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Re: [diy_3d_printing_and_fabrication] Re: Score!! $120 projector

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  • Spacecaptain
    Isn t this it?: http://cgi.ebay.co.uk/DuPont-FEP-Film-1-mil-thick-12-W-x-24-L-Longer-/320186922795 DuPont FEP Film; 1 mil thick; 12 W x 24 L, & Longer
    Message 1 of 29 , May 27, 2011
      Isn't this it?:

      http://cgi.ebay.co.uk/DuPont-FEP-Film-1-mil-thick-12-W-x-24-L-Longer-/320186922795

      DuPont "FEP" Film; 1 mil thick; 12" W x 24" L, & Longer



      On 05/27/2011 04:10 PM, vrsculptor@... wrote:
       

      Sticking to the glass isn't an insurmountable problem. There is no question that the bottom up works. The commercial machine tilts the front edge of the build tray down and then lifts. Tilt could be done with a solenoid.

      The top down sounds easier but maintaining the fluid/model level sounds like a big problem. How do you get the resin to the correct thickness on top of the part? How do you get around the issues of surface tension and how the resin flows? I suspect this stuff isn't as thin as water or alcohol. How rigid is your floor. On a large model with thin layers a minuscule amount of tilt caused by you walking around the room could affect the build. No thanks, I'm sticking with bottom up.

      If you read the old messages the Chinese researchers were successful without tilting using a silicone sheet cast on top of the glass. My concern for this method is the optical properties of the silicone, its not really clear but may not matter in thinner films.

      Teflon sheet can be glued to glass. There are some newer safe etching materials that will allow teflon to be epoxied. My two biggest problems with this approach is that I can't find retail clear teflon film and that I don't know if etching and bonding would result in a clear surface.

      There are probably many more solutions out there and hopefully someone else will come up with a solution before I get there.

      Roger


    • jocewang.tw@yahoo.com.tw
      After so many talks related to the bottom exposure issues, I am so great to see  Bertho rise the very important point that the limitation of this technology
      Message 2 of 29 , May 27, 2011
      After so many talks related to the bottom exposure issues, I am so great to see  Bertho rise the very important point that the limitation of this technology will be the separation caused by the air pressure. I have this experience many years ago while using two Japan RP system: SLP400 and EDART which are bottom exposure RP systems. At that time, I am using a soft thick silicon film to enable the deformation during lifting of the part. I put an attached drawing to show another possibility to go back to top exposure with the same advantage of the bottom exposure by adding a support liquid. This picture is extract from a Taiwan patent. No 225 is the support liquid heavy than the resin.   
    • Paolo Velcich
      Yes Roger, You re right about most of the points, however there s still a problem connected to the load capacity of the lifting tray. Will it work with larger
      Message 3 of 29 , May 27, 2011

        Yes Roger,

        You're right about most of the points, however there's still a problem connected to the load capacity of the lifting tray. Will it work with larger models ?

         

        About surface tension and viscosity issues, I think they're just the same for the SLA machines, which means they've been fixed already.

        I know that's part of the slower SLA process, a lot of time is required to smooth the surface of the resin.

         

        About clear teflon   film, I think the Du Pont link which has been posted here yesterday should be OK.

         

        The film should clear enough to avoid blurring.

         

        But, I think there're viable solutions already developed for some industrial or scientific applications which may cost but not too much.

        Like UV transparent pre-coat glass, UVs curable resins have being used for a long time now and for several applications, I think a similar problem has been fixed before.

         

        It will take time but will be solved.

         

         

         

        From: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] On Behalf Of vrsculptor@...
        Sent: venerdì 27 maggio 2011 18:11
        To: diy_3d_printing_and_fabrication@yahoogroups.com
        Subject: [diy_3d_printing_and_fabrication] Re: Score!! $120 projector

         

         

        Sticking to the glass isn't an insurmountable problem. There is no question that the bottom up works. The commercial machine tilts the front edge of the build tray down and then lifts. Tilt could be done with a solenoid.

