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 Rank: Super-Elite      Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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So Formlabs has a downloadable file to make a magnifying lens.I have to say I was a bit skeptical when I saw that, but I figured I would give it a try. So the question is can the Form2 print a lens that is optically perfect? The print comes as 2 parts and was printed with clear resin at 50 micron resolution.The print took 3 1/2 hours. The first part of the print is the lens itself.The lens has a support attached to it that can be fitted into an electric drill .This allows you to chuck the part in the drill and use the drill to spin the part as you sand and polish it. The second part is a holder so once you have polished the convex side of the lens you place it in the holder so you can polish the back side of the lens. The parts were printed and washed soaked in 91% isopropyl alcohol.Once they were dry they were placed in my home made curing oven for 40 minutes. The next step is to sand the convex face of the lens using progressively finer sandpaper and then use Novus plastic polish to polish the surface of the lens darbyvet attached the following image(s):
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Rank: Super-Elite   Groups: Registered
Joined: 31/05/2010 Posts: 5,679 Points: 17,011 Location: Wiltshire
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A good test for the machine. It looks good and will be interrsted to see how it cleans up. Happy Modelling
BUILDING: Hachette Spitfire Mk 1A, Constructo Mayflower
SUBSCRIPTION COMPLETE (Awaiting building): USS Constitution, Sovereign of the Seas, 1:200 Bismarck (Hachette)
COMPLETED: Porsche 911, E-Type Jaguar, Lam Countach
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Rank: Super-Elite Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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Now the lens is printed it is time to sand and polish it.I chucked the lens into a drill and using a slow speed I wet sanded the convex part of the lens using sandpaper.I started with 220 grit and then went to 400,600,1000,1500 and 2000. darbyvet attached the following image(s):
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Rank: Super-Elite Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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I then cut the lens from its holder and placed it in the second holder.The lens was placed so that the flat surface was exposed.I then put this back in the drill and wet sanded again using higher and higher grade sandpaper. darbyvet attached the following image(s):
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Rank: Super-Elite Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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Here is the lens after the sanding.It is very smooth to the touch, but still has scratches that make it opaque.The final step was to use NOVUS plastic polish system to polish out the scratches.This stuff is great for clear canopies too.You start with a coarse polish and then move to the finally polish and finally the buffing compound to get a clear lens.Here is the lens before using the NOVUS darbyvet attached the following image(s):
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Rank: Super-Elite Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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So did it work? In short YES IT DID. The lens wasnt perfect-it did show some vignetting and a bit of spherical aberration, but I suspect that was due to my polishing.Anyway I took a picture of the Launch tower instructions through the lens. What do you guys think? darbyvet attached the following image(s):
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Rank: Super-Elite Groups: Registered
Joined: 31/05/2010 Posts: 5,679 Points: 17,011 Location: Wiltshire
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I think that is really neat. To be able to make something like this at home is so scfi. You can almost see the next stages coming in the next few years is printing your own spectacles at home. Happy Modelling
BUILDING: Hachette Spitfire Mk 1A, Constructo Mayflower
SUBSCRIPTION COMPLETE (Awaiting building): USS Constitution, Sovereign of the Seas, 1:200 Bismarck (Hachette)
COMPLETED: Porsche 911, E-Type Jaguar, Lam Countach
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 Rank: Elite Groups: Registered
Joined: 13/02/2011 Posts: 2,227 Points: 6,801 Location: UK
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I think what you have achieved at home is quite remarkable,it looks about 4/5 Diopters of powder and a blank size 55/60 mm i can see waves around the edge but that can happen, could be the way the drill was moving which will happen, as this was your fist attempt very well down. Regards Trev Work in progress: Tombstone (Scratch) - San Francisco 2. -The Mayflower ( scratch by plan).
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Rank: Super-Elite Groups: Registered
Joined: 17/12/2013 Posts: 3,982 Points: 11,974 Location: NY, USA
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Cheers Trev,
the lens was wobbling as bit in the drill and I didnt sand as much close to the edge of the lens because I was worried I would break the lens.
Carl
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