E-clip C-Clip Circlip Slot Cutter DIY Tool You Can Build

e-clip installed on a metal shaft for my home gym, leg extension. Photo01 by Don Tai

My metal needs are quite simple and one-off. I needed to cut a single slot into a metal rod to insert an e-clip. This DIY slot cutter is quite simple, using 2 ball bearing drawer hinges, some scrap wood I had in my garage, and my rotary cutting tool. The slots it cuts are acceptable for an amateur like myself. It works.

Internet searches for slot cutting into a rod revealed only metal lathe recommendations and advice. Metal lathes look really cool, but I don’t have one, currently have no need for one, and they are intricate with a steep learning curve, like everything else.

I am modifying my home gym and replaced the crude bolt pivot hinge for leg extensions, with ball bearings and a 5/16″ shaft. I could have used a 5/16″ shaft collar to terminate the shaft, but this would have been bulky and more expensive at $4CAD for a single shaft collar. Instead I bought an e-clip kit for $9CAD. I often run into e-clips when taking apart broken tools, so was interested in learning more about them anyway. Circlips are often used in commercial gym equipment because they hold tight, are strong, streamlined and take up very little space.

Tools needed

• ball bearing drawer slides (2): You may have these lying around the house. Use 2 identical ones
• wood: plywood for the base and sliding platform, solid wood for the rod holders
• rotary tool, cutoff blade: I have an off-brand one from Crappy Tire. It works
• wood screws
• drill press
• drill bit: The diameter of your rod
• face shield, gloves

Why Choose a E-Clip
I had the choice of e-clips/C-clips or circlips. I even have circlip pliers. The ease of removal of the e-clip makes it much easier for me to install and maintain, just in case I need to take the hinge joint apart. I only need a small needle nose plier to install and a flat head screwdriver to remove. This is quite convenient. The e-clip slot does not need to be perfectly symmetrical around the rod to work.

The clip will not be under very much pressure or tension, it only needs to not fall off. The sealed ball bearings will have no more than 200 lb of radial force. The e-clip will have no radial nor axial force. It will just sit there and ensure the sealed ball bearings do not come out of their bearing holder.

General Design
I wanted to keep the rotary tool stationary when cutting. I would have the metal rod perpendicular to the cutoff wheel but also able to easily slide into the cutting wheel to increase the cut depth. The metal rod needed to be able to rotate so I can cut around the rod’s perimeter.

Sliding with Drawer Slides
I used ball bearing drawer slides because they are relatively smooth and I had them in my house. These need not be fancy nor large, but they should be ball bearing and all metal.

Attach the drawer slides to the sliding platform parallel to each other. If they are not parallel, when you try to slide the platform they will bind up. I used a 2×4 spacer between them to ensure they are parallel. The height of the screw heads will depend on the drawer slide. You may need to hunt down flatter screw heads if there is any binding.

Attach the drawer slides and sliding platform to the plywood base. How you do this depends on your drawer slide design, so you may need to look it up.

e-Clip slot cutter, sliding platform top position, furthest away from you, rod holders are on the sliding platform, the rotary tool holder is to the right, Photo02 by Don Tai

e-Clip slot cutter, sliding platform bottom position, closest to you, rod holders are on the sliding platform, the rotary tool holder is to the right, Photo03 by Don Tai

Drilling and installing the Rod Holder
Find wood that is thick enough to keep the rod off the sliding platform, with enough space on either side of the rod hole to attach it to the sliding platform with screws. I used a drill press to ensure the rod holder hole is straight, with very little slop. You do need to be able to rotate the rod though.

When installing the rod holders they need to be perpendicular to the drawer slides and the right edge of the sliding platform. You want to ensure accuracy here because if you are a bit out your slot will not cut in a straight line.

I only needed to cut a single slot into a 5/16″ rod, but drilled 2 identical rod holders, because I wasn’t sure this tool would work. If and when I need a different diameter I can add more rod holder sizes.

Build and Install a Rotary Tool Holder
Each rotary tool will be different. My rotary tool had a plastic bump out half way up the tool, so I had to account for that. Somehow be able to stop your rotary tool body from rotating or moving and allow it to cut parallel to the drawer slides and sliding platform.

Using the Slot Cutter

1. Put a cutoff wheel in your rotary tool and place it into the rotary tool holder.
2. place your metal rod into the metal rod holder. Move the metal rod far enough to the right to your rod’s cut line. Ensure the rod is not touching the cutoff wheel.
3. Wear eye protection. In the past I have had cutoff wheels shatter in use, so protect your eyes. You are not getting any prettier with age.
4. turn the rotary cutter on
5. carefully move the sliding platform either forward or backward so that the metal rod touches the cutoff disk
6. rotate the metal rod so you make a cut all the way around
7. try your e-clip. You may need multiple passes to cut deeper.

e-clip slot cutter, rod inserted into rod holder, rotary tool with cutoff wheel held in place, ready to cut, Photo04 by Don Tai

e-clip slot cutter, rod inserted into rod holder, rotary tool with cutoff wheel in place, ready to cut, Photo05 by Don Tai

e-clip slot cutter, rod inserted into rod holder, rotary tool with cutoff wheel in place, ready to cut, macro view Photo06 by Don Tai

e-clip installed on a metal shaft for my home gym, leg extension. Photo01 by Don Tai

e-clip kit, Princess Auto, $9, Photo07 by Don Tai

My rotary tool had a red screw-on cap behind the rotating bit. This interfered with the depth of my cut, so I simply screwed it off. The cap is just cosmetic.

The actual cutting of the rod is quite fast. It took a couple of tries to get the e-clip diameter correct because my e-clip kit has 1/4″ and 3/8″ sizes, but no 5/16″ size. In the end the 3/8″ clip fit quite snugly but was still easy to remove with a small flat head screwdriver. The single slot I cut with my rotary tool cutoff wheel was wide enough for my e-clip.

As for sparks, this tiny rotary cutter cutoff disk is quite small compared to my 4.5″ angle grinder. There were few sparks and therefore little excitement. In use the cutoff wheel will wear away and become smaller, but this does not affect the slot cutter at all.

If you make one of these tools, please let me know how it went. As for when I will need to cut yet another slot in a rod, I have no idea, but not in the foreseeable future.