I am experimenting with an inorganic binder/filler mix. You can mix a liquid organic binder with it by simply injecting the binder into a mixing tube just before extruding. That means only a single room tempature head on the machine. After the part is finished the inorganic binder is heat resistant enough to allow aluminum to be poured without issue. But while heat resistant the inorganic binderby ohiomike - General
Thats one of the major advantages of using a syringe type delivery system, I'm just going to create microbubbles the same way I would for an angel food cake, mix like crazy. Hopefully by changing the percent moisture and varing the level of surfactants, I will get at least a little control over the closed/open ratio and the bubble size.By staying at room tempature I can try and avoid the problemby ohiomike - General
SUCCESS!! Well at least in part. I got in contact with the head of the project at Cornell, and he said that while he cannot engauge in commercial activities as part of a univerisity project, that he will assist us in the creation of a proof of concept run. He requests that we wait and see if any of the other fabbers would be interested prior to him starting testing. Basically if he assists usby ohiomike - General
I remember Simon doing a beautiful job of drawing a cube with exactly that idea, who may have also been working on it I have no idea. One of my eventual intentions is to use material with air injected, in order to create rigid foam type material. Drywall joint compound, because it is cheap, readily available, recyclable, and can be post machined by hand tools has a great many possibilites. The cby ohiomike - General
True, if you dont manufacture the design for sale there really isnt anything they can do to you. It is very unlikley they would have been granted a patent on the production of a furfural bonded part (since bakelite was made with furfural). However I havent been able to find the patent so its quite possible that it was denied on the basis of prior art. Given how often that happens in the foundryby ohiomike - General
Not nice stuff, reeks to high heaven and can crosslink rather energetically. I use it occasionally in small amount with epoxies to make a free-radical cure system that uses the acrylate to form a short term handleing strength and then uses the epoxy to get the long term strength. But I mix it with about 50 parts sand prior to using it. Furfural alcohol is water-like in visocisity, but there is cby ohiomike - General
I posted an inquire to their forum but I am going to try and find a email for someone that is more familar with who has working systems. If you have any suggestions for who I could talk to drop me a line. Mike The thoughts and ideas expressed in this post do not reflect those of my employer and are intended only as communications between individuals. Any attempts at implement are at your own riby ohiomike - General
Well, the first results are in. I made a standard test piece out of joint compound and then impregnated it with polyurathene. The results were a tensile strength of about 120psi and from that I can assume a compression strength in the 1000psi range. Not concrete but more then strong enought to do what we need done. And one part poly is available for about $30 a gallon at any hardware store inby ohiomike - General
I dont know, reading their site it says they can print in gypsum. If I can get a gypsum part I can certainly try and impregnate it with support resins. We use plaster in our 3d printer and then flood fill the pourous parts with either polyurathane (one parts are available at hardware stores) or epoxy (expensive but it makes a part as hard as concrete). I need to go to the hardware and get some joby ohiomike - General
The bath I ran was an industrial electrocoating system, and I definitely agree that mixing is HUGELY important. We would use eductors that took the outflow of a pump and slowed it down by entraining large amounts of the surrounding fluid. An eductor is a simple little plastic part that would be ideal for the reprap to print, its basically a megaphone designed to be used in a liquid. With a couplby ohiomike - General
The displacemnt map only covers half the object but I wonder if you can make one of each half and then combine. It saids that the code can import into blender, and I would assume that blender can produce the STL files necessary for Darwin. But thats only an assumtion Mikeby ohiomike - 3D Scanners, Book Scanners, and Optics
I am going to try and answer a lot of questions in one post so dont get confused if I seem to jump around. The reason that they were painting on the circuits rather than using conductive filler is because conductive filler degrades the physical performance of the plastic and because the conductivity of the silver is FAR higher than a plastic/filler blend could ever get to. The only reason thatby ohiomike - General
Prior to my current position I worked for a electroplater/electrocoater, we never did copper but we did do about a dozen corrosion resistance alloys like tin/zinc and zinc/nickel. So having caught the recent posting of the use of copper electroplating to coat a nozzle I got to thinking. A low quality conductive polymer could likley be built by simply mixing large amounts of carbon black pigmenby ohiomike - General
A lot of universities offer "friends of the library" type memberships. Ohio State has one for $45 a year. That gives me library privilages including interlibrary loan. Which means that getting my hands on expensive engineering texts is easy. They allow you to check out for a month at a time and you can renew for as long as someone else hasnt reserved the book. I just put reserves on a half dozenby ohiomike - General
I suspect you could do a progressive fill so that the fluid level was flush with the top of the half finished part. That would negate a lot of the need for support material and rapiddly cool the material. There is also the possibility of using a flowable salt gel as the fluid and encapsulate a portion in order to create low voltage wiring. You could then use a nail with a little bit of caulk at tby ohiomike - General
