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.
- 1 Contributions
- 2 Favourite RepRaps
- 3 Considerations
- 3.1 Rigidity
- 3.2 Quality Control
- 3.3 Replicability
- 3.4 Pellets & Filament
- 3.5 Recycling Printing Material
- 3.6 Alternative Printing Materials
- 3.7 True Color (CMYK) Printing
- 3.8 Making RepRap a CNC Machine / Hybrid / 2D Plotter
- 3.9 Cost of Printing
- 3.10 Recycling 2D Printers / Scanner to RepRaps
- 3.11 Dynamically Adjustable Size of Nozzle Hole
- 3.12 Batch Printing
- 3.13 Remote Slicer
- 3.14 Remote Control Printing
- 4 Useful Resources
- 5 Further Considerations
- 6 Contact
- RepRapCloud (rrcloud), framework to distribute tasks like openscad, openjscad, slic3r and printing on remote servers and retrieve results back locally.
- GCodeToolbox (gctoolbox), manipulating gcode files e.g. concatenating multiple files to one print.
- svg2scad, converting Inkscape .svg (2d) paths to .scad polygons for further processing with OpenSCAD.
- Public RepRap Family Database (Google Spreadsheet), raw data of RepRap Family (to post-process and present later e.g. to draw alike the RepRap Family Tree)
- Thing Tracker Network, participating in the project and G+ community: "thing" metadata schema and tracking facility
- MakiBox, wiki-page started and basic information (not my invention, just realized it wasn't in the wiki yet)
- FFF illustration (see also File:FFF.svg)
- 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)
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
Low Building Complexity
- Printrbot, loosly based on Prusa Mendel, very simple, Z-axis in the open (one end fixated)
- 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
- FoldaRap, power-supply & controller nicely integrated, speciality: foldable (easy to transport)
- FoldaRap2, version 2 with scissor-like X-platform, and HBot XY, very small outer dimension vs build dimension
- MakiBox, case with power-supply, controller, all in a box, speciality: pellets to filament converter built-in but does not feed the printer extruder direct
- Rostock, beautiful setup and movement, yet, lot of motion on the bearing for XY movement of the head, also weight/inertia of the weight stresses more than cartesian setup.
- advantage: beautiful setup, 3 stepper motors.
- disadvantage: variable printing resolution depending on position, see for details on printing resolution at given position (higher resolution toward the edges, less in the center).
- PiMaker, rotational bed, Z & R head:
- advantages: less inertia of the bed compared to XZ head / Y bed ala Prusa Mendel → higher printing speeds, 3 stepper motors
- disadvantages: variable printing resolution depending on radius, developer aims to patent the setup
Stabilized Trapez & Trapez
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.
Prusa i3 (2012/11) and MendelMax 2.0 (2013/01) both look very alike, and reduced the trapez to what I call "Stabilized Bridge"; it is interesting how MendelMax and Prusa Mendel both in their newer generation become so similar. This design seem to get traction as of 2013/01.
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).
This variant become implemented with the Printrbot Jr, unlike the illustration the actual implementation has two smooth rods for the Z-axis, and due smaller printing volume the risk of X-way vibration has been reduced. Eventorbot on the other hand provides larger printing volume, and the frame is a thick steel extrusion and the bed moves X & Z-wise and the head moves Y-wise only (as with this orientation).
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 (aka eigenvalue) - 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 it allows to increase the printing speed further with little regards of mass of the extruder.
There are several upgrades available, e.g.
- Bolted Prusa Framed Stabilizer (quasi Prusa → MendelMax or "Trapez" → "Stabalized Trapez" upgrade)
- Printrbot Z-Axis Stabiliser Ends (quasi Printrbot → Bukobot or "Two Sticks" → "Bridge" upgrade)
There are many factors regarding quality:
- linear printing integrity / structural skew (misaligned framework)
- framework rigidity (vibrations within framework)
- surface linearity (unevenness of material dispension, chosen slice height)
- resolution (testing what the limits of resolution are)
- material (printing gaps / bridges)
Q: How to measure easily quality (verifiable and quantitative)?
