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  1. #1
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    Default Technique for casting old style 'Sunshine' farm gate

    Wondering if anyone has tackled casting something like the old McKay Sunshine Gate; the cast joints are apparently poured around the tubular (originally solid) members. I'm wondering if a reproduction might be feasible with a small home foundry setup, perhaps casting just a couple of the joints at a time. Assuming hollow tube was used for the members, with the tube laid through the sand moulds, what would be the best way to prevent loss of metal up the bore of the tubes? What would be the best technique for preventing the ends of the tubes pulling out of the cast joints; e.g. a bead of weld around the tube? I'm thinking a personalised decorative gate with the look of the old originals would be a great casting project.
    an original example:
    https://www.migrationheritage.nsw.go...ate/index.html

  2. #2
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    what would be the best way to prevent loss of metal up the bore of the tubes?
    If I was to do something like that, I'd probably turn down some solid bar to fit inside the pipe, pushing it in so that there was about 20-30mm of pipe not blocked. To keep it there, a plug weld would be sufficient. This, to me would also provide a keying effect.

    What would be the best technique for preventing the ends of the tubes pulling out of the cast joints; e.g. a bead of weld around the tube?
    You probably could get away with some shird bit welds around the ends of the pipe, it wouldn't need a full bead around the pipe, you could also tack/or weld the corners for extra rigidity.

    I'm thinking a personalised decorative gate with the look of the old originals would be a great casting project.
    Do you have access to an old gate or the cast parts?
    Asking, as to make the molds could/would be a painstaking job, depending on how ornate you wanted it.
    Ask Michael G
    HTH
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
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    I did think that it might be easier to cast the joining blocks and then tap them or even bond tubes in with loctite. You'd get the look without having to heft a large farm gate around. One of the issues you would have casting something like that is that not only do you have to stop the metal running down the inside of the tubes, but the metal may also want to run down the outside too. Probably not too bad in terms of clean up, but extra work never the less.

    Michael

  4. #4
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    I have zero casting experience, by my first thought was to perhaps create a solid steel structural "spider" from bar stock, cast the decorative around it, then slide on the tubes and plug weld to attach them.

    Steve

  5. #5
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    A few interesting thoughts there. I've been musing for a week or so about how you would assemble short lengths of tube onto a spider, the problem with this is that tubes need to be inserted from various angles simultaneously- picture a gate with a simple 'X' in the centre and each radiant of the 'X' needing also to be assembled into a joint where it meets the vertical and horizontal parts of the outer frame. I can't see a way this could be achieved except with an awful lot of slop in at least some of the joints, which surely would result in a gate with little structural integrity? It was an 'aha' moment when I learned that the joints were cast onto the bars.
    Kryn's suggestion of metal plugs in the tube ends is a definite go-er. Tacking the entire frame together first too- in fact I wonder if it would be less work to fully weld a frame rather than plugging the joints....
    Certainly the pattern making would be laborious, also preventing excessive flow of molten metal along the outside of the tubes where they exit the moulds is another problem to be solved.
    Presumably the original factory would have set up all the moulds and members on a jig and poured the joints all at the same time; one issue with a home foundry is that I couldn't melt that much metal (at least not iron) so would have to do it in several pours.

  6. #6
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    You wont need a complete seal around the pipes <1mm should be ok, as molten metal should be viscous enough not to flow too far.

    Another thing to consider is you will need to preheat the pipes in the mold, to stop cooling the pour too quickly.

  7. #7
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    I haven't been able to find much info online about casting iron or aluminium with captive steel elements. I did find one academic article where tests were made casting aluminium over stainless steel inserts at various temperatures and bond strength compared by pressing the inserts out of the casting and measuring the required press pressure; the best bond strength was obtained with the steel inserts at room temperature. Which is encouraging as making everything hot for a pour would massively complicate setup.
    My current thinking is: Flatten the ends of the tubes that will terminate in the joints, weld up the entire frame, make one pattern for the 'T' joints, one for the 'X' joints and one decorative centre pattern, pour one joint at a time with the joint to be poured set up in the flask and the rest of the frame chocked up level on the floor.

  8. #8
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    I’ve had a few thoughts about this so maybe these might help.

    Make the pattern in halves to fit over your completed joints.
    Possibly in wax sheet which can be heated and formed to layer around the pipe.
    The wax sheet is thin so would need to be built up in a few layers to get your desired metal thickness. It can be cut and shaped easily, possibly hot knife etc.
    Once the pattern is in place fit a ply box in halves around it.
    Use chemset or CO2 sand to make both halves with the sprue and runners in place.
    Split the mould and remove the pattern. (this May destroy a wax pattern) Ok if one off!
    Flaskless moulds need to be held together with clamps.
    H.

    Another thought, if the joints are accurate a mould in glass or bog or plaster could be made from the wax pattern in halves of course located on the gate. Barnes pinkysil or similar would do.
    You can then reproduce the patterns elsewhere with one of the 2 part pourable polyurethane mixes wot Barnes sell.
    Basically make a pattern on the gate, take a mould from it to then reproduce it in a ‘plastic’ material.
    Jimcracks for the rich and/or wealthy. (aka GKB '88)

  9. #9
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    I took a trailer load of metal to my local scrap bloke last week, as I was unloading I spotted a mangled Sunshine gate, every rail was cactus but all the joint castings were there. i thought 'There's my patterns!'. He would not part with it! A scrap metal dealer with a soul. Must be rare. got me thinking though, if I can source a stuffed gate and get the castings, the pattern making is pretty much done.

  10. #10
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    Can't make plaster casts of them?

    Michael

  11. #11
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    Quote Originally Posted by Michael G View Post
    Can't make plaster casts of them?

    Michael

    Would certainly be one way to go but the scrappy doesn't strike me as the bloke to go with this. I'm seeing a fair few of these gates at clearing sales at attainable prices, one thought is to buy a gate that has at least one of each casting intact, take some patterns and then sell it on. The next guy would have the joy of an original and I'd have the joy of one I made myself.

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