How to attach a sight glass?

Discussion in 'General Engine Discussion' started by blockmanjohn, Jan 15, 2020 at 4:24 PM.

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  1. Jan 15, 2020 at 4:24 PM #1

    blockmanjohn

    blockmanjohn

    blockmanjohn

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    Hi,

    I am putting together a brass gas tank that is 1 1/2 inches in diameter. I would like to make one end out of glass. I am wondering what would be the best way to glue the glass to a brass ring that would be soldered to the tank end. I was thinking of silicone, but I don't know if it would hold up to the gasoline.

    Any one have any experience with this?

    Thanks, John.
     
  2. Jan 15, 2020 at 4:58 PM #2

    Peter Twissell

    Peter Twissell

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    I wouldn't try to solder the ring in place after gluing the glass to it.
    My preference would be for a mechanical joint, with an O ring sealing the glass to the tank end and the glass held in place by a retaining ring, all held in place by some studs on a PCD.
     
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  3. Jan 15, 2020 at 6:30 PM #3

    blockmanjohn

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    Thanks for the reply Peter,

    For what it's worth, I planned to glue the glass to the outside of the ring after it was soldered. Also, I'm not sure what a PCD is.

    Thanks again, John
     
  4. Jan 15, 2020 at 7:17 PM #4

    Brian Rupnow

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    I have done this. Contrary to what you may hear, J.B. Weld is not effected by gasoline nor coleman fuel. It stands up fine and does not soften or lose it's ability to hold parts together. Machine a brass or aluminum ring and use J.B.Weld to glue the glass into it, then use it to glue the machined ring into the ends of the tank.---Brian
    [​IMG]
     
    Last edited: Jan 15, 2020 at 7:32 PM
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  5. Jan 15, 2020 at 7:32 PM #5

    Peter Twissell

    Peter Twissell

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    PCD is a pitch circle diameter. It describes a series of features arranged in a circle, such as a ring of screws.
     
  6. Jan 15, 2020 at 9:34 PM #6

    cheepo45

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    I glued a watch crystal to the end of the tank on my Jan Ridders Debbie engine with Gorilla super glue 4 years ago and it still doesn't leak.
    Just be sure everything is really clean before you glue it.
    Don't use silicone sealer-it will leak.
    Scott
     
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  7. Jan 16, 2020 at 11:07 AM #7

    blockmanjohn

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    Does anyone know where I can find a 1 1/2 inch clear glass disk? All I can find are disks that are textured on one side.

    Thanks, John.
     
  8. Jan 16, 2020 at 1:22 PM #8

    Engine maker

    Engine maker

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    I get mine here http://www.ofrei.com/page1190.html. There flat mineral glass watch crystals. They come in almost any size. They come in 1mm, 2mm, and 3mm thickness and go up in Dia. by .006" . Its a large sight so look around.

    Jim G
     
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  9. Jan 16, 2020 at 2:44 PM #9

    plipoma

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    Try Edmunds Scientific for the glass.
     
  10. Jan 16, 2020 at 2:54 PM #10

    WOB

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    IMHO Loctite 609( or similar) is a better choice for sticking the ring to the tank. You don't need any clearance for epoxy in the interface. A snug to .005" clearance fit with a short overlap will work well.

    WOB
     
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  11. Jan 16, 2020 at 4:39 PM #11

    Brian Rupnow

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    Find a local watch repair shop. They will have an assortment of clear glass discs.- You don't have to leave a large clearance for j.b. weld. A sliding fit is just fine. Loctite isn't good a filling voids or gaps. ---Brian
     
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  12. Jan 17, 2020 at 12:56 AM #12

    R Degen

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    Lexan works great for the tank end gasoline will not harm it.

    Randy
     
  13. Jan 17, 2020 at 8:42 AM #13

    bluejets

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    Instead of a complete end of glass, perhaps a couple of angle nipples soldered into the tank, one top, one bottom and a piece of clear plastic tube in between.
    Did this on my scale Rivierra boat.
     

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  14. Jan 17, 2020 at 12:59 PM #14

    ozzie46

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    I used lexan,(at least thats what Lowes said it was), and it became so cloudy I can't hardly see thru it.

    Ron
     
  15. Jan 17, 2020 at 3:27 PM #15

    awake

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    As I understand it, Lexan is a brand name of polycarbonate ... and polycarbonate has poor resistance to gasoline or other aromatic hydrocarbons. Acrylic (plexiglass) actually does better with gasoline, from what I can tell - but I hasten to say that I am no expert!
     
  16. Jan 17, 2020 at 7:17 PM #16

    bruedney

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    Here is my gas tank for my Rupnow IC engine

    [​IMG]

    It is thick walled Ali tube - Internal thread and watch glass and thin oring captured by retaining ring

    Works great
     
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  17. Jan 18, 2020 at 4:36 AM #17

    Balta

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    Policarbonate will become brittle in the presence of hydrocarbons (gas, oil, etc).
     
  18. Jan 18, 2020 at 10:05 AM #18

    R Degen

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  19. Jan 18, 2020 at 1:58 PM #19

    awake

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    Oh, the power of the internet - it can provide contradictory information faster than I can blink! Now I don't know what to think, since we have an apparently authoritative site saying PC has good resistance to gasoline, but I looked up several sites saying it had poor resistance to gasoline. Here's one that I found just now: http://kmac-plastics.net/data/chemical/polycarbonate-chemical.htm#.XiMQ66ZOkXA

    The proof is in the pudding, as they say ... but even above we have two different outcomes when people have tried it. Perhaps each person was *sold* PC, but one of them actually received something else - ?
     
    Last edited: Jan 18, 2020 at 2:08 PM
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  20. Jan 18, 2020 at 2:08 PM #20

    minh-thanh

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    Add an option: aluminum and glass :
    20200118_210230.jpg
     
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