- See Calibration for a start
- Linear Printing Integrity
- Framework Rigidity
- simple and fast printing model which stresses the axis which expose possible vibration affecting the positioning of the extruder
- different models, e.g. stress-01-ybed-xzhead.stl or stress-printrbot-original.stl, stress-printrbot-jr.stl etc
- Surface Linearity
- simple and fast printing model which reveals surface linearity: several low volume (fast printing) large surface items with different steppings (e.g. different slice height for a Y-bed XZ-head RepRap); optical measurement, e.g. take photo of surface with a light source near perpendicular (right angle) so ripples cast a shade, then use program to analyze the dynamic range and contrast of that photo: uneveness of the surface.
- Grid test print object, array of otherwise uniform grids of decreasing wall thickness (2, 1, 0.75, 0.5, 0.4, 0.3, 0.25, 0.2, 0.15, 0.1, 0.05 and 0.01 mm)
- Printable hole test array, array of holes, from 1 to 30 mm in diameter as printed, designed to test the ability of a 3D printer to handle voids accurately.
- Other Tests
- Accuracy Master - Printing Test Kit, small perimeters, bridging, taller extrusions / large inlays, holes & arcs, slopes, peaks & small perimeters and infills
- Printrbot anti-wobble: The basic plastic printerbot frequently produces bands on the sides of the prints which match the z-threaded rod pitch, that thingy provides a fix (see also here for z-rod coupling)
- Z-rod stabilizer for Printrbot PLUS
It has been debated among RepRap developers intensively and Z-wobble occurs due
- wobbly threaded rods (it seems majority of threaded rods have wobbles)
- fixation on both ends.
- Solution: give the threaded Z-rod some space for X/Y motion, and let the other end of the Z-rod in the open, only fixate one end at the stepper motor (see Prusa i3).
- Rounding error in stepping (aka Z ribbing)
A more general thought is about how improve or at least maintain precision from one generation of RepRap to the next, and by all means avoid degenerative quality of RepRaps printing themselves.
Q: What kind of forms or mechanisms improve, maintain or worsen precision?
A: For now it seems not to have been an issue, as
- motion precision is usually provided by smooth rods (all 3 axis), so linear motion precision is maintained
- case is usually not printed (e.g. threaded rods, or aluminium extrusions)
- Convergence to self replicating has some additional thoughts on this
- lack of perpendicularity of the axis causing parralelogram seems heritable, see also this post
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: Has been there any tests made with printed struts/rods/bars instead of steel rods, aluminium bars or laser cut plates?
A: Yes, listing projects:
- Ladder Rack (Lad) (started 2013/01: planning)
- Benbot (started 2012/07: planning)
- Plastobot (started 2012/09: planning)
- Snapdragon (experimental 2011/06)
- Ronthomp Mendel v3, printed arches for Prusa Mendel alike
- Tantillus (working, portable, case self-printed)
- Beiwagerl (formerly known as '(Prusa) Air 2 Mini'), case self-printed
- Hardtoe's Printable Mendel Frame, eliminates the following vitamins/non-printed items: 6 threaded rods, 28 M8 nuts, 32 M8 washers, 4 M3 bolts, 4 M3 nuts and 4 M3 washers
- Individual Pieces:
- Parametric T-Slot Library (vertically printed)
- M-Beam, (horizontally printed; printed without support by 2 interlocked pieces)
- Printable linear bearing
- Spur parametric gear rack
- Type A Printer MK1. Component module A., modular framework
- Chain tracks (mounting by hand)
- Printable T5 Belt, concept
- Printable Endstopper V2 (V1)
Regarding printing RepRap parts with PLA, Josef Prusa (2013/01/06) wrote: Few of my friends left their printers made out of PLA outside or in car on the sun, rendering the printers non functional. 50°C (120°F) can be enough., so it's recommended ABS even though it's less recycable than PLA.
I propose a RepRap Factor, printed parts (pieces & volume) in regards non-printed parts (pieces & volume), for example (made up numbers):
- rrf = (1 / (p + np) * p)
- rrfpieces = 1 / (30 + 220) * 30 = 0.12 = 12%
- rrfvolume = 1 / (20cm3 + 50cm3) * 20cm3 = 0.286 = 28.6%
A pure or 100% RepRap or rrf has 100% printed parts, 0% non-printed parts.
