Certainly not the first within the community to do SLS on a DIY setup, but possibly the first to do it with a DIY (where DIY includes devices made by someone else) drop-on-demand print head. Now, one question I have: are there any working, small (say 2 to 4 inches on a side), and inexpensive powder beds designs out there? The only design I'm aware of at the moment is Peter Jansen's and it is notby madscifi - Powder Printing and Selective Laser Sintering
I've cobbled together a very tiny manual powder bed using a fortuitous cylindrical magnet container, a small manual translation stage, some plastic sheeting and scrap of wood. Oh, and lots of hot glue. The powder consisted of baker's sugar and powered sugar, based on this recipe from the Open3dp website. The "Hi" pattern used earlier was printed, the stage moved down one turn, sugar distribby madscifi - Powder Printing and Selective Laser Sintering
Johnrpm, any thank yous belong to you, as it was your idea, design, and construction. I'm tweaking some things around the edges. Thank you for sending me a copy so that I can experiment with it. I don't actually know that the Delrin nozzle is any better than the others (except that it works over a wider range of water column heights). Mostly I'm probably just wanting it to be since I've made somby madscifi - Powder Printing and Selective Laser Sintering
I'm going to play the pessimist (unfortunately it does not involve much acting) and guess that this is pretty much the end of Bits From Bytes as a community player. As reported by Forrest Higgs, the question of whether or not they move to proprietary cartridges is an open question. If it is an open question at this point then I suspect that it will be a done deal by the time their next printer arby madscifi - General
Since I spent yesterday doing the relatively boring and repetitive part of the project, I thought I'd have some fun today. Image contrast enhanced as it is just plain water on the paper. Printing in progress. Wider view of setup. Note that the print head does not move, the paper is being moved under the print head. Sadly, HP and Epson have nothing to worry about. The Arduino controllinby madscifi - Powder Printing and Selective Laser Sintering
I'm using a TGM42-075-40-12V-040A-50R-LW6, which is unipolar, to drive my extruder. It works well with ABS. I have not tested it with PLA. I thought I had read that it was possible to configure Skeinforge so that it creates output usable by EMC directly. However, I'm unable to find any references to doing this at the moment.by madscifi - General
Johnrpm, I would be happy to try using a laser to measure the piezo movement, but I did not think that any method I could reasonably expect to construct would work. Your idea has promise, however... The gif was generated from Gimp. If you save a file as a gif in Gimp and the file has layers, Gimp asks whether you want the layers collapsed as a single image or saved as an animation. So, just opeby madscifi - Powder Printing and Selective Laser Sintering
Here is a photo of the current test setup. Did I mention that I'm mechanically inept? The useful part of the setup to mention are: 1) The bit of white plastic that is epoxied to the pipette and the short whitish tube are parts from a hand cleaner dispenser. They make a rotatable joint that is water tight, which is very useful when trying to flush the air out of the head. 2) The bit of acryby madscifi - Powder Printing and Selective Laser Sintering
I'm running such a configuration: EMC2 and a Taig. I've configured the A axis to drive the extruder stepper and I'm using an AWK script to convert the output of Skeinforge so that EMC understands the script (there are other ways to do this). I'm not controlling the temperature of the extruder via EMC, but rather I'm using a Arduino to control the temperature and just wait for the extruder to comeby madscifi - General
I ran a test where I got everything working correctly (it still takes a couple of minutes to get everything working, air purged, water to the correct level) and then swapped the wires to the piezo without changing anything else. Essentially the device becomes pretty random - occasionally squirting drops, often drizzling large amounts of water, usually producing just little "bumps" that never sepaby madscifi - Powder Printing and Selective Laser Sintering
Dalek producing single drops of water, pointing down (the animation is a fairly accurate record of the orientation), 31 volt, 500 us pulses. Nozzle is #1 from an earlier post (straight wall hole drilled with a #80 drill bit through a 0.27 mm sheet of polystyrene). I used a small bit of solder to bridge the crack on the piezo. The device will work in this configuration as long as I keep the wby madscifi - Powder Printing and Selective Laser Sintering
I suspect the Viktor is correct, it would be much easier to print a UV curable paste using a syringe. However, there are some papers available on the web related to using inkjets to combine precursors and produce an end product in situ. Fabrication of Two and Three-Dimensional Structures by Using Inkjet Printing Reactive inkjet printing of polyurethanes ROTATIONAL 3D PRINTING OF SENSOR DEVICEby madscifi - Powder Printing and Selective Laser Sintering
One of the problems with using very small nozzles is that the pressure required to push the plastic through the nozzle becomes too high. On that note I'm wondering if anyone has experimented with using ultrasonic vibration in an attempt to lower the required pressure? See Investigations on the effects of ultrasonic vibrations in the extrusion process and this commercial vendor. I've only read thby madscifi - Plastic Extruder Working Group
I'm pretty certain that the ceramic is cracked. It is difficult to tell with certainty. I'll probably try just bridging the crack along one edge with a bit of solder. I don't know how long that will hold up, but it sounds worth trying. If that fails then I'll move the wire. I'm about 99% certain that I broke it. I was using a spring hand clamp to clamp the needle value body to a support, and Iby madscifi - Powder Printing and Selective Laser Sintering
Broken piezos and sparks Here is a close up of the piezo on Dalak that is now sparking at higher voltages. I was concerned that the sparking was destroying the device, but that concern was misplaced. The device is already broken. The black arrows are pointing to a crack just that goes just to the left of the solder connection of the red wire. This crack completely isolates the top conductorby madscifi - Powder Printing and Selective Laser Sintering
