Prusa Mendel Documentation
A new reprap printer will built along the lines of the Prusa Mendel. You can find details of the Prusa design at the Prusa Mendel page on the reprap wiki, or you can view the sources for the Prusa at github
Having another 3d printer in the space will allow us to always have a working machine and to use one machine to help fix another if there are problems. It will also enable several people to print things out at the same time. The goal is to document this build so others can make their own printer following our documentation.
Frame is built! Next up: axes. And we have electronics.
Materials for the build
BOM for Prusa Mendel
|6||M8×30 mudguard / fender washers||Fastener||READY|
|2||M4×20 bolt||Fastener||(John) / or use M5x20|
|2||M4 nut||Fastener||(John) / or use M5|
|2||M4 washer||Fastener||(John) / or use M5|
|8||M3×20 bolt||Fastener||(John) / cut down 25mm or use as is|
|4||M3×40 bolt||Fastener||(John) / cut down 50mm or use 35mm|
|2||M3 grub screw / set screw||Fastener||READY|
|3||608 roller skate / inline skate / skateboard bearing||Bearings||READY|
|4||ballpoint pen springs||Spring||READY|
|6||M8×370mm||Threaded rod||3 per side - READY (Thanks Mark!)|
|4||M8×294mm||Threaded rod||front / rear - READY 4 x 340 (Needs cutting)|
|3||M8×440mm||Threaded rod||top / bottom - READY|
|2||M8×210mm||Threaded rod||Z-leadscrew - READY 2 x 300 (Needs cutting)|
|1||M8×50mm||Threaded rod||or bolt for X idler - READY|
|2||8mm×420mm||Smooth rod||X-bar - READY|
|2||8mm×406mm||Smooth rod||Y-bar - READY|
|2||8mm×350mm||Smooth rod||Z-bar - READY|
|1||225mm×225mm print top plate||Thick Sheet||(space)|
|1||140mm×225mm print bottom plate||Thick Sheet||space|
|1||840mm×5mm T5 pitch timing belt||Belt||READY|
|1||1380mm×5mm T5 pitch timing belt||Belt||READY|
|5||NEMA 17 bipolar stepper motor||Stepper||READY|
|50||small cable binder / ziptie||Misc||READY|
|1||Wade's Geared Extruder||READY|
|1||Electronics + endstops||READY (though I, Xaq, am still curious about TinyG...)|
1x gen3 mobo 2x gen3 EC 5x steppers 4x stepper controllers (we'll have to pull these from the cupcake and have the cupcake use the mbi ones) 1x p4ac 4 axis stepper controller carrier board (we'll have to pull this from the cupcake too) 1x wade's extruder (assembled and working) 1x 36mm brass barrel 1x 0.5mm mbi nozzle 1x 0.5mm makergear bighead nozzle Insulator materials (have to make and document on lathe) nuts/bolts/washers - I have tons plywood/mdf for build platform
Heated Build Platform
If we want it, can get away with some other hacks if we want, or leave it out altogether.
Alden has a Tiny G board... this is attractive
How to flash firmware
download arduino18 from arduino.cc (sanguino extensions appear to only work with 18) download the sanguino extensions from sanguino.cc unzip the arduino package unzip the sanguino package and copy contents to the hardware folder in the arduino folder you unzipped. get the latest sprinter fw from https://github.com/kliment/Sprinter fire up arduino and load the sprinter sketch edit the configuration.h file to list a motherboard type of 21 plug in the gen3+ motherboard to your laptop with a usb-ttl ftdi cable. set the board to sanguino in the tools in arduino. set the serial to the port in use by the ftdi cable save/compile/upload the sketch
How to connect and control the printer
Download printrun from https://github.com/kliment/Printrun make sure you have python installed, or follow instructions at the url above fire up pronterface.py set the serial port to the one used by ftdi cable click connect to printer button you should see confirmation of printer connection in the monitor box on the right load stl and slice it with sfact in the gui, or load up a gcode file you're already processed. SD printing should work too.
PSU: The electronics need an ATX supply (200W minimum probably, 350-700W+ would be needed if we run a heated bed) to power the mobo, and we'll need to hack out a 12V and a 5V line to connect up to the larger perfboard electronics that run the extruder/heatbed (these should be on a 12v2 rail on newer psu). I've got some connectors to do this the next time I'm in the space, or we can just cut the connectors off of the atx wires. Steppers: The P4AC 4 axis board will need to be pulled from the cupcake, and the XYZ connected to the mobo. (we'll need another 10pin idc cable. the current rainbow cable on the gen3plus setup is the X stepper cable from the cupcake stepper controller and will have to go back once we swap out the p4ac to the mendel. I have some 10pin idc cables at home I will bring in to replace the one in the gen3plus) I have the 4th pololu in the larger perfboard, but I can easily drop in a 10pin idc header so that we can have all the pololus on the one board, which I'll do the next time I'm in the space. Mosfets: The Nchannel Power Mosfets on the larger perfboard were ones I got from radioshack, so I'm not sure if they'll be able to run the heated bed, but they should be fine for the extruder. I have proper 50V 10A mosfets I can swap in place the next time I'm in the space or if the ones in there right now fail. Motor Connections: The motor wires need to be connected to the pololus. Any 4 conductor cable should work fine. I have solid core 4 conductor wire I used on my bot at home, but the single conductor is a bit fragile and I'd recommend a nice stranded set instead. I have matching molex connectors and crimps so the connection to the p4ac board is via a plugged connector instead of soldered in or done with some other hacked connector. Endstops: The ends stops need to be hooked up. The p4ac board has breakouts for the endstops, so just need to wire up microswitches on to that board. only need two wires to each switch, signal to the COMmon contact and GND to the NO (normally open) contact, the firmware uses internal pullups for the endstop pins.