Incomplete casting pour

Discussion in 'Castings, finishing/ repair/ and patina's' started by John Homer, Jun 12, 2021.

  1. Melterskelter

    Melterskelter Gold Banner Member

    OK, so I went back and looked at his “match plate” more closely (as I should have done previously) and what he has is a follow board not a match plate. See the first image in post 6.

    It would not be too hard to modify it for a core print if needed. Making little cylindrical cores would be very quick.

    Denis
     
    John Homer likes this.
  2. I have a question on semantics. I want to learn. I thought a follow board used a loose pattern which fit into the follow board (like an original being copied) while a match plate need not be flat on one or both sides.
     
  3. Melterskelter

    Melterskelter Gold Banner Member

    John Homer and oldironfarmer like this.
  4. Thanks!

    So as I understand it, the difference is with a matchplate you ram cope and drag separately. With a follow board you ram the drag, remove the follow board but leave the pattern, then ram the cope. I knew that. Duh. Looking at his pictures I didn't realize the patterns came out. (no pictures of the back of the follow board) That's why he said when he breaks a pattern he has to remake it. If it were glued in it would not be subject to breakage. Duh again.
     
    John Homer likes this.
  5. rocco

    rocco Silver

    I've only used one match plate so I'm by no means an expert on the topic. That match plate basically consisted of a split pattern with one half of the pattern fixed to each side of the plate along with patterns for the runners, gating and blind riser. When I used the plate, I put the cope upside down on the bench, put the plate on the cope then placed the drag on to the plate, ram the drag, flip the whole assembly, ram the cope, remove the rammed cope, remove the plate, cut the sprue, place the core into the drag, put the cope back on to the drag and pour.
    There are two reasons for doing it this way, first, the match plate has features on both sides so it does not sit flat on the bench top, setting it on the cope gives you a stable work surface, secondly placing the drag and cope together with the match plate ensures that the features in the top and bottom halves of the mold line up properly when the mold is assembled to be poured
     
    Last edited: Jun 29, 2021
  6. I only have two match plates. The first was for my trivets, it saved making a split pattern for the wagon wheel frame and keeps everything consistent. I put custom initials on each trivet and the match plate worked well.

    Like yours, mine are both double sided, so I ram a complete flask. With good layout a single sided pair of matched plates would ease sand ramming somewhat.
     
    John Homer likes this.
  7. John Homer

    John Homer Silver

    My plates are all one piece molded resin imprints of my patterns. Patterns are made from silicone rubber top and bottom and split then bolted to plywood. I drill holes into the sides of the plywood and pour the resin into it to fill the silicone rubber molds. Let it cure and unbolt it and remove the patterns. I do this for each pattern I have on my plate.
     

    Attached Files:

    oldironfarmer likes this.
  8. John Homer

    John Homer Silver

    The cylinder is located on the parting line. So it should be fairly easy to add a core. Sounds like a new plate will need to be made
     
  9. So did you try another casting feeding only the centers of the molds? Do you need a core?
     
    John Homer likes this.
  10. John Homer

    John Homer Silver

    Had to work today off tomorrow working in my shop. Going to try the centers on all castings. Fingers crossed.
    Just started considering a core...scratching my head how to build it into the match plate. Sure is rough as a green horn doing this foundry work. My focus is to also work on signal castings trying different ideas. May try a blind riser as well.
     
  11. John Homer

    John Homer Silver

    Better luck today. Got four straps out of the mold. Tried a different match plate and hand cut the gates and runner.
     

    Attached Files:

    Tobho Mott likes this.
  12. Melterskelter

    Melterskelter Gold Banner Member

    Yes!!! That has to feel good and so much better than if it had worked the very first time. Persistence pays off. You are on your way.

    Denis
     
    John Homer likes this.
  13. John Homer

    John Homer Silver

    For sure. For a while there I wasn't sure if I was going to crack this one but with your guys's help I did I want to thank you again. Now for clean up. I think I need to pour the straps facing up rather down. Getting some pitting.
     

    Attached Files:

  14. Congratulations!

    So going right into the centers worked. But these are not your real patterns? Nonetheless it looks like minimal shrinkage.
     
    John Homer likes this.
  15. John Homer

    John Homer Silver

    It's not the decorative pattern but it will do. Now just to convert the match plates to all do this.
     
  16. John Homer

    John Homer Silver

    Yes it did. If you notice I vented 2 off the parts and two I didn't. The two that I didn't had shrinkage.
     

    Attached Files:

  17. John Homer

    John Homer Silver

    Finished product. Now I need to work on my drilling and boring. I need a core I think. Would speed up this process possibly.
     

    Attached Files:

    oldironfarmer and Melterskelter like this.
  18. Melterskelter

    Melterskelter Gold Banner Member

    If you experienced grabbing by the drill bit when you were boring the holes out, you may want to dub the end of the drill bit so that the cutting edges are more or less vertical like a spade bit instead of a conventional drillbit designed for hard metals like steel. Also, avoid the temptation to step drill that larger hole. That will also encourage grabbing of the drill bit. If anything you could drill a 1/8 pilot hole if you’re using say 3/4 of an inch in diameter finish bit. The pilot hole will reduce the amount of pressure needed to drill down through the bronze but it won’t be such a large hole that the bit tends to advance too fast and grab. If this is all old information for you, my apologies. But I do know these are common missteps that people make when dry when drilling soft materials like brass and bronze.

    Denis
     
    John Homer likes this.
  19. John Homer

    John Homer Silver

    Denis thanks for information. Like casting I am a green horn on metal work as well. Sooo another learning opportunity..lol. I did use a center drill first..then drill bit and reemer. Got to work out the bugs and make some jigs
     
  20. Melterskelter

    Melterskelter Gold Banner Member

    Besides a reamer a way to get a drill to bore a nicely finished hole very close to nominal size is to drill your hole 1/64th undersized. Then finish with the desired size. That way the finish bit acts like a reamer and the hole will be within a couple thou or less of the size of the finish bit. But there isn’t enough material in the 1/64th step to cause the bit to grab. Again apologies if old info.

    And I agree, jigs are wonderful things for repeat jobs.

    Denis
     
    John Homer likes this.

Share This Page