Kossel construction notes

Preamble

Following on from Kossel 3D Printer, these are some points that I have noted, whilst constructing a Kossel XL using the Sintron kit and a Kossel mini using aluminium vertices…

Assembly gotchas

Parts

Bolts for frame

Using the aluminium vertices:

  • M5 x 10 mm bolts are required for the Aluminium vertices, not 8 mm as suggested by the RepRap Wiki:Kossel.
  • The aluminium vertices do not have gaps to enable additional nuts to be slipped into the aluminium extrusion, after the top and bottom deltas have been constructed

Using the Sintron kit:

  • M3 x 8 mm bolts are used for the frame.
  • The vertices have gaps for additional nuts to be slipped in horizontally. But not vertically.

Using the Kossel kit from M.Rut3D:

  • M5 x 10 mm need to be used, or 12 mm – 8 mm are too short.
  • The vertices have gaps for additional nuts to be slipped in horizontally. But not vertically.
  • The vertices have slots, for screwdrivers, to ease the steppers motors to be screwed on

Aluminium

When fitting the motor nuts, remove the frame bolts, or fit motors before the frame. The M3 x 6 mm bolts used to secure the steppers are hard to tighten, due to poor access.

It is easier to insert nuts into the extrusion and then, after positioning the nuts correctly, screw the vertices to the extrusion, rather than sliding partially screwed on nuts into the extrusion (as done for the Sintron kit).

The top vertices bearings, because the M3 bolts do not screw in to the vertices, as there are no threads. Use M3 x 25 mm bolts, with:

  • M3 washer
  • F623zz
  • F623zz
  • M3 washer
  • M3 washer (optional – it is rather tight)
  • M3 nut

Kossel/m.rut3d

Extruder

Insert three M3 nuts into the outer face of one of the verticals for the [printed] extruder stepper motor holder.

Build Plate

Insert one nut into two of the upper bottom horizontals and two into one, for the build plate holder. Check whether the holes in your [printed] build plate holders are M3, M4 or M5 – the m.rut3d printed build plate holders require M3.

Endstop

Insert one M3 nut for the printed endstop switch holders into each vertical length of aluminium extrusion, on the inside facing the print bed. Be sure to insert them prior to assembly of the vertical extrusions.

Sintron printed parts

Extruder

Extruder mount – two M3 nuts on the top face of one of the upper horizontals

Reel holder

Insert one nut into two of the top horizontals and two into one, for the reel holder. Check whether the holes in your [printed] reel holders are M3, M4 or M5.

Build Plate

Whilst the Sintron kit has no printed parts to secure the build plate, nuts are required for the bare bolts (M3, M4 or M5 – up to you) used instead. Insert one M3 or M5 nut into two of the upper bottom horizontals and two into one, to secure the build plate.

Endstop

See More endstop madness, in the blog Kossel 3D Printer – Fasteners, use two M3 T-nuts/flanged nuts for the end stops and printed endstop switch holders into each vertical length of aluminium extrusion, on the inside facing the print bed. Be sure to insert them prior to assembly of the vertical extrusions. The PCB mounted end stops are M3 holes. Note that the mechanical switches alone, have M2.5 holes.

Vertical carriages

The wheels required 30 mm bolts as the 25 mm bolts were too short. On eBay:

I used three M3 nuts as spacers, to space the wheels from the carriage, instead of five 0.9 mm thin M3 washers.

How to add nuts to plastic carriages:

  •  acetone, didn’t seem to soften
  •  screw , worked for some but then nut twisted in hole and lost grip. Now just rotates in oversized and worn hole
  • hammer, holding side of pliers over nut, hit pliers with hammer 

Carbon rods

As an alternative to #1: Preparing the carbon rods at 3:38. follow the guide for making a jig to ensure all rods are of equal length in the BLOMKER pdf, pages B8-B13:

Quick notes

Epoxy also bridges gaps — gap-filling, in other words. The glued surface becomes the entire area the glue is spead onto. Most superglues will not bridge gaps. The only areas bonded are those acutally touching each other — therefore though the actual bond may be very strong, the surface area bonded is very small.

  • Drop the Traxxas rod ends in hot water before popping in the metal bearing

 

 

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