Kossel Mini build : Part 2

Recap :

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

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

Building the top triangle did several things – it allowed me to get familiar with fitting, tightening the plastic on extruded metal, get familiar with the material and how best to fit the M3 nut in the extruded slot.

Using the handy Blomker’s PDF as a guide, I decided to build the diagonal rods.  The components(from the kit I bought from Tri D printing) are:

  1. 6 x Pre-cut graphite light wall tube rods
  2. 12 x Traxxas Rod ends
  3. 12 x m4 20mm set screws

But, while building this, I needed the following additional items;

  1. epoxy/liquid adhesive
  2. 12 x M3x8mm screws
  3. 12 x M3 nuts
  4. 2 x allen wrench for the M3 screws
  5. 1 x needle nose pliers
  6. 1 x piece of metal with a hole as wide as the eye hole on the rod ends(I’ll explain why later)

This is the only step that requires a curing time, since it involves gluing parts together permanently, whereas everything else is uses screws to hold things together.

Blomker’s guide has some nice illustrations on how they used 6 x 240mm extruded rods as guides to build these rods.  I found that I could just hand screw the set screw into a Traxxas rod end easily.  I tried my best to have all 12 set screws evenly in.

The next part, I needed to use a pair of needle nose pliers and a piece of metal with a hole in it.  I worried about bending/breaking the Traxxas rod end while trying to push in the ball pivot thing, so I used the metal and pliers to apply.

pivot ball aligned
pivot ball aligned
pivot ball successfully inserted
pivot ball successfully inserted
half way done with the rod ends
half way done with the rod ends

 

After doing this, I took 12 x M3 screws and nuts and put them in 12 x 240mm extrusions.  I aligned 6 x M3 screws on one end and tightened them, and left the other end loose. The next step is to combine the components.

components for diagonal rods assembly
components for diagonal rods assembly

First I mixed the epoxy as per its instructions and coated the exposed set screw on the rod end.

glue on the rod end set screw
glue on the rod end set screw

I quickly pushed it into one end of the graphite rod, before doing the same to the other. I took the rod then placed it on the slot on the extruded metal, one end aligning to the tightened M3 screw and then tightening the loose M3 screw on the opposite end to hold the rod in place.

After repeating that with all 6 rods, I placed the allen wrench through the hole in the ball pivots to test for alignment(to ensure that the rods are all even in length).  This is a great tip from Blomker’s PDF, and I took another hex wrench and placed it in the opposite end as well.

Once I was convinced the rods were even, I left it to cure(the instructions said about 6 hours)

complete!
complete!

It looks like this will be enough for this post – looking at parts and doing some test fittings, it looks like I will need to get a tap and die kit for the future components.

See you on the next post!

Leave a Reply