To compare weight seems not so informative, e.g. stepper motors are heavy, yet, a well designed strut with little infills but good inner structure weights little, so the information of the replicability to compare weight isn't so good. On the other hand does weight represent also usage of resources (matter), heavy metals as used by stepper motors require a long supply chain, whereas a PLA filament likely shorter one - that wouldn't be an indicator of replicability but resource usage in general. There are further considerations required how to qualify RepRaps further, keywords: "greenness" (quite broad term), "ecological footprint", etc.
Pellets & Filament
Pellets are available at industry level, where usually filament is made from. Several projects have aimed to provide filament production:
- FilaStruder.com (2013/01)
- Lyman Filament Extruder (2012/08)
- FilaBot, started as Kickstarter project in 2012/01 and since then has grown significantly.
- MakiBox aimed to be an All-In-One, e.g. you fill in pellets (1-2mm large pieces of material), it creates filament internally for the extruder - ideal for recycling, yet as of 2012/12 they did not manage to resolve to combine the pellet extruder with the printer extruder reliable, so the pellet extruder makes filament on a spool, and then later is used for the printer extruder
- Recyclebot, RecycleBot v2.3
Recycling Printing Material
With the growing printing activities also the issue of recycling arises, how can printed material recycled:
ABS (Acrylonitrile Butadiene Styrene)
Used for luggage, water pipes, LEGO, etc.
PLA (Polylactic Acid)
Used for packaging, organic-waste, bio-degradables, tea bags etc.
Interesting quote, Vik Olliver January 7, 2013:
HDPE (High-density Polyethylene)
Used for milk jugs, bottles, bottle caps, water pipes, etc.
See RecycleBot turning old milk jugs into filament for details.
LDPE (Low-density Polyethylene)
Used for trays, plastic wraps, slides, etc.
PET (Polyethylene Terephthalate)
Used for bottles, etc.
Alternative Printing Materials
- Wood: Wood Filament (LAYWOO-D3), wood/polymer composite (no details of actual composition)
- Caulk: Caulk Extruder, reference for future developments
- Conductive Plastic: Carbomorph Material Enables 3D-Printed Electronics (2012/12)
- Open3DP: Formulas, collection of recipes and procedures
Homemade Bio Plastics
To keep the idea of open hardware also apply to the source of material to be printed, I was looking for ways to make bio(-degradable) plastic from common available ingredients (short supply chain), e.g. from cornstarch, water, glycerin and vinegar (e.g. Make your own bioplastic) - and experiment thereby also with softer and bendable material to make elastic printed forms (e.g. soft parts of a wheel or ribbon) or foamy parts (extreme lightweight). Some critical thoughts (The Guardian, 2008) and here on bio plastic in general.
Q: Any experiments with direct ingredients to mix to make pellets or filaments or feed the extruder direct?
- Bioplastic: Starch, glycerine, vinegar and water: 7 parts water, 1 vinegar, 1/2 glycerine and 1 1/2 parts starch, and boil it up until it thickens:
- Make: Is homemade bioplastic viable fodder for 3D printers?: No (not for printing, but better for molding)
- takes long to dry
- water based plastics shrink a lot when dried
- Shapeways Blog: Laser Cutting Bioplastics, good reference
- Shapeways Blog: Cooking & molding bioplastics at home, in particular the comments are useful as reference, no direct printing yet
- Make: Is homemade bioplastic viable fodder for 3D printers?: No (not for printing, but better for molding)
True Color (CMYK) Printing
The commercial high end printers manage it, but not in FDM/FFF manner yet as far I know.
Q: Are there any open-source RepRap projects underway?
- RichRap: 3 Way Quick Fit Extruder & Colors (2012/08/01), first tests
- OpenAlia: RepRap 3D Printer Color Mixing Nozzle (2012/07/12)
Making RepRap a CNC Machine / Hybrid / 2D Plotter
Switch the extruder with a small milling head; consideration: strength of stepper motors and material to cut.
Q: Any projects?
- See Forums.RepRap.org: CNC Routers, Mills, and Hybrid RepRapping for on-going discussion
- SumPod, 3D Printer & CNC
- PopFab, machine that does 3D printing, milling, vinyl cutting, and drawing, all while fitting inside a small suitcase
- zMorph dremel mount
- 2D Plotter: Pen Holder/Head (adapter), Cad.py (software)
Cost of Printing
It was pointed out at User:Traumflug user page, that printing itself costs:
- wear of printer (parts/material)
printing a set for a RepRap takes up to 10 hours.
