Choice of stock – sawn or planed? Also need for discussion on design issues?
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I have just completed a simple project – a built-in table for a confined space.
I wanted to use 6″ x 1″ for part of it, so I bought 6″x1″ PAR(PSE?) redwood for the whole project, including the table top. So, the timber was sawn 25mm thick, planed to 19-20mm by the timber yard, and reduced further to 16-17mm by me in the process of getting the cup and twist out of the planks used for the table top. Surprising, because the timber was almost radially sawn. The finished result is adequate for its purpose, but thinner than I intended.
BUT nearly 40% of the original timber has been wasted in the process. Two points arise, I think:
1. There would have been less waste if I had used narrower planks ( or ripped and re-joined the existing planks) for the table top. Does anyone know of a rule of thumb for choosing optimum width for a given length/thickness?2. Since I planed off a lot of material, I probably gained nothing by choosing PAR instead of rough-sawn timber. In fact, it probably ended up thinner, and certainly cost more. Is it really worth buying planed timber from the average woodyard? (It probably is if you can select each length yourself)
Incidentally, the process of cutting joints etc went well using Paul’s techniques. He’s done a very good job of putting across the processes. The problems were in design. The situation was odd – the table had only 1 leg, at 1 corner, so I couldn’t just do what’s usual.
I eventually used 3 different joints for the frame. I think I chose the right ones, but I found it difficult to find guidance.
One edge of the top abutted a wall, so all the width movement of the table top needed to occur at the other side. Assuming 1% movement, a standard turnbutton/groove system might disengage with a sensible-looking groove depth, so I devised another way. Again, is 1% movement right? Could I have made the groove for the turnbutton deep enough to absorb the movement without losing too much strength?If Paul runs short of ideas for projects, I, for one, would value a discussion on practical design issues. Am I alone in this?
Geoff
Geoff, stock selection is indeed important, what I’ve decided on is using pre-dimensioned material, pine for the most part for projects that are utilitarian in nature, step stools, storage boxes etc. if I am going to to build a piece of furniture then I would almost always choose rough/skipped dressed hardwoods because as you flatten it you lose thickness. Generally speaking a 1 inch skip dressed piece of hardwood is going to end up 7/8 or 3/4 inch once all is done.
I don’t know if there is a standard number for wood movement, depends on species, how it’s milled etc and humidity fluctuations from season to season in your geographic location. I’ve seem a pine panel move 1/2 an inch from summer to winter here. My tool box has a walnut panel made from 1/4 sawn walnut and it moves about 1/4 inch.
As far as design ideas, read lots of books and browse the Internet, lots of stuff out there.
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