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RepRap Prusa Mendel (Taken from Wikimedia user Julianh72)

We started a project to build and maintain a 3D printer. After some discussion on 16. June, we decided that we will build the RepRap Prusa Mendel, because it seems to be well suited for a Hackerspace, costs less than 200€ if we get the parts locally and from recycled parts.

The parts needed for the Prusa Mendel are almost entirely standard parts that can be found in almost any hardware store. These are mostly M8 thread rods, M8 screws and nuts, standard skateboard bearings, the common NEMA 17 stepper motor.

Here's a list of the parts needed (taken partly from the RepRap Wiki)

X,Y,Z Frame

Printed Parts

(Iteration 2)

Quantity Description Type Comments Printed
2 coupling RP stl[[1]] none
3 endstop-holder RP stl[[2]] none
1 x-carriage RP stl[[3]] none
1 x-end-idler RP stl[[4]] none
1 x-end-motor RP stl[[5]] none
1 y-motor-bracket RP none
2 z-motor-mount RP stl[[6]] none
4 belt-clamp RP stl[[7]] none
8 bar-clamp RP none
2 rod-clamp RP none
2 pulley RP none
4 frame-vertex with foot RP none
2 frame-vertex RP none


Non-printed parts:

Quantity Description Type Comments Available
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. (Grade 2 works fine.)
6 M8×30 mudguard / fender washer Fastener These are also known as penny washers, they have a much larger outer diameter than regular washers.
2 M4×20 bolt Fastener To mount the extruder
2 M4 nut Fastener To mount the extruder
2 M4 washer Fastener To mount the extruder
2 M3x8 screw Fastener Anything 6mm or longer should do. Even M3×10 bolts will do the job.
22 M3×10 bolt Fastener
8 M3×20 bolt Fastener The M3x25 bolts are too long for the recent Prusa z-motor-holder, rod-clamp, and couplings.
8 M3×25 bolt Fastener
4 M3×40 bolt Fastener
70 M3 washer Fastener
40 M3 nut Fastener 8 optionally locknut / stop nut / nyloc
3 608 (roller/inline skateboard) Bearings Standard wheel bearings.
4 ballpoint pen springs Spring To fit over M3 bolts. About 25mm long and compress to about 10mm.
6 M8×370mm Threaded rod 3 per side - Can be cut from larger 6x1m pieces (see Threaded Rod Cut Order below).
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×420mm Smooth rod X-bar - 304 Stainless Steel, A2 Tool Steel, or O1 Tool Steel are recommended for smooth rods as it can help to prevent friction from rust and manufacturing (straightness) standards are higher. Rust issues can be prevented on the normal steel rods by maintaining a coat of oil. The smooth rods can also be cut from larger 3x1m pieces (see Smooth Rod Cut Order below).
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 Note: The Prusa Iteration 2 design does not use a print bottom plate.
1 840mm×5mm T5 pitch timing belt Belt Y axis
1 900mm×5mm T5 pitch timing belt Belt X axis
5 NEMA 17 bipolar stepper motor Stepper At least 20mm of shaft length. One should have a torque of > 40Ncm. 13€ each
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, Sanguinololu, Generation 6 Electronics, Generation 7 Electronics, Generation 3 Electronics, or any other Mendel compatible electronics. End-stops are either optical switches or micro-switches (Recommended), and you need three, one for each of the X, Y, Z axes.

Extruder (Print-head)

Wade's extruder design (Taken from the RepRap wiki)

Printed Parts

Quantity Description Comments Printed
1 extruder block none
1 extruder idler block none
1 11 tooth drive gear none
1 39 tooth M8 hub driven gear none

