Re: How much would making a one-off calculator cost? Message #10 Posted by bhtooefr on 22 May 2013, 10:08 p.m., in response to message #9 by LHH
So, there's four ways to legend a key, and HP's used two of them AFAIK.
The hardest, but most durable and best looking way is double-shot (or triple, or even quadruple-shot, if multiple legend colors are required). This involves molding the legend, and molding the rest of the key around it in a different color. This is what HP's used for most of their calculators, although only double-shot as far as I know. Upsides are durability, color flexibility, definition of legends, and smoothness of transition (because the legend and key body are melted together), downsides are cost and the fact that it's most commonly used on ABS keys (which go smooth more easily under finger wear).
The cheapest way in mass production is pad printing. Pad printing done right can be plenty durable, with adequate coatings over the keys (a lot of older Apple keyboards were, AFAIK, pad printed, and the legends are fine 30 years later), but those coatings make it more expensive. Or, without any coating at all, or a partially applied coating (like most laptops), it can be destroyed easily. Pad printing has low cost, color flexibility, and decent definition of legends, but durability is its weak point. As I understand, HP's pad printed the faces of keys that rarely get touched, as well as lower end calculators.
Another method, and it's what WASD does, is laser engraving. There's a couple ways to do this, and it depends on what color key you're starting with. If it's a white key, engraving it will leave a "burned" legend behind. If it's a dark key, some plastics will engrave white, whereas others need paint infill to get a colored legend. Lasering is cheap, but it makes the key feel "rough", if it's infill-based it has wear issues, if it's burn color based it's completely inflexible on color (and the color can be brownish), and text definition can be mediocre.
IBM/Lexmark/Unicomp and Topre use dye sublimation. This injects some dye deep into the key. I think cost is an issue here, but you get smooth, durable caps with moderate color flexibility. Downside is, dye sublimation can only make something darker, not lighter, so you can't do it to dark color keys and get an acceptable result. It's also not as durable as double-shots, but if you've worn the legends off of an IBM key, you've probably used it as your main keyboard for 30 years, and you're a typist.
Edited: 22 May 2013, 10:08 p.m.
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