How Smooth Is A Horizontal Surface On Fine Detail Plastic?

Discussion in 'Materials' started by Mr_Trainiac, Jul 30, 2019.

  1. Mr_Trainiac
    Mr_Trainiac Member
    I am pretty new to Shapeways, so I have never printed in the Fine Detail Plastic before. I am designing a train car kit where the sides, roof, and floor are separate components. If I lay the sides flat with the exterior facing up, how smooth will that flat surface be? I understand that there will be extrusion/print lines on vertical and curved surfaces, but what do horizontal surfaces look like? I have done some prints with traditional extrusion head printers, which gave kind of a crosshatch pattern as the nozzle moved along the X and Y axis. I am trying to learn about the Shapeways resin-based printers and their capabilities. Does the resin cure in uniform sheets, building up the model, or does a point (like an extrusion nozzle) move around and fill in the profiles/layers? If I need to sand anything smooth, I want to know how much surface detail I will need to build back up post-sanding and if it is worth adding to the model in the first place.
     
  2. barkingdigger
    barkingdigger Well-Known Member
    My experience has been mixed - some prints are mirror-smooth while others have lines on the horizontal surfaces that need sanded or scraped flat. I suspect it's a random effect of different runs on a machine, or different human operators setting up said runs, or different machines in the factory, or different outsource subcontractors, none of which can be predicted from one print to the next.

    Bear in mind something big and flat - like a train car side - is likely to warp in production, so you will need to do the hot water trick on a flat surface.
     
  3. It can be quite good...here is a 4mm scale wagon printed as you suggest, all the sides and ends laid flat for best surface finish. In this case the ends and headstocks are one piece, side and solebar one piece with V hanger, floor one piece and bolster one piece. This was perhaps the best finish I've had from Shapeways...

    FULLDSXT2349.jpg

    HOWEVER!...the current finish isn't as good, and is WORSE if you pay extra for the 'Smoothest' variant. Here, the outside axleboxes are printed face up in plain detail plastic, and you can clearly see ridges though they are smooth and rounded When printed in smoothest finish, the ridges are much sharper and easily felt with a fingernail.(This is in 16mm scale)
     

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