3 Phase Kiln Retrofit....from 1PH to 3PH

Discussion in 'Furnaces and their construction' started by BattyZ, Oct 17, 2021.

  1. BattyZ

    BattyZ Silver Banner Member

    Will just have to see how it goes after flipping the switch. With the crucible size I want run, might be just fine. In looking at the whole toolchain, waiting an extra 20-30 minutes during the first run could be time spent setting up CNCs on other jobs, making sure I have the right candles for the cast, yada yada
     
  2. BattyZ

    BattyZ Silver Banner Member

    On Monday, I finished winding and installing the other 2 elements. Wired up elements to high temp wire via ceramic connectors then to the 3 phase SSR. Did the proverbially flip of the switch. Way quieter than my old elements; could barely tell they were on. Yesterday morning I did a temp test up to 1800 degrees with the kiln empty.

    Real fast climbing right away
    2:45 mins 750 deg
    3:45 mins 1,000 deg
    Climbing started to slow, due to heat-sink I'd imagine.
    6 mins, 1250 deg
    12:50 mins, 1630 deg
    14:15 mins, 1700 deg
    Just under 17 mins, 1800 deg!

    Very happy with the results. Will be doing a charged melt here soon. I think the calculations that were made previously on this thread will be pretty close.
     
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I think that looks pretty good. How big will the range of crucible and melt mass be? Where are you measuring temp?

    Best,
    Kelly
     
  4. BattyZ

    BattyZ Silver Banner Member

    Measuring temp close to the center, on the bottom. Most likely where it is the hottest? 20 to 40 lbs of aluminum is typical for me. So is that like #6 to #20? I only use the graphites on for-profit casts. For the others I use my steel crucibles and recycled aluminum.
     
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    When empty, the hottest spot in my furnace is the top near lid. When there is a crucible in there it is most certainly in the gap between the coils and crucible, but I still measure temp in center top. You'll also want to have a look at your PID to make sure it isn't modulating (or fuzzy logic-ing as they say, LoL) and applying full power on the way up. In the A series crucibles the designation number is the brimful capacity of aluminum in lbs. So A20 is 20lbs. The attached below is the Morgan Salamander Super line and will give you a good idea of dimensions for various crucibles. I'll send you the pdf of the full line.

    I had missed this post. I had similar thoughts in past for high temp replaceable liners. Interesting idea but probably better to see how the performance turns out as is, because you'll want ample room for tongs/lifting equipment to avoid wall damage. In this respect, it's probably about right for an A40. Though t's nice to have faster heating times, like you, I always have productive things to while casting and another 15 minutes either way doesn't mean a whole lot to me.

    Best,
    Kelly
     

    Attached Files:

  6. BattyZ

    BattyZ Silver Banner Member

    Great info Kelly! Thanks for sharing. Will have to step up my crucible game.

    Oh....I have an idea for this!

    The temp controller I have is an Omega branded one. It has run my solid state relays very well the years I have had it. Says it can run up to 6 furnaces at the same time. In the near future it will have the chance to try 2 sinultaneously.

    I do have a kiln wiring question for the group. How would you guys attack this area. I know I need to have these live 3 phase wires covered but what is a good, simple solution?
    20211203_124417.jpg

    Thanks!
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Build an expanded or perforated metal enclosure around them to isolate them, mount the terminal blocks on same using further electrical insulation and arc distance, and call it a day.

    Best,
    Kelly
     
    BattyZ likes this.
  8. BattyZ

    BattyZ Silver Banner Member

    Just an update. Made an okay metal cart for both kilns out of old bed frame angle iron. The furnace is working great, just have it wired up to a switch. About 45mins to an hour for the first charge then half-hour after that. The furnace is faster than I am right now for having LF molds ready to go.

    Just flipping the switch and going is real nice.
     
  9. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    That used to be the case for me but not since I built my molding rig........at least on first heat.

    http://forums.thehomefoundry.org/index.php?threads/my-new-lost-foam-casting-rig.516/

    It's nice to have but you probably wouldn't need to mess with the vacuum part of the build. The suspension on spring for better vibe, and tilt to to dump, along with the flask extender and sieving screen, are recommended.

    Best,
    Kelly
     
  10. BattyZ

    BattyZ Silver Banner Member

    Funny that you bring this up. Have been scouring the marketplace for various metal barrels and kegs to start down this path. Lots of the 55 gallon "burn barrels" for cheap around here. Kegs would be smaller but offer more rigidity.

    Oh, the next step for this furnace is to make it lift off! That way I can switch up how I handle my crucibles so I can about triple/quadruple my pouring ability.
     

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