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Acrylic for sight class window?

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  • Acrylic for sight class window?

    Any reason I couldn't use acrylic- standard, off the shelf cast rod- to make a new oil-level sight glass window? Both are static reservoirs (no pressure, don't get hot, etc.) and hold gear oil (as in, no fuels or solvents.)

    Doc.
    Doc's Machine. (Probably not what you expect.)

  • #2
    No problem with mineral oil or animal based greases/oils, but limited resistance to vegetable oil and silicone based oil.

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    • #3
      Shouldn't be a problem for most oils. See: http://www.eplastics.com/Plastic/pla...iglass-Acrylic for a guide

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      • #4
        Glass, If the windows are circular, they can be cut with tubing and valve grinding compound. Use light oil mixed with the grinding compound and modeling clay for a dam to contain the oil. Run the drill press at a slow speed and use light pressure with intermittent raising of the cutter. Raising the cutter lets more grinding compound enter the kerf. You can make "custom" tube from solid as only the inside of the tube is important. Be careful when it is about to break through. I used a piece of Baltic Birch plywood as a base and clamped it the drill press.

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        • #5
          Doc, making them from a cut of cast rod seems like a very complicated and time consuming method. The acrylic plastic is available in sheet form from common building supply places. Cut a disc from the sheet and peel off the protective skins and it's ready to install. But cut from a round rod and you need to do some seriously laborious sanding and polishing to bring the discs back to transparency.
          Chilliwack BC, Canada

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          • #6
            You can also just "flame polish" the disk... easy.

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            • #7
              DX.Com has a lot of thin glass flashlight lenses, heres a sample:
              http://www.dx.com/p/glass-lens-for-f...5#.WAQzKoWcFMs

              this one is 1.49 OD, 5mm thick

              Steve

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              • #8
                The existing sight glasses are essentially threaded plugs. A black plastic outer portion with threads, with a clear window pressed in. On both, they leak from between the window and outer case, and I don't see an easy way to press them apart or reseal. The outer shell feels like a Delrin or Teflon type plastic, so I don't know of any glues that I can be sure will work.

                So the plan was to simply turn a new plug, out of a solid piece of acrylic, in the shape of the entire assembly. Polishing isn't an issue, I've made parts out of it before and it shines up nicely with standard buffing wheels and compounds.

                Doc.
                Doc's Machine. (Probably not what you expect.)

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                • #9
                  Another way to do this would be to 3d print it out of ABS and embed the acrylic window as it's being printed. Apply acrylic glue after it has been printed to seal the acrylic and ABS. You may also need to seal the ABS as well to make it water tight.

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                  • #10
                    No problem with acrylic Doc.

                    I tried to add a couple photos of several I've built recently and a couple I made many years ago but photo bucket wasn't working for me. The sight glasses I made probably 15 years ago are still clear and leak free but mine had o-rings for seals, press fit, no threads. I used the three step plexiglass polish to clean them up, worked great.

                    Ron

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                    • #11
                      In the absence of anything better to polish some acrylic I decided to go old school and wet and dry paper polish some, usual 180,240,400, then 600 and 1200, the finest I had was 2000 paper, it was nearly there, but not quite, I soaped the 600 and 2000, (rub the paper with a bar of soap, dry, then use wet)
                      I finished it off on a buffing wheel and some wax, the wrong one I think it was grey on an old wheel I'd used on all sorts, it worked, I was as suprised as anybody but it worked, I did one peice with metal polish, that worked too, happy days.
                      Mark

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                      • #12
                        If it is a wet oil level sight, a perfect polish isn't really needed. On the inside, once it is wet, the level will be visible, and, depending on the type of oil, a light frost might make it easier to read (or might not. Depends on how the oil wets the material and the resulting meniscus size). On the outside, a shot with an acrylic rattle can clearcoat will smooth it nicely once you reach a moderate finish. I wouldn't do it to the inside, though.

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                        • #13
                          Originally posted by lakeside53 View Post
                          You can also just "flame polish" the disk... easy.
                          Be careful here, unless you plan to anneal it. Heat puts stresses into acrylic that can show up as cracks.
                          Definition: Racecar - a device that turns money into noise.

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                          • #14
                            I went to my local watch repair guy. He had an assortment of round, clear glass crystals, and gave me two to use as ends in a see thru cylindrical gas tank.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

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                            • #15
                              Originally posted by Stepside View Post
                              Glass, If the windows are circular, they can be cut with tubing and valve grinding compound. Use light oil mixed with the grinding compound and modeling clay for a dam to contain the oil. Run the drill press at a slow speed and use light pressure with intermittent raising of the cutter. Raising the cutter lets more grinding compound enter the kerf. You can make "custom" tube from solid as only the inside of the tube is important. Be careful when it is about to break through. I used a piece of Baltic Birch plywood as a base and clamped it the drill press.
                              Thank you.

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