Introduction: Ground Cable Strain Relief
My stick welder has a cast bronze ground clamp. There is no strain relief for the heavy copper wire made of very fine strands. I have wanted a strain relief to keep the cable from fraying where it bends sharply as it comes out of the ground clamp. Below is the idea that came to me.
- Drill and bit
- Measuring tools
- Countersink bit
- MIG welder
- Slip-joint pliers
- Dremel tool and grinding stone
- 3/4 inch thinwall electrical conduit
- 3/4 inch flexible conduit, also known as BMX
- Plastic electrical tape
Step 1: Mark Thinwall Conduit for Drilling
Cut a piece of 3/4 inch thinwall conduit to about 3 inches in length. 3/4 inch is very close to the diameter of my bronze ground clamp where the cable attaches to it. I marked the center of the lug screw on the conduit. The conduit will need to fit around the raised part of the lug to secure it so it cannot pull off of the clamp.
Step 2: Make Hole for the Raised Part of the Clamp
i need a hole 7/8 inch in diameter. A step drill bit is too long. I do not want the hole to go through the opposite side. I decided to drill a pilot hole and enlarge it with a 3/4 inch countersink bit. It chattered too much to use a drill press. I carefully used a hand drill. I used a Dremel tool with a grinding stone to enlarge the hole to 7/8 inch.
Step 3: Make Saw Kerfs
I used a hacksaw to make kerfs as shown in the photo.
Step 4: Fit Thinwall to Ground Clamp
I opened the small kerf so I could insert the lug on the ground clamp into the thinwall conduit. I used a slip-joint pliers to close the conduit around the raised portion of the lug. I used a MIG welder to close the gap. (Try to remove as much of rhe galvanized coating In this area as possible before welding For a better weld.
Step 5: Fit the Flexible Conduit to the Thinwall Conduit
I made the long slit a “T” and inserted the flexible conduit. It was necessary to open the “T” cut a bit. Before welding The flexible conduit to the thinwall conduit (second photo) I squeeze the “T” cut closed again. I welded the “T” cut closed.
Step 6: Insert and Secure the Ground Cable
I bent over the stranded copper cable to make it double thickness where the lug screw is. I fed the ground cable into the flexible conduit and the thinwall conduit. Some twisting, pushing, and patience was needed to get the strands of the cable into the lug hole. The photo shows a generous amount of copper strands ready to be squeezed securely by the lug screw. I put a little oil on the lug screw and secured the cable with it very tightly with an Allen wrench,
Use a file to remove any sharp edges. Some plastic tape where the cable comes out of the flexible conduit could be added.
Step 7: Ready to Use
Admittedly, my strain relief takes more space, but I have never been unable to place a ground clamp because space was lacking. Some option was always available. Notice how bends in the ground cable are nice and gentle.
Step 8: Update
Although this strain relief worked fairly well, the flexible conduit began to separate from itself due to stress. I noticed a coil spring as a strain relief on another welder and decided to copy that. The photo shows the end product. I used 1/8 inch steel rod. I made a ring to fit around the ground clamp and welded its ends closed. I slipped the spring I had chosen onto the ground clamp as far as I could. In order to keep the spring from popping off of the ground clamp, I made a short piece of rod with a hook on one end. I hooked it over a coil in the spring and welded its end to the ring around the ground clamp. See text boxes in the photo. If needed, I can twist the spring to advance it in the hook and make it tighter against the raised terminal on the ground clamp. I had to select from springs available at the hardware store. This spring is the right diameter and length, but would be even better if it flexed just a bit more. Still, it will protect my cable from fraying where the cable enters the ground clamp.