Non-Printed Parts

Quantity Description Type Comments Available
Feeder
2 608 bearings, skateboard bearings Bearings
1 M8×50 bolt Fastener to be hobbed, M8×60 has a longer smooth part, allows a second lock-nut, and may be easier to find
1 M8 nut Fastener Nyloc works better, but a pair of nuts will also work
4-5 M8 washers Fastener to space the large gear clear of the motor retaining bolt heads
Idler
1 608 bearing, skateboard bearing Bearings
1 (M)8×20 Threaded rod
4 M4×60 or M4×45 hex head bolts Fastener Hex head will work best (they won't turn), and longer than 45 mm will be easier to assemble if you can find them.
4 M4 nuts Fastener typically wing nuts
8 M4 washers Fastener
4 ~4mm ID springs Spring Sized to fit over an M4 bolt, unsprung length of 10-12mm, each spring providing 25-35N load. For a given filament drive force, you'll need about twice the spring force - i.e., if you want 100N of filament drive, your springs need to push with about 50N each.
16 M4 washers Fastener optional; 4 washers on each M4X45 idler bolt between the main block and the idler block will limit the idler travel and make reloading filament easier.
NOTE: Some users have their extruders working without springs, but springs are recommended. A good source for these springs is in the cloth-cabinet on spring loaded skirt-hangers or trouser-hangers. Just cut the right length off the springs.
Hot End Mount
2 M3×35 bolts Fastener
4 M3 washers Fastener
2 M3 nuts Fastener
1 2.5mm drill See section Hot End
Stepper Motor Mount
3 M3×10 bolts Fastener Low profile bolt heads might work better here
3 M3 washers Fastener
1 M3 grub screw Fastener To secure the pulley, ideally 8mm long, but anything 6mm+ should be fine
1 M3 nut Fastener To secure the pulley
Stepper Motor
1 NEMA 17 bipolar stepper motors Stepper 5 kg*cm (=49 N*cm, 69 ozf*in) works well; Kysan 42BYGH4803 is what I used. Should be capable of creating a holding torque of at least 40Ncm (4.07 kgf*cm, 56.6 ozf*in), at the very least.
Extruder Mount
2 M4×20 bolts Fastener
2 M4 nuts Fastener
2 M4 washers Fastener

Electronics

The Generation 7 Board is easily self-made and extensible. It uses no SMD devices, needs only one layer of copper so it can be etched or possibly milled.

This list is ordered to match the order of assembly.

Electronic Components

Name Count Designations Vendors Remarks
0.6 mm Wire 50 cm Völkner Digi-Key Mouser for the wire bridges on single sided PCBs
Resistor 10 Ohms 2 R11, R12 Reichelt RS
Resistor 560 Ohms 2 R14, R22 Reichelt Völkner Farnell RS Digi-Key Mouser
Resistor 1 kOhms 6 R2, R6, R8, R10, R16, R18 Reichelt Völkner Farnell RS Digi-Key Mouser
Resistor 4.7 kOhms 2 RT1, RT2 Reichelt Völkner Farnell RS Digi-Key Mouser
Resistor 10 kOhms 1 R30 Reichelt Völkner Farnell RS Digi-Key Mouser
Diode 1N4004 2 D1, D2 Reichelt Völkner Farnell Digi-Key Mouser
Coil 100 uH 1 L1 Reichelt Völkner Farnell Digi-Key Mouser
Crystal 16 MHz or 20 MHz 1 U6 Reichelt Völkner Farnell Digi-Key Mouser
Reset Switch 1 RESET Reichelt Völkner Farnell Digi-Key Mouser
Ceramic Capacitor 0.1 uF 12 C5, C8, C9, C10, C11, C12, C13, C14, C16, C17, C18, C19 Reichelt Völkner Farnell RS Digi-Key Mouser
LED 3 mm Green 3 LED2, LED5, +5V Reichelt Völkner Farnell Digi-Key Mouser
LED 3 mm Yellow 1 Standby Reichelt Völkner Farnell Digi-key Mouser
Ceramic Capacitor 22 pF 2 C3, C4 Reichelt Völkner Farnell RS Digi-Key Mouser
Electrolytic Capacitor 10 uF 2 CT1, CT2 Reichelt Völkner Farnell Digi-key Mouser
Electrolytic Capacitor 100 uF 4 C1, C2, C6, C7 Reichelt Völkner Farnell Digi-Key Mouser
Jumper Header 2 Pin Pairs 4 pair J2/J3, J5/J6, J8/J9, J11/J12 Reichelt RS Digi-Key Mouser cut them into appropriate pieces
Jumper Header 2 Pin 2 J13, J14 Reichelt Völkner RS Digi-Key Mouser cut them into appropriate pieces
Jumper for the two above 9 Reichelt RS Digi-Key Mouser
ICSP Header 1 CONN6 Reichelt RS Digi-Key Mouser alternatively, assemble this out of the remainings of the Jumper 2 Pin Headers
Pololu Header 8 or 4 U2, U3, U4, U5 Reichelt Völkner Digi-Key Mouser cut them to appropriate length, you want 8x 8 pins
Socket for the ATmega 1 U1 Reichelt Völkner Farnell Digi-Key Mouser
ATmega 644 (or 644P) 1 Reichelt Farnell Digi-Key Mouser
Alternative: ATmega 1284P 1 Reichelt Mouser
MOSFET IRFZ 44N 2 Q1, Q2 Reichelt Völkner Farnell RS Digi-Key Mouser

