Lost Foam Dip Coating Rig – The Big Dipper

Discussion in 'Lost foam casting' started by Al2O3, Jun 9, 2019.

  1. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Brushing coating on bigger pieces gets to be a bit time consuming. I had done some work with dip coating foam and sampled some commercial coating. A couple years ago when I started to build my foundry equipment, I came across a fellow with a bunch of these airtight 30-gallon clamp-lid drums that were very economical, so I bought a handful of them. They looked to be about prefect to store slurry and dip coating parts. So, I decided to build a dedicated dip coating rig.

    1 Barrel and Hoop.JPG

    Since the drum will have about 300lbs of slurry, I built a stout dolly to make it mobile. I have a bunch scrap 2 ½” x 1” x ¼” channel with those formed ends. Good clean metal and sturdy.

    2 Dipper Dolley.jpg

    I had a portion of the barrel in the scrap pile left over from my furnace build several years ago. I used it to make a barrel clamp to attach the adjustable arms and hardware to hang foam patterns after dipping.

    3 Clamp.jpg

    Tacked together the various clamps and mounting hardware.

    4 Bits and Pieces.JPG
    5 Hangers.JPG

    Arms, clamps, hangers.

    6 Hanging Parts.JPG

    Capped and folded up for storage

    7 Storage.JPG

    The barrel is unmodified so I could conceivably swap out barrels to change dipping materials in the future….shell slurry for example. At the moment I don’t see that happening, but these barrels are absolutely airtight. In fact, you typically need to vent the lid in order to remove it.

    I call it The Big Dipper.

  2. Jason

    Jason Silver Banner Member

    What is this SLURRY you speak of? Did you finally decide to use suspendaslurry instead of drywall mud?
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Either my own home brew or possibly the purpose formulated commercial lost foam coating I've been experimenting with if I can get an acceptable price and minimum buy.

    For lost foam casting?.....No that would be absolutely stupid. My comment was merely that the barrels could be swapped and hardware could be applied to different coatings.

  4. PatJ

    PatJ Silver Banner Member

    So clean and professionally done.
    You are the fab king for sure.
    My stuff has that broken crayon look, but is functional.
    Your stuff is functional, and something that could be mass-produced and sold for good money.
    You should be in the fab business (that is a joke, I know you are already in the fab business, and it shows in your work). :)
    Petee716 likes this.
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Thanks Pat. Simple project and probably could have stopped at a barrel on the dolly but....well, you know. Now to fill it up and put it into service.

  6. garyhlucas

    garyhlucas Silver

    Nicely done! One comment, I never use Round tubing to make frame clamps like that. Too much work. Use a square tube with a setscrew on a corner that drives the round tube into the of the square and nothing wobbles. If you want no marks on the round tube use coupling nut welded on and put a brass slug in it for the set screw to press against.
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Not sure I understand all of what you are describing there, and to each his own, but if you had a business that manufactures mandrel bent tubing like I do, and you had an unlimited supply of free drop/scrap of round tube of all sizes and material, you'd probably have a different have opinion. It took me about 5 minutes to run that tube through the wire groves on my slip roll in my home shop and make those hoops. They added a convenient bit of mass to attach the arm upright clamps and weld the end plates for the pinch bolts. That chunk of barrel was only ~24ga so was a bit thin to weld but since it had the ridge rolled into it, it fit nicely over the same feature on the dip barrel.....and I had it, so I used it. -Works for me.



    I would like to know more about what your company offers.

  9. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I finished up the rig with a coat of primer on the piece parts. I have been experimenting with dip coatings……..and decided to fill it up with commercial refractory coating.

    8 Slurry Charged.JPG

    The slurry seems to stay in suspension well but I invested in a mixing paddle to re-suspended the slurry.

    9 Mixer.JPG

    Doing so only takes a few minutes. I spin it in a bucket of water to clean it after each use. The rig significantly reduces the labor required for the coating process to just a few seconds, but it does take up some shop space.

    I put it to work with one of my larger parts. A few seconds to dip, then let it hang for a few minutes.

    10 Dipped.JPG

    I’ve taken to adding legs to the patterns to use for drying stands.

    11 On legs.JPG 12 On Legs.JPG

    Tobho Mott likes this.
  10. Petee716

    Petee716 Silver Banner Member

    Simple and functional. Very nice.
    I like Pat's broken crayon reference. I've got a whole box full of broken crayons. It's 20x30' and looks like a barn! Lol.

  11. garyhlucas

    garyhlucas Silver

    In reading your drying legs comment it reminds me of my thinking about leaving legs when I cut a part from foam to make easier to fixture for machining. The pump part I posted is a perfect example. Years ago I was tasked with CNC machining some castings that were being made from drawings that were 53 years old at the time. It involved fixturing the part many times and very close tolerances. I really had to study the raw castings and the drawings to come up with a machining sequence. It was then that I gained a great appreciation for the engineer that designed that part. What appeared to be somewhat random bumps on the castings in a location that didn't have any bumps in the drawing turned out to be there for the 1st machining operation on the other side. It was brilliant as holding this part without them was extremely difficult, as I found out.

    Management had a guy on a manual machine do some initial machining and he removed those bumps as step 1 instead of leaving them until step 4! A different machinist also worked on them. He chose a completely different starting point. I was supposed to do all the machining on a CNC with raw castings, and two different premachined parts that wouldn't fit the fixtures for raw castings. Yep we lost our shirt on that job and the customer rejected half the parts too.

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