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3D Printed Littrow spectrograph

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  • John Paraskeva
    Hi Folks, Have had a break with BASS while developing my 3D printed spectrograph. The aim here was to keep the cost of optics and weight down. The main lens is
    Message 1 of 11 , Oct 16, 2017
    Hi Folks,

    Have had a break with BASS while developing my 3D printed spectrograph.

    The aim here was to keep the cost of optics and weight down. The main lens is a 50mm binocular objective, arguably one of the most common lenses on Earth. Focal length is about 185mm. The whole thing (without cameras)weighs just 724g and yet seems rigid enough.

    It was printed using a Creality CR-10 3d printer. It was rewarding, yet painful to learn 3D printing and CAD from scratch. I desiged it using Sketchup Make. 

    The design utilises the round multi-reflective slit found in the L200 for autoguiding. 


    The attached photos don't do it justice and there are loads of details/feaures I haven't mentioned. Hopefully you get the idea.

    Still some fine tweaking to do.

    Any questions just ask.

    cheers

    John

    Inline image


    Inline image

      

    Inline image
    Inline image
    Inline image





  • rspostrspost
    John, really amazing. How would you compare the spectrograph built with 3D printing vs machining from Al? Dick
    Message 2 of 11 , Oct 16, 2017
      John, really amazing.  

      How would you compare the spectrograph built with 3D printing vs machining from Al?

      Dick
    • pjhgerlach
      Congratulations on your design! Good to see that more people discover the 3D printer as a great tool. Any particular reason for constructing it out off sheets
      Message 3 of 11 , Oct 16, 2017

        Congratulations on your design!

        Good to see that more people discover the 3D printer as a great tool.
        Any particular reason for constructing it out off sheets of 3D printer material? Why didn’t you go for the two piece housing (body and lid)?


        Best regards,

        Paul

      • John Paraskeva
        Thanks Dick That s a big question.  A simple answer might be that Aluminium would be a superior material, but you need access to much more expensive milling
        Message 4 of 11 , Oct 17, 2017
          Thanks Dick

          That's a big question.  A simple answer might be that Aluminium would be a superior material, but you need access to much more expensive milling machines and presses etc. There are also physical differences to consider such as thermal expansion, melting point etc, (PLA plastic can melt if left in a car on a hot day!). Before I got the 3D printer I was using anything that came to hand, such as wood, laminate flooring and various plumbing fittings. 

          3D printers are now quite cheap, so long as you are patient and partial to tinkering.
           

          regards
          John

           



          From: "rspostrspost@... [astrobodger]" <astrobodger@...>
          To: astrobodger@...
          Sent: Tuesday, 17 October 2017, 2:44
          Subject: [astrobodger] Re:: 3D Printed Littrow spectrograph

           
          John, really amazing.  

          How would you compare the spectrograph built with 3D printing vs machining from Al?

          Dick


        • John Paraskeva
          Hi Paul, That s a very good question.  The L shape base late is quite compact for a littrow at 203mm X 177mm, but still quite big for a 3D print. There are
          Message 5 of 11 , Oct 17, 2017
            Hi Paul,

            That's a very good question. 

            The "L" shape base late is quite compact for a littrow at 203mm X 177mm, but still quite big for a 3D print. There are various trade offs and more things to try out.

            To print a monolithic body at 0.2mm resolution with a 0.4mm nozzle would take about 32 hours and would waste a lot of filament and time if it failed. (Especially as CR-10 comes with a warped build plate). 

            The L plate and sides were actually printed at 0.4 resolution using a 0.8mm nozzle. This reduced print time of the base plate from 8h 20m to about 2h 45m. 

            A single body would save 20 base plate screws, but then have infill to clean up etc. 

            If I were mass producing a stable design then I guess I would consider a monolithic body. 
             
            Having pain with ABS, but have some PETG to try. What material are you using?

            best regards

            John


            From: "paul@... [astrobodger]" <astrobodger@...>
            To: astrobodger@...
            Sent: Tuesday, 17 October 2017, 7:49
            Subject: [astrobodger] Re:: 3D Printed Littrow spectrograph

             
            Congratulations on your design!
            Good to see that more people discover the 3D printer as a great tool.
            Any particular reason for constructing it out off sheets of 3D printer material? Why didn’t you go for the two piece housing (body and lid)?

