<div dir="auto"><div>Thanks Carl.<div dir="auto"><br></div><div dir="auto">I've had success with the builder's line.  I made a small loop in the middle of the line for one curtain, and a loop at each end.  The cord is wrapped once around the pulley (a 16T GT2 pulley) and the whole thing is tightened by a zip tie that goes through the loops at the ends.  I closed the gap from about 10cm to 1cm, which makes the cord very tight.</div><div dir="auto"><br></div><div dir="auto">Now I can open and close the curtains using a switch.  The pulley slips at the extreme end of travel, which is fine, although I might use a larger diameter pulley so that there is more surface area in contact with the cord.</div><div dir="auto"><br></div><div dir="auto">To automate it I will use an ESP8266 running microPython, and either a motor driver board or a pair of relays.</div><div dir="auto"><br></div><div dir="auto">Andrew</div><br><div class="gmail_extra"><br><div class="gmail_quote">On Sep 26, 2017 10:13 PM, "Carl Ranson" <<a href="mailto:carl.ranson@gmail.com">carl.ranson@gmail.com</a>> wrote:<br type="attribution"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
  
    
  
  <div text="#000000" bgcolor="#FFFFFF">
    <div class="m_1671986269823556113moz-cite-prefix"><br>
      You might find that's not enough torque, depending on how the
      blind is weighted, but as they say. your mileage may vary. <br>
      <br>
      I've messaged my guy to see if he has an email with the specs for
      the one we used. <br>
      <br>
      3d printers are awesome. you'll enjoy it a lot.  I recommend
      learning freecad for software. Really good cos you can link all
      the dimensions back to a spreadsheet and then tweak the numbers if
      you need to make adjustments.<br>
      <br>
      cheers, <br>
      CR <br><div class="elided-text">
      <br>
      On 26/09/2017 9:27 AM, Andrew Errington wrote:<br>
    </div></div><div class="elided-text">
    <blockquote type="cite">
      <div dir="auto">Hi Carl,
        <div dir="auto"><br>
        </div>
        <div dir="auto">Nice to hear from you.  Glad you're still
          hacking on stuff.</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">I'm using this motor:</div>
        <div dir="auto"><a href="http://www.dx.com/p/diy-37mm-high-torque-silent-60rpm-12v-dc-precision-gear-motor-grey-383488" target="_blank">http://www.dx.com/p/diy-37mm-h<wbr>igh-torque-silent-60rpm-12v-dc<wbr>-precision-gear-motor-grey-383<wbr>488</a><br>
        </div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">It's pretty grunty, but 60rpm is a bit sedate. 
          Banggood have an 80rpm variant and a 130rpm one.  They fit
          nicely onto the smallest purlin bracket, which I've bolted to
          the wall with timber cladding screws.</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">Once I have one working I can buy six sets of
          parts for the windows in the lounge.</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">I have also just bought a 3D printer.  It should
          arrive tomorrow so for the benefit of everyone else reading
          this I'll start a new thread then (assuming it's not a dud).</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">Best wishes,</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">Andrew</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto"><br>
        </div>
        <div class="gmail_extra" dir="auto"><br>
          <div class="gmail_quote">On Sep 25, 2017 9:57 PM, "Carl
            Ranson" <<a href="mailto:carl.ranson@gmail.com" target="_blank">carl.ranson@gmail.com</a>>
            wrote:<br type="attribution">
            <blockquote class="m_1671986269823556113m_-8894338939417272735quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div text="#000000" bgcolor="#FFFFFF">
                <div class="m_1671986269823556113m_-8894338939417272735m_-6158507875113516016moz-cite-prefix"><br>
                  Hey Andrew, <br>
                  <br>
                  been a while. <br>
                  <br>
                  I actually did this for a blind in my house this year.
                  <br>
                  I had a friend building a house who wanted to do 18 of
                  them (yes, 18!). Not wanting to pay $400 each he
                  sourced the motors from China for about 50 bucks a
                  piece. These came with a remote control and settable
                  limits etc and they mount inside the blind itself. <br>
                  <br>
                  Problem was, they didn't have attachment hardware. In
                  comes the 3d printer. problem solved and I got a motor
                  for mine as payment. <br>
                  <br>
                  Before that I'd tried door window motor with extra
                  gearing. even that didn't have enough oomph to draw
                  the blind (although I probably could have added weight
                  to balance it a bit). <br>
                  <br>
                  Hope that helps. <br>
                  <font color="#888888"> CR</font>
                  <div class="m_1671986269823556113m_-8894338939417272735elided-text"><br>
                    <br>
                    <br>
                    <br>
                    On 25/09/2017 5:38 PM, Andrew Errington wrote:<br>
                  </div>
                </div>
                <div class="m_1671986269823556113m_-8894338939417272735elided-text">
                  <blockquote type="cite">
                    <div dir="auto">
                      <div>There's also "fishing line I happen to have
                        to hand", which is clearly unsuitable in this
                        case.
