... i mustn't have heat or air-pressure to move pistons - as in the 'Artificial Muscles'-thread mentioned, i can build solid-state pumps and valves only from hoses and solenoids, if i have MRF or ferrofluid as active and transporting medium ... With MRF i already designed peristaltic pumps, which move the fluid only through serial switching of solenoids, without any moving parts ... With a diffby VDX - General
Hi Samuel, ... this is a mixture from carbonyl-iron-spheres (grade CC, that means nearly 50 microns diameter), vaseline and some vegetable-oil (from the kitchen) to reduce viscosity - no surfactant, because it's a MRF, not a ferrofluid ... It stays stable over months (i have some fluid mixtures which are 5 years old and working), when i have to much oil and/or there would be sedimentation, i caby VDX - General
... here's my first experience with uploading a video to youtube: As you can see, i pour some MRF (Magneto-Rheological-Fluid) in the field of a neodymium-magnet, where it stiffens. With removing the magnets it went fluid again, and with applying the magnets it got stiff again, and so on, and so on ... Viktorby VDX - General
Hi Fernando, ... sounds really good! Actually i'm bound with other tasks, but that's a way, i want to go - keep us informed and be carefull, not to rocket your house in the sky To the diode-lasers: you should salvage lasers only from newer Drives, so 40x or faster - in older drives the diodes haven't enough power, in pointers it's the same - with a 5mW-Diode there isn't a sensable heat in theby VDX - Paste Extrusion Working Group
Hi Fernando, ... glass and ceramic melts much better then metall, but they have a higher thermal contraction, so i must mix materials with different TK-values for better stability, or it would brake apart, when cooling down ... Another point: - i have to dry the paste with lower energy completely, befor i can melt the powder to solid, or the evaporating solvant would blast the powder away ...by VDX - Paste Extrusion Working Group
Hi Fernando, ... you can make tests with stark instead of cellulose, should work similar ... My tests with laser-melting gold-dexpanthenol-paste went fine, the heavier part is now to adjust the output-power of the diode-laser, to liquidize the gold-powder, but stop melting, before the gold-pad under the paste is melted completely too ... Tomorrow i'll try sintering or melt the iron-paste, whicby VDX - Paste Extrusion Working Group
... here i have a static image-sequence of a MRF-mixture (Mangneto-Rheological-Fluid) of carbonyl-iron-microspheres, dexpanthenol and some glycerine for lower viscosity ... As you cn see, in a magnetic field (here from some NdFeB-magnets beneath the glassplate) the fluid stiffens, so it can hold the inserted stick -- without the magnets it went fluid again, and so on, and so on ... So this mixtby VDX - General
... maybe low-temp-melting wax (parafine/stearine?) is usable as easy to remove support? When i once had to optimise/debug a heatcuring glue-dispenser-system, the problems were drastically reduced, when i wound a heating wire around the dispenser body and the outtake/needle and put some aluminium-foil and a foam-hull around the complete dispenser-head. With this i could set and hold temperatureby VDX - General
Hi Samuel, ... an dc-motor with an excenter ist the simplest way for an oszillating pump with variable sinusoidal output and precise pressure-curves over the period. Maybe two separate (normal) pumps for static pressure and vacuum with tanks for charging and damping would be a try too for pneumatics, then you need two valves per muscle, but can act every muscle in asynchronous mode ... For a hby VDX - General
... i had some tsting with powders from VAC in germany - they fabricate high-quality but expensive magnets. Maybe the guys at www.supermagnete.de have some - i'll ask them ... Viktorby VDX - General
Hi Samuel, ... 'China'-magnets can be cheap bought in big amounts for some cents each, so in bulks bought in Asia it's not so expensive ... The coils can be wound manually with a drill, so it's best homemade ... And the accuracy is dependant of the relation: step-width of the magnets against the amount and displacement of the coil-series - with aligned series of 8 coils in 4 rows i can make 32by VDX - General
Hi Samuel, ... look on the image above - i changed it and inserted the holding magnets, so the solenoids acts only in short pulses, to pull the ball between the two possible end-positions ... With oszillating pressure-pulses the ball moves in the 'closed'-position slightly between the two holes - until it's properly pressed at the opposition hole and blocks the flow, a small amount of fluid canby VDX - Mechanics
Hi all, ... on sunday i was with my youngest son in the basement at my parents house, where we 'revisited' some of my old projects from scool-time, nearly thirty years ago ... One of them was a workaround, where i converted a Brother-HR1-typewheelprinter in a pen-plotter for my oldstyled Commodore C64-homecomputer. It was really working after the long time - a condensator in the powersupply fuby VDX - General
Hi Samuel, ... for me it's after 10:00 PM on Saturday night, it isn't much to work and i'm a sort of on the way in my bed It seems, we're on a side-way from the normal talk, so it's not so much folks involved - and the 'core-team' isn't at home now, to moderate or place comments ... Bye and good night, Viktorby VDX - General
