Warping Prints & Accuracy Questions
I'm completely new to 3D printing & just built my first MK4. I am generally pleased with the quality of the printer, but I've run into an issue. I have noticed that a lot of objects are warping when printed directly on the steel PEI sheet (I'm only printing using Prusament PLA filament so far). Especially with wide/long objects, the corners lift up & off of the build plate as the print continues. The top layers turn out fine, it's just the bottom that is warping like this. What can I do to prevent this from happening?
Second, I would like to improve the accuracy of the printer. I'm hoping to get 0.002" tolerances out of it & better would be a plus. So far testing has given me a mix of passing & out of spec. results as follows;
-X axis: +/- 0.0020"
-Y axis: +/- 0.0048"
-Z axis: +/- 0.0010"
-Printed pins have a diameter of +/- 0.006"
-Printed pin holes across the Z axis have a diameter of +/- 0.006"
Are there any physical adjustments I can make to the printer to narrow down these numbers?
RE: Warping Prints & Accuracy Questions
Accuracy: I think these numbers are as good as what you can get with FDM printing.
Warping: my standard list of suggestions:
Assuming Live Z is well calibrated and the steel sheet is clean (using hot water and dish washing soap), here are a few approaches that have worked for me (copied/pasted from previous posts):
- Slow down print speed (5-10 mm/s) for first layer(s).
- Add Mickey Mouse ears to the corners. There's a "helper disk" in PrusaSlicer's Add Part library but I prefer to simply add a cylindrical, maybe 10mm diameter, change height to single layer height, then place the part at the corner. Repeat for each corner.
- Add a brim around the model, 5 mm or more. Wider or 2 -layer high brims may be needed but may not work with the size of the model or may require being added in your CAD software.
- Use Layerneer Bed Weld ( https://www.amazon.com/Printer-Adhesive-Layerneer-Original-Filament/dp/B079984GV5/ ). You only need a thin layer.
- If you have design control over your part and it's possible considering the intended use, you can try to round the edges and/or add holes to the base of the model.
- Combination of above. Usually, brim/ears does the job, or some Layerneer if needed, but large, rectangular objects can be a challenge.
- Also, drafts can encourage warping, so printing in an enclosure (with doors open for PLA) may help.
A pretty good article:
https://the3dprinterbee.com/warping-3d-printing-causes-solutions/
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
Your basic unit of accuracy is half an extrusion width; with the default 0.4mm nozzle that's 0.45mm/2, with a 0.6mm nozzle it's 0.65mm/2.
For tolerances of print in place parts or threads and involutes you can reasonably expect to use half a nozzle diameter with ambitious design approaching a quarter of the nozzle size.
For highly accurate mechanical parts regard your prints as blanks - like raw castings they should be designed fractionally oversize and machined to fit.
Cheerio,