Pattern lifting screws

Discussion in 'Foundry tools and flasks' started by Melterskelter, Apr 13, 2018.

  1. Melterskelter

    Melterskelter Gold Banner Member

    IMG_4575.JPG Here is a pair of pattern lifting screws I recently put together from steel bar and drywall screws. I cut the screw heads off and center drilled the 4" round bar to accept the screw a half inch or so. Then silver brazed the screws into the end and tigged the cross bar. Very handy and promote control in lifting. FWIW
     
    Last edited: Apr 13, 2018
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  2. ESC

    ESC Silver Banner Member

    Nice, I used the same screws for my draw prick. The rapper is the same rod bent into a "U".

    IMG_20180413_154954.jpg
     
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  3. Melterskelter

    Melterskelter Gold Banner Member

    Yes, I like your rapper. I have some material left and could make one like it. That would make this a nice set for small stuff. Thx.
     
  4. DavidBlaker

    DavidBlaker Copper

    Hey there! Those pattern lifting screws sound really cool!
     
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  5. mytwhyt

    mytwhyt Silver

    Smear a little wax in the top of the screw hole to keep the sand out.
     
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  6. Melterskelter

    Melterskelter Gold Banner Member

  7. Melterskelter

    Melterskelter Gold Banner Member

    I recently started using the pattern lifting screrws in a way that should have been obvious but took a while to tumble to.

    Background: Nearly all of my patterns are long and narrow and are best drawn using two spikes or screws. Until recently, I have been tapping up on one screw and then holding that screw up with my left hand and then tapping up on the right screw. Inevetably the patteern would tend to fall back into the cavity a sixteenth or so as I set down the rapping tool and grasped the right spike. For many patterns that does not matter too much as there are no fine details damaged by that jockeying. But I have one, especially, that has shallow letters on it and those letters can look "double-struck" every once in a while. And that means a remelted casting---ugh!

    It finally dawned on me to use a small bar to skewer both spikes and grasp the bar in the middle and to put a little pressure up on the bar and consequently both spikes as I rap. This works perfectly with no falling back of the pattern and in fact generally easier drawing than my old method. For all I know this could be common practice, but I've never seen it reported or in a video.

    Here's a pic: That square red thing is a printed filter/sprue pattern. And there is a second pattern behind the one I am drawing. This is the cheek section of a cope/cheek/drag flask set.
    Double Draw.JPG

    Here is the resulting sand impression. It is crisper than almost all the prior ones and I believe will draw this way virtually evey time.
    Double Draw2.JPG

    It is a small incremental improvement in my molding work, but feels oh so good!

    Denis
     
    Last edited: Jun 3, 2023

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