User:Spiritdude

My name is Rene K. Mueller, got interested in RepRap a few years ago but didn't follow up as the first models were expensive and too complex to build and use - this changed and since about December 2011 got interested more thoroughly again, thanks to several Kickstarter projects, such as Printrbot.

Contributions

• MakiBox, wiki-page started and basic information (not my invention, just realized it wasn't in the wiki yet)
• trying to put some structure and compareable numbers for each RepRap:
  • Printed vs Non-Printed Items (calculate a RepRapFactor)
  • Printing-Size / Building Volume
  • Material Cost (just the items)
  • Cost (assembled)
  • Precision (position/printing)
  • Speed (position/printing)

Favourite RepRaps

High Building Complexity

• Mendel aka "Sells Mendel", classic (1x Z-axis motor), Z-axis is X/Y-way stabilized

Not recommended to build since simpler versions exist:

Medium Building Complexity

• Prusa Mendel, (2x Z-axis motors), printed parts massively simplified - quasi standard now
  • DurbiePrusaMendel, further refined
  • MendelMax, further refined

Low Building Complexity

• Printrbot, loosly based on Prusa Mendel, very simple, Z-axis in the open (one end fixated)
  • Wallace, parametric version, Z-axis stabilized using a horizontal rod to connect both Z rods.
  • Portabee, Z-axis in the open

• Bukobot, alike Printrbot but with aluminium extrusions (very rigid) and Z-axis is X-way stabilized
• FoldaRap, with aluminium extrusions, Z-axis is X-way stabilized, foldable

All-In-One

• FoldaRap, power-supply & controller nicely integrated, speciality: foldable (easy to transport)
• MakiBox, case with power-supply, controller, all in a box, speciality: pellets to filament converter built-in (still in development)

Considerations

Rigidity

The Mendel based RepRap's are very rigid as the illustration shows, the MendelMax does best and triangulates the top pretty much, whereas the Prusa Mendel lacks one element so the top points are fairly triangulated and therefore stable - with slight possiblity to skew X-way and have vibration.

Bukobot and FoldaRap got rid off or let go some rigidity but tried (successful?) regain some of it by using aluminium extrusions instead of threaded rods like the Prusa Mendel - yet, from a geometric point of view that letting go complexity introduces Y-way vibrations, in particular Wallace which uses rods as framework, yet very appealing in its simplicity.

The other simple ones, like Printrbot and Portabee sacrifice the rigidity of the Z-axis by skipping the stabilization further: Z-axis is in the open (only one end fixated), possible source of vibration to X-way and Y-way, even though the printing head / bearing provide some X-way stability at the height. Therefore at higher Z-elevation Y-way and X-way vibrations may decrease the position and printing precision, in particular at high speed printing and heavier printing heads (e.g. multi extruders).

Ideally, the printing base is moved only Y-way (in case of these RepRaps considered here), but in real world will shake the entire construction - perceive the RepRap as a complex music instrument in vibration with its own resonance - any part which can vibrate WILL vibrate. It is therefore desired to reduce the "open ends" which likely will vibrate and triangulate them to maintain precision in position and printing at any point within the printing or building volume - and for obvious reasons if framework is sufficiently rigid, permits to speed up the stepper motors further (outline slower to keep surface nice, infills faster, less precision required).

Replicability

Whether a threaded rod vs aluminium extrusion frame is closer or farther from RepRap I can't tell yet - it depends which part likely will be easier to be printed in the future.

Q: As been there any tests made with printed struts instead of rods or laser cut plates?

A: Yes:

• [Benbot] (started 2012/07)

Pellets

The MakiBox aims to be an All-In-One, you fill in pellets (1-2mm large pieces of material), it creates filament internally for the extruder - ideal for recycling. It's still in development stage (2012/07).

Homemade Bio Plastics

To keep the idea of open hardware also apply to the source of material to be printed, I was look for ways to make bio(-degradable) plastic without external distributor, e.g. from cornstarch, water, glycerin and vinegar - and experiment thereby also with softer and bendable material to make elastic printed forms.

Q: Any experiments with direct source material to mix to make pellets or filaments?

Making RepRap A CNC Machine

Switch the extruder with a small milling head; consideration: strength of stepper motors and material to cut.

Q: Any projects?

Further Considerations

On 3D Printing in general: 3D Printing - The Next Technical Revolution (2012/07)

Contact

Email: spiritdude AT gmail DOT com