free 3D flask Pattern

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

  1. Melterskelter

    Melterskelter Gold Banner Member


    Yes, I chose 2 hours which is on the shorter end of the precipitation hardening curve. That curve, though, had a decided shoulder beginning at about 2 hours showing some increase between 2 and 4 hours and reaching a peak near 9 hours with some mild fall-off after that. So, it looked like I could get 90% of the benefit in just 2 hours. So, being impatient and lazy, that’s what I did.


    I’ll be machining the ends some today. I think my plan is to use a 3/16” slot in the middle of each end, 3/32”+ deep and along the long axis of the turned-up end. I’ll put two 1/4” holes spaced in .5” from each side along the midline of the slot. 3 key segments will be used so that key more or less fills the slot not occupied by the 1/4” clamping bolts. A picture will probably make that idea clearer. I will mill the slots accurately so that there should be minimal racking of the flask as tested by placing it on a surface plate. But all the ends should be interchangeable nevertheless. We’ll see if theory matches reality.

  2. Melterskelter

    Melterskelter Gold Banner Member

    I just used my Leeb Hardness tester to check hardness on the unheat treated vs heat treated pieces. I checked 3 of each a half dozen impacts per piece. I first milled off 20 thousandths of skin and made sure the pieces were tightly held in a heavy Kurt milling vise to avoid inaccuracy due to inadequate sample mass. The hardnesses measured were in the general ballpark of expected hardness for as-cast and T5 356.

    The hardness of the untreated peices was about 60 Hb and the treated pieces were about 80. So there was a definite difference that was consistently seen. In the simple machining operations I have done so far, both the treated and untreated items machined quite well.

  3. Melterskelter

    Melterskelter Gold Banner Member

    I need to cast a bunch more flask parts. It turns out that casting the long wide sides would require 3 additional pours just to complete one cope, cheek, and drag set. I had only a single wide long pattern and decided to make a second using an already-poured casting. The lengthwise shrinkage of the casting was only a total of 1/4” on 27 inches. The width wise shrinkage was negligible at about 30 thousandths. I had some 1/8” aluminum sheet at
    hand. So, I sawed off a couple coupons and epoxied them to the ends. A little disc sander work and some file work followed by judicious use of Bondo and I am good to go.
    The added 1/8” added on before fairing and paint.
    The metal pattern above and the original wood one below.

    I intend to make 2 full sets so I can cast 2 18” straight edges per iron melt. So, 4 melts instead of 8.

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  4. Melterskelter

    Melterskelter Gold Banner Member

    Today’s results:

    42EA7EDD-10F9-4758-8435-2A031479BC11.jpeg 3CCEC93D-056A-401B-818A-1B64A909C6CC.jpeg

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  5. Melterskelter

    Melterskelter Gold Banner Member

    Yesterday was so much fun I had to have another go today. Actually I needed two more wide long flask sides so that I would have a complete drag, cheek, cope set. Because I had wasted space in the large steel flask I was molding the sides in, I decided, on a whim, to mold a ramming tool. I had made an ironwood one from scraps a few years ago, but often wanted to try an aluminum one. So, I decided to mold it in the extra space. I had no follow board and did not want to make one for a one-off, so I decided to cope it down.

    Al Flask31.JPG
    Al Flask32.JPG

    You can see in the following pics that my coping was not quite accurately to the mid-line of the ram. I did draw a white line where I thought the midline was.

    Al Flask35.JPG

    Some of the drag sand broke where I overshot the midline and had an undercut which I did not recognize until after the sand break. The lesson learned is that it is better to undershoot when coping down in the cope as that will result in a bit of excess sand in the cope to be trimmed or broken when drawing the pattern. But the amount of sand lost or pared from the cope will be less by far than the amount that fractures due to an undercut. I used a large open riser as I expected a lot of shrinkage in this chunky casting. Indeed, the riser fed the casting some, but it looks like it was larger than needed.
    Al Flask28.JPG Al Flask29.JPG Al Flask30.JPG
    After hitting it with the die grinder spinning a carbide burr and some sanding disc action.
    Al Flask33.JPG Al Flask34.JPG
    Not a thing of beauty, but a solid "forever" ram.

