Monday, January 26, 2015

3D Printer Linear Motion without Linear Bearings!

 I currently use several modified Printrbot Simple Maker's Editions. They are very solid machines and make some impressive and fast prints. My largest print size is 200mm x 320mm. Roughly 8” x 14".
  The one thing that is a constant battle for higher speed prints is slop or flexing parts during the movements. I started experimenting with different materials to use in place of linear bearings for use in 3d printing. Although 8mm linear bearings and case hardened rods are the go-to solution, they still have play that is evident in the prints (especially when changing direction)..
  One quick, possible solution for my existing printers are the small round parts in the pictures. They are 8mm I.d. x 10mm x 10mm linear bushings. The are self lubricating bronze linear bushings with a hardened carbon steel outer casing and a PTFE (Teflon) inner liner. Extremely nice fit with no play, but they will require some new mounts to be fabricated to fit my existing bearing mounts.

The white part on rails is a test for my custom designed printer. The plastic is also self lubricating, but is HDPE. 
  I am very excited about this test as it is smoother than the bearings could ever hope to be and will easily be fabricated so there will be no play when mounted correctly.
  It's 5/8” thick HDPE and has had all 4 sides routed top and bottom, leaving a 3mm tab that fits snugly into the 3mm screw rail of  15x15 mm extruded aluminum (openbeam v2.1).
   This is an idea that I hope to develop in my custom printer and maybe even for the CNC machine I have been planning for the future.

  The last item is a roll of PTFE tape. I had considered using it to line the edges of an aluminum plate that could also run in the extrusions rail with HDPE wheels to provide side pressure, removing all play. That is something I will be trying and sharing the results here as well.
  It may be necessary to use aluminum/Teflon combo over the HDPE glide depending on how well my ideas work out to prevent heat creep on the heated bed and extruder mount. HDPE is my material choice for these projects. Wonderfully smoother linear movements without bearings.