Thursday, June 28, 2007

Arm Dismantling & Reassembly...

First task was to insert wire armature pins into the broken finger surfaces. These areas were carefully drilled and then thin wire was epoxy glued into place. These wires will be clipped to length and bent into the correct finger positions prior to resculpting.


I used Z-Poxy 5-minute epoxy resin by Pacer.


Next stage was to disassemble the badly damaged right arm. I was able to easily cut the armature wires in the forearm and elbow due to the open breaks, but the upper arm needed to be drilled around the cracks in the shoulder area, so I could tease them apart. Once I'd removed the old armature wire, the upper arm section had seperated along the shatter lines into four smaller sections. These sections were reassembled using epoxy resin and wire pins.

[NOTE: it's best to score pins around their diameter using the plier jaw teeth or similar, this will give greater grip in the epoxy].


Whilst the upper arm repairs were setting, I turned my attention to the forearm. The two pieces of the forearm and the upper arm would all need to be reassembled using a metal pin and epoxy resin. But to begin with I simply epoxied the two forearm sections together to reduce them to one piece.


I then used a pencil to carefully mark the best axis for the pin through the upper arm & forearm. For the pin I used a corrosion resistant single thread screw, with the head cut off. The threaded screw shaft would provide excellent strength and a firm hold on the resin. I drilled holes slightly larger than the screw diameter in both pieces.

[NOTE: as with drilling most brittle materials, it's best to start with a pilot hole and gradually increase drill bit size up to your desired diameter - this increases control & accuracy, and minimises stress on the material].



I first set the screw pin into the upper arm section using epoxy resin, and then, once hardened, I ensured that the forearm section fitted onto the new pin correctly - this would eventually create a strong central repair through the wrist, elbow and into the upper arm.


The next stage was to attach the upper arm section to the shoulder - for this I used the same metal pinning and gluing technique. First the correct axis was carefully marked out, and then the oversize pin holes were drilled in the shoulder and the upper arm sections. A new pin was glued into the shoulder section - and to ensure correct alignment, the upper arm piece was placed [not glued] into position over the pin whilst it set.






Now all the arm sections were ready for final assembly.

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