Made a new crucible lifter

It's been raining a lot and I've been unable to work outdoors at the moment so I bit the bullet and fabricated a crucible lifter for my Vesuvius AT-30 silicon carbide crucible. This is a short locking lifter with an insulated lid that is tight fitting over the top of the crucible and forms a heat shield for the gloved hand. The AT30 is my biggest crucible and barely fits the furnace bore and it'll be for aluminium use exclusively. I need to do some lost foam castings to make parts for my sand mixer machine and get to making sand moulds.



It's a little bit taller and wider than the A25 clay graphite crucible I use for iron.

 

AT30 is an A30 right? Nice work, and nice design!
By the way if that is an A30 it is huge!
Patrick

 

Yes it's an A30 sized crucible, I should add that for my furnace that gripper sits above the rim of the furnace so I'm not reaching down into a hot furnace to lift the crucible. For a crucible of that size being lifted by one person, I think it's bit more manageable that using long handle tong type lifters as you don't have the crucible weight at the end of long handles. The design is a copy of one made by a foundry worker friend who built his in the 1950's so I don't know if it was in widespread use where he learnt his trade.

 

D A M N !

 

Mark, I like the concept of the cover. Do you have a video of you demonstrating the lift? It's just my thinking, but are you lifting this with one hand?

 

He's part cyborg, but you didnt hear that from me.

 

Here's an A16 full of bronze, normally he lifts A25's full of bronze and the second video is me with an A25 with 15Kgs of iron:

at the 12:20 mark:


At the 2:55 mark (you can see I forgot the refractory puck to rest the crucible on):

 

The design is absolutely amazing.

What I'd like to see improved is what is called "a cam bypass". When the handle has gone 1 or 2° past the 90° Cam that would be in it's bypass.... But it would be in a lock state with a dead stop.

I'm sure at some point with crucible shrinkage (due to use) it will go into Cam bypass with out too much spring force. This is where in adjustable stop and an adjustable top tensioner would be ideal.

 

In the photo it's not engaged just the slack taken out, it locks at about 15 degrees over center towards a hard stop....hmm better take a photo. The design will lift a loaded crucible without the latch engaged as the geometry clamps harder the heavier the load, a bit like those handles for cinder/concrete block lifting. The latch is to ensure it grips no matter what .

Latch engaged:


and disengaged:

 

I absolutely now love the design. I personally probably wouldn't go past 5°. Based on your situation, I don't think you're going past 3°.

With the link you provided, it looks like the foundry man stopped at top dead center. It also looks like he is using solid iron which could be cold forged (bent for adjustment) for crucible shrinkage.

 

He's using 15mm square hollow stainless steel scraps from the fab shop next door, the original had 1/2" hollow steel and had to be used quickly to avoid heat soak softening the clamp forces. I used 1/2" solid mild steel to allow for a bit of heat soak. And yes they get occasionally tuned to fit new crucibles or grip worn ones better by bending the arms in contact with the crucible.

Here's the original great granddaddy A20 lifter with asbestos insulation, it lifts A20's full of bronze but suffers from heat soak due to the thin metal:

 

I like yours 10 times more.... But… I think yours could improve on a crane lift pour.

 

Do you mean to use the gripper for a crane lifter?, it should need minimal changes to be used for that.