Builder 2010
Staff Sergeant
I didn't search the forum to see if this topic has been addressed. If it has, please forgive me. If not, please take a look since what I'm describing (to me) is really mind-blowing.
Up until about 2 years ago, high resolution resin 3D printers were about $3,000 USD and up…way up. Along comes a new approach using a high resolution LCD panel illuminated by 405nm UV LEDs. Sitting atop of the LCD is a resin reservoir with a transparent teflon film bottom that is in direct contact with the LCD. The only moving part is the Z-axis which which rises one layer at a time as the part is being formed out of the liquid. I bought an Elegoo Mars LCD Msking printer from Amazon for $359.00 a month ago. The UV light cures a photopolymer in about 8 seconds per layer. The object to be printed is sliced like a salami into specific layers. The resin printer is capable of resolving layers as fine as 10 microns. That's 0.0007". The average filament (string) printers are capable of 100 microns and is too coarse for model scales that we typically work in. This machine is so amazing that it transfers the challenge of modeling from "How can I build it?" to "Can I draw it?" While it can theoretically print anything within its size constraints—in this case 2" X 4" X 6" high—there are physics to consider. The print is created upside down. The first layers to form stick to the aluminum platen connected to the Z-axis lead screw. The platen touches down at position zero and then moves up one layer thickness. The LCD, which is effectively black and clear, shows the image of the first layer (like a cat scan), the LEDs light and the resin trapped under the platen cures to a solid. The platen moves up about 5 mm to break the suction with the teflon film and then repositions one layer higher and the process repeats, only this time the LCD displays the image for layer 2. At 40 microns which I'm using, most objects are between 800 and 1,800 layers. The time to print is not based on complexity since the entire LCD is exposed at one time. Instead, it is based on three factors, the height (= number of layers), the layer thickness, and the exposure time. The default is on minute for each of the base layers (about 10) and then 8 seconds per layer.
I found out about this through one of my build threads, and after researching, bought one. My son said, "Jeez Dad, for $350 how can you go wrong?" The resin is not cheap, but the Elegoo resin is one of the least expensive at $30 per liter.
The hardest thing to master is understanding how to design for this kind of machine. Adhesion to the platen is the critical factor. If the model being built separates partially or completely from the platen, the model ceases to build. If the part can't be lifted from teflon film, then a new layer can't be formed under it. It just sits as a blob stuck to the teflon. The slicer software that came with the printer can build a labyrinth of supports that hold all parts of the model to the platen. What I had to learn was how to fine tune this support network. You can customize the support structure at a very granular level, but there are three easy choices: light, medium and heavy. I was using the default light setting, but realized after some failures that medium and even heavy worked better. The more mass the object has dictates using a heavier support structure.
i'm building a massive 1;48 engine house with an attached machine shop. I wanted to populate it with some O'scale machine tools, but none were commercially available. Then along came the printer. I downloaded a 3D image from SketchUp's 3D Warehouse and after some fiddling to make it print capable, printed out a very respectable engine lathe. It's about 2" long.
It was my second attempt, but was very encouraging. I also want to build a 1:48 model of an ElectroMotive Division 567 Diesel locomotive prime mover. I was thinking for years how to scratch-build one of these and wasn't making any progress, and then along comes the printer. After a couple of tries with different print configurations, I produced a pretty successful start.
Here's the real thing.
And here's where I am so far. I'm having to draw this entire thing in SketchUp first since no one has done a SketchUp model that I can pirate. This is how far I've gotten. The detail is astounding. The cam shaft is actually sitting proud of the head deck as is the injector throttle shaft. Strangely, some of the details didn't print that were facing in one direction. I'll have to do some research on that. I'm in the process of drawing that complicated maze at the front end of the engine. EMD diesels had four exhaust valves. Under the two side rocker arms was a bridge rocker that pushed two valves on each side of the injector, which was operated by that middle rocker arm. There are actually valve springs under those, but they're hard to see.
