T3P3 Kossel Mini Kit Release 3
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.
General Notes on printed parts preparation
These instructions show the use of a sharp utility knife which is include in the kit for preparing printed parts. You should observe all necessary precautions when using this, such as those at http://safetytoolboxtopics.com/Small-Tools/utility-knife-safety.html. If you are not sure that you will be able to prepare the parts safely using a knife then we recommend that you use other tools such as files and sandpaper to remove excess plastic.
Wikipedia defines flash as “excess material attached to a molded, forged, or cast product, which must usually be removed. This is typically caused by leakage of the material between the two surfaces of a mold (beginning along the parting line) or between the base material and the mold (in the case of overmolding).”
The term has been extended to cover the excess material projecting beyond the intended outside surfaces of the first layer of a 3D-printed part. Flash occurs on printed parts because it is usual, especially when printing ABS, to overfill the first layer with excess plastic. This is to ensure good adhesion to the printbed, so reducing the tendency of ABS parts to warp.
Reaming Bolt holes
Reaming is the process of enlarging a hole using an accurately-sized tool. Small 3D-printed holes in ABS parts tend to be significantly smaller than the designed size, and so require reaming. Although we adjust the hole sizes of our parts to compensate for undersizing, we find that where holes need to be accurately sized for correct alignment of assemblies, undersizing and reaming gives the best results. We provide a 3mm drill bit in a handle for reaming M3 bolt holes. This can also be used with a “filing” action to remove any excess plastic from 4mm holes, though these generally print more accurately and seldom require much reaming. Hand-reaming is shown in the instructions but you can do this carefully with a power drill on slow speed instead.
101 Motor Brackets x 3
Trim off the anti-warping discs and any other flash on the underside (the smoother of the 2 horizontal faces) of the bracket
Ream the M3 motor bolt holes with the 3mm drill-bit supplied - push it through and pull out. Twist clockwise if you encounter too much resistance to pushing in.
The M4 holes may have some excess plastic at the top where the printed layers had to “bridge” across the holes. You can remove this by turning the part over and using the drill bit as a file to remove the excess plastic.
102 Top Brackets x 3
Prepare generally as for motor brackets by removing flash. Ream out the M3 idler bearing axle bolt holes and the M3 belt tensioner hole in the centre with the angled hole.
In addition, remove the small triangles of printed support material from both of the conical idler mounts.
In this picture the the triangles of support material have been removed.
Now chamfer the extrusion hole on the underside of the bracket, and also the sharp corners of the belt tensioner nut trap (the central angled hole)
Repeat for the other 2 top brackets.
103 V-roller adapters x 3
Remove printing flash from the bottom (smooth side) and ream bolt holes
104 Carriages x 3
Ream bolt holes as for V-roller adaptors.
Cut off triangular printed support material from conical delta arm attachment points, as on top brackets. Pictures show before and after.
105 End effector plate
Remove flash and ream 3mm bolt holes.
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. It should be a snug firm fit. 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/IR mount
NOTE 1 : This component will be supplied in black ABS
NOTE 2 : From 26 May 2016 this part is supplied with M3 threaded brass inserts for all M3 fixing bolts
For earlier kits without M3 brass inserts, DO NOT REAM any holes! No preparation is required on this part except flash removal
Do not ream any of the holes in this part - they are all pre-tapped M3 for mounting bolts.
Do remove flash from the V6 hot-end groove mount and check that the V6 fits well.
107 Print cooling fan duct
NOTE 1 : This component will be supplied in black ABS
NOTE 2 : From 26 May 2016 this part is supplied with M3 threaded brass inserts in the 2 bottom holes for M3 fixing bolts
For earlier kits without M3 brass inserts, BE CAREFUL - DO NOT REAM the 2 bottom holes - they are pre-tapped M3 for fan mounting bolts.
Do ream the 2 top holes and remove flash as necessary.
108 Endstop Mounts
DO NOT REAM THE TWO SMALLER HOLES IN THE ENDSTOP MOUNTS
The picture shows the flash on the first print layer (on top) and oversizing of the first 3 or 4 layers due to shrinkage during printing. This needs to be removed so the sides are parallel , so the endstop mounts flat on the bracket and the bracket flat on the aluminium extrusion. The M4 mounting hole should also be rounded using the 3mm drill bit as a file.
Excess plastic removed
109 Top-mounted Filament Spool holder
This consists of 6 printed pieces:
Ream baseplate M3 bolt holes and bracket M3 slotted bolt holes to 3mm and remove flash as necessary
Remove flash from the 22mm bearing hole in the turntable and also the 8mm bolt hole in the baseplate.
109 Self-tapping screw holes
Some parts have small printed holes for No 2 self-tapping screws, for mounting electronic PCBs. It is easier to start these screw in the holes before fitting the printed parts, as below. Remove the screws after they have cut their threads in the plastic.
Hot-end PCB bracket
Duet rear mounting brackets
Mini IR level sensor mounts
110 Other parts
Ream 3mm bolt holes and remove excess flash as necessary