Hoist and releasing tong build

Discussion in 'Foundry tools and flasks' started by Melterskelter, Dec 19, 2017.

  1. Melterskelter

    Melterskelter Silver Banner Member

    I've been working on a building a furnace, crucible trolley and on a crucible hoist/tong combination over the past couple of months as time has allowed. I had intended to wait to post until I had successfully melted iron and made some satisfactory castings. Hopefully that will occur in the next month as the trolley is finished, the furnace hotface is cast, the furnace lid and base are mostly done and all the needed bits for the Hago siphon-based burner are collected but not yet assembled.

    But, I think that I will just put up an introductory video of my hoist/tongs. It is 90% complete but needs some adjustment of location of tong contact with the crucible as it currently grasps the crucible higher than I like and the cable that pulls the tong release mechanism is not yet trimmed to length nor is there any sort of handle on the cable---well there IS a Vice Grip in the video;) These problems are relatively easy to fix though.



    My main goal was to make a setup that would allow me to solo safely handle up to 50 pounds of molten iron and not have to straddle the furnace and crucible to get it out of the furnace. It looks like this setup will work.

    What you will see in the video is the skeleton of the furnace base with a steel pipe column on the rear left for the completed lid lift/pivot (not shown) and the articulated hoist column on the right. A bucket of cast iron foundry returns provides ballast for the skeleton which would otherwise capsize absent the ballast of the furnace. You will see that the vertical hoist column has a pivot where the square tube walking beam connects to the vertical column and that there is also an offset in the vertical column where there is a second pivot. This second offset and pivot allows fore and aft movement of the hoist so that the location of the hoisted crucible can be adjusted both fore and aft and obviously pivoted as well.

    Your comments on practical limitations and improvements you envision are certainly welcome.

    BTW, the crucible shown is an A20.

    Denis
     
    _Jason likes this.
  2. Jason

    Jason Silver Banner Member

    Last edited: Dec 19, 2017
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Nice work so far Melterskelter. Being a one-man show myself, I’ve been down this road and would offer the following.

    First, for your set up, although the sliding wedging feature on your tong clamping mechanism is quite clever, I’m not sure it has the mechanical advantage needed and compared to most tong builds. I can't say for certain from appearances and may be off base here, but if this is so, it may be the reason it is gripping high because the mechanism jaws are relaxing and allowing the crucible to slide downward. If this is indeed the case, it will worsen with weight in the crucible. Most tongs have long handles and so much mechanical advantage people must install stops for fear of damaging the crucible with high clamping pressure. You may have to do the opposite and install some sort of locking feature that prevents the mechanism from walking up the wedge and relaxing its grip. Alternatively, you might also be able to increase the slope of the wedge so it gains the upper hand in mechanical advantage.

    Whatever you do give plenty of thought to failure modes. I only plan to do aluminum but the thought of dropping an A20 or A60 full of molten iron on the concrete is a bit sobering.

    I did my furnace build with the mind of two interchangeable furnace bodies, one electric for up to A20 and the larger fuel fired for up to A60. It is a lift-off furnace so I can snatch, pour, and replace the crucible with the same device. For smaller crucibles I use open ring shanks.

    I built a trolley for the A20 and A60. I can tell you that trolleys are not as intuitive as hand lifted/guided pours because you must move the handle the opposite direction you want to move the crucible for both side-side and up-down. Also, the place on the crucible you want to grip it (about 30-40% up from base) is not the same place you want it to pivot when you pour. You actually want to offset this so the axis of rotation is centered about the pouring spout because this provides a more controllable and uniform rate of pour. The other place trolleys can suffer a bit is having a fairly narrow range of pour heights they can accommodate which is why I added a power height adjustment.

    Here’s my pouring cart. It’s set up to handle an A20 and A60. It also has a power lift to adjust for different height molds. If you scroll through the post you’ll also see the open ring shanks and a couple short videos of the cart in action.

    http://www.alloyavenue.com/vb/showthread.php?12107-Kelly-s-Furnace-Build-Log&p=187795&viewfull=1#post187795

    I also have a crane on my rig but opted for a sliding gantry over a teetering crane because I thought in the end it would be more versatile.

    If you scroll down this link below, my overhead crane is shown. I haven’t built the walking gantry attachment yet but it would extend the horizontal pipe and have a vertical post connected to a base with a pair of wheels on the other end. At present I have only used it to lift my two furnace bodies on and off my lifting rig but the intent was being able to place multiple molds anywhere under the foot print of the walking gantry and also being able to lift and manipulate the molds. I was going to make a set of tongs that also pivoted so it could be used like a commercial ladle and then just use the gantry and cable hoist to manipulate it.

    http://www.alloyavenue.com/vb/showthread.php?12107-Kelly-s-Furnace-Build-Log&p=187797&viewfull=1#post187797


    Best,

    Kelly
     
  4. PatJ

    PatJ Silver Banner Member

    Last edited: Dec 20, 2017
  5. Melterskelter

    Melterskelter Silver Banner Member

    Kelly,

    I appreciate your failure mode concerns (and information you have previously shared here on your own furnace design.) The primary reason fr attempting this design is to make safe single-hand foundry work possible. Lack of stiffness and inadequate grip do not seem to be factors in setup I showed you. The crucible was not slipping even when loaded. And now that the grip location on the crucible is corrected, it’s grip is presumably more secure. Unfortunately, via video, it is difficult to convey and assess that information as opposed to a hands-on examination of the performance of that equipment.

