TONG
 
 
The tong to lift the crucible is of homemade design. I thought it to be very complicated to take the crucible out of the oven with a tong and then put it in a pouring shank. Not only an extra tool has to be made but also an extra opportunity to tip over the hot crucible. So to make things safer and easier a combined version is developed.
The tong

The tong in opened position

The open tong being put around the crucible

The tong is closed

Sideview
Details

Upside view

To the lower side of the main bearingspine a nut is welded. In this nut a allentype bolt is mounted. The hollow turning part of the spine is hold in place by the end of this bolt

Underside view of the topbearing

Topview of the topbearing. At the fixed part of the central spine a bolt is welded. The hollow tube which makes up the movable part of the centralspine is shoved over the small end from the fixed bolt .
Operational

The top of the crucible is about 50mm under the rim of the oven

The tong is slid in the narrow opening between crucible and ovenlining until the positioning nibble touches the top of the crucible

The tong is closed and the crucible can be lifted out of the oven

The crucible is in a position ready to begin pouring.
Drawings

While dimensioning the tong one should take in concern the gravitycenter of the filled crucible . This point wil be on about 1/3 tot 2/5 from the bottom of the crucible. The centerline trough the handlingbar must go also through this gravitycentre. The advantage is that one doesn't need extra force to turn the crucible in order to pour the metal out (from position A1 to position A2) The tong and crucible stay in balance during the pour.

In the frontview can also be seen that the centerline is in the gravitycentre of the crucible.

The crucible with the metal and the tong together are pretty heavy. Because there is no extra force needed to turn the crucible for pouring, it is easy to stay in position above the hole.

When grabbing the crucible attention must be paid to situate the pouring point not to the straight side. The outlet should be a little to the front. When the crucible is turned to empty it, the outlet will be at the lowest point. This can be seen at drawing A2.

click to enlarge

 A . the height of the crucible
B. is 3/4 of the crucibleheight.
C. depends on the depth of the oven. The C is the distance from the upper rim of the crucible (standing in the oven) to the upper rim of the oven. To this measurement should be added the thickness of the handlbar and some freeplay between the handlebar and the oven rim.
D. short part of handlingrod
E. lenght of the handle
F. angle of the handle
m1. bended strip
m2. 2 hingepipes diam.
m3. handle diameter 25 mm (1")

 

There are two strips (1) that take care off the crucible doesn't tumble over during the pouring session. At point (4) are two pipes that form a hinge. The lip (2) is an indicator of how deep the tong should be lowered in the oven in order to be at the right hight. Also the lip prevents the crucible from sliding out of the tong (1).The handlingrod (3)is made off an 25mm (1") gastube
Actionview

This picture is to get an idea of the size of the tong.