Sometimes, the torches will lose electrical contact due to the heating and cooling cycles. Here is something that you can try:
- Remove the cap from the torch:
- Using a 5/32 inch hex wrench, loosen the socket head cap screw in the torch cap:
- Once the screw is loose (it does not need to be removed), twist and wiggle the torch cap while pulling it away from the torch to remove the cap from the torch.
- If you look inside the cap, you will see the two electrical connection points. One is the clamping ring (which was loosened with the screw, above), the other in the center electrode.
- The torch has matching connectors. The center electrode mates to the wire mesh at the center of the torch. Sometimes, the torch will lose connection between the center electrode and the wire mesh because of thermal cycling. As a result, the mesh will need to be compressed.
- To compress the wire mesh, you will need to fabricate a couple of simple tools:
- Cylindrical metal rod 0.25 inch diameter by approximately 1.5 inches long.
- Cylindrical tube 0.48 inch outside diameter, 0.252 inch inside diameter by approximately 1.32 inches long.
- Insert the 0.25” diameter rod into the wire mesh. This will approximate the center electrode during this procedure. (In the illustration, we are using a spare center electrode, but a straight rod will work just as well.)
- Slide the piece of tubing over the rod, so that it makes contact with top of the wire mesh assembly. Notice that the tubing sticks out beyond the rod.
- Using a small press or other application method (even loading by hand will work) apply approximately 10 pounds of force to the tubing. This will compress the wire mesh assembly, and tighten it down on the metal rod. Hold the load for around 20 seconds, then repeat.
- Remove the tubing and rod from the torch.
- Reassemble the torch cap to the torch, making sure that the cap is fully engaged with the torch. Tighten the screw to lock the clamping ring electrode to the torch.
This procedure may or may not solve the problem, as these torches do have a limited life span. They are warranted to 100 hours. If there is less time than that on a torch, its replacement value is prorated by the number of hours on the torch. We have found that constantly cycling the temperature (on / off) can decrease the life of the torches. So typically, we will leave the torch running even if we are taking a break, for lunch, for example.
The cost of a new torch is $2695 (USD) each, and we typically recommend that customers have one or two spares on hand.