            Best regards,
            Paul


          • Steve
            Nice one John, could be a nice little earner churning those out😜. I think demand would be there ☺️. Cheers Steve Sent from my iPad ... Nice one John,
            Message 6 of 11 , Oct 17, 2017
              Nice one John, could be a nice little earner churning those out😜. I think demand would be there ☺️.
              Cheers
              Steve

              Sent from my iPad

              On 16 Oct 2017, at 23:50, John Paraskeva johnparaskeva@... [astrobodger] <astrobodger@...> wrote:

              Hi Folks,

              Have had a break with BASS while developing my 3D printed spectrograph.

              The aim here was to keep the cost of optics and weight down. The main lens is a 50mm binocular objective, arguably one of the most common lenses on Earth. Focal length is about 185mm. The whole thing (without cameras)weighs just 724g and yet seems rigid enough.

              It was printed using a Creality CR-10 3d printer. It was rewarding, yet painful to learn 3D prin ting and CAD from scratch. I desiged it using Sketchup Make. 

              The design utilises the round multi-reflective slit found in the L200 for autoguiding. 


              The attached photos don't do it justice and there are loads of details/feaures I haven't mentioned. Hopefully you get the idea.

              Still some fine tweaking to do.

              Any questions just ask.

              cheers

              John

              Inline image


              Inline image

                

              Inline image
              Inli
ne image
              Inline image





            • fulvio mete
              Hi, John, congratulations for your new, ecellent work.Did you get a CAD design for the the slit plate holder too? Fulvio Il 17/10/2017 00:50, John Paraskeva
              Message 7 of 11 , Oct 17, 2017

                Hi, John, congratulations for your new, ecellent work.Did you get a CAD design for the the slit plate holder too?

                Fulvio


                Il 17/10/2017 00:50, John Paraskeva johnparaskeva@... [astrobodger] ha scritto:
                 
                Hi Folks,

                Have had a break with BASS while developing my 3D printed spectrograph.

                The aim here was to keep the cost of optics and weight down. The main lens is a 50mm binocular objective, arguably one of the most common lenses on Earth. Focal length is about 185mm. The whole thing (without cameras)weighs just 724g and yet seems rigid enough.

                It was printed using a Creality CR-10 3d printer. It was rewarding, yet painful to learn 3D printing and CAD from scratch. I desiged it using Sketchup Make. 

                The design utilises the round multi-reflective slit found in the L200 for autoguiding. 


                The attached photos don't do it justice and there are loads of details/feaures I haven't mentioned. Hopefully you get the idea.

                Still some fine tweaking to do.

                Any questions just ask.

                cheers

                John

                Inline image


                Inline image

                  

                Inline image
                Inline i
mage
                Inline image






                -- 
                
                
                Fulvio Mete
                
                http://www.lightfrominfinity.org  
                
                http://www.pno-astronomy.com   
                
                http://www.amateur-astronomy-researchers.com  
                
                
                
                
                
                
              • pjhgerlach
                I think that printing it monolithic will give you the ability to make the design stronger and stiffer. You can avoid sharp corners by introducing fillets.
                Message 8 of 11 , Oct 17, 2017

                  I think that printing it monolithic will give you the ability to make the design stronger and stiffer.

                  You can avoid sharp corners by introducing fillets. Printing time will increase for sure, but I think that’s worth it.

                  I designed the body of the LOWSPEC classical spectrograph that way.


                  Printing with ABS can be challenging. I changed to ASA. A material with similar properties as ABS but with much better UV resistance and very good layer adhesion. Added benefit: it does not smell as bad as ABS.

                  I print with a Felix Pro 2 printer and an enclosure so I can maintain a constant temperature of about 40-45 degrees C. This will reduce warping and splitting of layers. I had a lot of problems at first with warping until I started to experiment with a raft of HIPS (The Felix pro 2 printer is a dual extruder). It turns out that ASA has enough bonding with HIPS to keep it attached to the raft during printing. As it cools down it can easily manually be removed. Also by printing it on the raft rather than directly on the heated build plate I can reduce temperature differences between bottom and top of the object thereby reducing stress build-up in the part.

