Printing small parts with small tolerances
Hi everone!
I have this small part which is going to be a model train bumper and therefore accepts only very small tolerances (<0.1mm).
For testing purposes I created a simple version consisting of a base plate 5x5x0.4mm (x/y/z) and a cylinder on top of this plate 3x3x5mm.
When printing this the base plate is nearly perfect. Using a caliper I can see max delta of 0.05mm. Therefore I guess the printer calibration is fine.
The cylinder is the part that gives me trouble. I see deltas from 0.15mm to 0.3mm. Using spiral vase mode creates the highes deltas but the best looking result.
After two days of experimenting I hope for some tipps or ideas to reduce the delta between the design and the print on the cylinder.
Here is my setup
- Prusa i3 MK3S with firmware 3.7.2
- Prusa 0.25mm nozzle
- Prusa PLA filament silver (shipped with the printer)
- PrusaSlicer 2.0.0+win64-2019050201652
- Printer settings: Original i3 MK3s 0.25 nozzle
- Presets: 0.05mm ULTRADETAIL 0.25 nozzle MK3S
- I modified the z-lift from 0.8 to 0.1.
A zip file containing my Blender, STL, PrusaSlicer and Gcode file can be downloaded from: https://c.web.de/@322360494314750644/zys3TOckT2W8YXzTQenSlg
Best wishes
Stefan
RE: Printing small parts with small tolerances
1 Try without spiral mode, and use infill, so the wall is more stable.
2 With small parts, you do not get enough cooling, print more parts at the same time, then the first can coo, down.
3 In the forum I also saw, with a print with thin walls, use no cooling.
if it helps i do not know.
RE: Printing small parts with small tolerances
You'll need to concentrate on extruder multiplier, extrusion width, and actual filament diameter. Any variation in these will cause tolerance build up. A vase mode test cube and measuring wall thickness is the GAP method for this.
Linear advance can help when it is properly set (controls start/stop extrusion multipliers); as will fine control of the retraction deretraction settings. This helps seam gaps, and over-under extrusion thicknesses.
And of course, layer 1 height is crucial to overall height of small parts: you'll need to carefully calibrate Live-Z to obtain a precise 0.2mm (or whatever L1 you are using.
RE: Printing small parts with small tolerances
Thanks @peter-m26 and @tim-m30. I´ll give that a try and report back.
RE: Printing small parts with small tolerances
There is an interesting set of posts on github that might help. (I haven't tried this myself, but the poster explains his tests and posts his results for you to try to replicate his results.)
https://github.com/prusa3d/PrusaSlicer-settings/issues/74
See my (limited) designs on:
Printables - https://www.printables.com/@Sembazuru
Thingiverse - https://www.thingiverse.com/Sembazuru/designs
RE: Printing small parts with small tolerances
Here is an update of my tries, currently I am tweaking the settings for filled prints. After this I will try again with spiral vase mode/single perimeter.
When printing 6 of my bumpers at the same time the accurancy increases dramatically.
Started again with presets: 0.05mm ULTRADETAIL 0.25 nozzle MK3S
- I modified the z-lift from 0.8 to 0.1.
- increased infill to 50%
- increased bed temp to 65°C
Put 6 of my parts side by side on the print table.
The results are pretty good. Delta of my 3mm cylinder is < 0.1mm. Delta of my 2.5mm cylinder is alsow < 0.1mm. This fits my needs perfectly.
I will try with a single perimeter tomorrow.
@sembazuru: I read the github post. Very interesting as there are similar dimensions used there. I will try with 1mm/s speed tomorrow. I wonder how long this will take 😊
Regards
Stefan
RE: Printing small parts with small tolerances
Here are my results with the perimeter/sprial vase mode settings.
Started again with presets: 0.05mm ULTRADETAIL 0.25 nozzle MK3S
- I modified the z-lift from 0.8 to 0.1.
- activated spiral vase mode
- increased bed temp to 65°C
- increased first layer extruder temp to 225°C to get a closed surface
- Print speed 1mm/s => creates a surface looking like melted glass with deformations on top and buttom of my cylinder
- Print speed 5mm/s => good looking surface but delta is again about 0.2mm
- Print speed 3mm/s => good looking surface and delta is about 0.05
I think 3mm/s is the best result. I will keep this.
Regards
Stefam