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Gina

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Blog Comments posted by Gina


  1. The hotend heatsink cooling on this printer uses a radial fan without any ducting to concentrate the airflow through the fins.  To test that this would be adequate I made a small modification to the same part on my Concorde printer then checked the heatsink temperature when printing PETG at 240°C - it ran quite cool even with only half the heatsink being cooled.

    694768399_Screenshotfrom2019-12-0421-42-34.png.bdf5590864626122e467319ddc0f981f.png

    273408848_ExtruderHeatsinkCooling01.JPG.665cb9b4c38e3c2611121e71e7f77b79.JPG


  2. Now to work out what depth the printer needs to accommodate the extra Y dimension.  The full Y range can be produced with a 362mm Y bar and 2x 13mm thickness of mini linear rail.  This gives a total of 362 + 26 = 388mm.  To allow for tolerances I think I'll make this 390mm.

    Next to work out how this can be cut from the 900mm x 900mm x 18mm sheet of plywood.  The inside width has already been determined as 410mm.  Since the back, front and base fit inside the sides, this will be the cut width.  Overall height of the box (outside) will be half the height of the ply less cutting, so a little less than 450mm.  Width of the side panels will be 390mm (from above) plus twice the plywood thickness ie. 390 + 2x18 = 390 + 36 = 426mm.  Base will be 410mm x 390mm.  This gives a total width of plywood of 410 + 426 + 5(ish) = 841mm Add another 5mm for the cutting gives 846mm and therefore just 54mm wide strip left.

    Adding up the back and base from the height of the board, we get 457.5mm + 5mm + 390mm + 5mm = 857.5mm leaving a strip of about 42.5mm.  I was hoping it would be 100mm to use as the top front piece.  However, I have some 18mm plywood left over from making my Concorde printer that I can use in necessary.


  3. Went on to design the XY Carriage - what on a standard 3D printer would be the X Carriage but in this case runs on two round bars at right-angles.  This carries extruder & motor, hotend with heater block and nozzle plus Z probe and cooling fans for the hotend heatsink and parts-cooler.  Four linear bearings run on the two cross-bars.  As a result of the design model and comparison with the print bed size, the depth has had to be increased a bit to give full bed cover.

    Here are some screenshots.

    431040185_Screenshotfrom2019-12-0120-20-59.png.70ce113d0ffaea3e7631a5ae6c9867da.png

    1964981422_Screenshotfrom2019-12-0413-08-20.png.340481cce7ed89db5bf340aed4f7a70a.png

    1442263144_Screenshotfrom2019-12-0413-08-55.png.ed3e5c0ef3f0f46b0342c633dbfae79f.png

    953711086_Screenshotfrom2019-12-0413-10-32.png.40a9db0fe35730b6f3603875523a68de.png

    1660204573_Screenshotfrom2019-12-0413-11-40.png.64015996b2fae4f72c68d7aa78e35ac7.png

    115419076_Screenshotfrom2019-12-0413-15-38.png.3156fba0eab8262903b9c95081b05f46.png


  4. The piece of hardwood ply I bought for the job is 900mm x 900mm x 18mm.  To allow room for motors, brackets etc. I reckon to add 50mm at each end of the XY rails.  So that makes 400mm x 400mm inside and about 440mm x 440mm outside.

    This is the sort of box I'm thinking of with a height of just under 450mm.  This should give a print volume of 190mm x 190mm x 220mm approximately using 6 off 300mm MGN12 rails.  The bottom front rail will come from the bottom panel and the top a piece of ply left over from my Concorde printer box.

    971242790_Screenshotfrom2019-11-2216-07-59.png.3dd5d75d3cd7165ee2ccefb0daf118a5.png


  5. My first thoughts were to use the same type of rails and drives as my Concorde printer viz. V-Slot aluminium extrusion with Mini V wheels including C-Beam extrusion and gantry plate carriages for the Z axis.  I am now looking into higher precision rail systems on a smaller scale.  Home made linear bearings using tiny ball bearings arranged in threes around round rods is one option but this means using dozens of ball bearings with every third being adjustable.  Although giving high precision, this is very labour intensive and time consuming, even with 3D printed parts.  My thanks to @Chriske for this idea.  Another possibility, apart from the ubiquitous cylindrical linear bearings on round rods, is these MGN12 rails.  A combination approach is also a possibility.  I shall be giving this a lot more thought before going ahead and ordering anything.


