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

Intro

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.

Status

Frame is built! Next up: axes. And we have electronics, mobo flashed with sprinter fw, use pronterface to interface with it. Have to wire in steppers to finish.

Materials for the build

BOM for Prusa Mendel

Quantity	Description	Type	Comments
83	M8 nut	Fastener	READY
93	M8 washer	Fastener	READY
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
22	M3×10 bolt	Fastener	READY
8	M3×20 bolt	Fastener	(John) / cut down 25mm or use as is
8	M3×25 bolt	Fastener	READY
4	M3×40 bolt	Fastener	(John) / cut down 50mm or use 35mm
70	M3 washer	Fastener	READY
40	M3 nut	Fastener	READY
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...)
1	Printed parts		READY

John

• 1x RAMPS 1.2
• 5x steppers
• 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

1x Prusa PCB HBP Mk1

Offers

• Alden has a Tiny G board... this is attractive
• Andy has fresh smooth and threaded rods to swap for all the rusted rods

How to flash firmware

• download Arduino23 from arduino.ccunzip the arduino package
• get the latest Sprinter fw from https://github.com/kliment/Sprinter or Marlin fw from https://github.com/ErikZalm/Marlin
• open up Arduino and open the fw of choice (select either Sprinter.pde or Marlin.pde)
• edit the configuration.h file to list a motherboard type of 21 (make sure right thermistor settings are chosen as well)
• plug in RAMPS 1.2
• set the board to Arduino Mega 2560 under "Tools"
• set Serial Port to appropriate port
• save/compile/upload the sketch

How to connect and control the printer

Download latest PrintRun from http://koti.kapsi.fi/~kliment/printrun/ for Win/Mac (precompiled), https://github.com/kliment/Printrun: Linux

• If running Linux version, checkout the Readme for dependencies
• If you dled for Win/Mac from link above, all dependencies are built in (INCLUDING Slic3r!)
• fire up pronterface.py
• set the serial port to one which RAMPS is connected
• make sure baudrate is set to appropriate setting (set in FW)
• 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 slic3r in the gui, or load up a gcode file you're already processed with other slicer

To do

PSU: Done 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: tip120 replacements are attached to the board in case the current ones die or if someone has time to do the replacement. 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.