Week 5 Group Assignments -¶
- Group assignment:
-
Test the design rules for your 3D printer(s)
-
Document your work on the group work page and reflect on your individual page what you learned about characteristics of your printer(s)
Design Rules¶
We did a number of tests to explore the fitness of our 3D printers. We made sample parts related to overhang performance, thickness, accuracy and press fit.
These tests were performed on both Prusa MK4S and Bambu A1 printers with PLA filament.
Overhangs¶
For overhang performance we made a jig with extrusions with bends from 0 to 90 degrees in 10 degree increments.
Then we ran this jig on both printers. They performed pretty well with the Prusa seemingly handling it a little better than the Bambu. In either case about a 70 degree overhang is achievable without surface imperfections.
Thickness¶
To test the minimum thickness performance of the printers, we made a jig in Solidworks to make bent walls in 0.1mm increments from 0.1mm to 1.0mm. The shape of the wall was to test both the X and Y performance to see if there was any discrepency.
We loaded it into each slicer and they both handled it a little differently. The Bambu slicer would not handle anything less than .5mm thick. Prusa did a little better getting down to 0.1mm, however the actual path for 0.1mm to 0.4mm was exactly the same.
Measuring the parts off of the printers was interesting. The walls of the Bambu print came in about 0.02mm uder the dimension and 0.5 and 0.6mm were the same thickness as 0.7mm wall. In contrast the Prusa print was much more accurate. The wall thicknesses were a little bit under designed dimension. However, it was able to build a 0.4mm wall accurately. However, the 0.2 and 0.3mm walls were the same thickness as the 0.4mm
Thickness Test SolidWorks CAD File
Accuracy¶
We made a jig to test the dimensional accuracy of the prints. We made a half cube that had dimensions of 25 and 50mm on each axis. Then we put chamfers on the corners to facilitate more accurate measurement with calipers.
Then we measured the blocks with calipers and the table of results is below.
| Direction | As Designed (mm) | Measured (mm) | Delta (mm) |
|---|---|---|---|
X |
25 | 24.90 | -0.10 |
X |
50 | 49.92 | -0.08 |
Y |
25 | 24.90 | -0.10 |
Y |
50 | 49.96 | -0.04 |
Z |
25 | 24.98 | -0.02 |
Z |
50 | 49.98 | -0.02 |
Then we measured the blocks with calipers and the table of results is below.
| Direction | As Designed (mm) | Measured (mm) | Delta (mm) |
|---|---|---|---|
X |
25 | 24.90 | -0.10 |
X |
50 | 49.84 | -0.16 |
Y |
25 | 24.04 | 0.04 |
Y |
50 | 49.98 | -0.02 |
Z |
25 | 24.96 | -0.04 |
Z |
50 | 49.94 | -0.06 |
Generally the results were quite good for both blocks. Generally they both measured a little bit under the target dimension except for one of the measurements on the Bambu. This correlates well with the press fit test as same size bosses and holes seem to fit well together which suggests that there is some built in clearance.
Press Fit¶
We also ran a test to evaluate the fit of cylindrical bosses into cylindrical holes. We made a CAD file with 5 bosses and 5 extruded hollow cylinders with different diameters. We tested both 3mm and 6mm hole sizes. We started by doing nominal in the center and going up by 0.1mm on one side and down by 0.1mm on the other side (range of 2.8-3.2mm and 5.8-6.2mm). However, after testing those, the fit was too tight for a slide fit. So the range was adjusted on the 6mm test jig to 5.6-6.0mm in the CAD.
The best slide fit was when the holes were about 0.1mm less than the boss diameter. The best press fit was when the holes were equal size or the boss was 0.1mm bigger than the hole.
updating this to see if i can push