  6. Final sketch and IDE report.

    // Filename :- Giant_Wall_Clock_v2_2019-11-15
    // Software timing from RTC using polling
    //
    #include <DS3232RTC.h>    //http://github.com/JChristensen/DS3232RTC
    #include <Wire.h>         //http://arduino.cc/en/Reference/Wire (included with Arduino IDE)
    //
    boolean lastSqWave = 0; 
    boolean ledON = 0; 
    int sqwPin = A6;
    int dirPin = 5;   // DIRECTION pin
    int stepPin = 6;  // STEP pin
    int enPin = 12;   // Enable pin
    int ledPin = 13;  // Internal LED pin
    //
    void setup() {
      pinMode(dirPin, OUTPUT);
      pinMode(stepPin, OUTPUT);
      pinMode(enPin, OUTPUT);
      pinMode(ledPin, OUTPUT);
      digitalWrite(enPin, 0);        //  enable
      digitalWrite(dirPin, 1);       //  set on test
      pinMode(sqwPin,INPUT_PULLUP);  //  RTC timing pin
      RTC.squareWave(SQWAVE_1_HZ);   // 4096Hz square wave
      }
    //
    //
    void runClock(void){
      for (int i = 1600; i >= 1; i--) { //  count 1600 pulaes in half second
        digitalWrite(stepPin, 1);
        delayMicroseconds(10);          // Make STEP pulse 10μs long
        digitalWrite(stepPin, 0); 
        delayMicroseconds(290); }       //  1600×300 = 480ms  **** 2019-11-17
      ledON = !ledON; digitalWrite(ledPin, ledON); }  //  flash LED on & off
    //
    void loop(){
      boolean val = ((analogRead(sqwPin) > 500));     // read logic level of 1Hz square wave
      if (val != lastSqWave)  { lastSqWave = val; runClock(); }  //  Call runClock on rising edge of RTC square wave
    }
    // End
    Sketch uses 3896 bytes (12%) of program storage space. Maximum is 30720 bytes.
    Global variables use 283 bytes (13%) of dynamic memory, leaving 1765 bytes for local variables. Maximum is 2048 bytes.
    /home/gina/arduino-1.8.10/hardware/tools/avr/bin/avrdude -C/home/gina/arduino-1.8.10/hardware/tools/avr/etc/avrdude.conf -v -patmega328p -carduino -P/dev/ttyUSB0 -b115200 -D -Uflash:w:/tmp/arduino_build_979028/Giant_Wall_Clock_I2C-control_2019-11-15.ino.hex:i 
    
    avrdude: Version 6.3-20190619
             Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
             Copyright (c) 2007-2014 Joerg Wunsch
    
             System wide configuration file is "/home/gina/arduino-1.8.10/hardware/tools/avr/etc/avrdude.conf"
             User configuration file is "/home/gina/.avrduderc"
             User configuration file does not exist or is not a regular file, skipping
    
             Using Port                    : /dev/ttyUSB0
             Using Programmer              : arduino
             Overriding Baud Rate          : 115200
             AVR Part                      : ATmega328P
             Chip Erase delay              : 9000 us
             PAGEL                         : PD7
             BS2                           : PC2
             RESET disposition             : dedicated
             RETRY pulse                   : SCK
             serial program mode           : yes
             parallel program mode         : yes
             Timeout                       : 200
             StabDelay                     : 100
             CmdexeDelay                   : 25
             SyncLoops                     : 32
             ByteDelay                     : 0
             PollIndex                     : 3
             PollValue                     : 0x53
             Memory Detail                 :
    
                                      Block Poll               Page                       Polled
               Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
               ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
               eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
               flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
               lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
               hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
               efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
               lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
               calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
               signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00
    
             Programmer Type : Arduino
             Description     : Arduino
             Hardware Version: 3
             Firmware Version: 4.4
             Vtarget         : 0.3 V
             Varef           : 0.3 V
             Oscillator      : 28.800 kHz
             SCK period      : 3.3 us
    
    avrdude: AVR device initialized and ready to accept instructions
    
    Reading | ################################################## | 100% 0.00s
    
    avrdude: Device signature = 0x1e950f (probably m328p)
    avrdude: reading input file "/tmp/arduino_build_979028/Giant_Wall_Clock_I2C-control_2019-11-15.ino.hex"
    avrdude: writing flash (3896 bytes):
    
    Writing | ################################################## | 100% 0.59s
    
    avrdude: 3896 bytes of flash written
    avrdude: verifying flash memory against /tmp/arduino_build_979028/Giant_Wall_Clock_I2C-control_2019-11-15.ino.hex:
    avrdude: load data flash data from input file /tmp/arduino_build_979028/Giant_Wall_Clock_I2C-control_2019-11-15.ino.hex:
    avrdude: input file /tmp/arduino_build_979028/Giant_Wall_Clock_I2C-control_2019-11-15.ino.hex contains 3896 bytes
    avrdude: reading on-chip flash data:
    
    Reading | ################################################## | 100% 0.44s
    
    avrdude: verifying ...
    avrdude: 3896 bytes of flash verified
    
    avrdude done.  Thank you.

     

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