        The top down sounds easier but maintaining the fluid/model level sounds like a big problem. How do you get the resin to the correct thickness on top of the part? How do you get around the issues of surface tension and how the resin flows? I suspect this stuff isn't as thin as water or alcohol. How rigid is your floor. On a large model with thin layers a minuscule amount of tilt caused by you walking around the room could affect the build. No thanks, I'm sticking with bottom up.

        If you read the old messages the Chinese researchers were successful without tilting using a silicone sheet cast on top of the glass. My concern for this method is the optical properties of the silicone, its not really clear but may not matter in thinner films.

        Teflon sheet can be glued to glass. There are some newer safe etching materials that will allow teflon to be epoxied. My two biggest problems with this approach is that I can't find retail clear teflon film and that I don't know if etching and bonding would result in a clear surface.

        There are probably many more solutions out there and hopefully someone else will come up with a solution before I get there.

        Roger

      • Jon Elson
        ... Wow, that s an interesting thought, continuous lift and continuous exposure. If it would work, that would be an enormous improvement. My feeling is that
        Message 4 of 29 , May 27, 2011
          roup kev wrote:
          >
          >
          > Hi,
          > I think the secret in preventing resin from stick is to decrease
          > exposure time ( rise the object before full curring).
          > What do you think increase in speed and no sticking problem.....
          Wow, that's an interesting thought, continuous lift and continuous
          exposure. If it would work, that would
          be an enormous improvement. My feeling is that it would NOT work, as
          some parts of the object would
          stick to the glass and continue to cure more resin on them, and make a
          big mess. The strongest illumination
          is right at the glass, and the resin and dye absorb light, so it gets
          dimmer the farther away from the glass.
          But, it certainly is worth trying out!

          Jon
        • Spacecaptain
          So if I get the idea right from this drawing, 210 is a static contraption, like a cylinder. The object 230 is lowered on it s tray 240 after the layer is
          Message 5 of 29 , May 27, 2011
            So if I get the idea right from this drawing, 210 is a static contraption, like a cylinder.
            The object 230 is lowered on it's tray 240 after the layer is cured. This should push up the support liquid by a variable volume (the volume of the layer just at the phase boundary). This pushes the resin up by a amount equal to that before-mentioned volume. The result is that, as long as the density of the solid resin is equal or similar to that of the liquid resin, the level in the vat 210 is always the same. (the tray 240 has to have same density as resin too!)

            Are my conclusions correct? Is there a link to an english version of the patent you mention?

            On 05/27/2011 04:51 PM, jocewang.tw@... wrote:
             

            After so many talks related to the bottom exposure issues, I am so great to see  Bertho rise the very important point that the limitation of this technology will be the separation caused by the air pressure. I have this experience many years ago while using two Japan RP system: SLP400 and EDART which are bottom exposure RP systems. At that time, I am using a soft thick silicon film to enable the deformation during lifting of the part. I put an attached drawing to show another possibility to go back to top exposure with the same advantage of the bottom exposure by adding a support liquid. This picture is extract from a Taiwan patent. No 225 is the support liquid heavy than the resin.   


          • Michael Couch
            On the other hand, overcuring the first layer might work better, no? Could be the dryer the first layer, the less sticking. Need to test both. But I have no
            Message 6 of 29 , May 27, 2011
              On the other hand, overcuring the first layer might work better, no? Could be the "dryer" the first layer, the less sticking. Need to test both. But I have no experience so this is just a logical statement.

              I thought I read a post a few months back by someone who gave a solution to this sticking problem. I thought it was just by switching from top build to bottom build or the other way around.

