Kossel Mini build : Part 7

**So, it’s been over 2 years since the last post – I had some things happen in my life that needed my attention and could not focus on my Kossel Mini build.  In the span of 2 years, many new players stepped up, but for the sake of completeness, I’ll wrap up my Kossel Mini build.**

Recap :

Kossel Mini build : Part 0 – a brief explanation of intent and also sources where I got the parts

Kossel Mini build : Part 1 – assembled the top triangle frame, as it seemed like the simpler of the 4 main components

Kossel Mini build : Part 2 – assembled the diagonal rods by leveraging parts used on the bottom triangle base

Kossel Mini build : Part 3 – while building the effector, encountered some fitting issues on both the plastic and nylon screws.  A combination of dremel and tap and die were used to make things fit.  Also finished the auto level probe.

Kossel Mini build : Part 4 – the diagonal rods were installed to the effector, and the J-Head hotend was also attached to the effector.  Also finished the bottom(base) of the Kossel Mini.

Kossel Mini build : Part 5 – the rails have been installed to the pillars and the printer has been assembled.  The RAMPS 1.4 shield was also mounted on the top of the printer

Kossel Mini build : Part 6 – Assembled the extruder piece, which required some work to make the pieces fit; also installed the PTFE tubing.

With the frame basically done, I mounted the glass plate on the glass tab.  Without any visible way to secure the plate(prevent shifting, wobbling, and spinning from calibration/printing), I used a double-sided adhesive on the glass tab;

Note the screw on the left side of the picture – this is for the probe retraction, and it’s proper place will be set during calibration.

Finally, I’m at a stage where I can start testing the printer, to see if the assembly so far has been correct.

First, I had to load the appropriate firmware.  I already had Arduino IDE installed from my past hobby projects, but if you have not, here’s the list of steps;

1. Download and install the Arduinio IDE from here.
2. Download the Marlin firmware(from the Kossel Mini’s creator’s GitHub page) from here.
3. Plug in the Arduino to the PC via a USB cable and determine the COM port
4. Open Arduino IDE and load the Marlin firmware(Marlin.ino)
5. Set Tools->Board to Arduino Mega 2560 or Mega ADK
6. Set Tools->Serial Port to [value you got from step 3]
7. [custom settings]
8. Compile & Verify code
9. Upload the firmware to RAMPS.  This allows the printer to be controllable by a 3d printing software.

About a year or so ago, I happened to run into the Simplify3D people at MakerFaire NYC.  At the time, they had a pretty speedy slicer and a support generation system that was highly praised.  Having had dealt with STLs with overhangs that drooped or slicers that couldn’t slice properly, I purchased a license.  Fast forward to 2016, there are plenty of open source and/or free software that one can use instead, but I believe YMMV depending on the strengths and weaknesses of each software.  I’ll continue using Simplify3D.

Things to note were:

• Firmware : Marlin
• bed size: 170mm x 170mm

Steps for X, Y, and Z : 100

Steps for E : 523.5959

This value was acquired through a repetitive process(FWIW, I used this process on the Cupcake and the Simple – and it worked!)

Using the tried-and-true “paper test”(put a sheet of paper on the surface, manually lower the hotend until it starts to drag the paper when you try to pull the paper), I got the MANUAL_Z_HOME_POS value of 231.4

I went through a similar process with the probe deployed, however, I found that perhaps I had worn out the post – the probe’s post and spring kept coming off, making auto-level not a feasible way.  However, I could still limp along w/o having the auto level feature.

Other documents mention the flatness test, but I won’t cover that here, as I lucked out and it seemed flat “enough”.  With the delta setup, there is a chance that when the 3 motors act in concert to move the probe, it may lift up towards the edge of the surface(concave) or lower(convex).  Obviously convex is a more dangerous situation as it can drive the hot end into the floor, whereas a concave setup would just mean wasted prints and time lost.

For test prints, I tried printing a few objects and the results are… acceptable.  I’ve certainly seen better prints online and at MakerFaire, but among the 3-4 printers I’ve built, this is so far the fastest and best printing one yet;

While printing the calibration cube, I noticed that the connector popped out of the extruder.  Without the connector, the filament has no pressure to drive into the hotend.  A quick job involving JB weld and a few hours fixed the extruder.

I was able to get a calibration cube to print satisfactorily.  And I get a little ambitious:

This finally concludes the Kossel Mini Build saga – it look a lot longer than I expected, and the offering now is vastly different from when I started.  This project merely completes the build saga – as right now, there are plenty of areas that need modification.  I’ll occasionally post updates.

Happy printing!