Test nozzles, or the more I try the less I know. I made up 5 brass screw-in nozzle holders for Dalak that can have thin plate nozzles glued on them. Since I don't have a lathe they were milled starting from brass hex bolts. Since I have never milled brass before, I made something of a mess of the first couple, but in the end all of the holders were usable. The picture below shows 4 of the nozzby madscifi - Powder Printing and Selective Laser Sintering
The specs on the ones I'm using (20mm diameter) are: 6.3 kHz, .2 mm plate thickness, brass 3.6 kHz, .1 mm plate thickness, brass I've also discovered that there are ones with .05mm thick plates available: 20mm piezo, .05mm thick I'll order a couple to add to the test pool. The other question I have concerns the max voltage rating of the devices. I cannot, even in the spec sheet, find the maxby madscifi - Powder Printing and Selective Laser Sintering
The nozzle diameter is about .343 mm (#80 drill bit). I believe you are correct about air getting sucked back in. I would like to know the thickness of the piezo on the device you sent, if you know. There is no question that Lord of the Rings (the book) is much better than Dr Who. It is almost sacrilege to even compare them to each other ;-)by madscifi - Powder Printing and Selective Laser Sintering
Progress report. Johnrpm has kindly sent me the acrylic inkjet device he made so that I can attempt to figure out how to make it work in drop on demand mode. It is constructed with a brass nozzle that screws into an acrylic body (with an o-ring) so it will be easy to try out different nozzles while keeping everything else a constant. Since it takes too many words to explain which inkjet device iby madscifi - Powder Printing and Selective Laser Sintering
Johnrpm, thanks, it is perfectly clear now. Martinprice2004, lots of interesting ideas. One of the complications is that all of the literature suggests that we need something a bit more complicated than a simple straight walled hole - a conic or pyrimidal opening apparently works much better. I have not been able to find any dimensional drawing of carburetor jets, so I'll probably just have to bby madscifi - Powder Printing and Selective Laser Sintering
Johnrpm, is the rear face the outside (the side that faces the paper in a printer) or the inside (the side contained inside the printhead)?by madscifi - Powder Printing and Selective Laser Sintering
You both have a lot of neat toys... This is a good thing. Viktor, the book I have does talk about etching, but it is rather involved, apply photo resist, expose, process. Plate with nickel, remove photo resist, etch using nickel as mask from both sides at once, one side a larger diameter region and the other side a small diameter region. This seems overly complicated (no doubt for good reason inby madscifi - Powder Printing and Selective Laser Sintering
Viktor , AOM? I could not figure out what that is... I'm pretty certain that tapering the nozzle is going to end up being critical to good performance (yes, I'm on a rant about tapering, last week it was rise times, and we all know how that turned out ;-). The only method that I've tried to date is to do it manually using a small 60 degree "V" etching bit. If you have any ideas for how to taperby madscifi - Powder Printing and Selective Laser Sintering
Johnrpm - sorry, my descriptions are often not well thought out, I'm afraid. Although I think you have the correct idea, here is a diagram. There is no need to use a glass U, just make an "U" out of tubing. The book recommends something like silicon oil for the liquid in the "U" since it has a low vapor pressue. Nothing in the drawing is intended to be to scale.by madscifi - Powder Printing and Selective Laser Sintering
I've learned a lot in a short time by playing with the led strobe setup with the nozzle. A lot of what is now obvious (since it has been staring me in the face, or rather, I've been staring at it) is documented in the various papers and articles available on the web, or was expected for whatever reason, but it is so much more real when the effect is visible in front of you and can be manipulatedby madscifi - Powder Printing and Selective Laser Sintering
Excellent! Congratulations on being the first here to demonstrate a thermal inkjet. You may have difficultly drawing the nozzle down enough to stop the water from flowing - Microdrop Generation shows a flexible tube connected between the top of the pipette and a manometer tube filled with liquid to create a small but definite back-pressure to keep the liquid from flowing out the nozzle (the fleby madscifi - Powder Printing and Selective Laser Sintering
I don't see any reason why brass shim material would not work, although it is possible to get a nozzle plate that is too thin, based on what I've read, so one does need to watch out for that (if it is too thin every drop of water out will let a small air bubble in). Too thin is going to be a relative value based on the nozzle diameter, not an absolute size. As I've mentioned earlier, some Delriby madscifi - Powder Printing and Selective Laser Sintering
I set out this evening to make a bunch of thin-plate nozzles this evening, all drilled with a #80 drill bit, some tapered, some left straight, some using plastic, some aluminum. Unfortunately i broke my #80 drill bit after drilling one plastic and one aluminum plate, so I cannot make any more nozzle plates until I get a new drill bit (next week). I took the one aluminum nozzle plate and taperedby madscifi - Powder Printing and Selective Laser Sintering
Nophead - thank you for pointing that out. A flyback diode across the transformer should solve that problem. I got carried away in the low parts count department.by madscifi - Powder Printing and Selective Laser Sintering
I wanted to see if a transformer based driver would work with this head so I put together the simplest one I could (without risking damage to the output devices in the atmega chip in the arduino): The transistor is your every day standard small signal switching transistor from an old pack of radio shack transistors. Specs: Typical Hfe: 200, Max VCE: 30V, Max Ic: 800ma. Body style: TO92. I sby madscifi - Powder Printing and Selective Laser Sintering