Reuasbale Offset Pouring Basin

Discussion in 'Lost foam casting' started by Al2O3, Mar 30, 2019.

  1. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    It’s been almost a year since I started using these pouring basins. I really like them. I had one develop a crack today.

    26 Crack.JPG

    Not sure how many pours it has on it. I have and use two of them this size. I’d guess at least fifty pours each. I took a razor blade, carved the crack into a vee, packed it full of the moldable ceramic fiber, and while the furnace was still hot, immediately fired it. About a 10-minute fix…. good as new.

    27 Crack Repair.JPG

    -Game on.

    Best,
    Kelly
     
    PROSTOCKTOM and Tobho Mott like this.
  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    In preparation for a 40lb aluminum pour I figured a larger pouring cup was in order. Instead of using a plug and moldable fiber, I used ceramic fiber board. I think this would be a good construction method and practical for most all sizes. I had a 24” x 48” sheet but it is available from many sources and in smaller boards on eBay and Amazon. Just search “ceramic fiber board”.

    It readily cuts with a razor knife. I cut the sides with 5 degrees draft, cut the bottom with a 1.5” square sprue opening, glued the joints with the “pumpable” ceramic fiber/calk, weighted the assembly, and allowed it to dry overnight.

    28 Weighted.JPG

    I cut and added additional pieces to transition from the square basin to the sprue, added internal fillets (with my finger), and fired the assembly. I’m pleased with how it turned out.

    29 Assy.JPG 30 Assy.JPG 31 Assy.JPG

    When the fiberboard is fired, there is a binder that is burned off and it initially turns black before becoming a pristine white. It does emit odor so should be done in well ventilated area. There is also a small amount of shrinkage when initially fired.

    32 Firing.JPG

    I still need to make the sheet metal lifting cradle but this one is looking good. Here’s a comparison with my other pouring cups.

    33 Three Cups.JPG

    …..and a video discussing and describing the same.



    Best,
    Kelly
     
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  3. Melterskelter

    Melterskelter Gold Banner Member

    Kelly,

    That was a superb video! Very informative. “Sticky” material or at least deserving of its own thread.

    Makes me curious if sodium silicate would work for insulating board glue instead of pumpable wool.

    Denis
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Thanks MS. I think SS would probably work well for glue. Only concern would be the corners and whether the aluminum would tend to stick in the cracks and crevices. One other thing I didn't mention, since the thermal mass and conductivity is so low, it doesn't pilfer heat from your melt!

    Best,
    Kelly
     
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I made the lifting cradle for the larger pouring basin. Just bent up some sheet metal and few spot welds with a detachable handle. It’s ready for hot metal.

    34 Cradle.JPG 35 Cradle.JPG 36 Cradle.JPG

    Best,
    Kelly
     
    Melterskelter likes this.
  6. Melterskelter

    Melterskelter Gold Banner Member

    Geez, Kelly, I wish you would take a little more “professional” approach to execution of your work. I mean you have some great ideas, but, sadly, just slap the prototypes together. ((smiling)).

    Looks ready for a slick brochure and marketing.

    Denis
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    My wife asked me where the roof was.........I made her a couple cedar birdhouses a few weeks ago. :)

    Best,
    Kelly
     
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I made an extension for the larger pouring basin. The lower basin is about 6.5lb of Aluminum brim full. The upper may hold another 5 lbs but is mostly just a big target and containment. The upper gets locked onto the bottom by the handle.

    37 Extension.JPG 38 Extension.JPG

    Best,
    Kelly
     
  9. boroko

    boroko Copper

    Kelly, curious about your reasoning on using square ports as opposed to the original round one. I can suspect that making square sprues are easier, but I don't know if there are any other reasons.
     
  10. rocco

    rocco Silver

    Square ports tend to get less swirling action which can sometimes result in air being entrained into the aluminum.
     
  11. boroko

    boroko Copper

    Makes sense, thank you.
     
  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Square sprues are easier to make but it's really what rocco said. I was using circular sprues for no better reason than foundry sprues have traditionally been round due to the use of sprue cutters and I had plug cutters that quickly made them.

