Hi all, here: i found a very easy receipe of a 2K-mixture, which could be usefull as fabbing material or support. Simple atach two syringes, one for dispensing a thin tray of Silicate, the other dispensing an even thinner tray of alcohol. Or a mixing valve-tip, so you extrude the ready mixed compound at once, which will harden soon after extruding ... Viktorby VDX - Plastic Extruder Working Group
Hi elwolv, STL is a highly common object-format in rapid-prototyping, so you can output the same parts on comercial fabbers too or import in a CAM-software and output with a 3D-mill. With any other 3D-format you have to source the CAD/CAM-software too what's sometimes more complicated then with STL - here you have more cross-platform-tools and such ... Viktorby VDX - RepRap Host
Hi Jay, ... it works fine for extruding thick trays in some millimeters diameter. But when reducing the hole in dispensing needle down to 0,3 or even smaller (i need 0,1 for some structures), then it tend sticking too. I'm testing with different solvents and additives for reducing the friction and the sticking, but then the amount of solidus is beneath 50% and you have much more shrinkage, soby VDX - Paste Extrusion Working Group
Hi all, i tried with ceramic- and glass-powders mixed with different solvents and pastisicers (with different and not so brilliant results) - but i'll try again as this would be very interesting for fabbing highly rigid and heat-resistant parts ... Here in the fab(at)home-groups is maybe some interesting discussion (and some hints) too: Viktorby VDX - Paste Extrusion Working Group
Hi Forrest, but they use air-hardening silicone, what's pretty adhesive and didn't curl. Maybe with reheating the old surface by hot air or an IR-heater would do it - or generally apply a nozzle beside the extruder-tip, which will blow a gentle stream of hot air onto the surface, so the tray will set on a preheated/molten area ... Viktorby VDX - Plastic Extruder Working Group
... today i borrowed from one of my previous boss an old pressure/vacuum-dispenser-system with a heated syringe-head and will try to bring this to work again. Then i can test with time<->pressure-dispensing and look if it's capable of some accuracy in thread-geometry ... Viktorby VDX - Polymer Working Group
... look here in an old discussion about reprapping/reprappable linear drives ... Viktorby VDX - Plastic Extruder Working Group
Hi Gene Hacker, ... if you wish a bit more accuracy at start and end, then a simple valve for releasing the pressure isn't enough - even the much expensiver vacuum-supported dispensers have problems forming a homogenous thread, so the aren't used in 3D-printers and the fab@home-guys decided to go the mechanical way ... The paste-flow isn't "switch-n-run", but has a bad hysteresis, which is heavby VDX - Polymer Working Group
Hi Gene Hacker, i've tried with a pneumatic powered dispenser too with extruding a heat-curing epoxy-glue of honey-like viscosity at room-temp, 'working' viscosity at 60by VDX - Polymer Working Group
... today i received another (finer) glass-powder from Schott for sealing-tests. While the other types i used mixed with water behave like normal dust-paste, this type is more like starch-powder with water - when moving the stick slowly, it's fluid like milk or juice, but when moving faster, it's suddenly stiff and brakes like a solid, but went fluid again when released. This type of paste woulby VDX - Polymer Working Group
Hi Erik, it's for testing reprap-fabbing with UV-resins - i want to atach the syringe to the toolhead beside the millhead and output some test-trays. Then i'll saturate the complete layer with the UV-lamp to cure it. Then output next layer ontop of the hardened trays, and so on ... It's testing for adhesion of the actual layer to the already hardened/cured sheet. Viktorby VDX - Polymer Working Group
Hi Howie, ... it's an extreme dangerous 'toy' which can melt and burn good absorbing plastic, but for normal use as sintering-laser or CNC-carving it has not enough power, so the application will be very slow and extreme limited in possible materials. The only application i see for reprapping or LOM-fabbing is cutting contours in thin sheets of black plastic (or other good absorbing and easy meby VDX - Laser Cutter Working Group
Hi Zach, nanotec sells cheap linear actuators for 25 Euros ( ) Or look at the images in the Thread "Easy to assemble linear drives" ( ) - here i built linear drives by fixing a threaded rod with the same diameter to the motor-axis and a nut or PTFE-block with threading as mover. When you atach a tube to the nut, which is longer then the threaded rod, and a fitting for the plunger, then you caby VDX - Polymer Working Group
Hi Fernando, ... actually i'm fully occupied with other problems and havent't searched for the resins. But it shouldn't be a long job to atach a motorized dispenser and the small UV-lamp to my CNC, so maybe you can send me some probes for testing? I'll send you my adress ... Viktorby VDX - Polymer Working Group
Hi Fernando, ... i recently found the specs of the bluray-laser - it has 405nm wavelength ... So maybe it's not so a bad idea to salvage a (old/broken) PS3-drive and searh some UV-curable epoxies at 400nm for high-accuracy fabbing? Viktorby VDX - Polymer Working Group
