Pattern Suspending "Bolts"

Discussion in 'Sand Casting' started by Melterskelter, Sep 18, 2018.

  1. Melterskelter

    Melterskelter Gold Banner Member

    I have posted previously about casting an 18 inch pattern in cast iron. I have encountered any number of technical problems making this part. One of the issues involves pulling the cope off the drag and insuring that the pattern separates from the drag cleanly and remains in the cope suspended above the drag. In a way this is a backwards way of separating cope and drag as it would usually be a lot easier to not fight gravity and let make the separation with the cope down and pull the drag off leaving the pattern in the cope. But because this pattern has features that include fairly steep and deep "mountains" of sand that stick up from the drag, it works better to draw it as stated. Otherwise gravity tends to pull away any part of the drag that might be slightly cracked in drawing and gravity puts additional stress on the drag mountains. See attached photos.

    I found that I could separate the cope from the drag and have the pattern remain in the cope about 66 to 75% of the time. But it was very frustrating to occasionally have the pattern fall out and spoil the pattern. To prevent the pattern from falling out of the cope I made up some long skinny "bolts" from bicycle spokes, a ball bearing, spoke nipples and a little 1" round stock. The bolts act like the roof bolts commonly used in mines. Rather than leave the ball bearing end perfectly round, after soldering them onto the spokes, I ground four facets on each ball to prevent free rotation and flattened the all to make it less intrusive into the sand mold.

    I think the following pics are fairly self explanatory. What is not shown is that I made the 1" discs by boring the center of each one out to fit a bike spoke nipple and then silver soldered a nipple into the bored hole and then faced off the excess nipple.

    PatternRetainingBolts (1).JPG
    PatternRetainingBolts (6).JPG PatternRetainingBolts (5).JPG PatternRetainingBolts (4).JPG PatternRetainingBolts (2).JPG PatternRetainingBolts (3).JPG
     
    Last edited: Sep 18, 2018
    oldironfarmer likes this.
  2. PatJ

    PatJ Silver

    That's pretty clever.
    Does it work well?
     
  3. Melterskelter

    Melterskelter Gold Banner Member

    Well, thanks! Yes, it works very well. It holds the pattern very securely. No more worries about the pattern dropping out in the middle of pulling the cope off the drag. When that happened after 45 minutes of ramming up the mold, I was pretty frustrated.

    Denis
     

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