Kossel – The Ratio

Preamble

I came across this problem, when looking into building and sourcing the parts for a Kossel printer in Bangkok.

The correct length of the push arms of a Kossel 3D printer is a bit of an enigma. The length is related to the length of the Horizontal frame lengths, that form the triangle. The ratio between the length of the push arms, from eye to eye, and the length of the horizontal lengths, is apparently 80%, or 0.8.

However, not all designers stick to this ratio, and often go higher, up to 92%.

I wondered why this is. Surely it is simple enough to cut a length of aluminium extrusion to the correct length? Certainly it is easier to cut aluminium than a carbon fibre rod to the correct length, although the latter is still certainly possible.

There are constraints, the most likely of which is the sizes of borosilicate glass discs (commonly 170/180/220/260 mm), and custom heated beds, but there may be others, such as a minimum horizontal length (in order to accommodate the steppers), the carbon rods come in pre-cut lengths (seems unlikely?).

Continue reading Kossel – The Ratio

The extraordinary extruder

Preamble

Following on from Kossel 3D Printer, and the tutorial videos (see Kossel construction videos) the BuildA3DPrinter kit comes with an extruder stepper motor with a planetary gearbox. This results in a very high torque. However, as stated below, it has been replaced by the 3325_0, a motor with the same NEMA size and same torque.

Continue reading The extraordinary extruder

Kossel 3D Printer

Preamble

The idea of building a Kossel came to me after:

  • Seeing on ReprapWiki – Kossel, that the Kossel uses OpenBeam, which is very similar to 2020 extruded aluminium, except that it is 1515, and as I had already sourced some inexpensive 2020 for my Wilson II 3D printer, in Bangkok, it would not be much of a problem to go and get some more;
  • Coming across HTA3D’s Kossel printed parts, on eBay, for €29.99, and;
HTA3D Kossel parts
HTA3D Kossel parts
  • Having watched the following video on the Micromake 3D printer, that uses 2020 aluminium and is similar to the Kossel (inasmuch as it is a Delta printer). See this explanatory video:

However, as I have stated above, the main reason was that I had the idea of sourcing the aluminium for the Kossel, whilst I was in Bangkok, as aluminium is relatively cheap in Bangkok, when compared to Europe.

Continue reading Kossel 3D Printer