Mendel90 Lasercut - Overview

Thanks for all the interest we have been getting for the new Lasercut Mendel90! This post is to give an overview for those new to 3D printers and answer questions about how easy the M90LC is to assemble. It is not designed to replace the detailed assembly instructions and user manual which are now awaiting final feedback from our beta testers before being published.

Printer Overview

The Mendel90 Lasercut is a RepRap printer: there is much more information about RepRaps in general on the wiki but in summary it is a printer which can print the plastic parts that go into its assembly along with many other interesting and useful things. To get an idea of what people are using RepRap-style printers for, a good place to look is Thingiverse. Most CAD and 3D design software can export ".stl" files which the printing software uses to generate print instructions. The printer works by laying down layers of plastic, one on top of the other, to build up an object, in a process called fused filament fabrication.

The Mendel90 lasercut has a build area of 200mm x 200mm x 200mm and comes with a single 0.4 mm extruder nozzle which can reliably print layers as thin as 0.1mm. With a smaller extruder nozzle it can reliably print as low as 0.02mm.

Looking at the printer from the front, the Mendel90 LC axis are X left and right, Y backwards and forward and Z up and down. The print head is in the 0,0,0 position when it is fully to the left (X=0), the heatbed is fully to the back (Y=0) and it is just touching the surface of the glass on the heatbed (Z=0). The "homed" or parked printhead position is at 200,200,200.

The main components of each axis are:

The frame parts are the base, portal, buttresses, back-top and extruder "sandwich" (for potential future developments) 

  

The electronics are mounted at the right buttress along with the power supply unit. They support the addition of other types of electronics in future upgrades.

General points

• The printer is made up of sub-assemblies which need to be completed before each major part of the printer is assembled. The sub assemblies can, in general, be worked on in parallel if more than one person is assembling the printer, reducing the build time.
• The printer design in regularly updated, so refer to the manual that is distributed with your printer for the most up to date instructions.

The next section will provide an overview of the assembly process

Tools

• Spanners/sockets:  5.5mm, 7mm & 13mm.
• Allen keys: 1.5mm, 2mm, 2.5mm, 3mm
• PZ 1 Pozidriv screw driver and 2mm slotted screwdriver
• Digital callipers
• Lithium/PTFE grease, glass cleaner (acetone recommended).
• Multi-meter (optional) 

X axis sub-assemblies

The X Idler and Motor brackets are the interface between the X axis and the Z axis and are the most complex sub-assemblies.

 

X Idler

 

X Motor

The X Carriage runs on the X rods between each motor end, and the extruder and fan are attached to it

X Carriage

Extruder Fan

Extruder

 Y axis sub-assemblies

 In comparison the Y axis and its sub assemblies are simpler.

Y Idler

Y Motor

Y Carriage

 Z axis sub-assemblies

 Similarly the Z sub-assemblies are quick to put together.

Z Endstop

Z Motor Boxes

 

Z Top Brackets

Frame Assembly

Once the sub assemblies are done the frame slots together using square captive nuts and M3 fasteners.

First the buttresses, back-top and extruder "sandwich" are assembled:

Then the portal and motor boxes are added:

Finally the base and the aluminium channels are fixed on:

 The assembled frame:

 Y Axis Assembly

The Y Axis runs along the base and is the first axis to be assembled onto the frame, starting with the bar clamps

Then the motor, rods and the Y axis assembly are added. This assembly sequence allows for the belt to be a pre-set length and for the rods clamps to be tightened with the axis in place to ensure it runs true

A heat shield is added before the bed is fixed above it.

Note how the electrical connections are pre-terminated for quick assembly. Strain relief is built into all the parts where required and ribbon cables are formed into defined and controlled bends between all moving and static cable attachment points.

 Z and X Axis Assembly

As noted earlier, the X Axis idler and motor brackets are the interface between the Z and X axis and these axes are assembled together.

First the Z top brackets are fitted, then the smooth rod is fed down through the X axis idler and motor brackets.The X rods are slid through the X idler and the X carriage.

The Z axis screws are then added and the wiring tidied up,

  

before the extruder is mounted on the X carriage.

Electronics

By this point all the wires from each motor, endstop and the hotend and heatbed are routed through to the back right of the machine ready for the power supply and printer controller board to be fitted.

The Arduino board and the RAMPS are mounted on the hex pillar standoff before the wiring is plugged in.

At this point the printer is assembled and ready for calibration! This post is long enough already so I will do another one to cover calibration.

Update:  The source files on github for the Mendel90 Lasercut have now been modified to include changes to the X Idler and X motor brackets that makes them easier to print and more robust. This is one of a number of changes that have been incorporated from Nophead's latest update to the design.