Foundry "Robot" - part 3

The controls for the robot are all located at the operator end of the device. The controls primarily comprise a pair of handles at 90 degrees to each other for swinging, turning, and moving the main beam (3m (10') pipe) through the spigot, tilt, and sleeve joints. The two handles are attached to the beam via a sleeve which is pinned to the beam with a thumbscrew. This allows the handles to be moved if the operator prefers a clockwise pour, or anticlockwise pour.
The end of the pipe beam is left exposed, and open to permit the future (possible) addition of counterweights should they prove necessary, although as yet they haven't, even when the robot was used with 5L of lead used to deaden a homemade anvil.

The control for the gripper is a simple push-rod which activates through a handle located at the operator end. At the gripper end, the push rod operates a slug which is linked to the gripper bell-cranks, whereas at the operator end, the push rod is connected to a handle which can be locked at any point of it's operating range.

In the above photo, the gripper control handle is back, towards the operator, and the grippers would be open. The arc shaped plate (quadrant) is actually the remains of a 9Kg (20lb) Propane cylinder top, left over from making a "George Vortone Muller".
The quadrant has a series of cuts in the edge made with the cutoff wheel of an angle-grinder. The lever at the top of the operating handle lifts a locking bar which engages with those cuts - similar to the rachet and pawl mechanism in a handbrake.
In operation, the user grips the crucible by squeezing the lever, and then pushing the handle forward to close the gripper. Once the crucible is gripped, the lever is released and the handle stays in that position. A small amount of "spring" is in the system to permit minor positioning errors in the cuts on the quadrant.

The above photo shows the griper control in the closed position.


The next sequence of photos shows the approach of the gripper to the crucible
Then the nose piece locating on the tang
and then the gripper closing on the crucible
At this point, the crucible can be picked up, and moved through all the axes of movement the robot offers, including pouring...


That pretty much covers the robot.. I did find one misplaced photo of the gripper mechanism without the fingers bolted on - see below. It helps clarify what I was trying to say about the mechanism being separate from the fingers and nosepiece.


The main thing this robot forces me to do is lay out my foundry area properly. I am constrained
by the centre of rotation of the robot, and the reach of the beam, and sufficient area to work in. I found these constraints allowed me to divide my work area into three distinct "zones" - HOT, WARM and COLD.
Hot is where the furnace is - pretty self evident.
Warm is for molding, pouring, degassing, skimming, etc.
and Cold is for charging, or loading the crucible.





If I pickup the crucible from the cold area, and use the robot to load it into the furnace, then I am guaranteed that it will have it's pouring lip pointed where I want it for the pour.

The robot is tall enough to permit me to place metal on top of the furnace for preheat, but I only do that when necessary - which isn't often here.

So, to sum up... The robot offers the advantage of not needing any significant lifting, in fact the heavier the crucible, then easier it is since your own body weight can be used to counterbalance the load at the gripper.
The gripper can be modified by simple bolt on fingers, and nosepiece for different crucibles, or to replace corroded parts.
The robot encourages the layout of the foundry work area into zones based on tasks, and risks
The robot can be built from scrap, and is fairly intuitive to use.
The robot permits a single operator to load, pour, reload, etc crucibles up to A30 without the use of a second person, with enough accuracy in the pour to pour water into the neck of a 2L coke bottle, and only lose 100mL (5% loss pouring into a target of 3/4" diameter at 10' away.)

Foundry "Robot" - part 2

Following on from "part 1".. the tilting joint (located under the main sleeve joint) is comprised a small pipe/bar joint atop the spigot joint.
The photo below shows the pipe welded to the top of the spigot joint, and the two cheek pieces holding the bar...

Photos of tilt joint in action - from one extreme...

To the other extreme...
The dust cover was also shown is those photos protecting the sleeve joint, and it's bearing shells. There is also a carry handle visible - I put it there since when I first moved the robot, I'd let the spigot joint open, and carry the base as a separate piece form the top... now they are always together with a hook, which is disengaged after movement.

The gripper...
Basically I designed this to be fully adjustable. By changing the "fingers" I can change what it picks up.
The fingers have a full range of movement between two extremes, shown below...

Above was "fully open", now this is "mostly closed"...


I say "mostly" closed since the finger design prevents further movement, but the mechanism permits more movement.

The gripper consists of some major parts - all of which are visible in the photo above.

a - The actuator and bell cranks -square pipe at low left and flat bar bolted to it, up to and including the small plates which tilt between the pincers

b - bolt on "fingers" - held to the bell cranks via 2 of 1/4" bolts - the angle iron "pincer" shapes with the small length of flat bar at the end near the bell cranks

c - nose piece - it's the small piece of round pipe visible protruding from the end of the square pipe... the nose piece actually includes the last inch of square pipe (removable)

These components allow the gripper to work, and be modified to suit the crucibles in use. My pipe crucibles have a "tang" which I use to locate them, and the nose piece mates with that. If I use a ceramic crucible, the nose-piece is swapped for one resembling an up-side-down letter "L" which locates the top rim of the crucible, and the fingers are broader, and more curved.

The next part will show the controls, and a test drive of the robot

Foundry "Robot" - part 1

I built a furnace/ foundry for casting in Aluminium, Brass, and Bronze. (more details on that later) - to manipulate the crucible, I looked at a number of options, but this.. is what I ended up building and using.
It's all home construction - tools used was welder (arc), grinder (grind, and cutoff discs), and miscellaneous hand tools.

The "robot" is not a real robot (powered with a form of control), but rather more a mechanical machine which I control. (yes I won't split hairs over semantics - compared to the robots at work, THIS doesn't count)


The distance between the operator, and the gripper is 3.0m (10'), and there is no lifting required, except to assemble and relocate. All "lifting" is done on a counterweight system, and my own body weight is used to my advantage.
Following over the remainder of this page, and the next pages will be photos of the robot, and text explanations of the mechanisms. All steel sizes are as much a reflection of my stockpile, rather than calculated engineering recommendations - in fact everything I write should be taken with the usual legal indemnities/ waivers applied. - in other words, if you don't know what you're doing, and aren't prepared to wear the consequences, don't use anything I've done help you qualify for a Darwin award.

Overview of the "robot" - open gripper facing camera.
The crucible is on the ground in the shot above - the pipe is 2 1/2" OD for the main beam.
Now some detail - working from the bottom up...
The spigot joint (Slew)...

The spigot joint is made of three lengths of pipe, two the same diameter, and the third a slip fit inside the first two. The bottom pipe, and the central (internal) pipe are welded together, with a washer across the top of the internal pipe. A steel mouse ball is placed on top of the washer, and the third pipe is dropped over the top of the whole lot. Inside the third pipe is another ppe with a wisher, so the bearing surfaces are the two washers, with the mouse ball between them. The three bits of pipe form a spigot joint for rigidity, and the ball/ washer bearing for friction reduction. The legs on my robot fold up, but that's a personal choice.



The top joint is complex - please bear with me.
On the top is a "sleeve" joint, complete with bearing shells (made from pipe halves), to provide a rotational, and sliding joint. The photo below show the bearing opened on the LHS and the upper bearing shell moved to the left. Obviously the whole bearing assembly is greased up in use.

The shells are tightened via the wingnuts at the lower edge of the photo, and normally there is a dust cover over the entire sleeve joint.



The other major axis of movement is the tilt joint located under the sleeve joint. It's hard to photograph, but it's simply a short length of pipe mounted across the top of the spigot joint pipe, and a slip fit bar running inside the pipe, welded between two "cheek" pieces (shown as yellow in the photo below.


Part 2 will show more of the joint, and focus on the gripper