I tried printing parts with them sitting horizontally in the slicing software. This works for parts with small surface areas, but as the surface area in the horizontal direction increases, the suction on the teflon is also increased and they start breaking away from the supports. It's best to situate the model at 45 degrees. This minimizes the horizontal contact area and produces a better print. It also increases printing time… a lot. The machine is very quiet and just goes about its business. You can start something at night and it's done the next morning. Unlike the string machines, it doesn't have a nozzle that can clog with molten plastic, or have a filament feeder that can jam. Everything here is optical and electronic except for the Z-axis. The orange acrylic cover keeps UV light out of the printer to keep the reservoir from curing by ambient light.
Here's what a part looks like coming out of the reservoir. The engine block was almost perfect. I wasn't careful enough cutting away the forrest of supports and damaged the thin bottom flange.
You'll notice the angular interconnecting supports that lock the entire network together. It's really tough! I used the heavy support setting and nothing broke loose. That whole network is completely and automatically created by the slicing software. It's really easy.
The resin is somewhat toxic and you need to use nitrile gloves when handling it. You wash it in two baths of alcohol, either ethanol (190 proof grain alcohol) or 95% isopropyl. You wash it in bath one and a final wash in bath two. The part out of the machine is not fully cured and is still a little rubbery. That's when you cut off the supports. I then purchased an inexpensive LED 405nm UV curing light and assembled a foil-lined cardboard box to contain the light and evenly cure the parts. It takes just a few minutes to finish the curing and then part is very hard, almost ceramic-like. It's similar to the resin used by dentists with photo curing dental resins.
All in all, it has completely changed how I'm approaching my model making. It's not whether I can build it. It's can I draw it. They say any technology sufficiently advanced appears as magic. To watch a fully formed 3 dimensional, real object rising out of a bath of liquid not even an inch deep, appears miraculous. You don't see how it happens since the LEDs are hidden by the platen.
Just for fun I prepared a list of all the technologies in my lifetime that had to be there to have this machine appear on my workbench. I came up with 13, but there are more. I didn't consider things like AC generators for electricity, but I did include transistors, micro-processors and micro-computers, solid state memory, high accuracy stepper motors and their controls, photo-curing polymers, LEDs, LCD panels and control circuits, Teflon, 3D software, Slicing software, machine code, and the lists goes on.
Up until about 2 years ago, high resolution resin 3D printers were about $3,000 USD and up…way up. Along comes a new approach using a high resolution LCD panel illuminated by 405nm UV LEDs. Sitting atop of the LCD is a resin reservoir with a transparent teflon film bottom that is in direct contact with the LCD. The only moving part is the Z-axis which which rises one layer at a time as the part is being formed out of the liquid. I bought an Elegoo Mars LCD Msking printer from Amazon for $359.00 a month ago. The UV light cures a photopolymer in about 8 seconds per layer. The object to be printed is sliced like a salami into specific layers. The resin printer is capable of resolving layers as fine as 10 microns. That's 0.0007". The average filament (string) printers are capable of 100 microns and is too coarse for model scales that we typically work in. This machine is so amazing that it transfers the challenge of modeling from "How can I build it?" to "Can I draw it?" While it can theoretically print anything within its size constraints—in this case 2" X 4" X 6" high—there are physics to consider. The print is created upside down. The first layers to form stick to the aluminum platen connected to the Z-axis lead screw. The platen touches down at position zero and then moves up one layer thickness. The LCD, which is effectively black and clear, shows the image of the first layer (like a cat scan), the LEDs light and the resin trapped under the platen cures to a solid. The platen moves up about 5 mm to break the suction with the teflon film and then repositions one layer higher and the process repeats, only this time the LCD displays the image for layer 2. At 40 microns which I'm using, most objects are between 800 and 1,800 layers. The time to print is not based on complexity since the entire LCD is exposed at one time. Instead, it is based on three factors, the height (= number of layers), the layer thickness, and the exposure time. The default is on minute for each of the base layers (about 10) and then 8 seconds per layer.
I found out about this through one of my build threads, and after researching, bought one. My son said, "Jeez Dad, for $350 how can you go wrong?" The resin is not cheap, but the Elegoo resin is one of the least expensive at $30 per liter.
