Heated build plate (pre-) mounted

Birds-eye view of the build platform

Today I mounted the build platform, to check for dimensions and fit of the heated build plate PCB. Looks good. I need to increase the diameter of the mounting holes to compensate for the thermal expansion of the heat bed PCB. I am still looking for a viable insulator material between the heat bed and the wooden carrier plate.

Side view

Also, I need some good idea on how to mount the glass pane onto the build plate.

Y axis endstop flag

Y endstop flag - mounted

When planning my Mendel I decided to use optical endstops. I did not find any solution I liked for triggering the Y endstop within 10 minutes of googling, so I decided to hack one up in OpenSCAD myself. It's just a quick hack, admittedly, but it's the first simple part I made myself.

You can find it on Thingiverse, as well as my Github mendelparts repo that will hold all other custom parts I feel to create.

Y-axis is moving, kind of

Stepper is moving the Y-axis

As a first result, the Y-axis actually is moving. Well, kind of. As Kliment already pointed out, the steppers are too weak. It was worth a try. I now ordered steppers with .43 Nm torque. This should suffice. Until they arrive I will have to figure out how to fasten the tiny T2.5 pulleys on the 5mm stepper shafts.

Tomorrow I'll print some more plastic parts.

Little baby steps... ;)

Building my Prusa Mendel

I decided to build the Prusa in October.

It will run on a RAMPS 1.4 with Sprinter.

RAMPS 1.4 with Sprinter and 4 Pololu stepper drivers, ready to use

There are several customizations I planned to implement. Here's a quick list for the plastic parts:

Already printed parts:

• most parts from the standard Prusa v2 set (LM8UU)
• integrated Z motor mount by theodleif
• Accessible Wade extruder by GregFrost; well, I bought an assembled hotend/extruder kit from Wolfgang, who changed the gear ratio to 9/47 for more torque. Wolfgang's hotends rock, several people around hackffm have one, so I simply got one
• triffid_hunter's endstop holder
• ElijahPost's Y motor mount with integrated belt tensioner

Still todo:

• macsboost beefy X-carriage with LM8UU bearings (derived from GregFrost's X-carriage)
• raldrich's Z-coupler with 4 grub screws
• custom Prusa X-ends with 17mm funnel for trapezoidal spindle bearings

As of today the frame and Y-axis is mounted and mechanically tested

Frame with adjusted Y-axis

Y-carriage mounted

The stepper pictured above is a Nanotech, which I got several from eBay for cheap. Mounting the molded pulleys made from acetate is a breeze with these motors. The motor got a M4 threaded hollow shaft. The pulley got a 3.5mm center bore. So I cut a M4 thread into the pulley and crewed it to an M4 threaded rod that is countered by a nut on the opposite side of the motor. Easy going.

Since I forgot to print the LM8UU holders for the Y-carriage, I measured the rod position precisely and drilled 5mm holes into the carriage to hold the linear bearings with zip-ties. Works like a charm.

As you can see there's only one Z motor mount installed. The next part I'll print is the second Z mount. The the spindle couplings, the X-ends, the carriage (in this order).

and it started with... a wooden Mendel

wooden Sells Mendel

This is a wooden RepRap Mendel made from laser-cut plywood. It was built over the course of several months by members of AUGE e.V. Frankfurt and Hackerspace FfM.

While being cut very precisely the plywood changes shape and volume according to temperature and humidity. This means that adjusting the whole system from bearings to zero-points of the axes is imperative before printing. The mechanics of the extruder also showed heavy wear after a few printing sessions.

The electronics used are RepRap Gen3 with serial extruder controller board. Driving the extruder via the second controller over a serial link using non-shielded cabling introduces several sources for malfunction to the system. Furthermore, being controlled over a serial protocol, the extruder produces stalls in movement of the X and Y axis when the main controller needs to wait for the extruder to complete commands.

I solved this via Kliment's excellent Gen3+ that integrates two input channels for thermistors, two MOSFET-driven power outputs and a Pololu Stepper Module (Allegro A4988) onto the main Gen3 electronic board.

Gen3 electronics with Gen3+ daughtercard and mounted Pololu module

Running this controller configuration with the Sprinter firmware yields usable results.

it's printing!

The wooden Mendel was then commisioned for printing stuff at the Hobby&Elektronik fair in Stuttgart.

Building a reprap

I am following the development of RepRap since quite some time now. Being a member of Hackerspace FfM, thus having access to some tools and resources I do not have at home, I decided to build a Prusa Mendel earlier this year. Coming up: some documentation on how the machine is coming to life.

Hello world

byteborg's got a blog