Furnace lid removal

Discussion in 'Furnaces and their construction' started by OMM, Sep 30, 2019.

  1. OMM

    OMM Silver Banner Member

    I know some guys just hand balm it if it is light enough, But I was thinking I don’t want a hot face scorching whatever ground it is on top of. My lid might weigh (I haven’t weighed it yet) 30 pounds. I don’t think this is something I want to lift on and off.
    - There is the simple flip hinge.
    - Then there is the foot lift and pivot.
    - Then there is the parallelogram pivot.
    - Then there is for the really heavy lids some kind of hoist (or drop fall).
    - Then there is the super fancy, lid lifts off and the whole furnace lifts up just leaving the floor.

    What method did you go with and why? And would you change your design in a future build? To what?

    I am really leaning towards the flip lid and having a stop at 225°. I’m thinking this will keep it, all in one, keep the hot face away from radiating at me during a lift, not singeing my fuel/air lines (that might be 15 inches away, in a pivot style).

    Any pictures of your design or other peoples designs that you think are really neat, and work well, I would love to see.
  2. OMM

    OMM Silver Banner Member

    This is one I’ve seen the other day. A little bit of lever action and a side twist. Hot face is towards the ground.
  3. The parallelogram is a bit fussy to get right dimensionally, it does keep the hot side away from the user and also lets you preheat ingots in the exhaust stream without having to remove them when opening the furnace. Also the leverage means you don't bear much of the lid's weight. So for 2-4 times as many moving parts as a simple hinge, there's few advantages over a lid that rotates in a horizontal plane away from the furnace (like the example above).
  4. OMM

    OMM Silver Banner Member

    Yes, I agree. But in my situation, the lid would be sitting right above my fuel/air supply.
    I didn’t think of this. Thanks! The parallelogram would keep the lid heat source still away from fuel/air lines....
    OK, parallelogram is back on my list! Preheating ingots would be a benefit with parallelogram design.
    Last edited: Sep 30, 2019
  5. Jason

    Jason Gold Banner Member

    Simple hinge for me. I caught a lot of grief from the peanut gallery that it was going to be reflecting tons of heat at me. I don't notice it one bit. I'd do it again in a heartbeat.
    The lift and turn is fancy, but I was L A Z Y! There is a stop welded on this to prevent it from going past about 60degrees.

    20141019_194633.jpg 20141019_194619.jpg
  6. Petee716

    Petee716 Silver Banner Member

    This is my lid. It works well but the temp exposure has promoted rust inside the nested tubes so I douse the mechanism with PB Baster (panther piss) before use.

    It sure worked smooth when it was new. The base of the furnace is triangular and the open lid swings over one of the corners so no real chance of tipping.

    On my smaller furnace which is a 5 gallon steel bucket I just lift the lid by hand and set it on a firebrick.

    I have a 3rd furnace which is a reverb. The lid tips back a few degrees past 90. It requires a longer skimmer or the heat from the exposed hotface would be too much. image.jpeg

  7. PatJ

    PatJ Silver Banner Member

    My first lid lifter design jammed on me in mid iron melt, and I could not get the lid open, and lost a #30 crucible.

    I reworked the lid lifter, and it worked better, but the lid leaked since I did not include a pivot to allow the lid to seat completely.

    This is lid lifter design #3, and it seems to be stick-proof.
    I decided to make the supports for the lid lifter completely independent of the furnace, so I can remove/break down/repair the furnace without disturbing the lid or lid lifter.

    The bearing at the bottom is just a caster wheel with the wheel cut off.

    All things considered, this lid lifter works pretty well.
    My second design is probably a better design if a pivot was added to it to allow the lid to seat completely.
    I will have to dig out the details of the second design.

    The lid lifter below has stops that prevent the lid from swinging back towards the furnace once it is open.

  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    If your aim is iron, I'd suggest you choose one of the options that keeps the lid radiating toward the ground. Based upon the position of the casters on your furnace base, you may find you cant have the lid in a cantilevered position that completely uncovers the furnace bore with the furnace tipping.......better test that early on before you commit one to one approach or the other.

  9. PatJ

    PatJ Silver Banner Member

    My furnace weighs in excess of 100 lbs, and the lid assembly weighs about 50 lbs, so I don't need an outrigger to prevent the furnace from tipping with the lid open.
    If you have a lightweight furnace, tipping is a very real possibility if you don't have outriggers.

    And the heat radiated off an open lid at iron tempertures is intense if the lid hot surface is pointed directly at you.
    For aluminum melting , the lid heat is pretty much a non-issue.

    Basically, and glove that is within 24" of a hot face or crucible inside a furnace that is at iron melting temperature will self-combust within about 30 seconds, regardless of how good the glove is. You can look at my videos and see my gloves begin to smoke while I am skimming.
    Long skimmer handles are a must at iron temperatures.

    If you load up your lid with scrap metal for preheating, then you could throw off the balance of the furnace and cause it to tip over.
    For the record, the books say "don't preheat iron in a fuel-oil waste stream" because of contamination.
    I hold my scrap pieces in the tongs above the lid hole for about 10 seconds before I drop the scrap into the crucible, to drive off any moisture.

    Last edited: Oct 1, 2019
  10. Jason

    Jason Gold Banner Member

    Remember that octopus OCD created when his furnace tried to roll over on it's back? :D
  11. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    In addition to the ratio of the lid weight to furnace body weight the length of the moment arm on the lid when removed and the location of where the furnace base contacts the ground can also influence stability. If you look at OMM's furnace build, it's on a base with casters. Tough to tell for certain but looks like the casters are mounted inboard of the furnace OD and the swivel/caster of the wheel can move the support point further inboard.......just speaking as someone who has all his equipment on swivel casters.

