free 3D flask Pattern

Discussion in '3D Printing' started by HT1, Oct 4, 2020.

  1. HT1

    HT1 Silver Banner Member

    OK I rammed up and Poured today , What a Pita!!! doing the double roll on 12X17 flasks is right at the bitter end on my physical capability , Jus the sand is 71 Lbs, add the flask, you are trying to roll 80+ pounds to make 12X12 flasks ,

    Crazybilybob has offed me a set of patterns much closer to Olfoundrymans , but in the size I need , I will make custom wood flasks to cast those so there is no extra sand at all to flip, hopefuly I can get the weight below 60Lbs

    as to the Modular patterns, they will need to be glued together, so other then for printing the modular concept is not going far,
    the patten itself is nice and pulls well , the followers could be a little bigger, but are easy enought to smoothe and cope out to get a good pull everytime

    image1 (1).jpeg image0 (4).jpeg


    V/r HT1
     
  2. Melterskelter

    Melterskelter Gold Banner Member

    Those came out nice. Looks like you’re level with a very long narrow gate—-correct? What temp did you pour at?

    Denis
     
    Last edited: Oct 18, 2020
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  3. HT1

    HT1 Silver Banner Member

    Aluminum is always wide and Shallow , so That is what I did ,

    They pulled and came out quite nice ,
    those wherepoured Probably just north of 750C, I do so much Brass, I have problems Not letting Aluminum Get away from me, so they where poured HOT!!!
    I'm going to Redo that gating and really thin it all down, so I can drop the flask size down from 12X17 to 10X17 , My old body cannot handle the Double roll with that much sand anymore

    V/r HT1
     
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  4. Melterskelter

    Melterskelter Gold Banner Member

    Sounds like I better add 100 degrees to my target temp.

    Denis
     
  5. Melterskelter

    Melterskelter Gold Banner Member

    I did a practice ram-up of a couple of the flask patterns using followers. I found that the followers I made which are similar to the ones modeled in the digital plans drew OK themselves, but the sand imprint in drag was difficult to draw since there was so little draft in the sand impression made by the follower in the cope. So I ended up using a thin spatula to widen the sides of the sand impression and then ramming up the drag. No surprise the broader and gentler transitions drew easily and cleanly. So, I redesigned my followers by splaying the sides of them out about 15 to 20 degrees rather than the original 3 degrees. I may still do a little sand carving to ease the transitions. But there is a good chance the new design will draw a lot better without hand carving. I think it would be a good idea to widen the follower design to print more widely splayed followers. Or if modifying the code is a little time consuming and perhaps challenging, just "print" them on the table saw and disc sander. It takes only a couple minutes to make a couple followers the old-fashioned way.

    The newer-design ones are on the right side of the photo and one is engaging the end of the main pattern and the 4 original designs are on the left.
    Al Flask16.JPG

    Denis
     
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  6. Melterskelter

    Melterskelter Gold Banner Member

    And this morning I rammed up 4 patterns in a 14 x 48 steel flask set I have that is usually used to cast iron straight edges. I did use the followers and did still do a little carving to “gentle” the edges. And I used long thin gates as suggested by HT1. 1F768000-E1F0-4C12-B6A6-023E1D93355E.jpeg F044839E-8C4D-4F59-9078-74B380FE2F11.jpeg Now there is nothing to do but try putting some metal in the mold. (A little nervous)

    Denis
     
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  7. ESC

    ESC Silver Banner Member

    That seems like a funny comment from someone that pours cast iron:).
     
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  8. rocco

    rocco Silver

    I thought the same thing but I guess you trust what you know and for him, that ain't aluminum.
     
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  9. Petee716

    Petee716 Gold Banner Member

    Once it starts melting things happen fast.
     
  10. Melterskelter

    Melterskelter Gold Banner Member

    Yes, I take this as “a word to the wise.” I plan to throttle back my burner considerably as my iron usually starts to sweat liquid in 15 minutes of light-up. I am worried I’ll way overshoot. I expect this first aluminum melt to be entertaining to watch!

    Denis
     
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  11. FishbonzWV

    FishbonzWV Silver Banner Member

    Keep it lean, no flame out the vent. Don't want any swiss cheese.
    Good luck.
     
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  12. Melterskelter

    Melterskelter Gold Banner Member

    Well, overall I'm pretty happy with my first foray into aluminum considering my expectation was zero yield. I did get some shrink of the bosses on 3 out of four end pieces, but two end pieces are usable and a couple of long pieces are too. I had trouble with leakage of my sprue lengthening cans. So, I need to figure out how to make a god base seal for them. I had one long piece not fill fully. I did cast them inclined 4 inches on 4 feet so there was little head pressure on the end that failed to fill.

    I poured at 1350 after overshooting and letting the crucible sit outside the furnace to cool down----took about 5 mins.

    I'll be adding risers to the bosses and work on my sprue extenders. Al Flask20.JPG Al Flask24.JPG Al Flask23.JPG Al Flask17.JPG Al Flask18.JPG Al Flask19.JPG Al Flask21.JPG Al Flask22.JPG



    Thanks for all the helpful suggestions.

    Denis
     
    Last edited: Oct 22, 2020
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  13. Melterskelter

    Melterskelter Gold Banner Member

    BTW, the pieces were straighter than I expected. The long piece had .040 bow in it the long way on the wide surface as checked with a feeler gauge. There seems to be no appreciable twist. They are essentially straight side-to-side. on the narrow face.

