... one of my ideas behind crosslinking LOM and RepRap is the general ability of the reprap to extrude sheets ... Imagine the reprap outputting a complete sheet with a height of 0,5mm (for example) ... Then the mill-head (atached second to the extruder) mills the contour-outlines of the actual sheet with the accuracy of the mechanic setup (in my actual CNC-repstrap =0,0125mm or 12,5microns, witby VDX - Plastic Extruder Working Group
Hi All, ... mostly for the pleasure of my sons (and some testing) we built our first LOM-object on an old CNC-system with a provisory atached minidrill ... I simply stacked 3mm thick deco-sheets with doublesided duct-tape and milled the slices of a mug with some overhang: Here the CNC-system: For a better overview of the fabbing-process i apended the complete image-sequence in ZIP-archiby VDX - Plastic Extruder Working Group
Hi Sebastien, ... ist's special in several ways - but i found some interesting hints for the possible near-future-evolution of the reprap-concept too Viktorby VDX - General
Hi Jay, ... here: you have a parallel-scara-robot in a similar setup with two motors for XY and a third motor for Z ... Orthogonal moving with angular driving isn't so complicated - you have clean conversions, what's called "Inverse Kinematics", where for every point in the working area you have a corresponding position of the motors. So you have only to brake down your line into elements smaby VDX - Mechanics
... i'll post some more images and infos, when i have finished my 'tripod-toy': look here under "Assembling the Tripod..." for more images and a short video of manually playing with the kinematics ... Actually i'm at optimizing my 3D-CNC-repstrap (in the BuilderBlog-link above under "Got the perfect RepStrap" too), so i can mill the needed parts for the tripod and some equipment for applyingby VDX - Mechanics
Hi all, ... i found a video of a very interesting planar-tripod/rotopod: [155.69.254.10] From here: [155.69.254.10] *** start EDIT ... and here an even older and very fast demonstration: From here: *** end This seems to be very easy to assemble and could solve the problem of reprapping parts for hierarchical bigger systems ... Viktorby VDX - Mechanics
... look at the injection-pressure for HDPE: equals 12400 to 20000 psi / 85.3 to 138 MPa / or 853 to 1380 bar! I didn't think, we could actually and in near future reprap an injection-head, capable of this forces - maybe with re-forming in metal with lost-cast-molds ... Viktorby VDX - Plastic Extruder Working Group
Hi Demented, ... congratulations! - good job I'm waiting until february with buying some needed hardware, but in the meantime i'll give my CNC-repstrap a better chance and then the tripod needs some optimizing and milled parts ... Viktorby VDX - Mechanics
... a problem could be carbonizing and oxydizing of the NiCr-wire, as there exhaust some organic acid, when overheating the plastic! When i built my first laser-cutter, the little amaount of fume passed by the evacuating hose very fast rusted the metal-parts around the toolhead, so in the next version i made all my rods, bearings and supports from stainless-steel and delrin. Another problem couby VDX - Plastic Extruder Working Group
Hi Jay, ... it's mostly a wide range between the melting point and ignition, so that's not the problem. For good forming you should heat the form too a little under the melting point and let cool it down slow after injection. The main probem is the needed presure - it should be high enough, to press the fluid plastic in all the small edges. Most plastics are not so low viscouse, even when preby VDX - Plastic Extruder Working Group
... update ... I tried with reprap-host-0.8.3 and the "3dp_clock2.stl": The original file in 'Rhinozeros Binary'-format is 3,3MB in size and didn't crash the host-software, but it slows radically down, so it needs half'n hour or more to import and render the clock! (i stopped after 10 minutes, when 3 parts were rendered) The converted ASCII-STL-output from SDview is 10MB in size and wouldn't bby VDX - RepRap Host
Hi Steve, ... i tried it too ... The original file '3dp_clock2.stl' says it's a "Rhinoceros Binary STL ( Sep 10 2001 ) ... " So i tried wit AOI, but got the error 'Not in GZIP-format' Then i imported in soliddimensions SDview and re-exported as STL, so i got an ASCII-STL, but host and AOI won't read it anyway (other STL-importers do) *** By the way i found another error in the host, what makby VDX - RepRap Host
... i'm thinkin of a direct-drive-extruder with two opposite gears which cut slightly in the filament and 'roll' it up and down ('up' when stop extruding for releasing the pressure in the melted area and avoid dropping) - this should eliminate most of the friction in the feeding too. Only one of the feeding gears is driven by the motor, the opposite gear is a passive counter-support and runs freby VDX - Plastic Extruder Working Group
Hi Assargadon, > 1) obtaining 0-poz (independent of workpiece and > toolhead) = a 'must have' for stepper-driven 'optimistic' systems - as long as no errors occure you can calculate all positions and paths from the 0,0,0 on ... > 2) hardrware alerting on out-of-axis moving > attempt = nice to have - when your optimismus or the software fails ... > 3) autodetection of toolheaby VDX - General
Hi Assargadon, > > For determining the 'workpiece-0-position' you > > move the toolhead/base manually to a > > representative position in respect to the > > workpiece and set the actual 0-pos. > Yes. And this step will be much easier if we have > Touch Sensor attached to TOOLHEAD or CARRIAGE. > "move the toolhead/base manually to a > representative position"by VDX - General
