When moving I recommend Einstby spota - Casting and Moldmaking Working Group
aka47 Wrote: ------------------------------------------------------- > Clever stuff > > I had originally suggested LED's because I was envisaging a ring of leds around the deposition type nozzel/needle. > The tool head can then Deposit, Deposit & Cure or Cure only and can be selective about which areas get cured and for how long. > > Whilst a syringe is an option, providiby spota - Polymer Working Group
Good ideas! If you don't mind, I will copy this to the other thread about the UV RepRapby spota - Polymer Working Group
Ok, Viktor. I'll PM you for your address. Maybe we can figure out how to get you some samples. Your equipment would be areal boost for the advancement of this device!by spota - Polymer Working Group
Hey Viktor. I read your post and you are right to point out this shrinkage issue. I have also concerns about the need of drying. This means that the water content of the paste has to be evaporated? Evaporation is quite a difficult technique to master in a even way. You can never be sure the paste dries out evenly on the surfaces and in the interior of volumes. This may cause cracks and objects wiby spota - Polymer Working Group
I have lately devised a couple of resins that cure very well with UV light (see builders blog: on Monday, February 11, 2008) The price of a kg of this resin would be around 10 to 13by spota - Polymer Working Group
Actually I'm seriously considering building a cartesian robot right now. I have almost all I need and the issues that I have to solve now are more of a construction of the robot with efficient UV lamps type. I will open a thread with my inputs on UV lamps. Maybe there are some ideas out there that will help me out.by spota - Polymer Working Group
Yeah, formaldehyde is thought to be nasty... I would try Acetaldehyde, the next heavier aldehyde: you can buy it online here I would expect the latter to be less reactive than Formaldehyde though, so don't guarantee it will work. Does anybody have a cost estimate of this plastic, all reactives included? It's also a little unclear to me how this stuff would be dispensed. Any thoughts?by spota - Polymer Working Group
Continuing tests on the recently discovered photoinitiator mixes: I made a series of tests I figured to see which of both mixes fares better. Don't forget, Benzil+Benzophenone is the cheap mix, Isobutybenzoinesther+Benzophenone is the expensive one. The layer thickness is 1mm in every test. No mentionable shrinkage will occur in any test. Test A) 5 minutes of UVC irradiation, followed by 2 minuby spota - Polymer Working Group
Thanks Viktor! I really think this will open the door for really accurate printing applications. As a reference, when I speak of UVC, it's 254nm. UVB is 365nm. maybe I should mail you or post the corresponding spectra of these photoinitiators, so that you see what UV sources would be valid. A very usefull link on UV ledsby spota - Polymer Working Group
Double whammy bingo success!!!!! You know those chemicals I have recieved? Well from the four, two have excellent curing behavour! They react with UVB light and in combination with Benzophenone and combines UVC and UVB irradiation I get fantastic curing at depths of +/- 1mm below 10 minutes of irradiation!! Here is the cheapest of both, called Benzil: This one needs combined UVC/UVB irradiatioby spota - Polymer Working Group
Actually near UV photoinitiators are the most expensive ones. I have just received a couple of chemicals that are less expensive and that I will test and hope to see some results in those wavelengths. But I'm not sure yet they will work well enough. I have found some leds that emit in th enear UV bands too. They come with colimating lenses and I guess it's probably cheaper and easier to build thby spota - Polymer Working Group
The cheapest types of photoinitiators work well with what is called germicidal UV fluorescent lamps. This is the cheapest combination I have found by now. There are some Leds I hav found lately that would fit into some photoinitiator spectra, but they have quite a low intensity (watt/cmby spota - Polymer Working Group
@ Jay: Yes, even for the UV-C type radiation which doesn't penetrate deep into the skin, and generally speaking, UV radiation is not good for you. The hyperbolic reflector is thought to direct the rays towards the printed resin parts only, but there still will be stray radiation escaping the apparatus. The best way to shield the thing, short from having the RepRap in a closed room, is to build aby spota - Polymer Working Group
Actually, th etime is more than enough. Stopping UV irradiation stops the curing process. Curing time is currently below 10 minutes and can be adjusted to greater values if needed. I have spotted a lamp and am designing a hyperbolic reflector that will reduce this time to below 3 minutes and improve curing depth. I'm currently also working on accelerating the curing process to below 1 minute irrby spota - Polymer Working Group
Although lately I have mostly been busy mixing heat triggered curing resins (Furfuryl Alcohol and such) I have made some very important progress on the UV curing resins as well. I was toying around mixing different kind of resins and seeing how those compounds improved the polymer properties. The two big problems I had remaining on the researched mixes I discovered were 1) surface wrinkling dueby spota - Polymer Working Group