Hi Samuel, ... if i insert two small permanent-magnets on the opposite sides, so the ball would stay without power in the last activated position - then the solenoids have to be powerfull enough, to pull the ball away from the opposite magnet, then the now nearer magnet holds the ball ... Viktorby VDX - Mechanics
Hi Samuel, ... look on my 'two-way-valve' in the other thread - here i can stop the flow properly in both directions ... From the 'Fischer-Technik'-plastics-toys i have very small one-way-valves (heart-like ) and manually driven pneumatic 3-way-switches, which could also be mechanically activated/switched by a solenoid. Instead of a sphere there could be a moving bar or a bending membrane, whby VDX - General
... here is an image of a valve, which can handle pressure from both dirctions - the ball in 'close'-position would be pressed on the opposite hole. One problem could be with oszillating pressure-pulses, that the ball in 'closed' position would be oszillating between the two holes an a small amount of fluid can pass by with every pulse-periode ... Viktorby VDX - Mechanics
Hi Samuel, ... i used the syringes only to apply pressure for demostration - in a 'real' setup there should be much more 'muscles' (with attached magnetic/solenoid valves each), and the syringe would be driven oszillating as central pump by a motor with excenter ... For solenoids you can salvage old solenoid-relays (?) or electromechanic switches, the use often 12 or 24 Volts and can perform hiby VDX - General
Hi zzorn, ... a better way for precise switching and applying short pressure-pulses of air or liquid could be a solenoid-valve with a trapped steel-sphere, which is through the solenoid moved in the way and settled on the tube to stop flow and pulled away, to give the way free ... Viktorby VDX - Mechanics
Hi zzorn, ... you can reprap hoses with inserted strings, when you manually inlay the strings during the fabbing process ... Another pneumatic muscle without strings is like a bicycle-hose - without pressure you can stretch it to full length, but when you apply pressure, it morphs to the ring-form (or other endforms with more displacement) and contracts with some force ... But this muscles areby VDX - General
Hi Samuel, ... 'soft' mean, that the ferrofluid in the magnetic field can perform only weak pressure forces - dependant of the size and strength of the magnets, the amount of feerofluid and the gap-width i achieved some Newtons as pressure on the complete surface, what mean, that the compressing force on the tube is a bit lower. Normally a wall of ferrofluid can withstand a pressue of 0,3 to 0,by VDX - Mechanics
Hi zzorn, ... the idea with the latex-'fingers' is good - as samuel mentioned, you should glue 4 to 8 strings along the sides of the finger, best with gummi-arabicum-glue or with the solvent-glue, you use for bicycle-repairs, because the glue should be elastic too ... It's the best, you wet the strings with the glue and press them onto the latex, so it could make a firm contact over the completby VDX - General
Hi Samuel, ... i like the tripods, because of the much simpler assembly and the simpler and easier reprapable parts. Compare the amount of the darwin-parts to the green coloured parts in my second post. I'll have 12 parts, which i can reprap easily (6 rods, 3 columns, 3 plates), three linear motors and three linear bearings (or complete, but expensiver linear stages, where the bearings and theby VDX - Mechanics
Hi Samuel, ... the pump in the second image should be filled with ferrofluid, which forms fluid threads on the spiral-magnets and on the linear magnets inside the tube. When i insert the spiral in the tube, both ff-thread-setups overcross and form cavities, which are surrounded by ferrofluid-walls. When turning the spiral, the cavities moves in the corresponding direction (as in a archimedic-pby VDX - Mechanics
Hi Samuel, ... it's half-on-half - sometimes i'm employeed (as now) for starting a microtech-branch in a company, sometimes it runs at home ... The parts i made on my own are mostly milled from aluminium or Delrin/POM on a ISEL-3D-mill. The fabbed parts from UV-epoxy, inkjetted plaster or stark i've got from 3D-printing companies - sometimes in tech-cooperation for free, sometimes with customby VDX - Mechanics
... i've found some stuff from my experiments with ferrofluids some years ago ... In the first image you can see an (UV-epoxy-fabbed) electro-magnetic nanopositioner with ferrofluidic-bearings and two prototypes of peristaltic pumps (without the normally inserted soft air-feeding tubes) - you can see the ferrofluid inside the nanopositioner or on the teeth of the pump-magnet-gears. The second iby VDX - Mechanics
... 'back to the roots' and to real life Here i assembled the linear axes and temporarily atached the magnetic joints and rods - i have to mill the 45by VDX - Mechanics
... it seems, we've lost the connection to the basic reprap a bit It's obvious, that simplifying the reprap-setup would be good for spreading the ideas and fabbing possibilities for selfmade home-manufacturing worldwide - and here is my aim, to initiate faster progress ... It's obvious too, that noncartesic systems need a more sophisticated software, to control them, but if the controls are prby VDX - Mechanics
Hi fernando, ... the gold is for a special problem: - we assemble a sensor, which is made from ceramic with gold-pads, on which we fix thin platinum-wires (10 microns and 1 micron diameter) as temp-sensing elements. Until now the wires were fixed with a conducting silver-filled polyimid paste, which will be heat-cured at 175by VDX - Paste Extrusion Working Group