              Michael Couch

              --- In diy_3d_printing_and_fabrication@yahoogroups.com, roup kev <halebahay@...> wrote:
              >
              > Hi,
              > I think the secret in preventing resin from stick is to decrease exposure time ( rise the object before full curring).
              > What do you think increase  in speed and no sticking problem..... 
              >  
              >
              > From: Fernando <spacecaptain@...>
              > To: diy_3d_printing_and_fabrication@yahoogroups.com
              > Sent: Friday, May 27, 2011 7:30 AM
              > Subject: Re: [diy_3d_printing_and_fabrication] Score!! $120 projector
              >
              >
              >  
              >
              > Yes, that would be worth a try. My concern would be that it would stop
              > working in the middle of a print. But if only for proof of concept, this
              > would be worth it. If it does work you would be able to use spray-on or
              > permanent treatments of the same concept.
              >
              > What about Dupont's Teflon sheets?
              > They are UV transparent, better than float glass, check out their data
              > sheet:
              > http://www2.dupont.com/Photovoltaics/en_US/products_services/frontsheet/teflon.html
              > http://www2.dupont.com/Photovoltaics/en_US/assets/downloads/pdf/Teflon_for_PV.pdf
              >
              > On Thu, 2011-05-26 at 21:17 -0500, Jon Elson wrote:
              > >
              > > Fernando wrote:
              > > >
              > > > As for non-stick silicone, I think that looking into anti-graffiti
              > > > silicone coatings would be a promising avenue to try:
              > > >
              > > I use a product called Rain-X on car windshields. It is a liquid that
              > > makes a low-stick
              > > and hydrophobic coating on glass. Since it is so cheap, you might try
              > > that. Even if you had to
              > > reapply it after every build, it wouldn't be much of a problem.
              > >
              > > Jon
              > >
              > >
              > >
              > >
              >
            • Michael Couch
              Awhile back I tested graphite in some PC-7 epoxy. I was amazed at how much stronger the resulting piece was than the normal PC-7. I just mixed it in
              Message 7 of 29 , May 27, 2011
                Awhile back I tested graphite in some PC-7 epoxy. I was amazed at how much stronger the resulting piece was than the normal PC-7. I just mixed it in thoroughly. But PC-7 is not translucent.

                Who knows it might work. Might even speed up cure time. Wouldn't that be cool? But it might block so much light that only the tiniest layer would harden. HHhhhhhhmmmmmm, that might even increase layer resolution though.

                This will be one of the first things I try when I get a DLP projector and stuff, unless someone has already played with it and reported results by then, which I hopw will happen soon.

