First Delivery from Shapeways

Discussion in 'CAD Corner' started by Rambler, 15 September 2020 at 11:30.

  1. Rambler

    Rambler Active Member

    I've just received my first delivery of 3D printed things from Shapeways and have to say that I'm very pleased with the results. Prior to this I'd searched the internet to see if I could find any examples of actual printed objects (as opposed to the Shapeways "Digital Preview") but could find very little, so I'm going to try to fill that gap a little by showing what I was attempting and how it came out.

    The artwork was prepared on a 5-year old MacBook Air using Fusion 360. In order to spread the delivery cost I produced designs for three different components that I need for models I'm building. There was also the hope that a problem with one of the designs wouldn't affect any of the others.

    In this post I'll show the designs as screen-grabs from Fusion 360, and then show the printed objects in a following post (if for no other reason than I keep my photos on a PC).

    Firstly some buffer bodies for O-gauge North Eastern hopper wagons.

    Screenshot 2020-09-15 at 11.00.38.png
    Secondly, some axle boxes for O-gauge North Eastern wagons. These No. 2 axle boxes were found on a lot of 10T wagons.
    Screenshot 2020-09-15 at 10.57.12.png

    and finally a pair of crossheads for a O-gauge Midland 0-4-0ST. I had these printed in brass, the others were in Smoothest Fine Detail Plastic.
    Screenshot 2020-08-28 at 17.15.46.png
     
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  2. Rambler

    Rambler Active Member

    So this is how the Midland crossheads came out:

    DSC_0609_small.JPG DSC_0612_small.JPG

    There's a crinkly effect on the wavy portion of the sides and some banding on the flanks of the small-end housing but otherwise its a reasonably smooth finish. Its also a rather bright finish, even though I asked for the lower level of polishing; it could pass for gold plating. All of the detail has been reproduced, some of which you can't actually make out with the mark-1 eyeball. The flats on the nuts on the top look good in the photos above but you need to look very closely to see them. NB: this is a small crosshead - to give an idea of the size, the nuts are about 2mm apart

    The holes for the small-end pin and the piston rod have come out slightly smaller than required, and the slidebar tunnel is also a bit smaller - I'm OK with this as I think its better this way than overlarge. I've separated the two pieces and fitted one to a slidebar; this required some sawing and filing, so I can confirm that this is real brass! It cuts and files as normal.
     
  3. Clarence3815

    Clarence3815 Member

    Do you know how thick in microns each layer of the printing is please?

    Bernard
     
  4. Rambler

    Rambler Active Member

    I’m not sure an exact specification is available. This is from the Shapeways website:

    Brass models are fabricated using lost wax casting. First, the model is printed in wax using a specialized high-resolution 3D Printer. It is then put in a container where liquid plaster is poured in around it. Once the plaster sets, the wax is melted out in a furnace, and the remaining plaster becomes the mold. ​

    Molten brass is poured into this mold and set to harden. The plaster is broken away, revealing your new product. Natural Brass is briefly tumbled. Polished Brass is carefully cleaned and hand polished. Please be aware that polishing can wear down or fill in very fine details and edges.​
     
  5. Clarence3815

    Clarence3815 Member

    I see. So not printed except for the armature.

    Thank you.
     
  6. Brian McKenzie

    Brian McKenzie Western Thunderer

    16 micron - when I was using Shapeways (New York) for brass, prior to the ownership change. However, I did wonder at times if they were cutting corners by reverting to 25 microns - which is why I began purchasing waxes only (when they allowed that), and then had the waxes cast by another business after my inspection.

    The lines you see on your crossheads are most likely an artifact from the model of printer used for the waxes. I get the same result from another supplier who uses the same machine as Shapeways (manufactured by 3D Systems), and the owner says he can't do anything about it.

    Yes, the brass is produced as a lost-wax or investment casting from a 3D printed wax - which was not made clear, or possibly not recognised by the author of a recent Gazette article.

    -Brian M.
     
  7. Clarence3815

    Clarence3815 Member

    Now that is interesting.

    I have used a firm in the UK for printing at 16 micron resolution. When I asked Shapeways some time ago they couldn1`t do 16 microns.

    I`ll have to ask again.

    Bernard
     
  8. Marc Dobson

    Marc Dobson Western Thunderer

    I have had a few issues with print quality from both Shapeways and I'materialize, in resent months. Prices have gone up quality has gone down. I had a feeling that the slices had got bigger. I decided enough was enough and ordered a Elegoo Saturn so i can do my own. As a side its now a month over due on delivery.

    Marc
     
  9. Clarence3815

    Clarence3815 Member

    What resolution can that acheive?

    Bernard
     
  10. adrian

    adrian Flying Squad

    I think I would design them to be smaller than required on purpose. No matter how good the casting process I would always ream out the holes to size to ensure alignment and concentricity. It will also allow you to cut a thread in part of it as well. I have done this in the past on crossheads - I've threaded the rear facing side so I can screw in a bolt to hold the connecting rod but it is then flush at the rear to give a bit of clearance to any coupling rods and crankpins from a front driver.

    Just curious as well - did you happen to scope out getting them produced in steel is that possible at this size? It's one of my pet hobby horses (a.k.a. soap box) to me motion gear should be in steel. The original items were steel and the colour difference is very marked, so it's always something I notice.

    As mentioned I believe from Shapeways that the brass castings are produced via the "lost wax" process so consumable/expendable patterns are 3d printed which are then sent for casting. In the casting ceramic the 3d printed is vapourised/melted/lost to be replaced by the molten brass.

    As I understand it the 3d steel printing is a different process in that they are "sintered". So minute steel particles are 3d printed and glued together with a binder. It's not quite sintering as I understand it but they take the printed items and coat them in a ceramic material. Then a molten bronze is injected which melts and replaces the binder to give it some strength. The beauty of this for me is that the castings would be the right colour, the proviso is how expensive would it be and can the resolution match these brass castings?
     
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  11. Rambler

    Rambler Active Member

    Adrian,
    I did consider getting the cross head done in steel but, as this was my first essay into 3D printing, I decided to stick to a material I’m familiar with. Also, the cross head will probably be painted red. The rest of the motion and the slidebars will be in nickel-silver, so not too different in colour.
    Eric
     
  12. Rambler

    Rambler Active Member

    The North Eastern wagon axleboxes came out like this:
    DSC_0605_small.JPG
    As you can see, I haven't quite got the hang of photographing translucent materials so I cut out one of them and gave it a (brush) paint with some Tamiya acrylic grey paint. Thus:

    DSC_0614_small.JPG DSC_0616_small.JPG DSC_0617_small.JPG

    In these photos it looks as though the surface is a bit rough but in real life it looks smooth enough. I'm amazed that you can read all of the lettering - I was expecting that it would come out as some undecipherable blobs in roughly the right place!
    NB: I think there's a bit of fluff on the right hand side , and I missed some of the back with my paint.
     
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  13. geoff_nicholls

    geoff_nicholls Western Thunderer

    An informative and very useful Thread. Thank you for posting it, I think I'll have a go at some brass prints myself based in your comments.
     
  14. Marc Dobson

    Marc Dobson Western Thunderer

    from what I have seen they are pretty high quality off the top of my head 0.01mm jumps to mind. Its big enough to print a medium size tank engine in 7mm or two gauge 1 box vans.
    Within 10 minutes of me saying it was overdue last night I had an Email from Elegoo saying that it had been dispatched from their European where house and it will be with me in the next few days.

    Marc