Connectors

Name Count Designations Vendors Remarks
Molex KK100 2 Pin Header 2 TEMP1, TEMP2 Reichelt RS DigiKey Mouser
Cable Connector for the above 2 Reichelt RS DigiKey Mouser
Crimp Contact for the above 4 Reichelt RS DigiKey Mouser
Molex KK100 3 Pin Header 3 X_MIN, Y_MIN, Z_MIN Reichelt RS DigiKey Mouser Reichelt are tested to be fully compatible with Molex
Cable Connector for the above 3 Reichelt RS DigiKey Mouser
Crimp Contact for the above 9 Reichelt RS DigiKey Mouser same as for TEMP1, TEMP2 above
Molex KK100 4 Pin Header 4 X_MOT, Y_MOT, Z_MOT, E_MOT Reichelt RS
Cable Connector for the above 4 Reichelt RS
Crimp Contact for the above 16 Reichelt RS DigiKey Mouser
Molex KK100 6 Pin Header 1 SERIAL RS DigiKey Mouser alternatively, use the same as for Jumper 2 Pin
Optional: Cable Header for the above 1 RS DigiKey Mouser only needed if you intend to solder your own USB-to-TTL cable
Optional: Crimp Contact for the above 6 RS DigiKey Mouser only needed if you intend to solder your own USB-to-TTL cable
Heater Header Molex 26-48-1045 (2 Pin) 2 HEATER1, HEATER2 RS DigiKey Mouser
Cable Connector for the above 2 RS DigiKey Mouser
Crimp Contact for the above 4 RS DigiKey Mouser
Alternative to Heater Header: 2 Pin Screw Terminal 2 HEATER_1, HEATER2 Reichelt DigiKey Mouser
Disk Power Header 2 CONN2, CONN3 Reichelt RS DigiKey Mouser also see DIY 4 pin molex connector
ATX24 Power Connector 1 CONN1 RS DigiKey Mouser Molex Mini-Fit 44206-0007. Also known as VAL-U-LOK (20 or 24 Pins).
Heatsink for the MOSFETs 1 or 2 Reichelt RS DigiKey Mouser Please note that Reichelt ones are quite wide (18mm). Two of them won't fit.
Bolt M3 x 8 mm for mounting the MOSFET heatsink 1 or 2
Washer M3 for mounting the MOSFET heatsink 1 or 2
Nut M3 for mounting the MOSFET heatsink 1 or 2 Not needed for the Reichelt heatsinks, which come with an M3 tap already.
Heatsink for the Pololus 4 Reichelt Völkner RS
Heatsink Glue 1 Reichelt Völkner For the Pololu's heatsinks, cut in appropriate pieces. Loctite(-like) screw locking glue works well, too.

Miscellaneous

Generation 7 Electronics uses a TTL header for serial communications to the host. As many modern PCs lack a serial port, these need an appropriate USB to TTL cable:

USB to TTL Cable DigiKey Mouser Adafruit Industries MAKE Store MakerBot Industries Watterott

An alternative to the USB to TTL cable is the same electronics in form of a small breakout board:

USB to TTL Breakout Board Watterott Sparkfun
Cable for the above Watterott

Another alternative is the E'go USB-TTL adapter, see instructions and limitations below.

Last not least, you need four stepper drivers, of course:

Pololu stepper driver boards Pololu stepper driver boards
Open Source Alternative StepStick