Bending strap

[sprucetop1]

It's not a new idea, but I've just been bending some mandolin sides, and decided to try a supporting metal bending strap on the outside of the wood, thus sandwiching the wood between the strap and the hot iron. StewMac supply these straps in stainless steel, but I don't have one of those. Thus cut up some beer can material into strips the width of the sides, using a Stanley knife and a steel ruler, and used that. It works very well indeed. An added bonus is that I had to drink the beer before making the tooling......in fact I'm thinking of carrying out an in-depth project by testing the slightly varying gauges of can metal to be found in a variety of beers......John

[8ch(pl)]

You can perchase Flashing Material, about .015 Aluminum sheet at any building supply. Draw a line on it with a marker etc and it can be cut with Tinsnips. The edges should be cleaned up with a file to remove the burr formed by cutting. It comes in a roll about 10 inches wide and 6 or so feet long.

[sprucetop1]

Glen.....I hadn't thought of flashing material. I did clean up the beer can sides though with a fine file to minimise the sharpness of the edge. Further trials with this system on some offcuts of very curly maple indicate that tear out and fracture of the outer side of the wood is nearly eliminated. Before bending I plane and then scrape my side wood to around 1.2 mm. thickness, and get it as even a thickness as I can along the length and across the width. I find this really helps the bending process. I'm a relative beginner at building and I'm learning all the time....John

[Stephen Perry]

One way to get the thickness even while using a scraper is to make a jig for marking. Base and top parallel, two very sharp nails or screws through the top as markers. Adjust so gap to base is what you want for thickness. Feeler gauge works well for setting. Then finish one side to final and drag rib through the gauge with the less finished side up. Draws two parallel lines in the wood. Then scrape to the lines. Line goes away, don't scrape there any more!

I have a rib roughing system using a safety planer. Works pretty well, but a thickness sander would be nice!

[Rick Turner]

McMaster Carr Industrial Supply has stainless steel sheet in coils in perfect widths and in many gages just right for this kind of thing. We now use Doolin style benders and make a sandwich of three pieces of stainless steel sheet with the heating blanket between 1 & 2 and the wood between 2 & 3. Works great.

[mandolinplucker]

What Glen said. If I was going to bend a lot, I would get a stainless strap. But for now the piece of flashing that I had laying in the shop works fine. For the tight bend between the neck and the point I made a sandwitch of flashing, paper towel, maple, paper towel, and flashing. I used a positive and negative mold out of plywood and heated with a heat gun while I pulled the mold together, with the sandwitch between them with clamps. Whatever works is a good way.

[sprucetop1]

What side thickness do most current mandolin builders aim at? What was the side thickness on vintage Gibson A's and F's........John

[Michael Lewis]

Side thickness cn vary from .060" - .120" (1.5mm - 3mm) Depends on the wood you have and your skill level. Thicker sides are quite a bit stronger and only a very little heavier.