts in 2967 days

#7 posted 12-22-2010 06:17 PM

Your method is tried and true. If you have access to a wide belt sander that works. If you have a smoothing plane, it works well and you get a good workout!


View AaronK's profile


1507 posts in 3667 days

#8 posted 12-22-2010 07:22 PM

i also agree that flattening it whole is ok for a small cup. i would also suggest some method of preventing future cupping such as using battens underneath or breadboard ends. I’ve used a quick and dirty planer sled with a lot of success. there are some really fancy designs, but all you need is something that is flat (particle board works great!) and some wedges. one thing people may not realize is that the sled itself can flex along its length as long as you set the wedges while the sled is on flat reference surface when you place the wedges.

if the cupping is more pronounced, then it’s easy to see how you’ll be losing substantial thickness doing it that way. if this is the case, ripping into smaller strips is the way i’d go.

View Kevin's profile


466 posts in 3408 days

#9 posted 12-22-2010 07:34 PM

Edge joint, rip into smaller strips, face joint, plane, dry fit with alternating grain unless grain pattern is horrible then glue back up. Run through a belt sander or sand by hand.

-- Williamsburg, KY

View 8iowa's profile


1587 posts in 3964 days

#10 posted 12-22-2010 08:05 PM

I agree with PurpLev. Since I have a great many rough sawn boards, I clamp a wide board flat on my bench, and then with winding sticks and a #5 hand plane I get the sticks parallel all the way down the board. Sometimes, if necessary I’ll take a #7 plane and run it full length a few strokes.

This sounds like a lot of work, but it is not necessary to finish plane the whole surface. The objective is to get the board flat enough to run thru the planer. I’ve done this procedure many times with boards as long as 104 inches. It works like a charm and really doesn’t take a great deal of time. My 4” jointer is used almost exclusively for edge jointing.

While ripping boards to smaller widths, and gluing up with alternating grain produces a more warp free board, it often is not nearly so esthetically pleasing as a wide board. These are trade off decisions that woodworkers must make.

-- "Heaven is North of the Bridge"

View miles125's profile


2180 posts in 4208 days

#11 posted 12-22-2010 08:52 PM

If it’s 8/4 maple or thicker you can simply run it through the planer concave side up and have an instant flat surface. If it is thinner and therefore too easy to flex in the planer for that approach to work, you can simply tack you a 1/8” +- strip down the center of the convex side to prevent the flexing and go about it the same way. Of course any twist or warp in the board will make this method not so good in achieving a desirable flatness and the old time consuming hand plane may be your best bet.

-- "The way to make a small fortune in woodworking- start with a large one"

View jusfine's profile


2422 posts in 3128 days

#12 posted 12-23-2010 12:50 AM

There is also a great video that impressed me by The Woodwhisperer on this exact subject (flattening a board too wide for jointer).

If I can find the exact one, I will add it here.

I learned a trick or two from the video, that’s what it’s all about!

All the Best!

-- Randy "You are judged as much by the questions you ask as the answers you give..."

View jevarn71's profile


83 posts in 3363 days

#13 posted 12-23-2010 04:14 PM

The method I use involves removing the cutterhead guard from the jointer and face jointing the majority of the board. Next I place a piece of MDF on the planer with a length at least the same as the in-feed and out-feed tables and a width at least the same as the jointed surface of the board. With the jointed surface of the board running on the MDF, I plane the full width of the opposite side of the board. Finally remove the MDF and plane the remaining surface of the jointed side.

One note of caution: be extra vigilant when jointing without the guard. Also, I still try to limit the width of the board to no more than a third more than width of my jointer simply because of the lack of support of the extra width during planning. So with my 8” jointer, 10.5” is my max. Anything wider (up to 13”) I’ll use a planer sled.

-- Jason, JEV Woodworking

View knotscott's profile


8150 posts in 3578 days

#14 posted 12-23-2010 07:19 PM

Boards up to 13” I put on a planer sled and use my planer. For boards wider than that or for fixed surfaces (like a table or standing workbench) that can’t be put through a planer without dissassembly, I use hand planes.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View griph0n's profile


68 posts in 3546 days

#15 posted 12-23-2010 08:58 PM

I use the jointer flip technique and handplane the ridge off if it’s only an inch or so wider than my six inch jointer.

For long table top boards I built a sled for the planer using FWW plan from here: There’s a good video with it.

I built a huge 24’” by 8 foot sled to use on a friends massive planer to joint a bunch of big 18” walnut and Cherry slabs. Way more accurate than skip planing them.

Then I built a shorter 5 foot version to fit my 12” planer. It’s bit unwieldy(?) working solo, so …

Then I built a little 3 foot sled to joint a bunch of 12” single board door panels I needed.

They are a little fiddly to use but perform well. I made simple torsion boxes for the sled base out of MDF and they are stiff and straight even over the 8 ft span. I only had 3/4 MDF handy for the short short sled and it ended up too thick for my little planer with a 5/4 board, so I just ran the sled through the planer until the MDF was a quarter inch thick on each side. Nasty dust, I really hate MDF, but works fine. I think the article says to use laminate for the bottom, but I poly’d and waxed the bottom and it slides fine.

The sled construction is a few hours work, but when they’re done, there always there. The boards always get handplaned in the end, but this is much faster than dimensioning lumber by hand. I learned my lesson flattening my benchtop. Fun but time consuming.

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