    Denis
     
  14. DavidF

    DavidF Administrator Staff Member Banner Member

    Could you move the ingate more towards the center of the casting. So the metal doesn't have to travel as far??
     
  15. FishbonzWV

    FishbonzWV Silver Banner Member

    The longer the melt is exposed to the furnace atmosphere the more chance it has to pick up H2.
    When you top off the crucible with that last ingot, you should be ready to pour. No fiddling around checking this and that. Watch that ingot melt and when it hot shorts and flattens out on the surface, it's almost ready to get out of the furnace. My furnace takes about 30 seconds more to get to pouring temp for thick patterns, up to a minute for thin patterns. I turn the burner off, do the major skim through the vent, pull the crucible, do a quick skim and pour.
     
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  16. Melterskelter

    Melterskelter Gold Banner Member

    Sure, I could, but my thoughts were that since this is a long narrow casting, it would be better to pour it on an incline beginning at one end and smoothly flowing the metal to the top rather than offer the metal "dealers choice" as to which way to flow at any given moment. Since there are two molds being filled simultaneously, that seemed even more important as gating differences could cause one mold side to lag behind the other more easily and significantly on a level pour. Maybe that is goofy. I would welcome comments.

    Interesting thoughts on the topping ingot drop-in to pour time. That was not quite (or even close) to the plan I followed. As it happened, when I was getting to the end of the melt I started looking for the sheet of temps vs millivolt reading from my thermocouple. That table is "ALWAYS" in a certain spot in the foundry, but it was no where to be found! Aaarrrrgh. So, I the figured temp was going up quickly, so I shut of the burner and, even so, radiant heat from the furnace was raising the melt temp as I rushed to find a table of mV online. Double aaarrrrgh. Then, I measured temp at 1450---too hot. So, I just pulled the crucible and set it on the stand outside the furnace for 5 mins or so to allow it to cool. I knew the overheating was far from ideal but also had heard lots of stories about pouring too hot. So....I just waited a few mins.

    I suspect some of the shrinkage I got was from still being a bit too hot??? Next time pour at 1250 or 1300??? As it was, I ran my furnace at about 1/2 to 2/3 normal fuel flow with a non-smoking exhaust and no flame out the chimney---slower and leaner than for iron. The melt only took about 20 mins at that. Comments???

    I did have major trouble, as you can see from the video, with leakage of metal at the seam of the sprue extensions and the cope. I was too casual about placing a "flat" bottomed extender on a "flat" cope surface thinking that aluminum did not run as fluidly as iron and, so, probably would not leak----wrong! So, next time I should put a bit of soft sand around the cope sprue and then put the extender on? I am inclined to pour these on a slight---4" on 4'--- incline unless someone convinces me that is nuts. If poured level, no extender needed.

    I'll be mulling and packing again today.

    Denis
     
  17. Melterskelter

    Melterskelter Gold Banner Member

    Did my second pour today. The leaking aluminum seen in the first video was informative to me as I was impressed at how fluid the Al was and how easily it ran. So, I dispensed with the riser extensions and simply raised the far ends of the molds 1” on 4 feet—-1/4th what they were the first time. One set of molds was vented and one not—-forgot until after the mold was closed and just did not want to risk horsing the mold opening and closure to add vents. No vents worked just as well as vented molds.

    I got six out of six usable pieces this time though shrinkage of the boss on the Short end pieces was still troublesome. I added small blind risers to the bosses, but not enough! Next time...

    Here is a video of the pour

    C7A71BA6-0E05-40B8-94FA-F3537E5EACED.jpeg B8028A55-AD0C-4987-A508-1E39AF6F36B2.jpeg F7231321-944D-4428-BCD2-2772D63FE279.jpeg

    I am thinking for the next pour to modify the long pieces so that they can be cut in such a way that they can be varied in length. More on that later.

    Denis
     
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  18. Tobho Mott

    Tobho Mott Gold Banner Member

    Looks great!

    Jeff
     
  19. Melterskelter

    Melterskelter Gold Banner Member

    So, I thought I should try t.o harden thecastings some as as-cast 356 has a reputation for not being great for machining. I took 2 castings and put them in the oven at 480 for. 2 hours and then applied a MUSICAL materials test.ing method ;-)



    I’ll also compare their performance on my milling machine.

    Denis

    photo added with primary tone freq noted
    0EAE0169-1883-442D-91DC-5E626F225E81.jpeg

    I just put the untreated ones in the oven. They should go up in pitch if this assumed heat-treat-related change is real.
     
    Last edited: Oct 24, 2020
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  20. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    MS, 2hrs seems a bit short by most schedules. You can also do a hardness test to compare temper, though they can be small differences. The great thing about T5-ish temper is it cant be overdone and is insensitive to cooling rate, so it's safe and easy. TiB and Sr help with grain structure and post treatment. If you ever need some let me know. Castings can still be a bit gummy compared to wrought alloys but precipitation treatment makes a big difference over fresh as cast castings. You'll notice the tempered castings can achieve better color and surface finish too. TiN coated bits and some cutting fluid help bit loading. These are just out of my machinist handbook but you will find the schedules are all over the road. Professional foundry men would tell you not to put too much faith in the published mechanical properties for sand cast alloys, and they are typically quite optimistic. Also, if the composition of the alloy isn't well established the higher tempers can be difficult to achieve, temperature control aside.

    Heat Treat Mech Properties.jpg Heat Treat Schedules Cast AL.jpg

    Best,
    Kelly
     
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