    I am 3/4th's happy with the flask sides. One did not quite fully fill. I must have cut my gates a shade small for my pouring temp and head height. I think you cna see that the metal flowed mostly in the thicker portions of the side working its way to the middle of the thinneer web. In this case it did not quite make it. The side will be perfectly usable if I rivet in a little patch and might be fine as is. But, my pride is hurt a bit. ;-) The web is only 1/4" thick. So, that must be pushing it a bit for the aluminum. I think Iron would not ahve had this issue. My pour temp was 1250F. Also, my mold would have been significantly cooler than yesterday as we had a Nor'easter come through last night. That could also have been a factor. It looks like just a tic more temp or a slightly larger gate would have done the trick.

    Al Flask38.JPG Al Flask37.JPG Al Flask36.JPG

    I promise not to whine too much. Still trying to get the hang of Aluminum!

    Last edited: Nov 8, 2020
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  6. DavidF

    DavidF Administrator Staff Member Banner Member

    Best sand rammer I've found....:cool:
  7. FishbonzWV

    FishbonzWV Silver Banner Member

    Looks good Denis.
    That Alumalloy rod might be a good candidate for filling the hole.
    I made my rammers lost foam style.
  8. Melterskelter

    Melterskelter Gold Banner Member

    Why do I even try? ;-)
    Good thought on the Alumalloy. I have some of that rod somewhere. You may have to cover your eyes , though, as I am leaning toward just cutting a little patch of aluminum sheet and using 4 pop rivets to cover the hole. Ugggly yes. But, also quick and functionally fine.

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  9. Melterskelter

    Melterskelter Gold Banner Member

    Here are a few brief vids related to milling the flask ends at 45 deg

    The angle block was carefully located to be at 45deg to the travel of the table. The flask pieces were prepped by jointing the inside faces on the jointer and the sides were trimmed straight and paralllel on the table saw. With those "true" surfaces they were located on 1-2-3 blocks to jack them up and then they were clamped to the angle block so I could get at them with the endmill mounted in the right-angle head of my mill. That was the most convenient way I could figure to do the job and the results were quite accurate.

    Kinda fun to look at the chips coming off in Slo-Mo

    Tomorrow will be keyway cutting and boring bolt and pin holes.

    Last edited: Nov 10, 2020
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  10. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Think you should just up your pour temp a bit Dennis. While it's true you should pour at lowest possible temp, it's also true that the risk of adverse impacting porosity, finish, and mechanical properties are probably minuscule for the intended purpose, compared to the risk of pouring short. You may have mentioned, but what is the approximate pouring time, and is the mold flat or tilted?

  11. Melterskelter

    Melterskelter Gold Banner Member

    I tilt the mold about 2” over 40”

    the pour time is about 19 secs as sen in this video. .

    My temp was 1250 or so. I suspect my gates may be a bit small. Maybe go to 1300? The long pieces are poured through the second pouring basin in the long mold.

  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    For many decades, unpressurized feed systems were deemed to be the best approach for aluminum. The more recent Campbell doctrine favors naturally pressurized systems.

    On a level mold, I'd have a runner in the drag running between the two with several gates in the cope feeding each along the length. But, I'd actually prefer a slightly (maybe only 1/2"-1") tilted mold with the parts fed from one end, accept (did you pour from high side?) I'd be inclined to feed from the low side. Sure you loose a 1/2" of head but the metal doesn't separate running into the mold and it just tranquilly fills from the low end up. This would be more aligned with bifilm theory and you would get directional solidification from the coldest metal at the high end back to the pouring end.

    There's theory, there's practice, and what works, and usually multiple versions of each. :)

    Can you temper those longer pieces in your kiln?

  13. Melterskelter

    Melterskelter Gold Banner Member

    I poured from the low side inclined about 1.5 inches over 40 inches. Similar to this photo:


    The longer pieces fit in the oven, but not my kiln. I cooked them at 450F four hours.

