Improved 608 Bearing Cleaner

Although this model is based on the idea of Dave K's bearing cleaner, it is a clean implementation in OpenSCAD with a number of improvements. I bought 100 cheap 608RS skateboard bearings from Aliexpress for my MPCNC build. Although the bearings weren't bad, they had been lubricated with some heavy, viscous sticky stuff and weren't running nicely. This model allows me to get them properly cleaned up before applying sewing machine oil, leaving them running beautifully.

Improvements

• Parametric - edit the OpenSCAD file to easily resize for different bearings, or to do more bearings at a time
• Better threads using Dan Kirshner's great OpenSCAD thread library
• 4-start thread closes easily and seals well
• Easy to handle with nice bevels all round and knurled lid

You Will Need

• 3D printed parts:
  • one tube (bearingcleaner_tube.stl)
  • one cap (bearingcleaner_cap.stl)
  • six spacers
• ¼" UNC (20tpi) 3" bolt
• Citrus cleaner - look for a cleaner containing d-limonene, I used ‘ASDA lemon all purpose cleaner’ which was cheap and works well
• Lubricant for your bearings (I used sewing machine oil which works well for me)

Preparation

• Pop the plastic shields of four bearings
• Thread two spacers onto the bolt, then a bearing, then a spacer, a bearing, a spacer, a bearing, a spacer, a bearing, a spacer.
• Screw the assembled bolt and bearings into the small thread in the cap. 
• Fill the tube approximately one third full with citrus cleaner
• Screw the lid on tightly. Because the threads are hard, they won't seal perfectly - typically I had a drop or two coming through each cleaning cycle. You could overcome this by making a lid seal with gasket paper, or maybe using PTFE thread seal tape. I didn't think the drop or two of seepage was worth the bother, though.
• The following cleaning cycle worked for me:
  • Shake well for about 30 seconds, leave for a minute
  • Shake well for about 30 seconds, leave upside down for a minute
  • Shake well for about 30 seconds
  • Rinse, dry and lubricate
• After cleaning, rinse the bearings thoroughly in warm water, and then dry carefully (I used a hair dryer while the bearings were still on the shaft
• Lubricate the bearings with 2-3 drops each of oil
• Replace the plastic shields
• Spin each bearing and give yourself a nod for a job well done.

Printing

This is an easy print, needing no supports in the default orientation (flat side down). Supports will likely cause you hassles with your threads, so best just leave them. I printed the spacers solid (100% infill), and used 5 walls for the tube and cap. Maybe overkill, but it works really well.

All the best with refreshing your bearings!

Update - Water Tightness

I found that if you shake the bearings up for an extended period of time, or leave it full and upside down for several minutes, the cap might leak a drop or two of the cleaner. No problem, you get clean hands :-). But I was fascinated to see if I could make it really watertight - and adding a small torus of gasket paper, glued into the lid for the lip of the body to seat against, makes for a watertight seal (provided your print is watertight - more walls, higher temp may help here.