    Indeed, when I first started putting together the tongs, I intentionally started out with what I thought might be a too thin design of the gripping portion of the tongs with the idea of modifying the design until more than adequate lifting power and stiffness was established. And I found out (as other have) that simple 1/4” by 1.25” we’re too flexible and would slip when lifting a loaded flask. But, once I reinforced them with ribs so that the grippers wrapped around the crucible, they hold very securely even with a fully loaded flask and jerking the beam up and down. I can assure you the grip is very secure currently.

    While I am currently concentrating my limited free time more on building and not so much on posting, I may be able to post a weighted lifting video and some build details later today or tomorrow.

    Denis
     
  6. Melterskelter

    Melterskelter Silver Banner Member

    PatJ,

    Thanks for your pics and explanation.

    "I used standard lifting tongs, which required a somewhat tall crane mast."

    Yes, the reason I designed my tongs in the way shown was two-fold:
    1) Avoid a tall lifting mast as the taller the mast the wider the needed base to support it and space is a limiting factor in my setup.
    2) I wanted to be able to grasp and release the crucible quickly and remotely without having to walk up to/over the furnace for safety and comfort reasons.

    Denis
     
  7. Melterskelter

    Melterskelter Silver Banner Member

    Here is a closer look at the tongs.
     

    Attached Files:

  8. Zapins

    Zapins Silver

    I'm in a similar boat. Putting together tongs for my 16 bilge crucible (51 lb bronze). I want to see your final build. Maybe I'll copy yours if it works out well :)
     
  9. Melterskelter

    Melterskelter Silver Banner Member

    Just a bit of an update. I have finally gotten my furnace together pretty well and have fired it a few times. I am gradually gaining experience with the tongs and hoist and feel that they are working pretty well for me.

    Here is a brief video of me doing the final emptying of the crucible to give some idea of how they work. Sorry for not videoing the pour itself---my videographer (wife ;-) ) was not there at that time. And I will attach a few pics of the casting result from this morning. The casting is 8 pounds total and includes a core made using weakened sodium silicate. first good pour (2).JPG first good pour (3).JPG first good pour (4).JPG first good pour (5).JPG first good pour (1).JPG
     
    Last edited: Feb 11, 2018
    _Jason and Mark's castings like this.
  10. PatJ

    PatJ Silver Banner Member

    Man did that hoist work well.
    Much better than my see-saw crane, and far more stable.

    And the pouring cart looks great, and even has a heat shield for the tires.

    Too cool.

    And the castings look good too.
    You are on a roll.
     
  11. Jason

    Jason Silver Banner Member

    Looks like a winner. Good thing you've got big knobby tires... That's a lot of rough terrain to get to the pouring site.
     
  12. Melterskelter

    Melterskelter Silver Banner Member

    Thanks to Jason and PatJ for the encouraging words. I feel considerable relief to see that the equipment seems to show promise.

    That pouring site is really just a prototyping site used for pouring only because it is near my shop. I have been building and tweaking at the shop. Since the amount of tweaking should be decreasing, proximetry to the workshop will become less important. In the next few days my trolley and furnace will move to a location out in the county where there will be a gravel spacious pouring site and barn to store the furnace and trolley. I am thinking of keeping the muller and molding gear close to home at least for now. But when the molds start to get larger, transporting them will become impractical and that gear will have to move too. Nevertheless, I do like the fact that both the trolley and furnace move easily over uneven ground as th county site is hardly driveway-smooth.
     
  13. Melterskelter

    Melterskelter Silver Banner Member

    Jason, in another thread, suggested I post more info on the hoist. In the last month I have had the opportunity to use it for four or five 50 to 55 pound melts and can report it works easily and seems quite solid and secure so that I feel no need to further modify it. (I had some concern that the tongs might be heated too much by the hot crucible resulting in some temp-related softening of the tongs. This has not been an evident problem.) I made a few pics yesterday of the tongs and lift arm and made some notes on the pics. I intend to make some additional pics and measurements and post them in the not distant future.

    The curved tee-bars that actually grip the crucible were made by making band saw cuts every half inch or so 3/4 of the way through the width of 3/16" x 3/4" strap to make it easy to bend the "hard" way. Once it was shaped to make good contact with the crucible it was returned to a stiff condition by closing up the kerfs with tig welds. Then another 3/16 by 3/4 bar was bent the easy way to fit the previously kerfed and welded strap and the two straps were welded together so that they formed a "T."
    Tabs were attached to the bottom of the tongs spraddled out at 45 deg to help the tongs nestle onto the crucible as the tongs dropped onto the crucible.

    I imagine all this is clear as mud. But I will try to clear up questions by answering the best I can any questions raised.

    Lift Tongs (2).JPG Lift Tongs (3).JPG Lift Tongs (4).JPG Lift Tongs (5).JPG Lift Tongs (1).JPG
     
    Last edited: Apr 10, 2018
  14. PatJ

    PatJ Silver Banner Member

    Thanks for the details.
    I am definitely going to use some of those ideas.
     
  15. chris.trotter

    chris.trotter Copper

    Inspiring stuff, thanks for taking the time to post it. Sub'd to your channel!
     
  16. Melterskelter

    Melterskelter Silver Banner Member

    Thanks, Chris. I was out at the barn this morning and made a few more pics. lift tongs (8).JPG lift tongs (9).JPG lift tongs (10).JPG lift tongs (11).JPG lift tongs (12).JPG
     
  17. Melterskelter

    Melterskelter Silver Banner Member

    lift tongs (13).JPG lift tongs (14).JPG lift tongs (15).JPG lift tongs (16).JPG lift tongs (7).JPG And a few more lift tongs (13).JPG lift tongs (14).JPG lift tongs (15).JPG
     
    Last edited: Apr 12, 2018

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