The hardest thing to master is understanding how to design for this kind of machine. Adhesion to the platen is the critical factor. If the model being built separates partially or completely from the platen, the model ceases to build. If the part can't be lifted from teflon film, then a new layer can't be formed under it. It just sits as a blob stuck to the teflon. The slicer software that came with the printer can build a labyrinth of supports that hold all parts of the model to the platen. What I had to learn was how to fine tune this support network. You can customize the support structure at a very granular level, but there are three easy choices: light, medium and heavy. I was using the default light setting, but realized after some failures that medium and even heavy worked better. The more mass the object has dictates using a heavier support structure.
i'm building a massive 1;48 engine house with an attached machine shop. I wanted to populate it with some O'scale machine tools, but none were commercially available. Then along came the printer. I downloaded a 3D image from SketchUp's 3D Warehouse and after some fiddling to make it print capable, printed out a very respectable engine lathe. It's about 2" long.
It was my second attempt, but was very encouraging. I also want to build a 1:48 model of an ElectroMotive Division 567 Diesel locomotive prime mover. I was thinking for years how to scratch-build one of these and wasn't making any progress, and then along comes the printer. After a couple of tries with different print configurations, I produced a pretty successful start.
Here's the real thing.
And here's where I am so far. I'm having to draw this entire thing in SketchUp first since no one has done a SketchUp model that I can pirate. This is how far I've gotten. The detail is astounding. The cam shaft is actually sitting proud of the head deck as is the injector throttle shaft. Strangely, some of the details didn't print that were facing in one direction. I'll have to do some research on that. I'm in the process of drawing that complicated maze at the front end of the engine. EMD diesels had four exhaust valves. Under the two side rocker arms was a bridge rocker that pushed two valves on each side of the injector, which was operated by that middle rocker arm. There are actually valve springs under those, but they're hard to see.
I tried printing parts with them sitting horizontally in the slicing software. This works for parts with small surface areas, but as the surface area in the horizontal direction increases, the suction on the teflon is also increased and they start breaking away from the supports. It's best to situate the model at 45 degrees. This minimizes the horizontal contact area and produces a better print. It also increases printing time… a lot. The machine is very quiet and just goes about its business. You can start something at night and it's done the next morning. Unlike the string machines, it doesn't have a nozzle that can clog with molten plastic, or have a filament feeder that can jam. Everything here is optical and electronic except for the Z-axis. The orange acrylic cover keeps UV light out of the printer to keep the reservoir from curing by ambient light.
Here's what a part looks like coming out of the reservoir. The engine block was almost perfect. I wasn't careful enough cutting away the forrest of supports and damaged the thin bottom flange.
You'll notice the angular interconnecting supports that lock the entire network together. It's really tough! I used the heavy support setting and nothing broke loose. That whole network is completely and automatically created by the slicing software. It's really easy.
The resin is somewhat toxic and you need to use nitrile gloves when handling it. You wash it in two baths of alcohol, either ethanol (190 proof grain alcohol) or 95% isopropyl. You wash it in bath one and a final wash in bath two. The part out of the machine is not fully cured and is still a little rubbery. That's when you cut off the supports. I then purchased an inexpensive LED 405nm UV curing light and assembled a foil-lined cardboard box to contain the light and evenly cure the parts. It takes just a few minutes to finish the curing and then part is very hard, almost ceramic-like. It's similar to the resin used by dentists with photo curing dental resins.
All in all, it has completely changed how I'm approaching my model making. It's not whether I can build it. It's can I draw it. They say any technology sufficiently advanced appears as magic. To watch a fully formed 3 dimensional, real object rising out of a bath of liquid not even an inch deep, appears miraculous. You don't see how it happens since the LEDs are hidden by the platen.
Just for fun I prepared a list of all the technologies in my lifetime that had to be there to have this machine appear on my workbench. I came up with 13, but there are more. I didn't consider things like AC generators for electricity, but I did include transistors, micro-processors and micro-computers, solid state memory, high accuracy stepper motors and their controls, photo-curing polymers, LEDs, LCD panels and control circuits, Teflon, 3D software, Slicing software, machine code, and the lists goes on.