Q: Are there any more substantiated numbers how many resources are used (usage of material, electricty) and therefore cost of printing of a RepRap?
A: Measure volume to be printed in cm3, assume a certain filling (e.g. 50%), given layer thickness (0.1mm-0.3mm) with speed (e.g. 30mm / s) determines the duration of the print.
- timeprint = ( volumeform (cm3) * filling ) / layer thickness (cm, e.g. 0.01cm) / layer thickness (cm) / speed (cm / s)
- e.g. ( 10cm3 * 0.5 ) / 0.03cm / 0.03cm / 1cm/s = 1851 s = 0.51hr (or 30min 51sec)
- electricity: power (kW) * time (hr) * priceelectricity kWh = costelectricity
- e.g. 0.2kW * 0.51h * 0.25 Euro = 0.025 Euro
- material: volumeform * filling * costper cm3 = costmaterial
- e.g. 10cm3 * 0.5 * 0.035 = 0.175 Euro.
- ABS density 1025kg / m3 = 1.025g / cm3 => 35 Euro (1kg filament) / 975cm3 = 0.035 Euro / cm3
First few layers a heat-bed may be used, drawing most energy (~3x than the motors). So, the costs in this example make up 87% for material, and 13% for electricity. Wear and resulting maintenance are neglected for now, but come in effect at longer duration of printing (e.g. weeks non-stop printing).
See also 3D Printer Calculator
Recycling 2D Printers / Scanner to RepRaps
Printer to RepRap
- The Phoenix Project: Recycled Epson Printer Parts into 3D Printer
- Low cost CNC mill/repstrap from old printers & scanners parts
- older printers (e.g. Inkjets) have strong stepper motors than newer ones which also often have servo motors (unuseable)
- 40-53 Ncm torque recommended for RepRaps (1-2A minimum), NEMA14 like with 12-15 Ncm seem to work too (from another source)
- 200 steps per evolution prefered, for Z-axis lower steps possible
I have disassembled a Canon multi-functional machine (scanner & inkjet printer), and to my surprise found only one small (flat) stepper motor for the scanner, but otherwise ordinary DC motors with optical encoder feedback for the printing part, also, the linear bearing did not have a distinct frame but used the plastic case - so not much could be resurrected.
Scanner to RepRap
Dynamically Adjustable Size of Nozzle Hole
The precision of the printing is highly dependable on the size of the nozzle hole e.g. 0.3mm or 0.1mm - usually the precision of positioning is much higher 0.02mm or so and therefore neglectable in this consideration. It would be interesting to consider a nozzle hole which can be dynamically adjusted in size: for outline lines (becoming surface) go 0.1mm, and for the interior 0.3mm or even bigger for structural strength.
Q: Any projects which has considered or implemented that?
With BotQueue (networked printing) the batch printing has become more in the focus.
Q: Are there any project to print in batches: clear the bed after the item(s) are printed?
- Automated Build Platform (ABP) by Makerbot (2010/09) - it seems to have some issues (no leveling mechanism, no way to tighten belt, belt made out of plastic instead something with higher melting temperature).
- RepRapCloud: slicing, openscad, openjscad and printing (backbone), command-line interface mainly (web GUI comes later)
- Remote Slicer (Alpha)
Remote Control Printing
Usually a RepRap is connected direct to a computer, some controllers with LCD display have SD card support and can print without a computer.
Q: Are there approaches to provide remote (e.g. web) control of multiple RepRap?
- Doboz-Web, python-based
- OctoPrint (formerly known as Printer WebUI), python-based, suitable for RPi also
- Raspberry Pi (RPi) based solutions:
- Repetier Server
- RepRap Magazine.com
- RichRap Blog: Reprap development and further adventures in DIY 3D printing, lot of experimentation with other materials, extruders, etc.
- HydraRaptor Blog by Nop Head, very informative as well, recommended
- Billy Zelsnack's "3D Printer Review 2012", useful summary
- G+ Discussion on "Kickstarter 3D Printers" (2012) started by Rob Giseburt, lot of information in the comments
In general G+ has become a place to connect with developers, in particular the G+ "3D Printing" Community.
Some articles by me:
- 3D Printing - The Next Technical Revolution (2012/07)
- RepRap, Open Source & Spirituality (aka "why my nickname is Spiritdude") (2012/08)