                Michael Couch

                --- In diy_3d_printing_and_fabrication@yahoogroups.com, "Paolo Velcich" <pavel@...> wrote:
                >
                > A few weeks ago someone was asking about rapid prototyping carbon fiber, if I well remember.
                >
                > At that time I didn't recall the name of the italian manufacturer which developed a carbon reinforced material suitable for SLS.
                >
                > Here's the link: http://www.windform.it/
                >
                > One of my customers used it in the development of a new RC Hely and it proved to be really excellent.
                >
                >
                >
                >
                >
                > From: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] On Behalf Of Fernando
                > Sent: venerdì 27 maggio 2011 01:13
                > To: diy_3d_printing_and_fabrication@yahoogroups.com
                > Subject: RE: [diy_3d_printing_and_fabrication] Score!! $120 projector
                >
                >
                >
                >
                >
                > Well, all I can say is that you won't have that space problem I have :)
                >
                > As for non-stick silicone, I think that looking into anti-graffiti
                > silicone coatings would be a promising avenue to try:
                > http://capital.net/com/eccotech/eagraffiti.htm
                > Graffity paints are often acrylic based.
                >
                > Another possible avenue may be hydrophobic self cleaning glass.
                > These exist as pre-applied panes or you can get the product and apply it
                > yourself on a glass pane (similar to anti graffiti spray I guess). Best
                > results is the previously applied solution.
                >
                > On Fri, 2011-05-27 at 00:24 +0400, Paolo Velcich wrote:
                > >
                > > Hi Fernando, Roger an all the others. Well done.
                > >
                > > I see that something is moving again and that's really promising.
                > >
                > >
                > >
                > > This Sunday the maintenance should start fixing all the wiring and
                > > plumbing problems in my new location (here they call these houses
                > > Villas, it's a typical Arabic style house with maid quarters on the
                > > back) so far I should have plenty of room (at least a couple of rooms)
                > > to dedicate to the workshop. Let say , in approx. three weeks I should
                > > be ready.
                > >
                > >
                > >
                > > I have quite a wise experience on CNC, since I developed a few ones,
                > > before purchasing a machining center, and I also designed and machined
                > > molds for injection plastic for several years (especially automotive
                > > tail lamps).
                > >
                > >
                > >
                > > If anything may be accurately developed in 3D which may be useful, I'm
                > > already available.
                > >
                > > I will also check the cost of CNC machining here in Dubai, however my
                > > first sensation is that costs of CNC machining aren't different from
                > > Europe. While the labor cost is very cheap.
                > >
                > > At least the prices for CNC laser cutting or routing plywood templates
                > > for the marine industry are almost the same as in Italy.
                > >
                > >
                > >
                > > I should have my own laser and router soon, in the boat yard.
                > >
                > >
                > >
                > > Keep doing this excellent research and we'll get to something good
                > > soon.
                > >
                > >
                > >
                > > Paolo
                > >
                > >
                > >
                > >
                > >
                > >
                > >
                > >
                > >
                > > From: diy_3d_printing_and_fabrication@yahoogroups.com <mailto:diy_3d_printing_and_fabrication%40yahoogroups.com>
                > > [mailto:diy_3d_printing_and_fabrication@yahoogroups.com <mailto:diy_3d_printing_and_fabrication%40yahoogroups.com> ] On Behalf Of
                > > Fernando
                > > Sent: venerdì 27 maggio 2011 00:05
                > > To: diy_3d_printing_and_fabrication@yahoogroups.com <mailto:diy_3d_printing_and_fabrication%40yahoogroups.com>
                > > Subject: Re: [diy_3d_printing_and_fabrication] Score!! $120 projector
                > >
                > >
                > >
                > >
                > >
                > >
                > > Hello Roger,
                > >
                > > Great buy you made there!! I wish I had more time, space and, bluntly
                > > said, money to go the way you are. Right now it's out of my reach for
                > > these 3 reasons. I have my monomers and photoinitiators stashed in my
                > > basement and can't get started on any serious experimentation, as much
                > > as I would want to...
                > >
                > > The only thing I can do is push things forward, publish as much of the
                > > knowledge I have and can gather to help others reach their goals as
                > > fast
                > > and efficiently as possible.
                > >
                > > On the non-stick front, I'm convinced that the silicone coating is a
                > > promising avenue. I know that when we talked about this problem on the
                > > list with junior, there was suspiciously little results published on
                > > silicone coating, where I was expecting at least some moderately good
                > > results. Now that we got the resin ball rolling, I will try shaking
                > > that
                > > tree as well, to see what fruits fall from it :)
                > >
                > > As always, I will post ANY results I find here.
                > > Keep posted!
                > >
                > > On Thu, 2011-05-26 at 19:09 +0000, vrsculptor@... <mailto:vrsculptor%40hotmail.com> wrote:
                > > >
                > > > I bought a HP xp7030 Multimedia Projector on Ebay with a broken
                > > color
                > > > wheel for $120. It uses the UHP bulb. Without the color wheel it
                > > only
                > > > does black and white which should be fine for our uses. Seems like a
                > > > common problem and there may be more of these out there.
                > > >
                > > > Unless something unexpected comes up I hope to get started on the
                > > > build in July. I'm pretty well set to go now that I have a
                > > projector.
                > > > I've got a stepper driven 24" linear slide under the table with
                > > Gecko
                > > > driver. Resin at $300 for first tests isn't a killer. Been there and
                > > > done that already on STL slicing software so no problem.
                > > >
                > > > The only show stopper is figuring out what to use to keep the resin
                > > > from sticking to the glass plate. The commercial teflon coated glass
                > > I
                > > > got for Junior was a failure and I haven't heard from him so I don't
                > > > know what he did to solve the problem.
                > > >
                > > > If you look back in the messages there is some advice from the
                > > Chinese
                > > > researchers on how to cast a thin silicone membrane on glass. I may
                > > go
                > > > with that.
                > > >
                > > > Roger
                > > >
                > > >
                > > >
                > > >
                > > >
                > >
                > >
                > >
                > >
                >
              • vrsculptor@hotmail.com
                Fernando, Thanks! Just bought some. I hope its not too thin to etch. Roger
                Message 8 of 29 , May 27, 2011
                  Fernando,
                  Thanks! Just bought some. I hope its not too thin to etch.