Hi Mythprogrammer, ... some folks tried with copper-filled epoxies and some comercial available conducting paste, what was used in a syringe-extruder (as in the f@h-printer) and seems to work fine ... I'm on laser-sintering a pure-gold-paste to solid gold, what went good too, but is a bit to expensive for 'ordinary' circuitry Others used graphite-filled polymers, what's limited by max currentby VDX - Mechanics
... think of security! -- you handle here with invisible radiation, which even unfocused is strong enough to cause severe damage on the skin and especially in the eyes!!! Even the 'weak' IR-LD's from salvaged DVD-RW-drives with up to 220 Milliwatts are strong enough to cut through plastic, so be extreme carefully, when testing or using LD's. You can buy special goggles for every wavelength, butby VDX - Laser Cutter Working Group
Hi Nighthawk, ... very impressive - the design isn't really selfdocumenting, but you can build a nice chess-family around the part as 'king' Viktorby VDX - 3D Design tools
... i actuall have a similar "NoClassDefFoundError" in javax/vecmath/Tuple3D in Windows XP on a dual-core-Intel ... At home with WinXP-home and the same install i finally managed to bring it to work after updating my OpenGL-drivers for the Ati-Radeon-Mobile9600 graphics card on my notebook ... Viktorby VDX - RepRap Host
Hi Ian, ... here is the vendor: ... and here the 8Watt-diodelaser: Viktorby VDX - Laser Cutter Working Group
Hi Assargadon, ... look at the behaviour of low-cost CNC-systems with manually or semi-automatically changed mills: With every mill-exchange you have another 0-position, so the home-/limit-switch is 'on the other end' - eg. the limiter is activated, when the reprap-base-plate is at the absolute bottom ... For determining the 'workpiece-0-position' you move the toolhead/base manually to a repreby VDX - General
... ... What's with 3D-fabric? Viktorby VDX - General
... yesterday we tried it ... I heated 500 ml milk short before boiling and poured a spoon of vinegar-conzentrate into - very fast separation of curd and whey. After filtering we got nearly 200 grams of 'farmers cheese' - it taste as cheese too, but a little poor without salt Then we pressed the water out and inserted the stuff in some play-doh-mold-forms. I tried with a milled counterform fby VDX - Polymer Working Group
... best way for collecting low-concentrated gases like CO2 or methane from air is filtering in 'bio-filters' with algae or bacteria in water or in a big greenhouse with fast-growing plants as reeds or special C4-plants. Then convert the bio-stuff in a high-pressure temp-curing process with citric acid as catalyst to pure carbon and water or a fractionable oil-basis. This would be some bigger,by VDX - Let's design something! (I've got an idea ...)
... because pure carbon is the ever best (ultra-strong and hyper-rigid) building-material (fullerenes/bucky-balls, carbon-nanowires, graphene-sheets and diamond) it should be enough to convert all Cx-stuff in carbon or carbonmonoxide as basis and exhaust the 'additives' as O2, N2, water or elementar ressources for second-stage processes ... I think in some years there should be the technology toby VDX - Let's design something! (I've got an idea ...)
Hi Assargadon, ... try to open a motor, then you can test, if it's a common stepper and how much phases it has. - 'normal' bipolar steppers should have 4, 6 or 8 wires - 3-phased have 3, 4 or 6 (sometimes you have some more wires for a tacho or coarse angular sensor, but separated from the motor-lines) - when opened, you should have a permanent-magnetized rotor toothed like a gear - the inner sby VDX - Russia RepRap User Group
Hi Assargadon and Sebastien, ... here is the image of the robot: It seems to ba a fully usable concept, but the motor-type isn't so clear - could be old-styled 3-phase-steppers, as they are longer and taller, then normal steppers ... When the motors arent't conventional steppers, then you have to bring to work the driver -- if they are, and you cant't run the driver, then it would be best toby VDX - Russia RepRap User Group
... one problem with complete infilling after fabbing could be bubbles between the criss-crossed filament-meshes inside the object. Maybe its better to output the contour-outlines of some layers (3 to 6 layers, so you didn't need criss-crossing filaments and it's faster too), then fill the inner volume with the filler-medium, wait the hardening time, and so on? With a 2K-head this should be theby VDX - Plastic Extruder Working Group
Hi Reece, ... the actual fabbing methods mostly aren't capable of making (really) usable threads - comercial FDM-printers manage to make bigger threads (as in bottle-caps), but you should have an accuracy in the filament-diameter and slice-height nearly four times finer then the target-thread, or it wouldn't fit properly and wear out or brake very fast ... Better cut the threading on smooth stiby VDX - Let's design something! (I've got an idea ...)
Hi Ian, ... next week (when on workplace again) i'll post the adress of the vendor and some more infos - it's a german company, but shouldn't be a problem with international shipping too ... You can find diode-lasers from 1Watt to 60Watts with then drastically increasing prices - actually we are in developing of an assembly/justage-stage for a special ring-focus-diodelaser with 60 to 80 20Watt-by VDX - Laser Cutter Working Group