Before I left on vacation, I ordered some 1/16″ balsa sheets for laser cutting as I was nearly out. As planned they arrived when I was away. Today, I had to open the box and weigh the sheets. I weigh them so that I can better control my laser cutting – I mean, provide you with the best product I can.
Since the beginning of the year, I have been buying from National Balsa because Sig had a fire in their balsa cutting room and they are not yet back in full operation. Sig always had pretty good balsa, so I was happy – and besides, I get no discount from National, so it costs me nearly twice as much as Sig.
This particular batch may be the lightest overall batch I have ever received. I ordered 100 sheets of 1/16″x3″x36″ and 20 sheets of the same size but from their “Aero Light Bargain Grade” – just to collect light wood (I don’t know why – I have more than I could ever use). National just lumps this all together without labels or separation, so I have no idea which is which (although the bargain grade usually has discolorations). Anyway, I was surprised at the results.
Notes: I weigh each sheet in grams and annotate it. This weight does NOT account for variations in thickness, width, or length. For my everyday kits I divide the stock into 12-13 grams, 14-16 grams, and 17-19 grams. I toss out (save for give-aways) anything over 20 grams. That means my short kits are cut from wood that is between 6.8 pounds per cubic foot to 11.2 pounds per cubic foot. I usually try to make weight sensitive planes (NoCals, Peanuts, etc) out of the lighter and larger planes out of the heavier.
Usually, I will get a handful of sheets below 13 grams and maybe up to 20% of sheets over 20 grams. This batch had a different distribution.
Why is the width variation a problem? Often I don’t cut a single sheet at a time. I arrange my CAD files to a standard 3.0″ width. If the sheet width varies and I do not account for this, part of the second sheet will be cut on the first sheet – or the bottom of the second sheet will cut of the sheet.
Now, back to cutting kits…oh,here’s a chart you might find useful (only for 1/16″x3″x36″ sheets)
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