Gantry Crane – A60 Crucible Handling Equipment

Discussion in 'Foundry tools and flasks' started by Al2O3, May 3, 2021.

  1. Melterskelter

    Melterskelter Gold Banner Member

    I think your concern about galling developing is well founded. If the plan is frequent assembly and disassembly, the pipe ends could be changed from aluminum to steel. What I mean is that it looks like the pipes insert about 3 or 4 inches into the sockets. So, if you want to get crazy, you could turn 6" long heavy-wall 3"steel pipe plugs that would be turned down for 3 or 4 inches of their length so the turned portion could be inserted into the aluminum pipe. Secure it using one of Loctite's permanent adhesives suited for Al/Fe. The clearance between the pipes would likely be specified to be between 1 and 4 thousandths---simple to hit that. The bond would be amazingly strong. Or, even crazier, you could shrink fit the Al onto the steel pipe if you were itching to show how precise you can be with your measuring and turning. Even that would not be that tricky since an interference of about 3 thou on a 3 inch pipe would be about right. Simply heating the Al pipe 200 degrees would be enough to make the shrink fit required. (assuming my math is correct) I have done a modest amount of shrink fits and find them to be a combination of nerve-wracking when in progress and very satisfying when complete.

    All the above blather aside, simply polishing them up on the lathe and using some decent lube along with cutting the flats for the set screws as you previously mentioned will almost certainly do the trick . It is entertaining to consider other solutions though.

  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I completed fabricating the hoist carriage. Here’s all the bits and pieces. Some lathe work for the axles and cut up some square tube for the legs.

    22 Carriage Parts.JPG

    ……..and assembled.

    23 Carriage Parts Assembled.JPG

    ….and mocked up on a beam with the pieces that mate with the Gantry post castings and furnace cart.

    24 Carriage Mock Up.JPG

    I have a little finagling to do with the pouring shank and then it’s time to fit it up and give it a test drive.

  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    The shank is ready for action.

    25 Shank.JPG

    Time to assemble everything and do some test runs. Have company all holiday weekend so will be a few days.

    dtsh likes this.
  4. DavidF

    DavidF Administrator Staff Member Banner Member

    What weights more, the pouring shank or the table saw?? :rolleyes:
    dtsh likes this.
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Ohh, a wise guy......Hey Moe! :D

  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I milled flats on the legs/posts everywhere the set screws bind the tubes, polished the sockets a bit with a cartridge roll, and applied a little paste wax. It’s a lot less grabby now and think I'll be fine with respect to galling but will need to be careful not to ding the tubes when disassembled.

    26 Flat.JPG

    I assembled everything and played with it a bit. The hoist has a lifting speed of 26 ft/min or 13 ft/min with it doubled with the lifting block. It’s supposed to have 400/800 lb lifting capability respectively. I think either would work but I like the slower speed for better control for actively adjusting pouring height.

    Here’s a few pics. I haven’t drilled the hole in the vertical post yet because I was having trouble measuring perpendicularity to the milled flats so I just marked and clamped it and will disassemble the walking end to drill the height adjustment holes. There was ample beam travel to snatch the crucible and position the flask to make the pour without needing to move the Gantry tripod. The cords need to be lengthened and routed better,

    27 Gantry Assy.JPG 28 Gantry Assy.JPG 29 Gantry Assy.JPG 30 Gantry Assy.JPG

    My larger furnace was intended to be fuel fired for melting but has an 8kw resistive electric insert for heat treating. It’ll take a while to melt 40 lbs of aluminum but think I’ll give the resistive heating a shot. I have a bucket of sold sprues, gates, and scraps. I think I’ll do a test run to see how it all goes.

    Tobho Mott, Clay and Petee716 like this.
  7. Melterskelter

    Melterskelter Gold Banner Member

    You mentioned the possible need to move the gantry to accommodate additional molds. However it might also be practical to leave the gantry in position and move molds. If the molds were positioned on a platform with wheels it wouldn’t be hard to pour a mold and then move the platform for another mold move the platform and pour another mold. You probably already have considered that idea but I thought I just throw it out there for consideration should that question ever come up.

  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    All good points. At the moment, it will take just about every pound of sand I have, which is about 450lbs and why that flask is on wheels and can tilt to dump.......but I only have one flask that size. Sand is cheap but setting up the larger furnace and gantry is a non-trivial one-man job, especially compared to just rolling out my smaller furnace (full A20 capacity) and flipping a switch. So if the required shot size was <20lbs of aluminum, I'd do multiple melts with the smaller furnace poured by hand rather than setting up the bigger rig.

