3D Printer Log

% Remco Bloemen % 2015-08-26

Hardware

Frame

RepRap Prusa i3 Rework with 6mm aluminium plate.

http://reprap.org/wiki/Prusa_i3_Rework_Introduction

http://www.thingiverse.com/thing:119616

End stop clamps

Extruder

Greg’s Hinged Extruder ( thingiverse ), which is based on Wade’s Geared_Extruder.

A J-Head Mk V-B or Mk V-BV with a 100k thermisistor.

Electronics

Sanguinololu, a Sanguino based Arduino clone with with four sockets for Pololu stepper motor controlers. Based on an Atmega644P, can be upgraded to Atmega128.

Wiring plan

14-05-24

Spool holder

Holder with spool adapter

Added on 14-05-24

Firmware

Sprinter

http://reprap.org/wiki/Sprinter

https://github.com/kliment/Sprinter

Changes made to Configuration.h.

#define MOTHERBOARD 62

#define _AXIS_STEP_PER_UNIT {80, 75, (200 * 16) / 0.80, 700 * .9}

#define BAUDRATE 250000

const bool INVERT_Y_DIR = true;
const bool INVERT_Z_DIR = false;
const bool INVERT_E_DIR = true;

const int X_MAX_LENGTH = 182;
const int Y_MAX_LENGTH = 219;
const int Z_MAX_LENGTH = 100;

Uploading

Use stock Arduino v1.0.5 with sanguino hardware plugin.

Note: disconnect and reconnect USB before uploading!

Choose "Sanguino Atmega644P" as compile target

Software

OpenSCAD and FreeCAD for modeling.

Slic3r (RepRap wiki) for slicing.

TODO: List slic3r settings.

TODO: Check out Cura: https://github.com/daid/Cura

Printrun (RepRap wiki) its pronterface for printing.

TODO: Check out http://www.repetier.com/documentation/repetier-host/

Calibration

The Y-Axis has its bed minimum at 19 and the bed maximum at 219

The X-Axis has its bed minimum at 17 and the mech max at 182.

Log 2015-09-13

Goal: Fix the leaking of molten PLA between the brass nozzle and the PEEK insulator.

Method: The extruder was heated to 200°C and run in reverse until the filament came out. I then cooled down the extruder and removed it from the frame. Then the J-Head nozzle assembly was removed from the extruder assembly. I heated up the head to 200°C and used pliers to twisted off the PEEK insulator, which came off smoothly.

The PTFE liner looked to short. The PEEK insulator with the PTFE liner and was heated in an oven at 200°C. This loosened the liner so it could be pushed through the insulator, clearing out some black (ABS?) gunk along the way. This was repeated several times until no more gunk remained.

The insulator was re-assembled with the liner as low as it could be placed and not screwed down. The nozzle thread was wrapped in several layers of PTFE tape. I then screwed the nozzle back on the insulator, pushing the liner up slightly and squashing the PTFE tape. It was screwed down quite tight. The liner was screwed down thight from the other end of the PEEK. The extruder was re-assembled and put back on the frame.

Result: The first print (25mm companion cube with 20% infill). The first ten layers had significant amounts of black gunk. After that there was an occasional clog followed by a small piece of gunk. The extruder never leaked.

Conclusion: The leaking issue is solved, there may still be some gunk left that will flush out.

Log 2015-09-15

Goal: Recalibrate the printer, in particular the extruder.

Method: Using Triffid's guider. The firmware was already at the latest version. The current calibration is:

Axis Steps per millimetre

X 80 Y 75 Z 4000 E 630

The Y axis has a slight tweak. This was originally done because the belt gear had it's teeth filled with plastic, making the effective diameter slightly larger. This was compensated for by giving the Y axis a tweak. This gear has now been replaced by a newly printed one and the tweak should be removed.

The X, Y and Z axis use timer belts and stepper motors. For the X and Z it is a NEMA 17 motor with T2 belt and 20-tooth pulley, the exact steps per millimetre should be 80. The Z axis is NEMA 17 with standard pitch M5 threaded rod, which has exactly 4000 steps per millimetre.

The E axis is currently at 630 steps per millimetre. A mark was made on the filament at the height of top of the frame. The nozzle is heated to 195°C and the command was given to extrude 50.0mm at 100.0 mm/min. A new mark was made at the same height. The distance between the marks is 45.5 mm ± 1 mm. The corrected E steps per mm would therefore be 630 · \frac{50}{45.5} = 694.

Based on this, the new calibration should be:

Axis Steps per millimetre

X 80 Y 80 Z 4000 E 694

The firmware was updated in Sprinter/Configuration.h, compiled and uploaded:

#define _AXIS_STEP_PER_UNIT {80, 80, 4000, 694}

The filament is measured at 2.8 mm. The filament settings in Slic3r are updated to 2.8 mm and 1.0 as multiplier. Now the steps in E step fine tuning are followed.

The first print had the brim being to thin, the Z offset was increased from 0 to .1 mm. The second print had a good brim but came loose due to wrapping. The temperatures were changed as follows:

Temperature Previous New

Nozzle initial 200 °C 190°C Nozzle 190 °C 185°C Bed initial 65 °C 60°C Bed 0 °C 60°C

The third print came out okay. The infill has holes, but the top fills are not solid.

The nozzle gets stuck, increasing temperature:

Temperature Previous New

Nozzle initial 200 °C 195°C Nozzle 190 °C 190°C Bed initial 65 °C 60°C Bed 0 °C 60°C

Wraps and does not stick, increasing temperature:

Temperature Previous New

Nozzle initial 200 °C 200°C Nozzle 190 °C 195°C Bed initial 65 °C 70°C Bed 0 °C 65°C

Communication breakdown, decreasing baudrate to 115200. Object still warped and came loose.

According to http://www.matterhackers.com/articles/how-to-succeed-when-printing-in-pla the bed should be 70°C. After much experimentation the cause was found to be a too low Z offset. The final settings are:

Setting Value

Layer height 0.3 mm First layer 0.35 mm Infill 20 % Nozzle initial 200°C Nozzle 200°C Bed initial 75°C Bed 70°C Skirt 2 loops Brim 15 mm Z offset 0.45 mm Filament 2.8 mm Multiplier 1.05

Extrusion calibration: The extrusion is re-calibrated. A 50 mm extrusion delivered 45.5 mm. Perhaps the firmware did not update. The firmware is recompiled and reflashed. Support for the M503 command is added and the printer now responds to it. A 50 mm extrusion delivered 46.5 mm. E was extended from 694 to 746. The extruder got stuck. The hobbed bolt was full of plastic and cleared. The spool holder was loosened.

772 51.6 745 41.0 745 49.0

It is left at the current firmware default of 746. The extrusion is remains inaccurate.

TODO

Remco Bloemen
Math & Engineering
https://2π.com