Any acid will cataysize furfuryl alcohol but straight furfuryl usally needs sulfuric. mike The thoughts and ideas expressed in this post do not reflect those of my employer and are intended only as communications between individuals. Any attempts at implement are at your own riskby ohiomike - Casting and Moldmaking Working Group
Excellent suggestions My thinking is that it will be easier to extrude drawn wire onto a bed and weld the surrounding powder to it rather than try and change the crystal structure of the metal using radiation. Speaking of induction however, what about the possibility of using high current to melt a small amount of metal for an extruder rather than a high tempature coil? Although I could see usiby ohiomike - Powder Printing and Selective Laser Sintering
Yes and no. Just like you can take furan alcohol that would explosivly polymerize and make it safe with the addition of fillers, you can do the same thing with thermites. We make a thermite material that is mixed with refractories to make a self heating cup for the metalworking industry. I would store a ton of those things in my garage and sleep like a baby, since nothing short of a MAP torch coby ohiomike - Casting and Moldmaking Working Group
I work with powdered aluminums all the time. A large part of my job is formulation of thermite derivatives. You want to be careful to use a coarser grade of aluminum (which is cheaper anyway ) but the surrounding metal is going to chill the molten material very quickly, likly far too quickly for their to be any real issue with oxidation. My concern would be that you wont get any interlayer adhesby ohiomike - Powder Printing and Selective Laser Sintering
Alright, I finally got the fitting for the air line to run my new binary paste gun. It works fine! The problem right now is that the material I am trying to extrude is too high in viscosity so it is tending to set up in the static mixer. But the system seems to work fine at about 50% polymer by weight, I just need to have enough solvent present to lubricate the mixer. See the attached pictures.by ohiomike - General
Where can I find pictures of the Darwin parts with dimensions? I would settle for just straight pictures if they are all in the same scale and someone can tell me what the size is supposed to be. I havent seen any on the website, but IT wont let me install AOI on my work system so I cant look at the raw files. I figure to start my mold making experiments with a clear idea of the where I am tryiby ohiomike - General
This is really what the polyceramic work is about. Taking a thermoplastic mold and using it to form a liquid catayst coldsetting thermoset composite. One of my future intentions is to look at then using the termoset material to mold INORGANIC (true ceramics) binders using 100C type heat to softset the inorganic then removing and firing it. Your initial point is correct, there is a very real poby ohiomike - General
My group at work uses primarily polyurathanes and so the first materials I will be looking at will be those. Next I will likley look at furan/furfural type resins with cheap fillers (sands mostly). This stuff is closer to concrete than it is to metal in fracture modes, so while it could be made thick enough to handle a lathe bed, pre-stressing it would likley be be desirable were you planning aby ohiomike - General
The thoughts and ideas expressed in this post do not reflect those of my employer and are intended only as communications between individuals. Any attempts at implement are at your own riskby ohiomike - General
Piston pumps are actually very popular for high viscosity pumping, pound for pound they put out more PSI than any other small pump design. I used to use one to pump a paint concentrate (that could best be described as sludge) up two stories and across an unheated warehouse, in Ohio, in January. They were metering pumps manufactured by LMI. But that would mean we need to be able to build checkvalby ohiomike - Paste Extrusion Working Group
The problem with the regular peristalic was that the high viscosity of the material meant that bubbles in the line were a problem. Filled polymer systems such as the polyfill (and my experiments with fillers) are almost always dialent suspensions and thus difficult to pump. My hope was that the large surface area of the linear peristalic would increase the vaccum enough to prevent so many bubblesby ohiomike - Paste Extrusion Working Group
I was reading the archive on the peristalic pumps and saw that the major issue was the pulseing flow of the pumps. Might I suggest linear peristaltic pumps, since the shoes are identical (thus easy to reprap and replace) and it doesnt pulse like a circular peristalic. The only difficult part to make would be the S-shaped axis in the center. The use of a spring loaded pressure plate on the bottomby ohiomike - Paste Extrusion Working Group
Have you considered the possibiliy of using filler in the thermoplast? Adding a little sand to the plastic would reduce the flexibility of the final product (maybe good maybe bad) but would dramatically reduce the dilation of the material. Polyester, nylon, or fiberglass fiber would also be a possibilty depending on if you wanted wear resistance, rather than stiffness. Either sand or fibers wouldby ohiomike - Plastic Extruder Working Group
They way that we used to control that problem with paint was to have an adjustable screw that controled how far the delivery orifice was allowed to open. We would then calibrate that for the different materials to standarize the delivery rate. Stick a graduated cylinder under it for 30sec and check the volume, then adjust and repeat. So long as you do this each time for each machine, the variatiby ohiomike - General
The product is Ashland's Pep-set Quantum line. Its listed under nobakes. Take a look around the site and check out the cold-box and furan stuff we also have. The refractory is sold under the name Exactherm, and the sand was standard silica sand. I picked that resin system because I was one of the inventors of the Quantum line. I figure I understand it a little better than most, so I am not tooby ohiomike - General