                        <div dir="auto"><br>
                        </div>
                        <div dir="auto">I'm going to try the builder's
                          line again.  This time with a cable tie that I
                          can crank down on to get the tension.</div>
                        <div dir="auto"><br>
                        </div>
                        <div dir="auto">Thanks,</div>
                        <div dir="auto"><br>
                        </div>
                        <div dir="auto">Andrew</div>
                        <br>
                        <div class="gmail_extra"><br>
                          <div class="gmail_quote">On Sep 25, 2017 5:01
                            PM, "Charles Manning" <<a href="mailto:cdhmanning@gmail.com" target="_blank">cdhmanning@gmail.com</a>>
                            wrote:<br type="attribution">
                            <blockquote class="m_1671986269823556113m_-8894338939417272735m_-6158507875113516016quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
                              <div dir="ltr">
                                <div>There's fishing line... and fishing
                                  line.<br>
                                  <br>
                                </div>
                                Nylon stretches like anything. Braid
                                (eg. <a href="https://www.completeangler.co.nz/line-95/braid-97/" target="_blank">https://www.completeangler.co.<wbr>nz/line-95/braid-97/</a>)
                                has practically no stretch and is
                                available in many colours and strengths.<br>
                                <br>
                              </div>
                              <div class="gmail_extra"><br>
                                <div class="gmail_quote">
                                  <div class="m_1671986269823556113m_-8894338939417272735m_-6158507875113516016elided-text">On
                                    Mon, Sep 25, 2017 at 3:51 PM, Andrew
                                    Errington <span dir="ltr"><<a href="mailto:erringtona@gmail.com" target="_blank">erringtona@gmail.com</a>></span>
                                    wrote:<br>
                                  </div>
                                  <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
                                    <div class="m_1671986269823556113m_-8894338939417272735m_-6158507875113516016elided-text">
                                      <div dir="auto">Hi everyone,
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">I thought I'd
                                          start a new thread, as we got
                                          away from the relative merits
                                          of Banggood vs DealExtreme.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">I am trying to
                                          motorise my curtains,
                                          particularly as there are six
                                          windows in one room, plus home
                                          automation is cool.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">So far I have
                                          identified a suitable motor
                                          and gearbox, 12Vdc supply,
                                          60rpm output, with good torque
                                          and fairly quiet.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">At one end the
                                          motor, with a 16-tooth GT2
                                          pulley, is attached to the
                                          wall using a purlin bracket
                                          (purlin brackets are cool). 
                                          At the other, I am using a
                                          sewing-machine bobbin on an M6
                                          bolt as a pulley.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">It's early days,
                                          but I have tried builder's
                                          line, which doesn't stretch,
                                          but does slip.  I have tried
                                          fishing line, which does
                                          stretch, and slips.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">I think GT2
                                          toothed belt would work well,
                                          but I haven't tried it yet.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">The motor is
                                          temporarily connected to a 12V
                                          battery for testing.  Later I
                                          will use an ESP8266 with
                                          microPython to control the
                                          motor.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">Finally, I'll
                                          link it to home automation
                                          software and relax in my chair
                                          as the sun goes down and the
                                          curtains gently and quietly
                                          close.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">That's my plan,
                                          but there is plenty of room
                                          for alternatives or failure.</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">The attached
                                          link is for a belt clamp and
                                          tensioner made from zip-ties,
                                          which I think I will adopt!</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">Best wishes,</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto">Andrew</div>
                                        <div dir="auto"><br>
                                        </div>
                                        <div dir="auto"><a href="http://diyprojects.eu/wp-content/uploads/2017/01/belt-connection-zip-ties.jpg" target="_blank">http://diyprojects.eu/wp-conte<wbr>nt/uploads/2017/01/belt-connec<wbr>tion-zip-ties.jpg</a><br>
                                        </div>
                                      </div>
                                      <br>
                                    </div>
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