Prusa Mendel

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Prusa Mendel

Release status: working

If you are building this machine using SAE (imperial) fasteners, see also SAE Prusa Mendel.

Prusa Mendel does less. But what it does it does better. It's a pure 3D printer.

  • If you want to pay more for a cool brand and worse quality, buy a Makerbot.
  • If you want a printer that will last forever, buy a Shapercube.
  • If you want to use linear bearings, go ahead and modify it.
  • (I've been corrected that Prusa and Sells are both crappy for milling; if you want to mill, check this out.) If you want to do milling, its probably not as good as Sells Mendel in case of milling more then PCBs.

Prusa's main goal is to be the purest and simplest 3D printer you can build.

  • It's much simpler to build it.
  • It's much simpler to modify it.
  • It's much simpler to print it for your friends.
  • It's much simpler to repair it.
  • Because of small complexity, it can be living thing. I update it all the time. It's unique feature but it should be standard. We are living in feature, we don't care if it's a bit different every time; our printer will print it in same time ;-)

Prusa Mendel is the Ford Model T of 3D printers.

The Prusa Mendel is a simpler remix of the original Mendel. It uses bushings instead of regular bearings. The current version uses three 608 bearings in total, one for the X axis and two for the Y axis. The 624 bearings are gone altogether. I have the entire machine up and running, with printed PLA bushings. It's pretty smooth.

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Development

The development of the Prusa Mendel is hosted on github: http://github.com/prusajr/PrusaMendel.

You can follow the changes on Changelog.

You can sign up for github for free and fork the project to begin working on it.

History

Bill of Materials

Printed Parts

Quantity Description Type Comments Diagram
2 coupling RP Pm-coupler.jpg
3 endstop-holder RP Pm-endstop-holder.png
1 x-carriage RP Pm-x-cariage.jpg
1 x-end-idler RP Pm-x-idler.jpg
1 x-end-motor RP Pm-x-motor.jpg
1 y-motor-bracket RP Pm-y-motor-bracket.jpg
2 z-motor-mount RP Pm-z-motor.jpg
4 belt-clamp RP Pm-belt-clamp.jpg
8 bar-clamp RP Pm-bar-clamp.jpg
2 rod-clamp RP Pm-rod-clamp.jpg
2 pulley RP Pm-pulley.jpg
4 frame-vertex with foot RP Pm-frame-vertex-foot.jpg
2 frame-vertex RP Pm-frame-vertex-footless.jpg
12 pla-bushing RP-PLA check your build file, the file makes either 4 or 12 Pm-bushings.jpg

Non-Printed Parts ("vitamins")

Note that additional parts are required for the extruder, although some extruder parts are included in the table below.