Sorry, I tried to post something in this thread before but somehow my firefox shunted and all my post was lost! I see now that most of what I wanted to say has peen already said, so yes. PU is great if you manage to dispense it fast enough. Polyester hardens slower and epoxy is also an alternative. Maybe using some sort of helicoidal mixer head would solve the problem of syringe clogging. you cby spota - Plastic Extruder Working Group
I'm not really sure but the fact is that it doesn't really need to block UVs as standard glass does that pretty well. Nevertheless there are plastics, or better said additives that make a transparent plastic become UV filtering. You will just have to ask for it if you want to have that characteristic, but chances are that they will make you pay $$ for an otherwise quite cheap to achieve UV blockiby spota - Polymer Working Group
Better shield with any type of opaque material, kind like a box and put a lid on top. make it a glass lid or if you need continuous monitoring, insert a webcam in the box. That would be the easiest way. Or else, just start the job and leave the room while it's working.by spota - Polymer Working Group
My wager is that nylon will be problematic to print. As Viktor says, the stuff you get when mixing the adipic acid with a diamine, for example, releases molecules of water that need to be carried away or they interfere in the properties of the end polymer. I would rather look into Polyurethanes: polyols and diisocyanates can produce very hard and tough polymers. They can also be bough as bi-compby spota - Plastic Extruder Working Group
Hello Robert! I have done some research to achieve resin mixtures that would be UV cured. My goal was to make both the resins and the UV-lamps affordable, as well as fast curing. There have been a couple of problems that have been encountered on the way. Achieving cheap and fast curing mixes produced an effect that's called surface screening: The top layer cures fast but the bottom layers don'tby spota - Polymer Working Group
Sorry if I'm a little late to join in on the thread. I just saw it recently and as a chemist just wanted to confirm what BDolge has said above. Sadly PLA is not so easy to synthesize as would be desirable. Several of the steps above are cumbersome, some of them are even frankly dangerous. But it is possible to do, specially if done in a bigger operation. Will you m,anage to eat the price of imporby spota - Polymer Working Group
SebastienBailard Wrote: ------------------------------------------------------- > I wonder; could one make a slurry of powdered > bronze and monomer, squirt catalyst on the surface > to make a hardened slice of the object, put down > another thin layer of slurry, another squirt, and > so on? > > > Definitley a good idea, yes! The only requisite here would be that the timby spota - Powder Printing and Selective Laser Sintering
SebastienBailard Wrote: ------------------------------------------------------- > There are two kinds, piezoelectric and thermo. > *Piezoelectric uses a piezoelectric element to > mechanically push the droplets out. > *Thermo heats up a resistor. The heat creates a > steam bubble in the (usually aqueous with thermo) > ink, and that bubble pushes the droplet out. > See: >by spota - Powder Printing and Selective Laser Sintering
I've been thinking and this might be the ideal technique to use the "spray-on" catalyzer on top of a layer of liquid resin. Imagine a surface of resin in a vat that is being filled a layer at a time. after thi sfilling step, the inkjet sprays catalyzer on specific points, initiating the polymerization. neigbouring points would merge together. Newly sprayed points on top of the previous layer wouby spota - Powder Printing and Selective Laser Sintering
Hmmmm, inkjet! That's the perfect technology for my UV-setting resins! What is the viscosity needed for the ink? Also, won't it clog easely with resins? AFAIK, it's based on microbubbles generated by explosive evaporation... Thats the kind of thing that could cause a monomer to polymerize in the inkjets canules.by spota - Powder Printing and Selective Laser Sintering
TheGuy Wrote: ------------------------------------------------------- > Spent my spare 3.5 minutes today tinkering with > polymer mono filament and an electrostatic module. > Easily got 7 inches of deflection from 7.5kvolts > at 80hz. So the extruder head I envision could > cover at least that much area with minimal > expense. Picture 2 electrodes at right angles (or > 3 at 1by spota - General
What about using heat resitant cements? It woul dbe a matter of having the correct molds. Maybe silicon molds would work nicely. Also i'm trying to mix resins that have a degree of flexibility but still maintain an accurate shape. This would be useful as mold material.by spota - General
Hey Viktor! This Waterglass investigation is really cool! And it has a LOT of possibilities i see. I have been reading up a little on this Sodium Silicate. It really is the ideal sintering composite! Do you have pictures of a final glass sintered with this stuff? Does it look like regular glass or is it more like aerogel? Now that we have a separate forum for our gooey threads, don't you thinkby spota - Polymer Working Group