3D Printer decisions
3D Printer decisions

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)
Contents
Printed Parts
(Iteration 2)
Frame and motors
Quantity | Description | STL model | Status |
---|---|---|---|
4 | frame corner with foot | [1] | to be printed |
2 | frame corner | [2] | to be printed |
8 | bar clamp | [3] | to be printed |
2 | rod clamp | [4] | to be printed |
4 | belt clamp | [5] | to be printed |
2 | belt clamp nut holder | [6] | to be printed |
1 | X-axis carriage | [7] | to be printed |
1 | X-axis idler holder | [8] | to be printed |
1 | X-axis motor holder | [9] | to be printed |
1 | Y-axis motor holder | [10] | to be printed |
4 | Y-axis bearing holders | [11] | to be printed |
2 | Z-axis motor holder | [12] | to be printed |
2 | Z-axis coupling | [13] | to be printed |
2 | belt gear pulley | [14] | to be printed |
3 | endstop switch holder | [15] | to be printed |
Extruder (print head)
Quantity | Description | STL model | Status |
---|---|---|---|
1 | Wade's extruder body (2 parts) | [16] | to be printed |
1 | large gear | [17] | to be printed |
1 | swall gear | [18] | to be printed |
Non-printed parts:
Frame and motors
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)

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 |