Musings and Experiments on the Art and Science of 3D Printing


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Post 2: Improved Z Screw Bearing Blocks

By Michael Hackney → Sunday, November 27, 2016
I had an idea to improve the bearing blocks so they also help stiffen the frame. I designed and 3D printed a test piece to verify the geometry. It came out great so I am machining these in 1/2" x 3" aluminum now. The left and right side are mirror images of each other.

The pocket is 7mm deep for the 12mm x 7mm bearing (8mm shaft). I also test fit the bearings on the machined ends - they were perfect. The machining is excellent. 

The ball nut will need to be flipped around and they shipped bearing retainers so this will be easy. The screws (4 of them) are Hiwin 1210s (10mm/rev) and here's the machining specs:

Once I get the mounts finished I'll assemble the Z stage and table framework and figure out how to drive the 4 ball screws from a single stepper motor.

Post 1: My new Core XY build

By Michael Hackney → Monday, November 21, 2016
I've been working on a design and collecting parts for a new Core XY 3D printer. This one is BIG! My goal was to have a 300mm x 600mm build area plus a lot of Z too (540mm). I won't reveal why I need such a larger area but let me say "I have a plan"! Here's a rendering:

The folks over on the Google H-bot and CoreXY printers Group have been really helpful with feedback and design critique over the last 9 months or so. The main features of this build will be:
  • all aluminum (30x30) frame and corners - no printed structural parts
  • four 1210 ballscrews and nuts - one on each corner, these should be fast
  • .8° steppers on all axes
  • SG10 Speed Demon linear rails
  • Duet Wifi controller with dc42 (RepRapFirmware)
  • Initially an E3D V6 hot end but ultimately a quad hot end (4 in, 1 out) that I'm working on
  • BondTech QR extruder (s when I add the quad hot end)
  • MIC6 (or equivalent) bed with custom heater (likely 120VAC)
  • PEI print surface
I'll fill in more details as the build evolves. This won't be a speed build though, I have lots of other projects going on in parallel (plus life, work, etc).

More information on my posts in the Google group threads:!topic/h-bot-and-corexy-3d-printers/sVyTyfYoOwQ!topic/h-bot-and-corexy-3d-printers/SncQWymq0ac!topic/h-bot-and-corexy-3d-printers/u5kYZwlxk4E

This weekend I started cutting 30x30 to build the frame. Here's the cut list:
  • Long Horizontal Members: 4 @ 815mm
  • Short Horizontal Members: 4 @ 447mm
  • Vertical Members: 4 @ 835mm - keep these as long for as long as possible
I used my aluminum chop saw, careful measurement and gang cutting. I don't have a granite machinist's table large enough to do the assembly on but I do have granite counter tops that are pretty flat. I started by installing corner braces on the four vertical leg members.

Then I assembled the short horizontal members to these.

Here's the assembly. The ext step is to break out the precision machinist squares, meter stick, and other tools to square it up. Everything will be referenced off the top. I can square and level this on the granite countertop. Then I'm thinking about cutting a gauge stick to align the lower horizontal parts so they are all the same. This should ensure the top and lower members are parallel. I'll put adjustable rubber feet on the leg bottoms.

At this point I can measure and cut the Speed Demons I'm repurposing. I also need to order some additional rails so I'll do that this week. The screws, bearings and 32 tooth pulleys are all in house. I need to machine the bearing blocks for the screws, that's the next step after aligning the frame.