Surface finish help

Discussion in 'Investment casting Ceramic shell method' started by ka_6772, Apr 11, 2020.

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  1. ka_6772

    ka_6772 Copper

    I'm going to sweep some of it up and figure out what it is.
     
    ka_6772, Apr 15, 2020
    #81
  2. DavidF

    DavidF Administrator Staff Member Banner Member

    Can you position your mold sprue down?
    Or is your kiln dimensions limiting you from doing so???
    You should really try the pla I recommended earlier.
     
    DavidF, Apr 15, 2020
    #82
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    Doubt you'll be able to sweep any up. In its raw form it is a talc like powder.

    I tend to over analyze things alot of times but since you are laying the shells on their sides during burn out it just makes practical sense that this is where you problem is originating from..
    Dont get me wrong, there is still a few spots that are shell material floating around, but I'm certain that most of the problems are from the filament and orientation during burn out..
     
    DavidF, Apr 15, 2020
    #83
  4. ka_6772

    ka_6772 Copper

    I couldn't find any natural pla in stock. I ordered 3 spools of different "pro" natural PLA's to test out. I have plenty of room to stand the shell up. I'll try that.
     
    ka_6772, Apr 15, 2020
    #84
    DavidF likes this.
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Filament change and burnout orientation would be a good solve and easy fix!

    Best,
    Kelly
     
    Al2O3, Apr 15, 2020
    #85
  6. DavidF

    DavidF Administrator Staff Member Banner Member

    I have tried just about every filament on the market over the years and so far the filament has worked the best for investment casting. It's made such an improvement for myself that I dont even want to bother trying anything else... although results may vary I'm confident in recommending it..
    Get the green color if you can :D they dont make the a in a natural color...
     
    DavidF, Apr 15, 2020
    #86
  7. DavidF

    DavidF Administrator Staff Member Banner Member

    @Jason Have you tried flushing your shells with water to clean them out??
    I've seen it done with other shell systems but not sure if it can be done with suspendaslurry.

    Kevin if you do try the water flushing be careful the the shells are good and dry before you re fire them. Your kiln heats up super fast and might cause the shell to spall if there is any trapped water in them...
     
    DavidF, Apr 15, 2020
    #87
  8. ka_6772

    ka_6772 Copper

    I flushed one before. I could hang them overnight to dry before preheating and casting.
     
    ka_6772, Apr 15, 2020
    #88
  9. DavidF

    DavidF Administrator Staff Member Banner Member

    In front of heat lamp??
    I'm just concerned about doing this as the shells are very porous and could hold water in for some time... slow roasted at 190 F would be ok I think??
     
    DavidF, Apr 15, 2020
    #89
  10. ka_6772

    ka_6772 Copper

    I have a high temp temperature controller and a bunch of 20a solid state relays. I plan to get some big relays to control my kiln.
     
    ka_6772, Apr 15, 2020
    #90
  11. ka_6772

    ka_6772 Copper

    I'm not going to rinse out the one I cast tomorrow. I'm going to cool and blow it out.
     
    ka_6772, Apr 15, 2020
    #91
    DavidF likes this.
  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Done that deed several times. Start a new thread on that one. How many KW, coils, and voltage?

    Best,
    Kelly
     
    Al2O3, Apr 15, 2020
    #92
  13. ka_6772

    ka_6772 Copper

    I think it's 45 amps, 220 single phase. I would just control the outlet and leave the knobs alone. It has three rings of two coils. I have one ring out so I don't have to reach so far into it.
     
    ka_6772, Apr 15, 2020
    #93
  14. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    My smaller resistive electric melting furnace is 2 coils, 32 amps 240VAC....8KW. It is 10"bore and does up to 20lb aluminum melts with an A20 crucible. My larger furnace is 14" bore and is really a fuel fired melting furnace but I have an electric section I can insert with same coils for heat treat and burn out. It has a ramp and soak PiD. I built my own controllers. Since US 240vac single phase is 120v to ground from either leg I open circuit both the up and downstream side.

    Electric Furnace Controller

    Controlling the downstream leg is OK but the big difference between a pottery Kiln and melting furnace is you handle tools inside and are accessing the interior frequently so some extra precautions for shock hazard are advisable. Also, Pottery guys would call opening a Kiln at temp poor practice and "crashing the kiln" and we do it as a normal course of business.

    What's your typical melt size and how do you measure melt temp?

    Best,
    Kelly
     
    Last edited: Apr 15, 2020
    Al2O3, Apr 15, 2020
    #94
  15. Jason

    Jason Gold

    sorry, been glued to the mill all day. I'm slow as hell, but accurate as all get out!

    YES, no worries at all washing out shell after it's gone up to temp. I've done it many times. They dry really fast too. Goes back to that gas permeable thing I suppose. When filled with water, they will not hold it. It seeps through the material.
     
    Jason, Apr 15, 2020
    #95
  16. DavidF

    DavidF Administrator Staff Member Banner Member

    Yea I thought I was too. Then a guy gave me a couple micrometers that read .000001"
    Puts a new perspective on "accurate" lol
     
    DavidF, Apr 15, 2020
    #96
  17. Melterskelter

    Melterskelter Gold Banner Member

    Tell me about the mics that read to millionths. Really? Wow!

    Denis
     
    Melterskelter, Apr 16, 2020
    #97
  18. DavidF

    DavidF Administrator Staff Member Banner Member

    DavidF, Apr 16, 2020
    #98
  19. Melterskelter

    Melterskelter Gold Banner Member

    And a times 5. Still a superb mic. Infrequently will most of us need to measure to a hundredth +/- .5 tenths. But, yah, mighty fine. Have to be careful how you hold it, keep out of sunshine, not too near your body etc..

    Denis
     
    Melterskelter, Apr 16, 2020
    #99
  20. rocco

    rocco Silver

    FWIW, Mitutoyo has ones that are accurate to ±0.000005", they're for sale on that site starting at the low, low price of $1520, I might have to order a few:p.
     
    rocco, Apr 16, 2020
    #100
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