Tuesday, May 17, 2011

Here we go again

Here is a quick sketch of the basic idea. As you can see it's a little different from the previously mentioned lesson plan. In the example in the lesson plan the image is projected on the surface of a tank (in that case a beaker) of resin and the part is submerged into the resin as it is solidified. A variation of this method is to expose the resin at the bottom of the tank to the UV and have it stick to a plate which is raised up out of the resin. Each new layer sticks to the previous one and is lifted upward. I chose a bottom up method because then I don't need a resin tank deep enough to contain my maximum z travel. Also the submersion tank method requires a large volume of resin from the start. A shallow tray only requires a small volume of resin be maintained (and possibly exposed to the degrading effects of unwanted UV and moisture). Also the Z build height will not be limited (theoretically) by a fixed tank depth or my financial ability to fill said tank. Most of the designs I have found in my research place the projector vertically directly under the resin tank. I am going to place the projector horizontally behind the z axis. Initially I plan to borrow a projector as I see this as being the single most expensive component. By placing it behind I can easily remove/replace the projector and also have much more flexibility over the focal distance. This also will keep the total height of the printer smaller. If I went all vertical the total height would probably end up close to 4 feet. Lastly, since the projector won't be mine (at least initially) I really want to protect it from any resin drips!

I'm going to try and keep this as simple (basic) as possible. I envision a build plate that is in a carrier so it can easily be removed when the print is done. Also the resin tank needs to be removable for easy cleaning. Then there is the matter of preventing the cured resin from sticking to the bottom of the tank. I think some combination of non stick surface and mechanical movement. As you can see it will be easy to get very complex. I'll have to resist the temptation to over engineer. I'm working on a more detailed design mock up that I'll have ready in a few days.

My goal is to create a 3D printer that can be built with readily available, easily fabricated and affordable components.

I hear you thinking..."He must be MAD! It just can't be done!"

Only time will tell.... Cue the manical laughter.

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