RepRap Work

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Rep Rap 3D Printer Work, Paul Dale, 2/1/17.

I did some maintenance to the printer over the past couple of weeks. Test print BEFORE changes:

Boat r.png

Here's a list of the changes I made:

- Couldn't get PronterFace working under Linux (Xubuntu?) on the Bridge Rectifier PC. I have now set it up to dual boot with Lubuntu Mint, which does work. I suspect it's a Python thing, but couldn't fix it.

- Bed thermistor open circuit, repaired. Bed LED resistor value increased to 2K2R.

- Extruder thermistor sometimes shorting. I've pulled the insulation closer to the glass bead which seems to have fixed it for now. Still needs better Kapton tape applying to hold in place.

Before (thermistor removed for clarity) / After:

Thermistor before r.png Thermistor after r.png

- Nozzle slightly blocked, (probably me keep getting the wrong bed-height, so covering the nozzle in filament). I removed the nozzle and used a blow-torch to burn off, then poked some soft copper wire through.

Nozzle hole r.png

- Extruder feed-bolt fouled with filament pieces. I scraped out most of this. I loosened the hinge of the part that squeezes filament against the feed-bolt too.

- Some linear bearings are rusty and rough. They've been lubricated all round, but the X-axis are still poor, maybe could be replaced if we decide it's worth it.

Rusty bearings r.png

- Z axis captive-nut holders broken. I've added washers but at some stage they may need re-printing.

Broken z-nut holder r.png

- Z-axis couplings weren't holding the motor spindles. Instead they were only clamping the transparent tubing. The couplings have been re-fitted to clamp the motor spindles.

Before / After:

Z-spindle before r.png Z-spindle after r.png

- Bed-height adjusters changed to spring-loaded type.

Spring loaded bed r.png

  • I'll take this opportunity to post a picture of the correct PC connections, for future reference:

(Note connection to PC USB port shown on left of PCB can fit two ways. Image shows correct way.)

PCBs Connectors r.png

To be done (Hardware):

- Kapton tape to hold extruder thermistor in.

- Tie-wrap x-axis bearings to carriage.

- Dress remaining loose cables.

- Raise bed (maybe 0.5mm to 1.0mm).

- The connection between the wooden bed and the transparent-plastic bed is spring-loaded, and / or lots of washers are used. Maybe we can make this a solid, fixed connection.

- Heated-bed PCB corner broken. It's "ok" today but may need fixing in future.

- I've been using a little hair-spray on the bed to help the first layer stick. I've read some people use some type of tape. To be investigated.

- Z-axis (electronics end) threaded rod and smooth rod aren't perfectly parallel to each other. This might be related to how the motor is screwed to the frame. Both Z-motors are mounted slightly loose, maybe intentionally. I suspect one side of the motor could be packed to make the rods parallel.

To be done (Software)

- Install Slicer SW on PC.

- Various Calibrations:

- Other settings in Slic3r: Nozzle diameter. Z Offset. Filament diameter, (white stuff already in the printer measures 2.8mm dia. Filament material. Nozzle temperature. Layer height. Retraction Length, Lift and Speed. Print speed (7 types): Perimeters, Small Perimeters, Infill, Solid Infill, Bridges, Travel, Bottom Layer Speed Ratio.

- G-Codes for Start and stop.

- Atmega: Since the firmware on the Atmega MCU hasn't changed, motor calibrations aren't expected to be required. A 20mm test box was printed and measured 20.4mm x 20.1mm.