This is the todo pile which has anything and everything that needs to be designed/tested/verified/made/built/coded/researched/documented/shared etc.

Metric version development

Has dedicated page


Has dedicated page

Makerbot SMD v2.3 + Alltronics steppers

Do they work? Are there heating issues without heatsinks? Are they better than SMD v1.2?

Noise/vibration/resonance problems

  • Will microstepping help with vibration and noise?
  • Etch/make or wait-and-buy Makerbot SMD v3.x and test it with Alltronics (or other) steppers on Contraptor mechanisms
  • Try HobbyCNC kit (need interface w/Arduino)
  • Damper on the motor shafts
  • Steppers mounted on plastic spacers
  • Alternative stepper mounts

Better steppers as far as performance/cost?

Are there steppers that offer better performance/cost ratio? Contraptor's $10 Alltronics seem to outperform Reprap's $25 Keling, at least in speed tests. Are Kelings more reliable?

Accuracy of basic linear motion mechanisms

Need to come up with a jig to measure the actual positional error of:

  • Leadscrew drive
    • with sliding elements
    • with linear rails
    • with ACME precision kit
  • Belt drive
    • with sliding elements
    • with linear rails

Document ACME precision motion (or precision drive) kit

Design files exist (tweet @albanetc); prototype has been made

  • ACME lead screw (probably multistart)
  • Delrin nut
  • Thrust bearings
  • End nuts (ACME) Shaft collars
  • Oldham (disk) couplings
  • ABEC rated bearings with true 0.25 ID?

Chain drive

  • Suitability for accurate motion (what's the error/backlash)?
  • How is accuracy dependent on length? What are usable lengths?
  • Perhaps could work for routing MDF/plywood with 80/20 and Rotozip type tool
  • Inexpensive components available on Mcmaster and SDP/SI

Rack and pinion ideas


  • Pulley rolling on the timing belt glued with epoxy to angle?
  • HDPE rack cut with mini-router and Dremel?
  • Acrylic rack (lasercut) with timing belt profile and timing pulley on it? (How to DIY? Bootstrap miniCNC and route acrylic?)

Industrial components - main question is cost.

Reliability of linear bearing/rail?

In the linear bearings R3 bearings are loaded axially on one end. This is not good. How long will the ball bearings last before having too much play? Also, how long will drill rod last before it has a groove?

Designing Contraptor components

Has dedicated page

Contraptor 3D source files for other 3D apps

  • Convert component designs from DXF/SKP
  • Host on Thingiverse?
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