Flask and Gating for Casting Weight

Discussion in 'Sand Casting' started by Tops, Feb 15, 2023.

  1. Tops

    Tops Silver Banner Member

    Hello Everyone,
    Long story shortened...how would a person like me flask and gate this plate form for cast iron?
    Assets: pattern is made-drafted-rounded-Bondo'd-sanded-painted, oil bonded sand is available, cast iron will be available (invited to attend pour)
    Liabilities: my largest flask at the moment is only a strong inch (28mm) a side bigger than the pattern and 3" (75mm) deep cope and drag. I am still new to this and this is a large part for me.

    -Start with larger flask?
    -How to position and gate/sprue/riser?

    It is a casting weight and not an airplane part...so doesn't need to be flawless...but I also don't want it to go sideways while pouring. I still may be able to get some hands-on help with this from other iron casters before the event, contingent on travel plans. In case I cannot go early, I want to show up ready to mold and pour.

    Thanks!

    tops_castweight2.jpg
     
  2. Melterskelter

    Melterskelter Gold Banner Member

    OK, I'll take a stab at it. It probably is thin enough not to develop shrinks. So, I think I'd just gate it one of the corners, tilt it up with that corner lowest and maybe a half inch of rise to the opposite corner. If it shrinks it should be in middle of the lobe nearest the gate. It is conceivable that a small shrink could happen in all 4 lobes as they will freeze off independently though the gated lobe should be hottest and freeze last and feed the others a bit.. If this were 1/2" thick, I think you would be safe. But, it is 3/4. Tough call.

    I wonder if it really needs to be so complex. It seems like a simple keyhole or just a single eccentric oval should provide a widow to pour through and that window could be positioned however needed. When would four portals ever be needed?

    Denis
     
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  3. Tops

    Tops Silver Banner Member

    Thanks Denis. I drew one that had the opening more in one corner but then saw a picture of some that looked more like this in the USN foundry manual and I kept going as shown.
     
  4. Tops

    Tops Silver Banner Member

    Update, picture of the weights (looks like I missed the step detail in the corner) and a gating system for an aluminum plate part as described around page 96 of the USN foundry manual.
    https://maritime.org/doc/foundry/index.php

    Is there a minimum amount of oil bonded sand to keep around a pattern and gating system sort of this size? Assume wooden flask and amateur operator...

    usn_foundry_fig90.jpg usn_foundry_fig112.jpg
     
  5. HT1

    HT1 Gold Banner Member

    casting weights have finger groves under them . look at tops picture above you can see them at the corners , ive also seen them centered on all 4 sides ,
    if you pour cast Fe into petrobond you will seriously degrade the sand , you can do it, but you will have to toss all the "GLASSED" out sand in contact with the metal

    pour then open faced no gating , its a mold weight , again look at tops picture above those are poured open topped

    they dont have to be Cast Fe Bronze/brass works just as well and weighs more (It's a weight more is better)


    V/r HT1
     
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  6. Melterskelter

    Melterskelter Gold Banner Member

    HT1, The finger grooves wouold be a definite plus. Why do they clover leaf holes?

    I know some of those Navy guys drink... ;-)

    Denis
     
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  7. Tops

    Tops Silver Banner Member

    Thank Guys, really appreciate the comments and suggestions. My next shot at cast iron looks to be far enough out to have better patterns and a better idea what is needed.

    I missed that they were poured open. Not having to gate them opens up possibilities. I had not thought about what it would do to the sand either. I have much to learn thanks. Going from lead diving weights to bronze bespoke weights would be an upgrade for sure.

    LOL Denis. I hear that some of them use colorful language too... :) !
     
  8. Ironsides

    Ironsides Silver

    If you have plenty of scrap lead pour the mold weight in lead because lead is nearly twice the weight of cast iron.
     
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  9. HT1

    HT1 Gold Banner Member

    if your mold has risers you dont want to cover them, the clover leaf shape gives you best odds of keeping everythijng visable
    dont pour then out of lead, an overflowed or just a little mis-pour could give you brass encrusted lead weights , add to the fact the a 12x12x2 inch mold weight in lead would be heavier then you really want to lift
     
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  10. Foundry Rat

    Foundry Rat Silver

    The open clover leaf design will let the weight be moved around so the pouring basin can be exposed to pour while still giving good weight coverage on the mold
     
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  11. Foundry Rat

    Foundry Rat Silver

    easiest weights to get are 30 lb brass ingot. They are small with a lot of weight and are easy to position, I usually use two to a mold...
    Get 'em from brass foundries, buy the cheapest metal..
     
