From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Bell mouth 3D printed
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-12972314@logan.com>
Message-ID: <2ec9e378-cca0-2a17-e3a7-a8943a24a474@verizon.net>
Date: Thu, 19 Sep 2019 14:10:47 -0400
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Thanks, that's a good tip!

I suspect that 20% infill is plenty strong in this case.

Finn

On 9/19/2019 10:03 AM, Dustin Lobner dmlobner@gmail.com wrote:
> Finn,
>
> I've been doing 3D printing for awhile now, never tried ABS though.
>
> I've used 3D printed parts primarily for model rockets, things around 
> the house, etc.?? The stuff holds up well, moreso than one would think 
> normally.
>
> One suggestion I'd have is higher infill - when I'm printing something 
> that needs to hold up, I usually??run about 75% infill.?? I'm not sure 
> if that's possible with ABS or not, so I don't know if that's actually 
> good advice.?? One thing you can do, and only with ABS, if you take a 
> shop rag and wet it with Acetone (I think, google it) if you wipe the 
> part with the acetone, it dissolves the first layer or so (until the 
> acetone evaporates).?? This allows you to smooth the ABS with the rag 
> and get a gloss finish on it.?? You can also do vapor polishing: 
> https://www.matterhackers.com/articles/how-to-vapor-polishing I don't 
> like the hot method, if you look down the comments section someone 
> explains how to do the "cold" method.?? I'd try that.
>
> Good luck!
>
> Dustin
>
> On Thu, Sep 19, 2019 at 8:36 AM Finn Lassen finn.lassen@verizon.net 
> <mailto:finn.lassen@verizon.net> <flyrotary@lancaironline.net 
> <mailto:flyrotary@lancaironline.net>> wrote:
>
>     My first experience with 3D printing.
>
>     I had bought a new Ender-3 and a 1Kg spool of ABS for less than $200.
>
>     Article and pictures here:
>
>     https://drive.google.com/open?id=1LbQcJIGnjsfNWfL5qiwz5ev7ze9IWAzm
>
>     I copied the "best" picture from the RET_Bellmouth_Sept.pdf article,
>     pasted it into Paint and saved as Bellmouth.bmp.
>
>     Imported that into Fusion360 as canvas. Calibrated it so throat was
>     19.972mm (1.18")
>
>     Made a spline matching the left curve up to the top.
>
>     Added a tangent arc (radius).
>
>     Added a 2mm rectangle that extended the throat about 1" with an 1.25"
>     ID. (The bell mouth will slide 1" down on the 1.25" OD pipe.)
>
>     Added a "looks good" spline from part of the arc down to the
>     throat. (I
>     believe that in our case, where most of the air comes from behind the
>     bell mouth, air should have a smooth path along the outside of the
>     pipe
>     and radius of bellmouth.)
>
>     Revolved the whole thing to get the solid bell mouth.
>
>     [The result is actually a bit smaller overall diameter than the
>     recommended 2.13 * 30 + 2 * (0.08 * 2.13 * 30) = 74mm]
>
>     Exported to a .stl file.
>
>     Downloaded and installed Ultimaker Cura 4.2.1.
>
>     Opened the .stl file with Cura and "sliced" it. 20% infill. This
>     changes
>     the solid inside to a criss-cross pattern. Looking at it being
>     printed
>     it appeared?? to produce about 3/32" thick walls by default.
>
>     Saved result to .gcode file.
>
>     Printed with the Ender-3. Took 3 hours and 15 mins.
>
>     Nozzle temp default for ABS is 240*C. Spool says 230-260*C. Seeing
>     how
>     some of the strands didn't stick and pulled across the mouth, I think
>     I'll use a higher nozzle temp on the next print.
>
>     I printed it with mouth down. Unfortunately that resulted in a radius
>     quite different from the design model. I'll try to smooth the lip
>     on my
>     first attempt with epoxy or JB Weld and sandpaper. If I print it
>     throat
>     down, it'll probably need support along the outside that'll have
>     to be
>     cut after printing.
>
>     Will ABS be strong enough? I think so. The airflow should keep temps
>     well below 85*C.
>
>     Finn
>
>
>     --
>     Homepage: http://www.flyrotary.com/
>     Archive and UnSub:
>     http://mail.lancaironline.net:81/lists/flyrotary/List.html
>


