Monday, September 26, 2011

Building A Townsend Document Chest, part 2

(Go back to part 1)

A quick but important followup to yesterday's post. In retrospect, I think trying to resaw a full length board was just plain silly. It was unnecessarily laborious, and risked ruining the middle section of the board. It's just not practical. Chalk it up to experience (as in, the acquisition of).

I was partly inspired by Bob Easton's board-length resawing. But Bob is building boats, where keeping a full-length plank is important. There's no reason for me to keep this lumber full length. Different types of projects, different priorities.

I was also concerned about getting the maximum yield out of the board, even if the lengths of the pieces in different thicknesses didn't line up well. By resawing into two full-length boards, I could break them down into individual lengths later with minimum waste.

However, I think a much more sensible approach is to break the board down into rough lengths first, then resaw. The shorter pieces are much more manageable, whether resawing by machine or by hand. This breaks the job down into multiple smaller tasks rather than one large one. So the first step turns into a layout puzzle, adding up the lengths of the pieces in each thickness to come up with a segmenting plan that minimizes the waste. This is three-dimensional layout.

You just need to accept that there will be some waste. Say for instance you need to break a board down into four 24" lengths of 1/2" stock, and four 20" lengths of 1/4" stock. If you cut the board into 24" sections and resaw those, then cut the 20" sections from the thin pieces, you'll have four 4" lengths of thin waste. That adds up to 16" of waste, which might have been a useful length if not cut apart. But that's the compromise to make the resawing job easier.

Take the time to try out a few layouts to get the best yield. This is where cutting out full-size cardboard templates can help. Make one for every single part. Then lay one set on the board, all of the same thickness, allowing space for rough cutting. Lay the next set (of the other resawn thickness) next to the board, and group them to match up with the cut lines of the first set. Rearrange them to get the best match. When working with figured wood, this task is further complicated by trying to select for grain patterns.

There may not be a perfect solution to this puzzle, so don't drive yourself crazy trying to solve it. Eventually you have to make a decision and get on with the project, prioritizing between grain, waste, defects in the lumber, or other considerations.

For this project, the first board would be the top, sides, and vertical dividers, all the longest pieces, so my layout and cutting decisions for it were pretty simple. I marked them out and cut the first piece, which was partially resawn, then finished resawing it.

Some additional foreshadowing: while the piece I show here turned out pretty well, the next two did not. You'll see how I dealt with that in part 3, by first ripping the piece in half, resawing the narrower pieces, then gluing them back together.


Breaking down the first board into shorter lengths.


Completing the resaw of the first short piece. Bob Easton suggested getting up over the work a little more, and this did help. It changes the angle of attack and body mechanics. By rotating the piece to each corner repeatedly, you end up sawing down a diamond pattern in the middle until you get all the way through.


The pieces cut apart. There's a flap in the middle of the thin piece on the right that may be a problem. We'll just have to see how the final thicknesses all work out once I go to work with the handplane.

It's tempting to try to be perfect in every step when working with such fine stock, but this is after all a learning experience. A few mistakes are inevitable. Al said that many surviving period pieces show mistakes. The builders just dealt with them and moved on. Some mistakes are recoverable. And sometimes you have to be willing to set a part aside and make a new one. As you'll see in part 3.

(Continue to part 3)

2 comments:

  1. Yes, breaking the boards down first is a good idea. It can actually save wood if some of your components are thicker than others--you need to give the cuts some thought.

    Resawing in any quantity, especially in harder woods, is just a pain in the butt. I'm always looking at different ways to do it but one thing really seems to hold true every time: if you're not careful and try to save time, you'll end up with poor results that will take more time than if you were careful.

    I've really had to do more resawing lately than I care for. Every time I do it, I think about how much faster and accurate it would be with a bandsaw. And then I go and saw another one.

    Brian

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  2. Another "Yea" vote on breaking down before resawing. It looks like you're well on your way. That lumber looks fabulous.

    As for that little "flap," I had one of those on a boat plank once. It ended up making the plank slightly thinner than I would have preferred in that area, but not unusable. I'm just careful about avoiding banging into rocks with that part of the plank. :) I'm sure you'll be creative with your "flap"

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