    Also have to be careful when moving the furnace around on concrete because when one of those casters runs upon a pebble they can get a little tipsy.........in this regard OMM's tow handle is connected to the base.

  12. Jammer

    Jammer Silver Banner Member

    I pick mine up and set it on some bricks.
  13. HT1

    HT1 Silver

    here is mine, it is the same as Lionels Hobby melter , I dont think I will do this method again, but it is very simple and forgiving

    V/r HT1

  14. OMM

    OMM Silver Banner Member

    Yes it is on swivel casters and the caster axle is 2 to 3 1/2” (depending on orientation) inboard from the 24 inch diameter cart. This ruler roughly shows the base in relationship to where the wheels are. If they are all swivelled inboard, they would be all picking up the very outer edge of the brick.
  15. If the furnace is only going to be used on concrete surfaces, you could even fit a rubber strip around the rim and use compressed air to make it hover half an inch off the ground until you get it in position and then cut the airflow. If the air seal is good then very little airflow would be used to make it hover.
  16. Tobho Mott

    Tobho Mott Silver Banner Member

    My big heavy furnace has a pedal to lift the lid slightly so it can swivel sideways out of the way. I swivel it to the left, because my fuel lines come in from the right. I think it might have been Indiscriminate Scavenger on alloyavenue who once melted (or almost melted) his fuel lines by hovering a cast iron temperature furnace lid above them during a pour... My heavy duty furnace lid has 50# of dense castable refractory in it, so no way was I going to make it hinged or just to be picked up and set down.

    My newest furnace is the lightest furnace I've built to date. Ceramic fiber blanket lining behind a thin layer of Satanite mortar. It just has a hinge at the back of the lid, it opens and closes like a kitchen garbage can but with no pedal. It's so light, I just went with the easiest approach.

    My oldest furnace is my Gingery charcoal furnace. That thing hasn't been lit up in years but its cheap sand and fireclay lid just got lifted off and set down on the ground or on a couple of bricks. No hinges or swivels or pedals. Reason: That's how the instructions in Gingery's book said to do it!

    Many ways to skin this cat... Which way is best? IMO that depends mostly on your work space and your own preferences.

  17. HT1

    HT1 Silver

    furnace lid design.jpg

    I think this is about the Cleanest furnace lid design . on my next furnace i'm going with a slightly simplified version of this
  18. PatJ

    PatJ Silver Banner Member

    I used the band around the top of the refractory as the upper support for my vertical lid lifter pipe, but due to expansion/contraction, the band slipped and jammed the lid partially open, ruining a #30 crucible.
    It was a very heavy lid, and so I could not really just cut it out of the way, although that is really what I should have done with an angle grinder.

    My new furnace vertical pipe is supported from the base completely, and does not contact the furnace.

    Here is the second lid lifter mechanism I used on my first furnace.
    If I would have had more time for my second and newest furnace, I would have used a variant on this method.

    I will most likely add the hinge mechanism of this lid lifter to my new furnace, but with a lid than can pivot a few degrees for self-leveling.
    This mechanism works really well.
    And like my current design, this design does not contact the furnace in any way.

    I did away with the overhead threaded rod supports on my new lid lifter, and they should not be used and are not required.
    I would use the wishbone support that I used on my new furnace lid opener, not a complete band around the lid.



  19. joe yard

    joe yard Silver

    I guess that I would fall into the last category with a lift off furnace build. The lid lifter is the last major part I have to complete my new furnace.
    Many years ago when they first published the Charcoal Foundry, I as many others were hooked. I went electric in the beginning. I tried the swing to the side type, that worked very well. Then a counterbalanced hinged lid assist. I preferred the counterbalance type.
    On this furnace it will be a cable lift from a lever behind the heat shield. This will lift and lock the lid in an up position. The lid will be moved to the side by hand. It is yet to be seen if I like this arrangement.
    My latest furnace build is by fay my most ambitious. I built to fit my needs.
    Matt your furnace build is looking good. It is similar to mine in design. We both used fire brick interiors. I had to spread mine out a bit and fill in the gaps with refractory to increase the chamber size. I am already having regrets for building in a keg with such a small chamber.
    The other pictures. I took is of 4 grams of wool, saturated in watered down Green Sand 85 made from the .5" cube and around 1 Oz. Of water. This was enough water to dissolve the 85. I soaked the k-wool in that solution.
    P1030916.JPG P1030915.JPG The 85 was around 20% grog that would not dissolve.
    I will let it air dry for a few days then throw it in the heat treat oven.

  20. Tobho Mott

    Tobho Mott Silver Banner Member

    My lid lifter and pivot is pretty simple. Shown with the lid swung wide open here, sorry that this is the best pic I've got.


    The black painted pipes are the hinges.

    The unpainted pipe is the hinge pin, which sits on top of the far end of the foot pedal that is on the opposite side of the cart, so the pin gets slid upwards through the hinges when the pedal is depressed.

    The hinges are attached to the furnace body (lower left) and lid (upper right) via some angle iron that I welded in place.

    The pipe nipple and flange are welded to the hinge pin, so when the hinge is pushed upwards by the pedal, the flange pushes the lid upwards by its hinge and angle iron, so that it lifts off the bore and can be swung away toward the side where my fuel lines aren't. I had turnbuckles from the top of the lid hinge to two spots on the far side of the lid to add some support that far out as the lid is quite heavy, but the turny bits wound up being made of zinc, and melted off from the flaming exhaust stream one time during a bronze melt when I had the burner running a little too rich. I haven't yet replaced them, but the lid hasn't broken in two. Yet.


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