Because I don’t work with pre-dimensioned timber, it always takes a while when working on a new build to get to the point of actually doing any joinery or reaching for the glue bottle. There is always a goodly amount of time spent on stock preparation. After a bit of a slow start on this build, all of the stock for the desk is now processed and lying in stick ready to be used.
I’ve written before about the benefits of traversing in order to flatten and thickness stock, but I’ve not spent much time talking about how to deal with the crowned side of a board. Which I think is an oversight for two reasons. Firstly, traversing is dead easy providing you can sharpen a plane and resist the urge to tilt it down as you exit the cut. Secondly, traversing the cupped face of a board before you have flattened the crowned face is a recipe for stock that wobbles and tilts under the weight of the plane, which definitely makes flattening more difficult. Because the cupped face generally provides a stable surface on the workbench, I normally flatten the crowned face before moving on to traversing the cupped face. So why not talk about flattening the crowned face?
In my defence, I don’t think I have come across a detailed description of flattening the crowned face of a board (most books will say something similar to “plane the peak with the grain until it is level with the sides” without giving much more detail, which is technically accurate but misses some of the nuance) so I’m not alone in neglecting this subject. I was reminded of this as I flattened the three 9″ wide and 54″ long maple boards that will make the top of my staked work table, all of which had a decent amount of cupping from their time drying at the tinber yard. And so I thought this would be a good opportunity to shed some light on an essential, but often overlooked, element of flattening timber.
Before I start planing any board, I first check for twist using winding sticks. Now, I really wish I had a beautiful pair of winding sticks by my friend Dan Schwank (and one day I will add these to my tool chest, because Dan’s work is impeccable). But in the meantime, a pair of 36″ long aluminium corner pieces works just fine. On this board the winding sticks showed that the extent of the crown was inconsistent across the length of the board, but this is easily planed out when removing the crown. For heavy stock removal like this I use the sole of my plane as a straight edge – it is always at hand, and is plenty accurate when judging where to take the next heavy cut from. My Starrett straight edge stays in the tool chest until I’m checking finer work.
All of the crown is removed with a jack plane fitted with a cambered iron, set for as heavy cut as I can comfortably take. A heavy cut removes more material, and gets the job done quicker, but there’s no point exhausting yourself by trying to take superhuman-thick shavings! Start off by planing the very peak of the crown, along the grain, focusing on the highest areas of the length of the board, and then working the peak of the crown across the full length of the board.
When the plane bottoms out in the cut, I check the crown with the sole of the plane. What you expect to see is a small hollow where the peak of the crown was, and a new peak to either side of the hollow. I plane the new peaks out, and then work the mid-point (where the original peak was) to ensure that I’m not planing a new crown into the board. Skewing the plane a little helps the toe and heel of the plane ride on the two new peaks, and when you bottom out in the cut you know it is time to work the new peaks again. I try to take an equal number of shavings from each of the new peaks, check my progress with the sole of the plane, and then work the middle.
And then repeat. Many times. What you find is that as the middle of the board gets lower, the two high points move further apart towards the edge of the board. When the high points are on the very edges of the board, the board effectively has a very slight hollow. Check with the winding sticks to make sure that the board is free of twist, and then lightly traverse it until it is flat. All of this is done with the jack plane, and only after that light traversing do I reach for a different plane.
I’m trying to learn from Joseph Moxon, and allowing the purpose of the timber to determine which plane I reach for – does the workpiece need to be dead flat but not super smooth, dead smooth but not necessarily cricket-wicket flat, or both deadnuts flat and super smooth? The tyranny of assuming everything needs to be perfectly flat and smooth can be hard to shake, but thanks to Mortise and Tenon, and Moxon I’m making progress in my rehabilitation. For the top boards for the staked worktable, I reached for the No.8 jointer once the crowned face was flattened with the jack, as I need the boards to be flat before they are jointed and glued, but won’t be smoothing them until the table top is glued-up. And so my No.3 stayed in the tool chest for this session.
With the stock for the table all processed, my next task will be to joint and glue up the boards for the top, after which I can start work on shaping the battens and legs.