                  Roger

                  --- In diy_3d_printing_and_fabrication@yahoogroups.com, Spacecaptain <spacecaptain@...> wrote:
                  >
                  > Isn't this it?:
                  >
                  > http://cgi.ebay.co.uk/DuPont-FEP-Film-1-mil-thick-12-W-x-24-L-Longer-/320186922795
                  >
                  > DuPont "FEP" Film; 1 mil thick; 12" W x 24" L, & Longer
                  >
                • vrsculptor@hotmail.com
                  Hi Paolo, Your concern is legitimate. I have given the size issue some thought and these are my conclusions. I have nothing to back any of this up and could be
                  Message 9 of 29 , May 27, 2011
                    Hi Paolo,
                    Your concern is legitimate. I have given the size issue some thought and these are my conclusions. I have nothing to back any of this up and could be totally wrong.

                    On bottom up modeling the build tray never bears the weight of the model. The weight is totally on the Z axis slide.

                    The model size with a DLP projector is limited in the X/Y dimension by projector resolution. ZCorp systems print at (theoretical, no where near this because of bleed) 600 DPI. Using round numbers a DLP projector at SVGA has a little better than 1200x750 resolution. At 600 DPI this would give a model size of 2" by 1" and a fraction. At a more reasonable 200 DPI the model size is 6" by around 3.75". At 100 DPI you could double that. I don't see me printing large parts in one pass. I can see gluing many small pieces together to build a large assembly.

                    I am never going to deal with models with a very large X/Y cross section unless we find some clever way to shift the projector around in the X/Y plane. I think that at this point that is beyond the pale.

                    Also, there is no benefit in printing large solid objects. With the cost of resin where its at it would make more sense to print thin shells with an open infill like RepRap. This is muck easier to un-stick.

                    From Junior's experience with the rein sticking to everything I don't think the model separating from the lifter is going to be a problem. Plain 1/2x10 Acme threaded rod can lift a whole lot of weight. You just have to build a big enough structure to support everything.

                    On very tall models (Z dimension) we will need to build pauses in the software to allow refilling every so many inches.

                    Roger

                    --- In diy_3d_printing_and_fabrication@yahoogroups.com, "Paolo Velcich" <pavel@...> wrote:
                    >
                    > Yes Roger,
                    >
                    > You're right about most of the points, however there's still a problem
                    > connected to the load capacity of the lifting tray. Will it work with larger
                    > models ?
                    >
                  • Paolo Velcich
                    Hi Roger, yes, the model is supported (inverted) by the Z-axis and that may be the problem, should the model have a small base (top in this case) and a wider
                    Message 10 of 29 , May 27, 2011

                      Hi Roger,

                      yes, the model is supported (inverted) by the Z-axis and that may be the problem, should the model have a small base (top in this case) and a wider mid section.

                       

                      I would never consider solid objects, of course. Even should we need solid like objects, in SLA there's a technique developed to fill the models with a honeycomb structure, very stiff and light.

                       

                      Sometime ago I calculated the max. resolution available on the DLP projectors (1920 x 1200 I think) at 50 microns resolution and it would be wide enough, much larger than the currently achieved by Junior (however he already stated his final design would allow for larger builds).

                       

                      BTW, this RP technology doesn't fit the large models, a reasonable size could be in the 20x30 cm x 20 cm (Z).  Pretty big, uh ?!

                      :-)

                       

                      But I can see most of the applications in much smaller sizes, like it's for jewelers, toy makers, and so far.

                       

                      Personally, I would be really happy to be able to build a monitor or TV size (one of the products I design) but to achieve that we would need an array of projectors or a shiftable projector on the X-Y axis (multiple exposure).

                      I believe a bottom-down method would be easier to manage for this configuration, but I agree that leveling the resin would take pretty  long (I'm used to long awaiting periods in boat testing in the towing tank, just waiting for the water surface to level flat in between the runs).

                       

                       

                       

                      From: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] On Behalf Of vrsculptor@...
                      Sent: sabato 28 maggio 2011 07:03
                      To: diy_3d_printing_and_fabrication@yahoogroups.com
                      Subject: [diy_3d_printing_and_fabrication] My thoughts on model size

                       

                       

                      Hi Paolo,
                      Your concern is legitimate. I have given the size issue some thought and these are my conclusions. I have nothing to back any of this up and could be totally wrong.

