Hello Eric, Theoretically this should work, but I have never tried to cure them with such torches. It is a matter of power, as the wavelengths you mention are very well suited. 3W in the window between 365 and 405 is actually plenty! By thin and thick viscosity, do you know the figures or comparative liquids you are aiming for? Also, I suppose water resistance is very important and a serious phby spota - Polymer Working Group
ah crap... Back then I was testing several different resins and didn't name the samples very explicitly. But in the end I managed to evolve all the currently available products. If they work well at 405nm it means you have the prime photoinitiator, which by the way should also work fine at 337nm. Actually you may need to be carefull with those zillion powered pulses or you'll cure the whole tanby spota - Polymer Working Group
Hello Viktor. 445nm is indeed in the extreme fringe of the activity of my prime photoinitiator. I do have an alternate one that works at 470nm and has a decent absorption at 445-450nm. But you have to take in account that this alternate photoinitiator is slower than th eprime one. But I have seen it being used in several resins used for DLP 3D printing, so it works. I don't remember which photoby spota - Polymer Working Group
Hello! I just saw you PM with your request. I will answer you over there and we can discuss the details by mail. As a general info, my resins work both in the visible blue as well as in the UV spectrum. You can see details of the available resins here: Cheers!by spota - Polymer Working Group
Hello Rob, My resins are designed to be very versatile, but they have not been tested on a Pojet before yet. Correct me if I am wrong, the projet is based around an ink-jet head, am I right? It looks like the resin jets ink-jetted slided to a UV curing stage and hardened, to come back to the ink-jet area. This means that the viscosity, surface tension and cure speed has to be just right.by spota - Polymer Working Group
Hello Mustafa and wellcome! Let me get some details clear: You want a resin that solidifies (completely cured or pre-cured?) in 1/1000 of a second (?) What depth of layer do you need to solidify at that speed? One consideration you need to have is that the photoinitiated resins undergo a chemical reaction that is exothermic. The heat that is being generated depends on the thermodynamics of theby spota - Polymer Working Group
Heh, I know where you are coming from! I am an Organic Chemist but originally with no specailization in Polymer Chemistry. Had to learn a wide array of Polymer specific subjects on the way. You should look into Aliphatic Urethane Acrylates over at the usual suspects (depending on what quantities you need), Sigma Aldritch, Eternal, Sartomer, Polymer Technologies (these are in the UK and are excby spota - Polymer Working Group
Hey Viktor! Seems like you have interesting times ahead af you. I'm very happy for you and I know you'll have a good time! Lookig forward to more input for your side. I'll also have a go and post the news at the CNCEcke, as I have ventured to translate my web to German as well, I think people ther will appreciate Cheers!!by spota - Polymer Working Group
It really does depend on what Urethane Acrylate you are using. Some have the polyol and isocyanate synthesised into the molecular structure. Did you check out this page? They offer a clear UV curing Urethane for doming purposes.by spota - Polymer Working Group
Yeah, quite complex formulation. Did you formulate this on your own or are you basing it on a standard formula from literature? One question: why do you use a complete Urethane system along an acrylic? The Urtehane Acrylates have the Urethane structure embedded in their molecule, no need for further raction with polyol and isocyanate, right? As for flexibility and tougness without yellowing, yoby spota - Polymer Working Group
Hello RepRap enthusiasts! After years of dwelling among the 3D printing community and month sof arduous work sourcing providers and finetuning resin formulas, I am finaly done setting up a website that I will use as a platform to distribute my resins. You can have a look at: For now I have 2 resins available, a 3rd one coming shortly and a 4th still under development. They are: Spot-GP, aby spota - Polymer Working Group
Okay I have kindly been pointed to the fact that the pico they are talking about is a *pico projector*, not the Asiga Pico 3D printer. So ignore my previous comment, this is actually a new and interesting result they are showing! Love the elastic polymer from the video...by spota - Polymer Working Group
This is interesting but a forseable result. The pico machine has excellent resolution although a limited build area. The cost of the printer is around 6000 - 7000$ Junior's printer kit is listed at around 4000$ and can easily replicate these results, an beats the Pico in build area size. I still think that Junior and other DIY printers have the advantage here. My 2 cents.by spota - Polymer Working Group
Massive power!!! OK, I will try and send you some thixotropic paste or fumed silica so that you can play around with paste like resins. The light under which it will be active remains the same, so everything between 365 to 425nm is good. Add your current resin to small amounts, little by little, and homogenise. This fumed silica is powerfull stuff and makes resin become extremely thick in low dby spota - Polymer Working Group
Hello Viktor, I wasn't aware you were going to try dispensing the resin. I have made some mixes with the resin you have with fumed silica. This very effectively adds thixotropy to the mix, achieving ranges of rheology from thick liquid to paste. The resin you have now has specifically been formulated to achieve a very low viscosity without having any volatiles. If you are interested in dispensiby spota - Polymer Working Group
