Magnetic Ball Bearing Work Holder

This is a quick little project to build a light duty work positioning/holding device that uses a gigantic ball bearing. I happen to work in an industrial facility, so I've managed to salvage a few large ball bearings over the years. If you don't have access to this component, this might be a difficult project for you to replicate.

I designed the 3D printed base in Onshape, my preferred modeling software, and made the customizable design for Thiniverse in OpenSCAD. First try, no warmup :)

Supplies

• Large Ball Bearing (40-70mm diameter)
• Neodymium Magnets (minimum of 3) with mounting screws or glue to fasten them in place
  • I would strongly recommend using these "cupped" magnet sets (https://www.leevalley.com/en-ca/shop/hardware/rare-earth-magnets/magnets/disc/58750-rare-earth-magnet-cup-and-washer-sets) from Lee Valley or another manufacturer.
• 3D Printed Base, customized from Thingiverse
• Something that you need to position. I'm using this device to hold a stained glass template.

Optional

• Mounting screws for base, #8 button head wood screw will suffice
• Hot Glue, Double-sided Tape to mount the work holding piece
• Cyanoacrylate glue and accelerator
• Screw Driver
• Drill bits

Step 1: Customizing the Base

1. Measure the diameter and thickness of your magnets as closely as possible. I normally print everything in high speed mode on my Lulzbot Mini, so I generally add an extra 0.2 - 0.4 mm to the measured dimensions for ease of assembly. Depending on the filament/print settings/printer quality, your results may vary.
2. Measure the diameter of your ball bearing,1 mm accuracy is fine
3. Head to the Thingiverse page (https://www.thingiverse.com/thing:4154384) and open up the Customizer app for the "Ball Bearing Magnet Mount"
4. Enter in the measured values into the customizer and generate the base according to your specifications
   1. If you don't require screw mounting holes for either the magnets or the base, simply set the screw diameter values to 0 mm.
5. Generate the part

Step 2: 3D Printing

1. Open the STL files in your favorite slicer
2. Slice the part
   1. My preferred material is HIPS because it's slightly less brittle than PLA and just as easy to print on my machine.
3. Send the G-code to your printer
4. Collect Parts

Step 3: Installing the Magnets

This all depends on the type of magnets that you've chosen. I'm demonstrating 3 different installation techniques: Screw mounting, super glue, pressure fit.

• If you're screw mounting the magnet cups, use a drill bit to drill the pilot hole to the recommended size.
• Use a scraper to clean up the edges in the shallow holes before gluing.
  • Accelerator can help speed the process.
• Ream all larger holes with a hand held drill bit.
  • You'll need to clamp the 3D printed base if you're using a cordless drill for the task
• Press fit by hand or with a clamp.

Step 4: Attaching the Base and Work Piece

• Hot glue for a semi-permanent mount to another 3D printed part jig.
• If you're mounting the 3D printed base drill a pilot hole (pictures are upside down for some reason)