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  12. Tops

    Tops Silver Banner Member

    Thanks Everyone! All good ideas for sure.
    Wondering if it would not be such a bad idea to get some 1/4" (6.4mm) mild steel plates cut into various clover patterns and then top weight them with ingots (thanks Ben), kettle balls, diving weights, etc. I notice with the lead and an old filing cabinet divider to shield the wooden flask, once I position the divider the lead usually gets close to the pouring zone and so I raise the crucible to miss the lead and feel like I am missing an opportunity to pour closer to the sand. Some of this is probably brought on by the fact that my flasks are pretty small. I might have a piece of scrap plate to test this idea. It's been a while since I've ran the cutting torch... :)
     
  13. Melterskelter

    Melterskelter Gold Banner Member

    I virtually never use weights. My copes are always fastened to the drag or cheek for safe transport from the bench to the pouring area. So, copes never float. With flasks fastened in that way, the sand is virtually always itself strong enough to prevent upward rupture of the cope and a run out. If there is a concern about the sand not being strong enough, on wooden flasks I just put a slat or two over the mold and drive a screw through it into the flask. (My metal flasks have threaded holes on the top of the sides that I can use for slats too and are really there to routinely use them to attach top boards for flipping.) The times I do use slats on the cope are when I am doing patterns with a lot of horizontal surface area like plaques. I know some of tthe people here do a lot of plaques so weights or slats will be routine. The point I wanted to make was to suggest that weights are usually not needed and there are good alternatives to weights----slats. Slats are a lot easier to handle and much lighter taking minimal storage space. Just offering an alternative to consider.

    Denis
     
    Last edited: Feb 17, 2023
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  14. Foundry Rat

    Foundry Rat Silver

    Thats true, when pouring certain types of large castings I will clamp down the cope to the drag, and also use weights. "Bind it up and strap it down!" gotta keep that metal in...
     
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  15. Melterskelter

    Melterskelter Gold Banner Member

    I also find cope/drag clamps unwieldy as they stick up in the air and tend to interfeere with pouring. So, for wood flasks, the cope can be conveniently attached to the drag with a piece of 1/4" plywood 1" wide and 4" long. One screw in the cope and one in the drag and it will resist hundreds of pounds of separating force. Two straps per mold will more than do the trick. My metal flasks all have straps used as part of the lifitng gear.

    Denis
     
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  16. Foundry Rat

    Foundry Rat Silver

    Thats is true...I am talking large molds, Example, a flask I use to cast matchplates in is 18x48, 5 over 5 . That flask is large enough so that the clamps are not in the way.
    I have used at other shops C type clamps, these use wedges to tighten down the clamps...These are not true C shaped but square with one side cut. Low profile and even pressure.
    Those can be cast in house to the size of the flask.
     
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  17. Petee716

    Petee716 Gold Banner Member

    I’ve had the cope sand heave on large surface area molds as you describe so I use slats or scraps of plywood to cover the sand, supported by the cope’s edges. I either weigh them with brake rotors (very handy to have laying around) or clamp them with the smaller cheapie harbor freight squeeze-handle bar clamps.
    I have several alloys of home made bronze in different buckets sitting in the workshop from my latest scavenger haul. Quite a bit of it. Mostly in the form of casting returns. They’re very cumbersome to store and are in the way as-is. I usually don’t care to melt stuff just for the sake of melting it, but FR’s ingot suggestion above is pretty tempting. Part of that haul I mentioned includes a pretty large 4cavity ingot mold that would probably yield 25# bronze ingots. Although the brake drums are handy they create an obstruction to pouring sometimes with the smaller flasks and I think some beefy ingots would work well, at least until I decide to use them for casting.

    Pete
     
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  18. Jammer

    Jammer Silver Banner Member

    Brake discs would be a good idea. I have a couple that I knocked the center out with a hammer so it's almost flat. As far as casting, if you can melt Iron I would make them with Lost Foam. I wouldn't want to tie up a bunch of Brass or Bronze in weights.
     
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  19. Tops

    Tops Silver Banner Member

    I found some 1/4" (6.4mm) scrap about the same size as the first pattern and gave the old cutting torch a go. Decided to make 3 openings instead of 4. One of my kids said they might be able to run a couple out at work for me on a laser once they get caught up in the factory. I cannot say it's my best work ever on the torch but the day was pleasant outside, almost 40 F (4 C) and I got to wear my new welding leathers and goggles and stuff... :)
    tops_250_6mm_weight.jpg
     

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