Flattening Big Pieces of Wood

One of the most common questions I am asked is how I flatten the large pieces of wood I often use in my work.  This table top, for example, is approximately 45 inches wide and 96 inches long.

Relationship Study
Relationship Study

Machinery is Not the Answer

Perhaps one of the quickest ways to surface a board is to feed it through a thickness planer which removes material from the top.  The bottom of the board rests on the bed and the cutterhead above removes material until the board is of an even thickness.  However, the thickness planer is ineffective at making material flat unless the bottom is already flat.

Thickness Planer
Thickness Planer

When flat is the objective, the jointer is the answer.  This machine specializes in making one face flat, and one adjacent edge straight, flat and square to the face.  The board is slid across the flat tables and over the cutterhead between them.  Although you can establish four flat surfaces with a jointer, they likely will not be parallel.  The jointer and thickness planer need to work as a team to produce flat material that is even in thickness.


Another drawback of machinery is capacity.  To thickness the top of Relationship Study, I would have needed machinery with 48″ of capacity.  Most woodworkers have never seen a thickness planer that size, and I’m not even sure that a jointer that size even exists.  Machines also require the material to be brought to them and handling large pieces of wood gets tiresome quickly.

Hand-Held Tools Have No Limits

Unlike the jointer and thickness planer, hand-held surfacing tools have no capacity limits (but to require more skill and stamina).

When I am faced with a lot of material that needs to be removed, especially over a large area, I start with my power planer.  This one is made for large-scale work and is capable of taking a cut wider than many small-shop jointers.  It has a long sole which helps ensure that it leaves a flat surface.

Power Planer
Power Planer

After having done the preliminary flattening with the power planer, I use hand planes to refine the surface, removing any ridges or tearout.  I start with a long plane equipped with a convex blade which allows me to work fairly quickly, then I progress to a shorter plane with a straighter blade for a more even surface.

Hand Plane
Hand Plane

To get the second face parallel, if required, I use a cutting gauge or combination square with a pencil to mark the desired thickness on the edges.  Then I turn over the material and plane down to those lines.  It’s a lot of hard work, but it’s all worth it in the end.  It’s also a great fitness regime.

Pencil, Sliding Double Square, and Cutting Gauge
Pencil, Sliding Double Square, and Cutting Gauge

Hand-held tools, while not always as efficient as machinery, allow me to work with any size and shape of material I choose.  If I were to limit myself to working with material that I could surface with machinery, my work would look very different.

Machinery has its place, but so do hand-held tools.

19 thoughts on “Flattening Big Pieces of Wood

          1. Rob,

            As always, there are a number of considerations you need to take into mind before deciding whether a certain technique, such as setting up and using a router sled is worth the effort. Here are some of the things I would look at before deciding how to proceed:

          2. the size of the slab compared to the amount of space in which I will work;
          3. the flatness of the slab;
          4. the required flatness of the slab; and
          5. other tools available to do the job.
          6. Chris

  1. dajavoodoo :) nice lesson teach :)

    Note: an 24 inch planer would work nicely to get the two sides perfectly parallel after flattening the bottoms with the power plane and hand planners. Though (as you know) I prefer to glue up “rough” then flatten the top with hand tools power and manual- leaving mill marks etc on the bottom aka (max thickness in appearance with dead flat “true” top surface.

    There are machines “wide belt sander planer combo” machines that can be rented –
    in Chilliwack BC there is one 52″ wide there is a spiral cutter head top and bottom( two head molder) that is fallowed by two sanding belts. these work great BUT you loose much thickness and often some parts of the “Live Edge” is very thin and un-uniform.

    Again I really like this post
    Dan N

    1. Hi Dan,

      Sure, a 24″ planer would have worked in that situation, but I think there’s always going to be a slab of wood bigger than the planer.

      Would the two-head moulder create flat surfaces?

      Good to hear from you. Thanks for your input.


    1. Jonathan,

      This Makita 1806B power planer is the only one I’ve used (I’ve held others in the store), so my comments are based on that.

      As with hand planes, longer soles mean flatter surfaces with less checking. Wider cutterheads get work done faster, and some power planers come with shear-cut cutterheads. Bigger power planers are considerably heavier than smaller ones. The smallest one I’ve seen is 3-1/4″ and the largest is 12-1/4″ in width.

      Although I never use it to produce a finished surface, I’ve never noticed it create severe tearout whether used with, against or across the grain. Stock, square-edge knives tend to leave plane tracks, but the corners of the knives can be rounded (as done with hand planes) to eliminate those ridges. I like the edges square, as it gives me an easy way to tell where the planer is cutting and to what depth.


  2. Hello Chris,
    Yes there will always be a bigger piece of wood then your planner can handle and you “know”
    what I always say- a planner simply fallows a “plane” or if you put a think potato chip in you get a thinner one out. AKA a planner is Useless without a jointer!!!

    As for the “industrial thickness planner sander combo- # 1 it is a $600 000.00 machine meant for production work the one I mentioned mostly does Cedar,alder,maple,birch,&cherry smoking boards for the BBQ about 10 000 a day!

    These are Two head Planners one top and one on the bottom with depth of cut controlled by a computer so YES the joint and plane in one pass giving a “perfectly parallel dead flat surface.
    Though not a very natural look like hand Flattened work like mine or “yours” gives.

    I still am a huge fan of an 23 hp 9 foot Stroke sander like mine mixed with hand tools to work large pieces or huge glue ups in an timely manner with plenty of hand made appeal in the end product.
    as I always say it is ALL in the prep.

    again good post you brought up some very over looked facts about proper milling of any lumber!

    your friend and fan
    Dan N

  3. I’m just completing a milling machine having for flattening live edge slabs. It’s limits are 6 foot in width . . . and up to 18 feet in length. It is powered by a 3hp motor with A 4″ face milling head.
    The last phase of this project is the power feed. I have flatten three slabs (walnut & white oak) with very good results. I will post photos when it is completed.
    Google Dan R Braucht to find my flickr photostream . . . thanks for this site; enjoy, Dan

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