**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.**
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;
- Download and install the Arduinio IDE from here.
- Download the Marlin firmware(from the Kossel Mini’s creator’s GitHub page) from here.
- Plug in the Arduino to the PC via a USB cable and determine the COM port
- Open Arduino IDE and load the Marlin firmware(Marlin.ino)
- Set Tools->Board to Arduino Mega 2560 or Mega ADK
- Set Tools->Serial Port to [value you got from step 3]
- [custom settings]
- Compile & Verify code
- 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.