                      On bottom up modeling the build tray never bears the weight of the model. The weight is totally on the Z axis slide.

                      The model size with a DLP projector is limited in the X/Y dimension by projector resolution. ZCorp systems print at (theoretical, no where near this because of bleed) 600 DPI. Using round numbers a DLP projector at SVGA has a little better than 1200x750 resolution. At 600 DPI this would give a model size of 2" by 1" and a fraction. At a more reasonable 200 DPI the model size is 6" by around 3.75". At 100 DPI you could double that. I don't see me printing large parts in one pass. I can see gluing many small pieces together to build a large assembly.

                      I am never going to deal with models with a very large X/Y cross section unless we find some clever way to shift the projector around in the X/Y plane. I think that at this point that is beyond the pale.

                      Also, there is no benefit in printing large solid objects. With the cost of resin where its at it would make more sense to print thin shells with an open infill like RepRap. This is muck easier to un-stick.

                      From Junior's experience with the rein sticking to everything I don't think the model separating from the lifter is going to be a problem. Plain 1/2x10 Acme threaded rod can lift a whole lot of weight. You just have to build a big enough structure to support everything.

                      On very tall models (Z dimension) we will need to build pauses in the software to allow refilling every so many inches.

                      Roger

                      --- In diy_3d_printing_and_fabrication@yahoogroups.com, "Paolo Velcich" <pavel@...> wrote:

                      >
                      > Yes Roger,
                      >
                      > You're right about most of the points, however there's still a problem
                      > connected to the load capacity of the lifting tray. Will it work with
                      larger
                      > models ?
                      >

                    • Boman33
                      To improve the top resin fill problems with the bottom down type, there are several patents describing wipers that mechanically sweep over the top surface to
                      Message 11 of 29 , May 27, 2011

                        To improve the top resin fill problems with the bottom down type, there are several patents describing wipers that mechanically sweep over the top surface to spread/level the resin in-between each exposure.

                        Bertho

                         

                        From:  Paolo Velcich    Sent: Saturday, May 28, 2011 01:07

                        Hi Roger,

                        yes, the model is supported (inverted) by the Z-axis and that may be the problem, should the model have a small base (top in this case) and a wider mid section.

                        I believe a bottom-down method would be easier to manage for this configuration, but I agree that leveling the resin would take pretty  long (I'm used to long awaiting periods in boat testing in the towing tank, just waiting for the water surface to level flat in between the runs).

                         

                      • Eric Young
                        Fernando - I think you re right about the constant resin level in this design, assuming that those solid and liquid resin densities are the same.
                        Message 12 of 29 , May 31, 2011
                          Fernando - I think you're right about the constant resin level in this design, assuming that those solid and liquid resin densities are the same.



                          On Fri, May 27, 2011 at 8:54 AM, Spacecaptain <spacecaptain@...> wrote:


                          So if I get the idea right from this drawing, 210 is a static contraption, like a cylinder.
                          The object 230 is lowered on it's tray 240 after the layer is cured. This should push up the support liquid by a variable volume (the volume of the layer just at the phase boundary). This pushes the resin up by a amount equal to that before-mentioned volume. The result is that, as long as the density of the solid resin is equal or similar to that of the liquid resin, the level in the vat 210 is always the same. (the tray 240 has to have same density as resin too!)

                          Are my conclusions correct? Is there a link to an english version of the patent you mention?

                          On 05/27/2011 04:51 PM, jocewang.tw@... wrote:
                           

                          After so many talks related to the bottom exposure issues, I am so great to see  Bertho rise the very important point that the limitation of this technology will be the separation caused by the air pressure. I have this experience many years ago while using two Japan RP system: SLP400 and EDART which are bottom exposure RP systems. At that time, I am using a soft thick silicon film to enable the deformation during lifting of the part. I put an attached drawing to show another possibility to go back to top exposure with the same advantage of the bottom exposure by adding a support liquid. This picture is extract from a Taiwan patent. No 225 is the support liquid heavy than the resin.   



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