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Jackie Pease edited this page Feb 20, 2018 · 2 revisions
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We have a "RepRap" Prusa Mendel printer which is quite an old model. However Ming Chu has recently been working on providing it with Octoprint capabilities. His instructions are here:

The printer is currently assembled, her motors and electrics all work and has been running prints for a while with some good successes. This printer might be better for printing with flexible filament than the Ultimakers.

See Calibration for tips on how to choose the correct settings for a new filament colour or type.

Picking Your Design

The best website to use when looking for 3D printing files is You are looking for an "stl" file so that it works on the RepRap. When you have found a design you like click on "Download this thing". We recommend starting of with a design with the least amount of components as possible. Right click on the stl file and select "save link as", save it in a place you can refer to later.


Slic3r is a free software we use to convert stl files to the GCode that the printers uses. You can download the software of Slic3r. After downloading this you also want to get hold of a copy of the printer settings. Depending on the colour of the plastic, the settings may have to be altered slightly, go to and choose which setting you want. Click on the "pla" file and then press raw. Right click and press save page as, save it in a sensible place.

Now go onto Slic3r. Go to file,load config. Load the ini. file, Slic3r now knows what printer settings you want. Remember that stl file you saved earlier? You need to drag and drop that into the space under the tab "plater". You have three other tabs "print settings", "filament settings" and "printer settings". These allow you to change what the printer is going to do. If you go to file, preferences and change the mode to expert you can change the settings and save them separately. has a good description of some of the settings you might alter, and why.

Once you have done this you are nearly ready to print. Press export Gcode and save it to doesliverpool, dropbox, DoES-laser.

Printer Interface

Now go onto the latop next to the printer. Open Printer Interface, and load the file from the DoES-Laser folder. Press Connect and then Print. The printer will warm up first and then begin. In some cases the plastic may not come out straight away, simply get rid of the excess plastic and click restart. Allow to cool at the end to get the best finish.

Detailed Settings

For a good starting point for refining your own prints use the following settings in Slic3r.

Print Settings

Layers and Perimeters

  • Layer height: 0.3mm

  • First layer height: 0.4mm Infill

  • Fill pattern: rectilinear

  • Fill density: 0.2-0.6 (20-60%)

  • Infill every: 1 layers

  • Fill angle: 45⁰ Speed

  • Perimeters/Small Perimeters: 30 mm/s

  • External Perimeters: 100%

  • Infill: 60 mm/s

  • Travel: 130 mm/s

Filament Settings

'''White ABS'''


  • Diameter: 2.9mm

  • Extrusion multiplyer: 1

  • Extuder temp

  • First Layer: 217⁰

  • Other layers: 212⁰

  • Bed temp

  • First Layers: 115⁰

  • Other layers: 110⁰ Cooling

  • Enable cooling: On

  • Fan speed: min. 35%, max. 70%

  • Enable Fan if layer print time is below: 40 seconds '''Black ABS'''


  • Diameter: 2.9mm

  • Extrusion multiplyer: 1

  • Extuder temp

  • First Layer: 235⁰

  • Other layers: 230⁰

  • Bed temp

  • First Layers: 115⁰

  • Other layers: 110⁰ Cooling

  • Enable cooling: On

  • Fan speed: min. 35%, max. 70%

  • Enable Fan if layer print time is below: 40 seconds

Printer Settings


  • Bed Size: 200 × 200 mm

  • Print Centre: 100 × 100 mm Extruder 1

  • Nozzle Diameter: 0.4mm

  • Retraction Length: 1mm

  • Lift Z: 0.1mm


  • To get quicker prints, you can easily make them hollow by setting the Fill Density in Infill on the Print Settings tab to 0
  • If you're having problems with the model not sticking to the bed, increase the bed temperature, cleaning the bed (wipe it down with some acetone on a paper towel), or applying fresh kapton tape to the bed.
  • If you have problems with smaller areas losing definition, turn on cooling in the filament settings.
  • It should be possible to have the print run fine without any problems. The main issue is usually with getting the first layer down cleanly. You can fine-tune the "zero height" of the bed by twisting the microswitch for the Z end-stop. Rotating it ~10 degrees will make a noticeable difference to where the extruder stops when the Z-axis homes.
  • You can run at a finer layer-height than the default 0.3mm if you want finer prints. Generally leave the first layer at 0.3mm as that's more of a tolerances for hitting the bed just right, and tweak the other layer-height value in Slic3r. 0.2mm or 0.15mm work pretty well, 0.1mm is possible, but an initial test wasn't amazing.


threadlock on everything?

z connectors threadlock isues.

z stop problems

reread last bits of manual for stepper controller caleberation etc.

work out if there is an actual problem with the filement feed or whether it's meant to be like that.

finish wireing routing and case up electicals

work out some way of maintaining sync between z motors like optical flags somewhere or something

Notes from playing with it 28/8/2012

Bed isn't quite flat The X/Y axes aren't running true - if you print a 20x20mm cube one side is almost 20mm, and the other more like 18mm (IIRC) - we've tightened the "top" belt (the x-axis) to try to compensate for that

The X axis is mirrored (which we knew)

Finishing has a good collection of ideas and techniques for finishing and post-processing your 3D prints


(This will probably move onto its own page sometime when we get things more organised here)

  • 20130104 - AdrianMcEwen - Removed printrun-gui package and installed pronterface, because a package update had broken printrun-gui (and the recommended option to install on newer Ubuntu versions is now to use pronterface instead)
  • 20130317 - PatrickFenner - The x-axis is now flipped so it's correct.

3d Filament

Obviously, from time to time our filament will run out - either that, or you might want a particular colour. If you want to purchase filament, you can do so from

RepRapPrusaMendel Calibration

Tips on how to work out the right settings in Slic3r when you put a different colour or different type of plastic filament into the RepRapPrusaMendel. Of course, once you've worked out the settings, add them to the RepRapPrusaMendel page.

General Process

  1. Measure the diameter of the filament in a number of places (including around the filament, in case it's oval rather than truly round)
  2. Use the average of your measurements in the config wizard, along with 0.4mm nozzle and a starting temperature for the type of plastic
  3. Print off test of [ _40x10.STL (I think the link is correct, remove this comment if it is the same as the prints in the photo below...)] single-wall test
  4. Repeat with different filament temperatures, diameters, and heated bed temperatures until you have a good result. And make notes of what you learn on here to make the next filament calibration easier :-)

Spotting Problems (and Correcting Them)

Heated Bed Temperature Too High

The print on the left has the correct bed temperature - note the (pretty much) straight vertical wall. The rightmost print has the bed temperature far too high (making the ABS very hard and brittle). The middle one has the temperature in between.

Extra Cooling Required

TODO: Take photo of the white Liver Building prints - one with clean towers (with cooling) and one with warped towers (without cooling)