                  I have a success rate of 95 percent with long prints (more than 24 hours)


                  Best regards,

                  Paul

                • andyjwilson_uk
                  Impressive work John! You are becoming a one-stop-shop for spectroscopy by both building spectrographs and the software to go with them :) Cheers, Andy
                  Message 9 of 11 , Oct 17, 2017
                    Impressive work John! You are becoming a one-stop-shop for spectroscopy by both building spectrographs and the software to go with them :)
                    Cheers,
                    Andy
                  • John Paraskeva
                    Hi Fulvio, The attachments show the multi-slit disc and auto guider assembly. The disc sits into a retainer, that sits within an additional retainer tilted at
                    Message 10 of 11 , Oct 17, 2017
                    Hi Fulvio,

                    The attachments show the multi-slit disc and auto guider assembly. The disc sits into a retainer, that sits within an additional retainer tilted at 15 degrees. The guide cam sits in a 1.25" holder, not shown, that fits into the tube at the top.

                    best regards
                    John


                    Inline imageInline image




                    From: "fulvio mete fulvio_mete@... [astrobodger]" <astrobodger@...>
                    To: astrobodger@...
                    Sent: Tuesday, 17 October 2017, 18:18
                    Subject: Re: [astrobodger] 3D Printed Littrow spectrograph

                     
                    Hi, John, congratulations for your new, ecellent work.Did you get a CAD design for the the slit plate holder too?
                    Fulvio

                    Il 17/10/2017 00:50, John Paraskeva johnparaskeva@... [astrobodger] ha scritto:
                     
                    Hi Folks,

                    Have had a break with BASS while developing my 3D printed spectrograph.

                    The aim here was to keep the cost of optics and weight down. The main lens is a 50mm binocular objective, arguably one of the most common lenses on Earth. Focal length is about 185mm. The whole thing (without cameras)weighs just 724g and yet seems rigid enough.

                    It was printed using a Creality CR-10 3d printer. It was rewarding, yet painful to learn 3D printing and CAD from scratch. I desiged it using Sketchup Make. 

                    The design utilises the round multi-reflective slit found in the L200 for autoguiding. 


                    The attached photos don't do it justice and there are loads of details/feaures I haven't mentioned. Hopefully you get the idea.

                    Still some fine tweaking to do.

                    Any questions just ask.

                    cheers

                    John

                    Inline image


                    Inline image

                      

                    Inline image
                    Inline i                   mage
                    Inline image






                    -- 
                    
                    
                    Fulvio Mete
                    
                    http://www.lightfrominfinity.org  
                    
                    http://www.pno-astronomy.com   
                    
                    http://www.amateur-astronomy-researchers.com  
                    
                    
                    
                    
                    
                    


                  • John Paraskeva
                    Hi Paul, Your high-end printer has some very nice features indeed.  Thanks for the tips, I will have a few more tries with ABS.  regardsJohn From:
                    Message 11 of 11 , Oct 17, 2017
                      Hi Paul,

                      Your high-end printer has some very nice features indeed. 

                      Thanks for the tips, I will have a few more tries with ABS. 

                      regards
                      John



                      From: "paul@... [astrobodger]" <astrobodger@...>
                      To: astrobodger@...
                      Sent: Tuesday, 17 October 2017, 19:57
                      Subject: [astrobodger] Re:: 3D Printed Littrow spectrograph

                       
                      I think that printing it monolithic will give you the ability to make the design stronger and stiffer.
                      You can avoid sharp corners by introducing fillets. Printing time will increase for sure, but I think that’s worth it.
                      I designed the body of the LOWSPEC classical spectrograph that way.

                      Printing with ABS can be challenging. I changed to ASA. A material with similar properties as ABS but with much better UV resistance and very good layer adhesion. Added benefit: it does not smell as bad as ABS.
                      I print with a Felix Pro 2 printer and an enclosure so I can maintain a constant temperature of about 40-45 degrees C. This will reduce warping and splitting of layers. I had a lot of problems at first with warping until I started to experiment with a raft of HIPS (The Felix pro 2 printer is a dual extruder). It turns out that ASA has enough bonding with HIPS to keep it attached to the raft during printing. As it cools down it can easily manually be removed. Also by printing it on the raft rather than directly on the heated build plate I can reduce temperature differences between bottom and top of the object thereby reducing stress build-up in the part.
                      I have a success rate of 95 percent with long prints (more than 24 hours)

                      Best regards,
                      Paul


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