  9. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I did a test run of the Gantry and A60 today. Glad I did. Lots of little glitches and areas for improvement. I charged the crucible with all the small sprue stock and scraps that had collected in my scrap bucket…..

    31 Scrap Charge.JPG

    Then topped it off with some larger scrap…..

    32 Scrap Charge.JPG

    Parked it in the cold furnace and flipped the switch. First surprise was the slower than expected rate of temperature climb in the furnace. With the furnace mass, crucible and charge, I figured it would probably take a couple hours. After almost two hours, the Thermocouple was only registering 450C but I peaked in through the vent and saw a completely melted charge. With the heat only applied at the bottom, along with a large crucible charged with 30lbs of Aluminum filling up the majority of the furnace bore, the center of the furnace lid where the thermocouple lives was not nearly as hot. I’ll have to give some thought to that but it may be no big deal……..just need to watch and measure the melt temp.

    Then I went to lift the furnace. The lift used one of those imported wireless controls, which failed. Luckily I had several provisional options and used a jumper to power the linear actuator and opened the furnace. I’ll fix this before the next go round.

    Then opened the shank jaws, positioned it about and grabbed the crucible, only to discover plinth had stuck to the crucible, which ordinarily wouldn’t be too big of a deal except with the added resistive electric section, the furnace doesn’t open high enough to clear the crucible with the added plinth, so then I’m rapping the plinth on the furnace base with a half full A60 stuck to it…….and fortunately it let loose. Next time, it will get a couple pieces of cardboard. So I proceeded with the pour.

    33 The Pour.JPG 34 The Pour.JPG

    I had just zip tied the cheesy hoist control tether to the shank. It was awkward to actuate the hoist switch with my back hand and at the same time steady shank which was fairly nose heavy. I’m going to add a little counterweight to the tail end of the shank for better balance and make a purpose-built switch/trigger so I can keep both hands on the shank and comfortably control the hoist switch. I did extend the power and control cords. They were ok but I think I will add some further cord management and routing hardware.

    I had positioned my largest ingot tray on top my flask to simulate the pour height for my intake manifold. Each of those ingots is about 8lbs so poured 24 lbs at that height. The good news is that was easy even with the aforementioned, as was lowering the crucible to ground level pouring of the other ingots and parking the crucible on a couple bricks.

    35 Big Ingots.JPG

    I let the furnace run empty up to 1000C and shut it down. Not sure if I’ll preheat the furnace before introducing the crucible next time. I think I could have executed the pour but I’d just assume not have to contend with such things so I’ll be making some refinements.

  10. Great Progress Kelly! It looks like heavier lifting will be manageable.
  11. 3Dcasting

    3Dcasting Copper

    That's a nice setup over there. I like that everything is on wheels.
  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I’ve got the Gantry completed, some refinements to the shank, furnace controls, and other pouring aids.

    I added a more rugged and easily accessed switch for the hoist on the shank.

    36 Shank Switch.JPG

    I also added a tail to the shank to accept ballast to better balance the shank.

    37 Tail Stub.JPG

    I made a flask extender by sheering and slip rolling some sheet metal. When this is installed in my large molding rig, it makes increases the interior mold height to 40”. Since it’s on a frame with casters that makes the pouring height almost four feet! The intake manifold is as tall as my big flask with the extension and I figured I was going to need some additional sprue and head pressure, thus the additional extension.

    38 Flask Extension.JPG

    I drilled a single hole in the Gantry post to suit use with the foundry furnace. Completion of the other side of the Gantry will happen another day. I made a more robust reversing circuit with limit switches for my larger furnace.

    I made a large reusable offset pouring basin. With the extension, the opening is 6x6 and holds almost 10 lbs of aluminum brim full.

    It will hopefully provide a large buffer volume of molten metal and if I can’t hit that target I need to hang it up.

    I had to make a new IFB insert to hang my contact pyrometer in the furnace lid. It didn’t have enough length to reach the molten metal in the larger furnace. Cut some sacrificial cardboard to ensure the crucible doesn’t stick to the plinth this time. I’ll use Sr and TiB. And the candles? Offerings for a successful pour.

    39 Assorted Stuff.JPG

    I needed a place to hang the skimmer and pyrometer so made a mount. I don’t have the additional Thermocouple display on this controller so I just mounted the hand held to monitor melt temp

    40 Hanging Tools.JPG

    Cut up a 40 lb charge from ingot.

    41 Charge.JPG

    Think I’m ready for a 40 lb pour. Need a good weather day.


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