Required
Quantity Description Type Comments
83 M8 nut Fastener Buy a 100-pack to be on the safe side.
93 M8 washer Fastener Buy a 100-pack to be on the safe side.
6 M8×30 mudguard / fender washer Fastener
2 M4×20 bolt Fastener
2 M4 nut Fastener
2 M4 washer Fastener
22 M3×10 bolt Fastener
16 M3×25 bolt Fastener Or eight M3×25 bolt plus eight M3x20 bolts. The M3x25 bolts are too long for the recent Prusa z-motor-holder and rod-clamp, and also for the Z motor couplings. See Section 8, steps 4 and 13 for details.
4 M3×40 bolt Fastener
70 M3 washer Fastener
40 M3 nut Fastener 8 optionally locknut / stop nut / nyloc
2 M3 grub screw / set screw Fastener M3x8 seems about ideal but anything 6mm or longer should do
3 608 roller skate / inline skate / skateboard bearing Bearings
4 ballpoint pen springs Spring To fit over M3 bolts. Ballpoint pens are a common, cheap source of suitable springs. They are about 25mm long and compress to about 10mm.
6 M8×370mm Threaded rod 3 per side
4 M8×294mm Threaded rod front / rear
3 M8×440mm Threaded rod top / bottom
2 M8×210mm Threaded rod Z-leadscrew
1 M8×50mm Threaded rod or M8x30 or longer bolt for X idler. Take care: if the bolt is too long, it may not be threaded along a sufficient length
2 8mm×495mm Smooth rod X-bar (consensus seems to be that this is too long, and 420mm might be a better length, but this still requires confirmation from a finished builder. [As a "finished builder" I can confirm 420mm would be better.])
2 8mm×406mm Smooth rod Y-bar
2 8mm×350mm Smooth rod Z-bar
1 225mm×225mm print top plate Thick Sheet
1 140mm×225mm print bottom plate Thick Sheet
1 840mm×5mm T5 pitch timing belt Belt
1 1380mm×5mm T5 pitch timing belt Belt
5 NEMA 17 bipolar stepper motor Stepper Be sure to get ones with ~20mm of shaft length. Shorter shafts require modifications to the X pulley assembly and Z motor couplers. One of the five motors, for use with the extruder, should be capable of creating a holding torque of at least 40Ncm.
50 small cable binder / ziptie Misc
1 Wade's Geared Extruder for 1.75mm filament RepRap Universal Mini Extruder; or any other compatible extruder for either
1 Electronics + endstops This can be RAMPS, Pololu Electronics, Gen6, Gen7, Gen3, or anything else compatible. Endstops are either optical switches or microswitches, three of each.
Optional
Quantity Description Type Comments
3 30mm×10mm Optoflags Thin Sheet if using opto endstops
2 8mm ID spring Spring to eliminate backlash in the z axis
1 object with precisely 290mm length for frame alignment
1 object with precisely 234mm length for frame alignment

You can combine the latter two by having a piece of thick sheet with dimensions 290mm×234mm. Make sure to mark which side is which.

When cutting the threaded rods from 1m lengths, you will need 6x1m pieces (or 5x1m pieces and 1x50cm piece). Cut them as follows:

 Rod 1: 370mm, 370mm, 210mm, ~50mm (The last piece will end up somewhat shorter than 50mm. Use it for your idler. Alternatively, an M8x30 or longer bolt can be used.)
 Rod 2: 370mm, 370mm, 210mm, ~50mm
 Rod 3: 370mm, 294mm, 294mm, ~42mm
 Rod 4: 370mm, 294mm, 294mm, ~42mm
 Rod 5: 440mm, 440mm, ~120mm
 Rod 6: 440mm

The Prusa Mendel uses the 4 drivers in the standard Mendel electronics package to drive 5 motors by using "two steppers wired in parallel to one driver" [1].

Where To Purchase

See the Mendel Buyers Guide for information on where to purchase all of the parts needed.

Printing the Parts

A printed set of Prusa Mendel parts

Printing a Prusa on a Mendel

An easier option then individually printing each part if you are printing Prusa on a RepRap Mendel is the pre-assembled build file containing the Prusa parts. With this option you only need to print the Mendel plate and the PLA bushings to get a complete Prusa Mendel:

Printing a Prusa on a CupCake CNC

There are also pre-assembled build files available to fit your CupCake CNC's build area (download using right click => save as)

Note:

  • These plates are 85x95mm in size.

Plates for the MakerBot (the plates have changed, these print times are no longer accurate):

Printing a Prusa on anything else

Last but not least, if you have a machine that doesn't fit into any of the previous options all the .stl files necessary to print a Prusa Mendel are available on the PrusaMendel Github where you can download them and print them individually.

Buy the printed parts

Mendel_Buyers_Guide#RepRapped_Parts_Kits

Assembly

Assembly instructions >> Prusa Mendel Assembly.

Media

Prusa Improvements/Hacks

  • Rob's Auto-centering shaft coupler - designed to reduce shaft/motor vibrations (print 2/replaces 2x coupler). May require widening the openings on the z motor mounts to allow the rotation of the zip tie. Use a zip tie gun to get maximum compression on the coupling.

See Also

External Links