Loading ...
Sorry, an error occurred while loading the content.
 

Powder spreading Not smooth at all.

Expand Messages
  • ben.mahony@ymail.com
    A few years ago a build a 3D printer of the plaster powder spreading type. I used a Lexmark printer as I found one that reversed the paper feed motor to flick
    Message 1 of 5 , May 11, 2009
      A few years ago a build a 3D printer of the plaster powder spreading type. I used a Lexmark printer as I found one that reversed the paper feed motor to flick a new sheet off the paper feed stack. It was simple to modify this printer into a flat bed printer. I simply remounted the paper detection optical sensor in a more suitable position and made an arm that moves when the gantry hits one end, the printer then thinks it's out of paper so drives back until it hits the other end, moving the arm so it now thinks it has paper again. This simple mechanical set up means I can use the printer without any electronics modifications. flat bed printer done!

      But then I ran into a problem, I couldn't get the plaster to spread, I used a spinning scrapper roller but it left a corse sand like texture.
      Recently I found this yahoo group and read about adding maltodextrin to the dental Plaster. I though this might be the key and the two slightly different grain sizes may help lubricate one another, Sadly this has made no difference.

      Anybody got any suggestions. My current set up is spinning the scrapper roller at the same surface speed as the gantry and in the same direction relative to the bottom surface, This means the bottom surface is spining over the plaster at twice the speed as the gantry travels hence it pushes the plaster ahead of it and lifts it, not pushing it under the roller. My roller is about 18mm in diameter.
      I have tried spiing it faster and in the opposite direction but no luck. What am I doing wrong? Maybe it needs to be larger diameter, smoother, higher RPM, different direction, maybe I should bake the powder before using? So I have a few variables to try and would just like a push in the right direction before I shelf the project for another few years....
    • Jack Coats
      At least for me it would help to see a picture or two of your problem, plus we LOVE to see other folks 3D printing setups! Actually a couple of digital
      Message 2 of 5 , May 11, 2009
        At least for me it would help to see a picture or two of your problem, plus we LOVE to see
        other folks 3D printing setups!  Actually a couple of digital pictures would help at least me
        visualize your issue.

        You say you are using plaster as the media.  Could you please be a little more specific?

        Thanks
      • Kevin Hawkinson
        From observing Z-Corp printer powder spreading roller: -roller is smooth -roller rotates against direction of motion -roller spins fast, i.e. 600rpm -older
        Message 3 of 5 , May 11, 2009
          From observing Z-Corp printer powder spreading roller:
          -roller is smooth
          -roller rotates against direction of motion
          -roller spins fast, i.e. >600rpm
          -older models had small roller  (10?-13?mm dia) new model has larger roller (17?-20?mm dia)
           


           
          On Mon, May 11, 2009 at 3:05 AM, ben.mahony@... <ben.mahony@...> wrote:


          A few years ago a build a 3D printer of the plaster powder spreading type. I used a Lexmark printer as I found one that reversed the paper feed motor to flick a new sheet off the paper feed stack. It was simple to modify this printer into a flat bed printer. I simply remounted the paper detection optical sensor in a more suitable position and made an arm that moves when the gantry hits one end, the printer then thinks it's out of paper so drives back until it hits the other end, moving the arm so it now thinks it has paper again. This simple mechanical set up means I can use the printer without any electronics modifications. flat bed printer done!

          But then I ran into a problem, I couldn't get the plaster to spread, I used a spinning scrapper roller but it left a corse sand like texture.
          Recently I found this yahoo group and read about adding maltodextrin to the dental Plaster. I though this might be the key and the two slightly different grain sizes may help lubricate one another, Sadly this has made no difference.

          Anybody got any suggestions. My current set up is spinning the scrapper roller at the same surface speed as the gantry and in the same direction relative to the bottom surface, This means the bottom surface is spining over the plaster at twice the speed as the gantry travels hence it pushes the plaster ahead of it and lifts it, not pushing it under the roller. My roller is about 18mm in diameter.
          I have tried spiing it faster and in the opposite direction but no luck. What am I doing wrong? Maybe it needs to be larger diameter, smoother, higher RPM, different direction, maybe I should bake the powder before using? So I have a few variables to try and would just like a push in the right direction before I shelf the project for another few years....


        • ben.mahony@ymail.com
          I just uploaded some photo s of the plaster spreading and showing how rough it is. Maybe this always happens if you spread too thick a layer, what thickness
          Message 4 of 5 , May 13, 2009
            I just uploaded some photo's of the plaster spreading and showing how rough it is. Maybe this always happens if you spread too thick a layer, what thickness are other prople making their layers. I think in the photo's it was perhaps a 0.5mm step, seems to work better if I make it 0.1 steps, which will help with the plaster wetting anyway!
          • gsi11135
            What is going on with the toner cartridge powder spreader? Joseph Owner/Moderator
            Message 5 of 5 , May 14, 2009
              What is going on with the toner cartridge powder spreader?

              Joseph
              Owner/Moderator

              --- In diy_3d_printing_and_fabrication@yahoogroups.com, "ben.mahony@..." <ben.mahony@...> wrote:
              >
              > I just uploaded some photo's of the plaster spreading and showing how rough it is. Maybe this always happens if you spread too thick a layer, what thickness are other prople making their layers. I think in the photo's it was perhaps a 0.5mm step, seems to work better if I make it 0.1 steps, which will help with the plaster wetting anyway!
              >
            Your message has been successfully submitted and would be delivered to recipients shortly.