Wednesday, March 6, 2013

Processing Stock By Hand: Reference Surfaces

Last weekend I had the opportunity to play with my local big band, the oTunes.  This gig was fantastic!  It was the culmination of years of rehearsals, recruiting musicians, and... well, ok, some adult beverages have been consumed as well.

I love playing trombone because it another way for me to express my creativity.  Funny enough, that is the exact same reason I do woodworking.

In fact, one could look at a lot of similarities between musicianship and woodworking.  They both take some practice, and they both take mastery of the fundamentals before you can make something worth listening to/looking at.

If a big band concert is like putting the last coat of finish on your latest work, then processing stock is like taking the trombone out of the case and putting it together.

Gig, from my point of view.
I mentioned in yesterday's post that there were a few steps to processing lumber by hand.
  1. First plane one face flat.  This is your reference face.
  2. Plane one edge square to the reference face.  This is your reference edge.  All other measurements are gauged off of these two references.
  3. Cut to length
  4. Rip board to width.
  5. Plane to thickness.
You can change up the order a bit, as long as you first do a reference surface, and  make your measurements from that reference.

Perhaps I should talk a little bit of what I mean by a reference surface.  Ideally, a reference surface should be a face or an edge of a board that is perfectly flat, free from bow, cup, or twist, and as smooth as you can make it.  In reality, it should be as perfect as you can make it.  Or, at least as perfect as is needed for your project.

It might seem like I am lowering standards a bit, but think about it, do you really need to work to the same standards if you are making a chipendale highboy as you would for a shop cabinet?  There comes a point when overkill is way too much done over again and again.

Let's do an example.  If you haven't done this before, I would recommend doing it on a small board first.  A good project could be a try square.  There are only two parts, and they are both small.

Take your rough stock that is somewhere around the size you need, and plane one face flat.  Once you get the saw marks off of it and the surface looks finished, it is time to check it.  If it is a small piece, I check it against the sole of my plane, which is flat.  If it is any larger than that, I'll check it with a straightedge.  If there is daylight under the middle, I know I need to keep planing.  Chances are better that there is daylight on the ends.  This means that I have to remove a hump.

To remove a hump, I start my plane with the handle lifted up, so the blade doesn't engage the wood.  As I push forward, I lower the plane until I start to cut, and before I get to the end of the board I lift the back of the plane up again.  All while making a smooth forward motion.

This takes wood out of the middle without also removing wood from the ends.  After a couple of these, I will clean up the surface with a few full length strokes.

Check again with your straight edge.  Repeat the above step if you need to, until the board is flat on it's length.

Next, I turn the straight edge to check the width.  If there is daylight here, do some targeted planing until it is flat in this direction, too.  The edge of my jackplane makes a fine straightedge for this job.

Once your board is flat on it's length and width, it is good, right?

WRONG!

Neither of these tests will detect twist.  Twist happens when the board is twisted along it's length.  This is easy to see with winding sticks.  Winding sticks are just a pair of sticks that have parallel edges.  You lay them across the grain of the board you are planing, one at each end.  Sight from a few feet away, and you will be able to see clearly if there is any twist.

If there is, plane from high corner to high corner a few swipes.  Then clean the board up, and check again.  Once your twist is out, check along the length and width again to ensure you didn't mess anything up.  If you did, fix it now, or you'll be sorry later.  A great project starts with some attention here.

Now, you can draw a swirly mark on like we did yesterday.

Once your reference face is done, you can start on your reference edge.  Do all of the same steps here as you did on the face, and you'll be good.   Of course, you also need to check that it is perfectly 90 degrees to the face.

If it is not square, use your fingers as a fence and take a shaving half of the width of the edge all the way down.  Follow this by a regular, full width edge shaving.  Repeat until your edge is perfect.

Reference face and edge.
This is a process that overwhelmed me at first, because I was used to being able to flatten a face and an edge on the machine jointer, followed by running through the planer.  While this process is slower, you do wind up with surfaces practically ready for finish.  Boards processed this way also give a certain something to a piece that one can't identify when looking at the completed piece.

The good news is that this is a skill that gets easier and easier the more you do it.

Next up, what to do with the other surfaces.

ps:  by the way, this is much easier if you have stock that is relatively straight and flat to start with.  So, if you weren't too picky at the lumber yard before, you will be next time!

2 comments:

  1. Winding sticks... that'll probably be the first build on my list as soon as I get my shop stood up.

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  2. I recommend the PS to go to the front of the class. It saves a lot of calories.

    ReplyDelete