    Last edited: Nov 11, 2020
  14. Melterskelter

    Melterskelter Gold Banner Member

    Since I posted I went out and tigged the hole shut. Welded pretty easily with 4043 rod.


    81060B33-8182-471A-BEA7-9D39A90A5CBB.jpeg Back

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  15. Melterskelter

    Melterskelter Gold Banner Member

    I finally got some time to cut key slots in the flask component ends. I will use keys in the slots to maintain alignment of the sides and prevent racking. This may be overkill, but I like the idea of having very secure flask assemblies. I used a carbide 5/32 end mill to cut slots a shade under 3/16” width. I will surface grind the keys to fit snugly in the slots. Two clamping screws per joint will finish the job.

    I used a compressed air stream to blow chips out of the cutter and there was a fine mist of Koolmist lug in the airstream which also helps prevent welding of chips in the cutter.

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  16. Melterskelter

    Melterskelter Gold Banner Member

    Well, at long last I have a set of flasks---cope, cheek, and drag for one of the straight edges I cast.
    I am quite happy iwth the results. I think the only thing I will change for next time is to thicken the up-turned end piece. It is presently 1/4" thick and I think making it 3/8" would allow just a little more metal to make machining the ends a little less hairy. Having a bit more metal to allow for slight mistake would be comfortable. Otherewise the design seems to be very robust.

    I also think the idea of putting keyways and keys in the end pieces is not needed. The assembly is plenty rigid with both 1/4-20 screws and nuts drawn up tight.

    One thing I think may be worth mentioning ois the idea given to me by a firend recently of using bulb-ended pins for guide pins. The idea is that we all know trying to slide a long straight pin into a long straight hole is a recipe for jamming as it is nearly impossible to lift or set a flask on another while maintaining perfect horizontal alignment of the flask. One side or end always tends to be a bit higher than the other. And immediately the pin jams in the hole. One way to get around that and still have pretty tight tolerances on the pin diameter and hole diameter is to make the pin with a bulbose nose. That way if there is slight misalignment of the pin in the hole, the bulb still follows the hole but does not jam. One of my pics shows how I relieved the area behind the nose of my 1/4" diameter pins about .015" The leading end was not reduced. The mating holes are nominally 1/4" diameter---surely a few thou over that and I did make one hole of a pair a bit elongated to allow some lengthwise slop in the way pretty standard for many builders, I think. But the bulb noses really do allow for smooth sliding together of cope on cheek and cheek on drag.
    You can just see where the pin is relieved beginning about 3/16 of an inch from the end.
    AL Flask 39.JPG

    The set. The whole set is about 27 x 11 x 9 inches
    AL Flask 43.JPG AL Flask 42.JPG
    You cna see where I welded in a shrink defect on the cope pin boss. My tendency to have everything perfect pushed me to recast the otherwise perfectly functional end piece. I resisted.
    AL Flask 41.JPG
    Torx-drive flat-head screws were used for end lifting and fixing pins.
    AL Flask 40.JPG

    I feel a little bad I seem to be the only one posting on this thread. Is anyone else proceeding to make patterns and/or casting flask parts?

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  17. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Not planning to cast any flasks but have been following along. They came out very nicely. When is the maiden voyage?

  18. Melterskelter

    Melterskelter Gold Banner Member

    I think they will taste sand tomorrow and hopefully iron Thurs or Friday. The weather is the pits of late. But I really need to get some straight edges cast and to get them cast pretty soon.

    The whole assembly weighs 27 pounds.


    I am indebted to HT1 for starting the thread
    Last edited: Nov 17, 2020
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  19. DavidF

    DavidF Administrator Staff Member Banner Member

    I've been following along too.
    Wish I had the time to make myself a set.
  20. OMM

    OMM Silver Banner Member

    I've been following along. I'm just watching and educating myself. Dennis I absolutely love watching the videos. Please keep them coming. I wonder sometimes if there is an extrusion that is already designed that can pick up most of the features of a corebox. Something that is just easy to cut to length and add pin locations and corners

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