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    <div class="moz-cite-prefix">Thanks, that's a good tip!<br>
      <br>
      I suspect that 20% infill is plenty strong in this case.<br>
      <br>
      Finn<br>
      <br>
      On 9/19/2019 10:03 AM, Dustin Lobner <a class="moz-txt-link-abbreviated" href="mailto:dmlobner@gmail.com">dmlobner@gmail.com</a> wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:list-12972314@logan.com">
      <meta http-equiv="content-type" content="text/html; charset=utf-8">
      <div dir="ltr">Finn,
        <div><br>
        </div>
        <div>I've been doing 3D printing for awhile now, never tried ABS
          though.</div>
        <div><br>
        </div>
        <div>I've used 3D printed parts primarily for model rockets,
          things around the house, etc.?? The stuff holds up well, moreso
          than one would think normally.</div>
        <div><br>
        </div>
        <div>One suggestion I'd have is higher infill - when I'm
          printing something that needs to hold up, I usually??run about
          75% infill.?? I'm not sure if that's possible with ABS or not,
          so I don't know if that's actually good advice.?? One thing you
          can do, and only with ABS, if you take a shop rag and wet it
          with Acetone (I think, google it) if you wipe the part with
          the acetone, it dissolves the first layer or so (until the
          acetone evaporates).?? This allows you to smooth the ABS with
          the rag and get a gloss finish on it.?? You can also do vapor
          polishing:??<a
            href="https://www.matterhackers.com/articles/how-to-vapor-polishing"
            moz-do-not-send="true">https://www.matterhackers.com/articles/how-to-vapor-polishing</a>??
          I don't like the hot method, if you look down the comments
          section someone explains how to do the "cold" method.?? I'd try
          that.</div>
        <div><br>
        </div>
        <div>Good luck!</div>
        <div><br>
        </div>
        <div>Dustin</div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Thu, Sep 19, 2019 at 8:36
          AM Finn Lassen <a href="mailto:finn.lassen@verizon.net"
            moz-do-not-send="true">finn.lassen@verizon.net</a> &lt;<a
            href="mailto:flyrotary@lancaironline.net"
            moz-do-not-send="true">flyrotary@lancaironline.net</a>&gt;
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">My
          first experience with 3D printing.<br>
          <br>
          I had bought a new Ender-3 and a 1Kg spool of ABS for less
          than $200.<br>
          <br>
          Article and pictures here:<br>
          <br>
          <a
href="https://drive.google.com/open?id=1LbQcJIGnjsfNWfL5qiwz5ev7ze9IWAzm"
            rel="noreferrer" target="_blank" moz-do-not-send="true">https://drive.google.com/open?id=1LbQcJIGnjsfNWfL5qiwz5ev7ze9IWAzm</a><br>
          <br>
          I copied the "best" picture from the RET_Bellmouth_Sept.pdf
          article, <br>
          pasted it into Paint and saved as Bellmouth.bmp.<br>
          <br>
          Imported that into Fusion360 as canvas. Calibrated it so
          throat was <br>
          19.972mm (1.18")<br>
          <br>
          Made a spline matching the left curve up to the top.<br>
          <br>
          Added a tangent arc (radius).<br>
          <br>
          Added a 2mm rectangle that extended the throat about 1" with
          an 1.25" <br>
          ID. (The bell mouth will slide 1" down on the 1.25" OD pipe.)<br>
          <br>
          Added a "looks good" spline from part of the arc down to the
          throat. (I <br>
          believe that in our case, where most of the air comes from
          behind the <br>
          bell mouth, air should have a smooth path along the outside of
          the pipe <br>
          and radius of bellmouth.)<br>
          <br>
          Revolved the whole thing to get the solid bell mouth.<br>
          <br>
          [The result is actually a bit smaller overall diameter than
          the <br>
          recommended 2.13 * 30 + 2 * (0.08 * 2.13 * 30) = 74mm]<br>
          <br>
          Exported to a .stl file.<br>
          <br>
          Downloaded and installed Ultimaker Cura 4.2.1.<br>
          <br>
          Opened the .stl file with Cura and "sliced" it. 20% infill.
          This changes <br>
          the solid inside to a criss-cross pattern. Looking at it being
          printed <br>
          it appeared?? to produce about 3/32" thick walls by default.<br>
          <br>
          Saved result to .gcode file.<br>
          <br>
          Printed with the Ender-3. Took 3 hours and 15 mins.<br>
          <br>
          Nozzle temp default for ABS is 240*C. Spool says 230-260*C.
          Seeing how <br>
          some of the strands didn't stick and pulled across the mouth,
          I think <br>
          I'll use a higher nozzle temp on the next print.<br>
          <br>
          I printed it with mouth down. Unfortunately that resulted in a
          radius <br>
          quite different from the design model. I'll try to smooth the
          lip on my <br>
          first attempt with epoxy or JB Weld and sandpaper. If I print
          it throat <br>
          down, it'll probably need support along the outside that'll
          have to be <br>
          cut after printing.<br>
          <br>
          Will ABS be strong enough? I think so. The airflow should keep
          temps <br>
          well below 85*C.<br>
          <br>
          Finn<br>
          <br>
          <br>
          --<br>
          Homepage:?? <a href="http://www.flyrotary.com/"
            rel="noreferrer" target="_blank" moz-do-not-send="true">http://www.flyrotary.com/</a><br>
          Archive and UnSub:?? ??<a
            href="http://mail.lancaironline.net:81/lists/flyrotary/List.html"
            rel="noreferrer" target="_blank" moz-do-not-send="true">http://mail.lancaironline.net:81/lists/flyrotary/List.html</a><br>
        </blockquote>
      </div>
    </blockquote>
    <p><br>
    </p>
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