Flattening Really Wide Boards

Years ago I came to possess a really large walnut log and had it sawn to my specifications on a band mill. I then air dried it and have stowed most of it ever since. Many of the plain-sliced slabs yielded widths of between 20″ and 33″. Yes, I consider myself a lucky man.

I’ve used a few of the wide slabs over the years for special projects, mostly tabletops and doors where the beautifully colored walnut displays all its glory. And no, I don’t rip the boards into narrow pieces and glue them back. I just use these wide pieces as they are.

But wide stock like this can be problematic when it comes to flattening it. Jointers don’t have the capacity and sending it through a planer, even if you had one that big, would not remove twist or cupping. Flattening could be done with handplanes, but I don’t have the requisite planes and blades; besides, it’s not my style of working.

So over the years I’ve tackled the problem by doing some work with one handplane then switching to an 18″ “C-arm” drum sander. First, I make sure that the board I’ve selected is reasonably flat to begin with. Most of my stock is, because I stickered it carefully while drying it. And this log, and maybe walnut in general, didn’t have a lot of stress in it.

I put the board on my bench and assess how much twist may be in it by looking at the corners. Are any off the table and by how much? Next I use a straightedge the check across the width for high/low spots. There usually are some near a knot or at the edges of the new wood growth.

When I’ve made these determinations, I use my handplane to knock down the high spots and the corners that show the twist. By flipping the board to the side I’ve planed, I can reference the side to my flat benchtop. This work may take 15 minutes at most.

Next I go to the drum sander with an #80-grit belt installed. The thing about these relatively small drum sanders is the infeed and outfeed rollers that hold the work down don’t really exert much pressure like a planer does, and therefore they don’t force the stock flat to the table. The other thing is, I’ve found these sanders will consistently sand widths wider than their 18″ capacity with differences edge to edge of only a few thousandths. All you do is turn the board and send through the portion that didn’t pass under the sanding drum on the first pass.

Because only light passes are possible on these machines, they will first sand high spots on the board. And because the side that will be reasonably flat from the handplaning is always down, you just keep sanding the one side until it is uniformly sanded. Then you turn the board over and follow the same procedure on the opposing face. Depending on the board, the whole process may require 30 passes or more in all. Then, when both faces are cleaned up, I switch to a #120-grit belt for a couple passes to get rid of the coarse sanding scratches.

I won’t claim the process leaves this wide stock dead flat. But given it’s width, and given that it’s often being used for a top of some sort, any minor twisting can be pulled out when fastening it to it’s base. Using the sander this way has been effective for me. My only complaint is it can be a bit boring.

Steve Shanesy

 

19 thoughts on “Flattening Really Wide Boards

  1. kwhp1507

    Steve, I want to thank you for the informative article! I am new to woodworking (1.5yrs) and my background as an Electrician, FF/A-EMT, PI (primary instructor for EMS) do virtually no help for me other than a respect for and general tool knowledge. That is why I subscribe to “Popular Woodworking” and not Fine Woodworking. I feel I learn more from you guys and gals articles because it’s not all “high end” woodworking! I would have not thought of using the sander to aid in the milling process. Keep up the good work!

    If I could make 1 suggestion to the magazine it would be to do more than 7 issues a year. Thanks again.
    Kevin from Ohio

  2. Richard Dawson

    I think we are being a little harsh in dealing with Mr. Matthews. It is obvious he is frustrated due to the fact that he isn’t where he belongs — in Congress. I’m sure he would be a BFF to the lady from MN, or any of the particularly vocally adroit gentlemen who hail from places such as TX, KY, or the former members of the club who claim FL and IL as home turf. Apologies to any (un)worthy members omitted.

  3. JayWC

    I agree with the author and have used my machine to do the same. Now having said that, I have a Delta 18-36, like the one shown, for sale. I hope this comment gets left up because I’m not trying to spam the post. For those of you who are interested in trying this technique and interested in purchasing a used machine with low miles, please contact me via email – one_in_millions AT hotmail DOT com. It’s a great machine and I no longer use it because I upgraded to a Jet 22-44 Oscillating Drum Sander. I apologize for posting this on this article and hope I don’t offend any of the readers or editors. I’m just trying to get the machine into hands that want to use it versus it sitting in a corner of my shop collecting dust.

  4. aksarben1010

    If I were to use power tools I think I would have done router rails instead. Fairly efficient and the width is flexible, also you can both flatten and thickness the board at the same time.

  5. dave_willemain

    You have made it much too hard for yourself!
    If you do not have a scrub plane or electric (heresy to some), get one. Using winding sticks, this is very managable.

    The other alternative is to use a jig to guide a router. Many have been published, the most recent in Fine Woodworking last fall.

    These methods are NOT mutually exclusive.

  6. Jim Matthews

    “This is a brilliant idea, I never would have thought of it! (SARCASM) Is this the best idea for an article, that you could come up with? I’m truly glad I no longer subscribe to your magazine.” gsm627

    This is a useful inexpensive technique for starters.
    If you have a better method, feel free to educate the rest.

    You don’t subscribe, yet you deride?

    This sort of criticism is the best you can do?
    The sarcastic think themselves witty, but are only half right.

  7. gsm627

    This is a brilliant idea, I never would have thought of it! (SARCASM)

    Is this the best idea for an article, that you could come up with?
    I’m truly glad I no longer subscribe to your magazine.

    1. Megan Fitzpatrick

      We get asked such questions regularly. We do our best to provide a range of information to help readers of all levels of woodworking experience; sorry you found this particular free post unworthy of yours.

    2. snburton72

      Maybe they forgot that when you lay your hands on your first piece of rough cut lumber you are instantly imparted with unlimited knowledge of wood working. (SARCASM)
      Did you ever stop to think that maybe there is some one new to woodworking that did not know this already.

    3. nateswoodworks

      I have done the same on grarly woods that are fighting the planes and it works good. As for you gsm627, I am thinking with that tude it would also be best if you stayed off the website as well. These fine editors do their best to provide new material and keep us entertained-not an easy task in a a hobby that has been around since before Jesus himself used a plane and saw! Not to mention this part is free, and you still must complain!! Great article Steve.

        1. Steve_OH

          When someone plays the “free speech” card after having been criticized for being an ass, it is a pretty clear indication that they are, in fact, being an ass.

          -Steve

  8. bubbainmiss

    Just a note–I can assure you that walnut in general has as much (if not more) stress than any other wood. I’ve surfaced & squared up pieces & come back to the shop in a day or two to find a crooked, bowed, diamond shaped piece of wood. You should be very thankful for the walnut you’ve got.

  9. introp

    Most big commercial shops that make tables will let you rent time on their monstrous wide (closed) belt sanders. (In the two cases I’ve done it, you hand the board off and stand well back while an employee runs the machine.) It’s really quite cheap once you figure out how many hours it takes to do it by hand.

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