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CNC mill JarBeRi

CNC Mill by Jarni, Benedik, Richard

Workflow:

Links: 

https://cloud.tu-ilmenau.de/apps/files/files/104312242?dir=/Benutzer/CNC%20JarBeRi

3D modeling:
  • Everyone is working on their subassemblies.
  • Work in private directories
  • Upload versions to the shared folder

Design decisions:

General

Standart PCB Sizes:

  • metric: 150mm*100mm
  • imperial: 127,38mm*102mm (5inch * 4inch)

Material Goals:

  1. PCB milling very precise
    • 0,4mm traces
  2. Engrave stone 
    • soft limestone

Work Table (fixed)

  • 160mm*120mm
  • 15mm? height

Outer Dimensions: (might change based on final design)

  • 350mm width
  • 300mm depth
  • ? height

Assembly Groups:

Mechanical:

Y-Axis: (Jarni)
  • leadscrew: trapezoidal thread T8
    • two T8 nuts countered for minimal backlash
    • new stepper + axle coupling
    • preferred: prusa stepper axle assembly
    • bushing for trapezoidal axle
  • guiding rods
    • 8mm
    • linear bearings
  • sled
    • 3d printed part, maybe milled aluminium
    • support structure for lower bed
  • interface plate
    • holes for T-Slot nuts
    • friction fit for guiding rods
X-Axis: (Benedikt)
  • leadscrew: trapezoidal thread T8
    • two T8 nuts countered for minimal backlash
    • new stepper + axle coupling
    • preferred: prusa stepper axle assembly
    • bushing for trapezoidal axle
  • guiding rods
    • 8mm
    • linear bearings
  • sled
    • 3d printed part
    • connected to z-axis
  • interface plate
    • holes for T-Slot nuts
    • friction fit for guiding rods
Z-Axis:
  • manual adjustment with screws
  • flexure mechanism
Machine Bed (work table):
  • upper bed: (waste board)
    • HDF/MDF
    • screw holes for fixturing?
lower bed: steel or aluminium
  • connect upper bed and lower bed with screws
Spindle and Spindle Mount: 
    which BLDC motor?  BLDC motor treaded inserts for the mount spindle collet
      high strength ABS 3d print  mill out of aluminium
      Frame:
      • use existing: ITEM Profile 6 30mmx30mm (0.0.419.06)
      • IMG_4269.jpeg
      • vertical: 60*30 extrusion
      • horizontal: 30*30 extrusion
      • additional support by steel wires for structural rigidity 
      • T-Nuts

      Electric: 

      • human interface 
        • housing
        • display
      • powersupplypower
        • lab bench powersupply
        • cables 
      Motors
        Stepper Motor 
          plugs mechanical coupling Spindle Motor
            BLDC BLDC driver board Endstops
              microswitches

              Software:

                search for: 
                  Arduino mega software motor drivers libraries uns Fusion360 for 3D model -> nc code

                  Project Progress / Docu:

                  First Idea to Sketch:

                  On Thursday, the day after the Mechanical Design and Machine Building lecture we decided to form groups in our local lab. It wasn't easy to form a group in the first place but after longer discussion we formed a group of three: Jarni, Benedikt and Richard. 

                  We wanted to build a use full tool for our lab and get some redundancy for our existing CNC the Carvera Makera. Machines often have issues or have downtime due to maintenance thats why it is use full to have a backup if something goes wrong with the Carvera mill. For us building a X-Y-Z computer controlled coordinate system was a completely new topic, what made this project exiting in the first place. We took our existing machines in the lab as a reference and did some research online about homemade CNC's. We checked the following: 

                    Carvera Makera  Prusa MK4s printers Pico V2 milling machine  Ferdis existing knowledge on CNC's

                    Ra

                    What ist RapRep?

                    RepRap is humanity's first general-purpose self-replicating manufacturing machine.

                    RepRap is openSource soft- and hardware framework that has many derivitives  and versions. For our project we used the standart RAMPS 1.4 board and a Arduino Mega.

                    RAMPS board

                    We used the offical documentation of the RapRep

                    Functions we need: 

                      Endstops

                      Functions we do not need: 

                        Heatbed controll Hotend controll
                        Endstops

                        official Wiki RepRap - Endstops

                        RAMPS 1.4 offers no pull-up circuits, current limiting resistors or other protections.

                        Wiring improperly an endstop that uses 5V may damage an IO port on the ATmega 2560 or the Arduino itself, this is a particular issue with clones of the Arduino ATmega2560.

                          put pull up and pull down resistors close to the board

                          In firmwares a setting is available to enable or disable built-in pull-ups, for example in Marlin you have the ENDSTOPPULLUPS constant in configuration.h, this option is enabled by default.

                            different Endstop versions are available usually PCB mounted

                            Motors are a common source of noise. Keep endstop wiring away from motors or use strategies like twisted cables or or used screened cables to reduce the noise.

                            Firmware
                              use Marlin Firmware

                              idea list:

                               

                              component list: mechanical structural: - alu extrusion 20*20 moving: - 2x 8mm leadscrews with brass nuts - 4x 8mm guide rails - electrical: mechatronic: manufacturing methods:

                              • milling parts

                              Links:

                              • https://marlinfw.org/

                              • design decicions:

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