T3P3 Kossel Mini Kit Release 2
Chapter 1 - Printed Parts Preparation
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Note: Printed parts designs are on our Github repository at https://github.com/T3P3/kossel - the original designs are in the main folder and our additional and modified designs are in the T3P3_additions folder.
101 Motor Brackets x 3
Note on bracket versions
We modified the bracket design in mid-November 2014 to make it easier to assemble the frame. The original version has inward projections which prevent nuts being inserted into the nut channels of the tower extrusions after they have been fitted to the motor brackets.
We removed these in the revised version.
If you still have the original version then we recommend that you remove the 2 small inward projections on the curved side of the bracket, above and below the 2 bolt-holes, to make assembly easier.
The pictures that follow may show either the old or the new bracket version. There is no difference in the preparation of the two versions, except as described above.
Trim off the anti-warping discs and any other flash (excess plastic: the shiny side may have a thin layer of “overhang” plastic) on the underside of the bracket.
Ream all bolt holes with the 3mm drill-bit supplied - push it through and pull out. Hand-reaming is shown but you can do this carefully with a power drill on slow speed instead. This applies to all bolt holes in all parts unless otherwise stated in these instructions.
Note on motor bracket warping
These motor brackets have a tendency to warp when printed in ABS, despite the anti-warping discs just removed. The top picture shows a severely warped bracket which we would not send out. Note how the bottom right hole has moved up off the horizontal line representing the centre-line of the aluminium extrusion to be fitted to it
Even so, it is usable if the hole misplaced by warping is slotted as shown in the lower picture.
This illustrates in an exaggerated way that you may have to slot this hole slightly if your parts show some warping.
Chamfer the sharp corners of the nut-fitting openings, top and bottom, to make it easier to drop nuts in after assembly (take about ½ mm off).
Chamfer the sharp corners of the frame-extrusion holes, both top and bottom.
You are now going to hammer one of the short frame-extrusions into the bracket to prepare the holes.
You will need a hammer that will not damage the aluminium extrusion. The 50-year-old wooden mallet shown is ideal but a modern equivalent or an ordinary hammer and a protective piece of wood will do.
It is very important to support the motor bracket on a solid flat surface like a block of wood on a workbench. If it is not well-supported the plastic may split. You also need to ensure that the extrusion goes in straight.
When the extrusion is hammered though it will clear out any excess plastic - remove this.
Support the printed part firmly on the edge of a worktop with the extrusion hanging down over the edge. Carefully tap the extrusion out using a blunt-ended metal rod with some padding, while holding the bracket firmly onto its support. The picture shows a 6mm rod with the end wrapped in masking tape.
Repeat for the other 2 brackets.
102 Top Brackets x 3
Like the motor brackets, these also come in 2 versions, with and without inward projections, and the same comments apply.
Prepare generally as for motor brackets by chamfering all nut holes including the one in the centre with the angled hole. Don’t forget to chamfer the extrusion hole and hammer a extrusion through the extrusion holes to clean them out.
In addition, remove the two small triangles of printed support material from both of the conical idler mounts as shown. (Note: some colours may not have these)
Before support material removal, left, and after, right.
Ream out the idler bearing axle bolt holes, and all other bolt holes.
Chamfer the sharp corners of the belt tensioner nut trap.
Repeat for the other 2 top brackets.
103 V-roller adapters x 3
Remove printing flash from the bottom (shiny side), ream bolt holes, chamfer sharp corners of captive nut traps.
Note: This picture may show a slightly different part to the ones you have, but the procedure is exactly the same.
104 Carriages x 3
Ream bolt holes as for V-roller adaptors. Also cut off triangular printed support material from conical delta arm attachment points - picture shows before and after .
105 End effector plate
Ream 3mm bolt holes.
IMPORTANT: Check that the top of the V6 hot end heatsink fits in the 16mm recess on the bottom of the effector shown in the picture. If it is too tight a fit then carefully remove a small amount of plastic by scraping round the side to make it fit.
106 Hot-end fan bracket
DO NOT REAM! - no preparation required on this part
Do not ream any of the holes in this part - they are all pre-tapped M3 for mounting bolts.
107 Mini Extruder Big gear
The hexagonal hole needs to be carefully prepared for the head of the M3 hex drive bolt, by chamfering the edges and removing any loose strands of filament from the bridging layer. Carefully ream the hole.
Prepared hole with bolt fitted. Be careful not to remove too much plastic. The full torque of the highly geared extruder motor is transferred to the M3 hex drive bolt by contact with the hex hole in the gear, so it is really important that this fits well.
108 Mini Extruder block and mounting bracket
Mounting bracket: The bolt-holes should be reamed out for M3 capscrews, and the recesses for the bolt-heads may also need to be opened up.
DO NOT REAM OUT THE FILAMENT PATH or the IDLER SCREW HOLE
The filament hole has already been reamed to 2mm, and the idler bolt needs to cut its own thread
You will need to open up the rectangular hole in the extruder block for the captive nut used when mounting the extruder to the bracket.
On the extruder block, clean up the slot between the drive side and idler side - both the top ……
and the side. There should be a visible gap all the way through. You can use a hacksaw blade for this if you have one.
Chamfer the sharp edges of the bearing holes, both sides.
109 Extruder motor spacers
Your kit may have 2 x 2mm thick spacers, or 1 x 4mm thick one. In either case, check that it/they fit over the boss on the mounting face of the motor. If not, then remove flash so they fit, and ream 3mm bolt holes as usual
110 Endstop Mounts
DO NOT REAM THE TWO SMALLER HOLES IN THE ENDSTOP MOUNTS
The picture shows the flash on the first print layer and oversizing of the 3 or 4 layers due to shrinkage during printing. This needs to be removed so the sides are parallel , so the endstop mounts are flat on the bracket and the bracket flat on the aluminium extrusion.
Excess plastic removed.
111A Filament Reel holder - original version up to kit No 366
This is printed with support material which needs to be removed. There may also be some sagging of the supported layers to clear so that the holder fits on the aluminium extrusion without being forced on, which may make it split.
111B Top-mounted Filament Spool holder - new version from kit No 367
This consists of 6 printed pieces:
Ream baseplate and bracket M3 bolt holes to 3mm and remove flash as necessary, including from the 22mm bearing hole in the turntable and 8mm bolt hole in the baseplate.
112 Z Probe Holder
DO NOT REAM the holes in the side of Printed Z-probe holder
DO clear out the groove in which the brass Z-probe slides, ….
…… so that it will move freely up and down when fitted.
113 Electronics bracket
DO NOT REAM THE FOUR HOLES
114 Other parts
Should not need further work but be prepared to ream 3mm bolt holes and remove excess flash from a few other places during the assembly.