For future designs, has a hybrid system been considered? The idea that came to mind today was from the forum post "Heating via infra red" . One of the ideas discussed was using a combination of heating elements. First, one would thermally pre-load an area, bringing a mass of sugar or substrate near to its melting point. Then, one could come in with a much smaller point source of heat to do high resolution sintering. I think this idea has merit - if there ends up being a upper end to the number of DPI that a cheap heated-air printhead can bring to bear, a hybrid head may be the best alternative.
My back-of-the-envelope design for a hybrid head would use something similar to Heater 2.0 married to the ubiqitous 245mw red laser diodes used in commercial DVD burners along with a cheaply available colimating lens. I leave the optimum placement of these components to smarter people, but their intended use is pretty specific. The heating element should be directing a stream of hot air down at the surface of the substrate sufficient to get it within 10-20 degrees of melting. This may require some control circuitry and the addition of a temperature sensor. Once thermally loaded, relatively short bursts from the laser should be sufficient to melt particles already near the correct temperature. ("relatively short" being relative to the time needed to melt particles at room temperature using the same laser)
I feel this is a viable approach as it makes best use of the characteristics of each heating element. The forced-air heater is cheap and easily controlled. Keeping its thermal output generally below that needed to actually melt the substrate should allow a much lower-power laser to work than has been suggested. The laser, of course, brings vastly increased printing resolution, presumably capable of sub-millimeter accuracy. (if this is not true, of course, then the whole idea is silly. Heater 2.0 itself can get 1/4 this resolution - which is generally close considering the grainularity of sugar)
The largest problem with this idea is heat. How does one keep the heat from the heater-head away from the laser diode? I do not have an answer to that problem yet, but I am still working on it. Any ideas would be appreciated. (The minor problem of dangerous light-reflection should be fixable with a shroud made of nearly anything. I was thinking a cardboard toilert-paper tube at the absolute lowest end. Watching the device print is nice, but at the cost we're seeing for sugar right now, I don't think it's that important to stop errors as soon as they occur.
Anyway, this is all back-of-the-envelope stuff and just being dumped to spur discussion. Recent mentions of a "Heater 3.0" may make all of this moot anyway.
- If we need a preheater, a standard "heat lamp" or even a halogen is a better choice than the air system. I'm not yet convinced.... SugarDaddy 17:50, 16 May 2008 (UTC)
I vaguely remember an IR halogen bulb from Osram. The reflector was part of the bulb (like with so many of the usual MR16 halogen bulbs). The IR output was, AFAIR, focused on a rectangular patch a few millimrters long and wide. Too big I guess for CandyFab puposes. Don't remeber wattage or life time of the bulb, just that it was from Osram and that it was intented for welding. --18.104.22.168 06:18, 31 July 2009 (PDT)
Why Heat and not use a liquid?
I guess sugar will also bound together by moist. Why not use water in a sort of ink jet way?
just a silly tought when i was wondering how this marvelous project works. I was suprised it was by means of heat.
BK --22.214.171.124 13:52, 6 September 2009 (PDT)
- It's not really obvious, but once you introduce moisture in the bonding process, that sugar is stuck in place. What you end up with ends up with the consistency of *sticky* hard candy, not rigid and dry, like rock candy. SugarDaddy 23:10, 6 September 2009 (PDT)