Hi mimarob, ... this is exactly the 3D-printing strategy of common stereolitho-machines. As UV-source they use an UV-laser for a spot-size of around 100 microns. With this layer-stepping the printed object dives in the epoxy-bath and only the topmost slice is processed. When ready, you pull the object out of the bath - when printing hollow honeycomb-structures in the inner volumes and a thickby VDX - Polymer Working Group
... my hint for the 'pure stuff' is freezing in a centrifuge I knew that 'ice-beer' ('Eis-Bock' or doubled='Doppel-Eis-Bock' in german) is made by concentrating the alcohol, malt and solved aromatic additives by freesing the water out. The container is freezed down to -30by VDX - Polymer Working Group
... i can assist with building/construction or conversion of 3D-objects - in the past i made some VRML-3D-worlds for exhibitions and presentations and for our microtec-fairs or customer-purposes i regularly designed and constructed the objects for 3D-fabbing or visual presentation/animation in raytraced scenarios. For construction, animations and 'photorealistic' rendering i used/use 3D-Studio oby VDX - Administration, Announcements, Policy
Hi skirmish, ... the idea with old walkmen or taperecorder-heads sounds brilliant! Then it's worth thinking about CD- or DVD-drives as rotary or 2D-polarcoordinate-encoders too. In the past i was playing with the idea of triangulating sound-waves in a base-plate, where i'll inject three different pulse-sources at the edges of the plate and a piezo-microphone in the toolhead would sense the timby VDX - Mechanics
Hi blerik, ... have a look on LOM (Layered Object Modelling or Laminated Object Modelling) - here you have the technology and some systems for building highly sophisticated and sometimes really big objects from paper or thin sheets of different materials. Or search in the forum, here i posted some ideas of a lathe-type of LOM-fabbing too ... Viktorby VDX - RepRap Host
Hi deadgenome, ... good to know - i'll have a look on this ... Viktorby VDX - RepRap Host
... yeah ... i won't name it. Many years ago i tried to design a scalable virtual constructor-world, where i start with coloured balls resembling single atoms, then stick the balls together in the wished order, a physics-engine adjust the distance and angles to form simple molecules, and so on, and so on ... When the object gets to big or complicated, i would change the dimension or collapse itby VDX - RepRap Host
Hi deadgenome, ... looks very interesting! It seems to have much bigger potential then Blaxxun's first try, but now it has some more competition in virtual- and simworlds. You must have a minimum amount of users and common interest for driving it over a time long enough, so i wish the very best ... Viktorby VDX - RepRap Host
... here i have some samples of 3D-milling with my old CNC-system - the rooster in the images is 70x60x10mm in size, but the millhead can move until 500x500x90mm. Back-side only roughed: Front-side finished: This was a test-output with Cut3D from vectric, but with the basic-software from Isel i'm capable of 3D-constructing and milling with 3 or 4 axes. I think with some experimenting and goby VDX - Shape Deposition Manufacturing Working Group
... i think for building big objects with sand/concrete the best way should be to reprap the outer surface of the object with normal plastic in slices of some millimetres or centimetres height, fill the structure completelly with the sand-mixture, let it harden and then process the next slice ontop ... 'Normal' sand-particles are to sharp-edged and rough to go through a dispenser and when mixingby VDX - Polymer Working Group
Hi Andy, ... it's every type of 2K-epoxy you can find, the people didn't fix on a special type, it's simply the 'glue' ... For the best results you have to mix coarser and finer sand with some sort of cutted fibres (glass, carbon or such) with 6% to 12% of epoxy. The mixture didn't flow, so you have to insert it with some force and compress by vibration to exhaust air-bubbles. Viktorby VDX - Casting and Moldmaking Working Group
... i'm repstrapping with a fully functionable CNC-mill too (beside mey experiments with parallel-kinematic-robots). The problem is not the communication to the steppers - here i have an Isel-CNC-controller, which ist driven by the PC with proprietary Isel-NCP-code or common G-code over the serial RS232-port. Many others have other CNC-mills or PCB-routers with DIR/CLK-drivers over parallel porby VDX - RepRap Host
Hi Andy, ... the images are out from the building process (and this are two different machines) - in the end the complete machine should be embedded in virtual stone ... The framework is made from steel, not from aluminium - the people building this targets mainly rigidity and stiffness, not leightweight systems - so some hundred kilograms per component aren't bad and some complete assembled sby VDX - Casting and Moldmaking Working Group
Hi Gene Hacker, ... i had run the golem-project nearly two years on my PC in background, but got only the common 'hoppers' and 'sliders', so it seems to be someting limited in evolutional bandwith ... My favorite are the morphing blocks: - it's a very interesting path into the nano-world of fogglets or utility-fog ( ) Another very interesting evolutionary approach are the framsticks - - heby VDX - Let's design something! (I've got an idea ...)
Hi Sebastien, ... i can post some images, but you have to login to read the posts - it's mainly the Forum "CNC-Ecke" [5128.rapidforum.com] (or www.cncecke.de ) Viktorby VDX - Casting and Moldmaking Working Group