This proces is called post cure and can take different forms, using a range of UV or visible sources. My resins will only need a cuple of standard fluo bulbs and a final black-light fluo bulb to do the post-curing. There will be no to very little tackyness left and the object achieves final hardness withing 30 minutes. Post curing in the sun is also very effective. If you ar elosing some reolutiby spota - Polymer Working Group
Wow, excellent! I would actually love to have a machine that uses the 405nm 200mW laser for printing large objects. I may get one built for me at a later stage. Will you be using a CNC or RepRap machine together with the Laser instead of 2 galvo mirrors? Be it as it may, I will get you the 1kg resin, I may add some mineral filler to the mix to help you deal with any heat peaks, add some thermalby spota - Polymer Working Group
... > > Spota, have you actually been able to > significantly decrease the cure depth using the > Castin' Craft dyes? We had somebody achieve 0.025mm resolution by twaking exposure times and playing with Castin'Craft Yellow clear and opaque dyes. But you are right about the 405nm inefficiency. I have measured the absorption spectra of CC's clear amber dye and the peak is around 46by spota - Polymer Working Group
Does this means you will go with 445 or 405nm? This I need to know too on top of the power, as it tells me what photoinitiator to use. 445nm would mean I have to get myself a very expensive PI as Camphoroquinone, that is also quite slower than BAPO. 1kg should be no problem for this test. There are still some test to be done and questions to be answered (dyes) and I think I will share the costby spota - Polymer Working Group
And I forgot: another series of tests would be to try an pinpoint what is the cure time/resolution boundaries that one can achieve with the 405nm system. What is the minimum voxel you can get and how long do you have to irradiate for curing it? Adding dyes may become necessary for having a better control of voxel dimentions. There are some succesful tests that have been made using Castin' Craftby spota - Polymer Working Group
Excellent work and very interesting results! It is interesting that the photoinitiators I have will not work at 445nm. This is a wavelength that will be very difficult to cover with PIs that have an acceptable price... The effect you see "curing from the bottom up but never at the surface" is what we mean by "Oxygen inhibition". The interface layers of the resin with air is saturated with Oxygenby spota - Polymer Working Group
Here is a link showing some absorbance of liquid water bewteen 300 and 400nm (3000 and 4000A) There seems to be a peak at 340nm. The crucial information here would be to know if the water is at all necessary and what wavelength the Chemence Verbatim photopolymer works in. You may have a try with germicidal UV lamps to test the reaction at shorter wavelengthsby spota - Polymer Working Group
You may indeed have more power than needed. Well more is always better than less as you may use different approaches to mitigate that output, by pulsing it on and off real fast. As for resins, you may want to have a look at this: These work at 359nm mostly, so you 355nm should hit close enough to the maximum absorption peak to work fairly well. Plus the excess power will help. But no kidding, vby spota - Polymer Working Group
I fail to see the point of some of your comments, which seem rather dismissive. Anyway, you are wrong. The furthest along is this guy: [3dhomemade.blogspot.com] He has ceased posting info on his build as he is planning to go closed source to sell kits. His reasons are his own. You may scuff at what the yahoo group has published or, as so many others, not even bother to read some of the info thaby spota - Polymer Working Group
Hey one question, how did you manage to get your LED source to collimate. As I heard from some optical engineers, in the DLP projectors the light souce has to have a certain shape (mostly a point source in lamp driven DLPs) to have a uniform exposure map at the projection surface. I do not know how this works in LED driven DLPs. Do you have some info in that regard?by spota - Polymer Working Group
If you are going the DLP way, be sure to have a look at the diy_3d_printing_and_fabrication@yahoogroups.com group. We have done a lot of work on that and have several usable prinby spota - Polymer Working Group
You can use PIs that only work in a given range of the visible spectrum that you can shield against. This way, you can observe your printing progress through a tinted glass or plexiglass sheet. Using syringes for viscous or thyxotropic resins is problematic as you don't have a proportional response to actuation and extruded volume. A lot of tweaking would probably be necessary for achieving highby spota - Polymer Working Group
Actually doing what you describe would be even easier with a visible light curing resin. Imagine not having to have any dangerous-over-long-exposures UV light, with resins that have a wide palette of properties, all curing with the output of standard HDI or Tungsten Halogen spotlights . I have even cured some of my resins with a regular 50W GR10 spotlight, although some post-curing with harder lby spota - Polymer Working Group
Heheh, I will have to dig up my German too and go through that forum. Thanks for the info! Today I received several packages with resin samples and a spectrophotometer. I guess you could call these my christmas present To bad the spectro is for 110V and the transformer is still due to arrive!! I can't wait! Now that I have these samples I am fairly confident that I will be able to closely matchby spota - Polymer Working Group
This is Junior Veloso's famous blog. He was not the first to use the DLP technology in the DIY world, I think. There was a previous article form the Univ. of Illinois. But he was the first to get these great results from his equipment and he helped reverse engineer Envisiontec's professional equipment. He managed to boost resolution and with the help of the community over at could resolve many oby spota - Polymer Working Group