JB's 3D CAD & Printing bench

Discussion in 'CAD Corner' started by John Baker, 31 December 2019.

  1. Mike Trice

    Mike Trice Western Thunderer

    During Summer using Anycubic resin I managed a 60sec bottom exposure but for Winter reverted back to 90secs.
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  2. John Baker

    John Baker Active Member

    Having increased the bottom exposure time and beefed up the top section of the supports a bit, everything printed pretty well. Here are the prints of the renders in my previous post - pretty much straight off the printer with minimal cleaning up.

    Talk about cruel closeups....The layer lines on the smokebox door are barely visible with the naked eye. I'm going to try a couple of things. Firstly just paint it and see if the paint smooths the steps, and secondly reduce the layer height from 5 microns to 3 microns. May not be necessary, particularly as these will eventually be cast, but we'll see. For scale, this is just under 2cm wide.
    The springs need a bit of remodelling in Fusion to make the join between each leaf a little more distinct.
    Coupling hook - perhaps half a mill of so too long, but printed really well
    Blowdown valve - needs a dusting but at 2.8mm long (including the spigot at the top) this is the smallest thing I've tried printing. My poor photography equipment (skills?) doesn't do the detail justice.
    The buffer body and heads printed well. These are 2 separate components, which once cast will have a self contained spring - the wire, which prevents the buffer head from falling out will be trimmed back, soldered in and filed smooth. I need to alter the 3D model a bit though as it's a bit of a tight fit at the moment.
  3. DavidB

    DavidB Active Member

    I had a couple of smokebox doors printed for me a couple of years ago. The first ones were printed flat and came out like yours with contour lines. Reprinting with the doors supported at an angle of about 45 degrees eliminated the contour lines.
  4. John Baker

    John Baker Active Member

    I printed mine at about 20 degrees, do when I print it next time I'll tilt it a bit more
  5. Mike Trice

    Mike Trice Western Thunderer

    Anti aliasing might help.
  6. John Baker

    John Baker Active Member

    Slowly getting there with the iClass - etches are almost done which I'll share a preview of before they head to the etchers. In the meantime I have been designing the inside motion. I was hoping Laurie Griffin might have something that would fit, but this loco is so tiny that I needed to start from scratch. Here are the slide bars - the rest of the components to follow. I'm hoping to learn how to animate all this in Fusion if time allows.


    Slidebars detail.png
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  7. John Baker

    John Baker Active Member

    Here's the rest of the crank motion - the benefits of 3D modelling this first is that I can check everything fits! And it seems to work so far. Valve gear next.
    Screenshot 2021-02-13 at 21.26.32.png
    Screenshot 2021-02-13 at 21.27.45.png
    Screenshot 2021-02-13 at 21.28.18.png
    Screenshot 2021-02-13 at 21.09.22.png
    Screenshot 2021-02-13 at 21.29.12.png

  8. John Baker

    John Baker Active Member

    Here are the first test prints for the inside motion for the Old Class i. For those of you familiar with resin 3D printing, you'll understand how critical getting settings and supports for the prints exactly correct for them to print correctly (or at all). I prefer to print in standard grey ABS-like resin first, as it tends to be the cheapest, meaning failure are less costly. The next phase in their development is to print it in a 'tough' resin (made by e-Sun). I've never used this before, so there will be a lot of experimenting with settings. I'll be interested to see how 'tough' it is, and whether it could be used as a final material for the model, or whether they will need to be cast (which is where I originally envisaged it going). Time will tell.

    Slide Bars

    Connecting Rods - the eagle eyed amongst you will notice that the big end needs to be in 2 parts to allow it to be fitted to the crankshaft......doh [​IMG].



    Eccentric Sheaves

    Eccentric straps (2 printed fine, but the other 2 I tried printing in a different orientation, and didn't work). They are a bit bent - this resin isn't really strong enough to stand up to handing/sanding, as the rod is only about 1.5m thick.

    Expansion Links

    Balance weights

    One half of the motion mocked up for a picci
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