    I was using what home casters refer to as Kush cups, which is just a can or piece of muffler pipe stuck into the sand surface around the sprue. I even started making conical foil sprues out of foil tape to transition from the can to sprue diameter. I did this because it seemed all hell would break loose at the beginning of lost foam pours with flames and smoke, and I'd occasionally get small folds and flaws at the bottom of my castings from what appeared to be that initial metal from the cup. This did help, but cylinders and conical shapes tend to naturally entrain air (Coriolis affect) and smoke and fire in the cup was still common.

    There was a fairly lengthy thread here discussing Campbell's bi-film theory and part of that discussion was the value of using offset pouring basins and that's when I decided to make these. They have been more impactful (in a positive way) than I might have imagined. I commented in my Timing Cover Thread that I have been using longer very low density foam sprues where possible and with such I almost never have smoke or flame in my lost foam pours.

    That pour was just amazing. The cup initially filled, sat there with the classic lost foam pause, and then started taking metal, most likely because the sprue and feed system had filled and now was exposed to the larger cross sectional area of the gating and part. It may seem like a lot of nuance and anal retentive BS, but it's a become a very reliable, high performing feed system that makes flaw free parts and just plain works!

    I've gotten many, many (re)uses out of the offset pouring basins. In fact, after the pour I mentioned above, I clumsily dropped my mid-sized square port basin from about waist level and it broke into four pieces when it hit the ground. I used the moldable ceramic fiber as glue, held it together with a rubber band to air dry, then fired it.....and now it's good as new.

    Best,
    Kelly
     
  13. boroko

    boroko Copper

    I got a few pages into Campbell bi-film thread, but not far enough to feel I was getting much out of it, so I missed that. I'll have to try again. The swirl makes sense, and the cup appears to be a relative necessity. Already adding moldable ceramic to my shopping list. Before I got sucked into this vortex of LF casting, I was in the process of building a waste oil burner for my garage. A little more elaborate one with furnace gun, heated nozzle, an heated feed tank with PID controllers. Got it running, but not had a lot of experience with it yet, and still needing some tuning. Might just leave that in the garage heater, and build a simple propane or manual oil gun for the furnace. This all started because I want a manifold for a set of ITB's on a new motor. I have been stunned at the work you have been able to put out. I had no idea that quality like that could be attained. I'm under no illusion that I will get anywhere near that in the foreseeable future, but it sure is easier learning the pitfalls here than going into it blind. I appreciate the long answer when you obviously have other things you could be doing.
     
  14. rocco

    rocco Silver

    My first serious casting project was an intake manifold too. In my case, it was for single two barrel sidedraft carb mating to a 2.0L VW crossflow 8v. It was a very fun project, a great learning experience.
     
  15. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    To me, the meat of it is the naturally pressurized feed system and how to calc the corresponding cross sectional areas, offset pouring basins with weir, and the rest is common sense about preventing agitation of the melt and avoiding turbulence during the pour. Spin traps are interesting and can be of value too. For me as a lost foam caster, the pouring cup is about all that is directly applicable because the velocity of metal in a lost foam feed system is low by comparison and controlled by the rate of foam evaporation, not gravity, height/head and open cross sectional area.

    Best,
    Kelly
     
  16. boroko

    boroko Copper

    I have been watching your sprue lengths and can see that they add head to fill and allow for cooling/shrinkage take-up. The slowing of the flow by the foam looks to help a lot too.

    I should have picked up on the "rocco". This one is for a 16v head on an ABA block, making for an copy of a European ABF.
     
  17. rocco

    rocco Silver

    "rocco" is indeed a VW reference, I've owned a few Scirocco's over the years. There was a time when I too had planned to build an ABF clone with ITB's for a 1980 Scirocco, I'd accumulated a few of the necessary bits and pieces but never got around to putting it all together.
     
  18. Robert

    Robert Silver

    Thinking about making one of these out of castable refractory since I already have some. Comments?
    Robert
     
  19. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Too dense/massive and will rob mooocho heat from your melt and cause short pours. Depending upon refractory, the aluminum may adhere. You might get a couple pours out of a sodium silicate bonded sand version.

    Best,
    Kelly
     
  20. Al2O3

    Al2O3 Administrator Staff Member Banner Member

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