Notes on CAD Software and the Prusa Slicer

Version 2.7.x   MK4/3.9/3.5 must have 5.1 or newer Firmware.

CAD Software

CAD modeling is use Solid Edge for Makers.   Free unless you make money with it.  I like having professional, well supported software.   I tried many of the "free" CAD packages and got little out of them for the large amount of time they took to use.  

Prusa Slicer

Prusa slicer has many functions.  It will take a while to become an expert.   I find default settings to be effective.  Advanced things to learn beyond the basics.

Prusa Slicer has 2 parts.  The slicer software and the configuration data.    Configuration data is updated many times between software updates.  Keep the configuration data updated.  The configuration data drives the default settings.  As improvements are made and new filaments and hardware are supported, the configuration data is updated.

A link to the Prusa Slicer Documentation

A note on Keep/Transfer/Discard/Save menus that appear when changing the printer, filament or layer size.

Save means update the defaults for future use.  I DO NOT recommend using Save until you are sure you want them for future defaults.  

Transfer means keep the old settings, even though they may not fit.    See below for details.

Discard means remove the old settings and use the appropriate new/default settings.   

When you change the primary filament or Printer Settings in PrusaSlicer, a menu with Transfer, Discard, Save  or Cancel options will often appear.  One example is when using a .3mf file that was set for another printer, you need to set it for your printer.   When you change the printer, this menu will appear.   My recommendations.

When changing the printer, the first menu page is usually related to the printer settings.  G/M code options, file naming and so on.  This one should be Discarded.  If you Transfer these settings, your printer may not work correctly.  When you Discard the settings, the defaults for your selected printer is used instead.

Another menu that pops up shows default settings for printing.  Usually the second page when changing the printer or the page when changing layer height. Any of the default print settings that were changed are shown.  Profile passes, number of top/bottom layers, supports enabled and so on.   This you normally Transfer.   Since these effect the part directly.

When you change the filament, a page may pop up showing temperature settings and so on related to the old filament setting.  This should be Discarded.   Use the defaults for the new filament selected.  Keeping PETG settings for PLA use does not work well.

Supports, their effect on speed and material usage

I have part that takes 29 meters of filament.  It is a boiler for a train so it is like printing  a cave.   I tested with grid and organic supports and this is what I found.

  1. Organic supports are easier to remove.   This is very helpful with PETG supports in my experience.  I have found PETG supports much harder to remove than PLA supports overall.
  2. Uses less material.   In my  test part, 29 meters of filament for the part,  29 meters of filament was for traditional grid supports.  This drops to 20 meters for organic support 1/3 reduction of the support material. 
  3. Time wise organic supports may not be faster.  Time estimates show this.   For an MK4 with input shaper.  The part alone would take. is 4.2 hours. 7.3 hours with grid supports,  11.8  hours with organic supports.  In this case it increased print time 39%.   Why?  It is Acc/Dec, Acceleration/Deceleration.   A long straight line is faster than a lot of short lines or small arcs.  Even though the circles are less overall distance.   A lot of small 1mm moves to make a 100mm movement are not as fast as a single 100mm straight move.  The main difference between grid and organic.   An MK3s+ is slower than the MK4.  9.2 hours for the part with 17.5 hours for grid supports and 20.3 hours for organic supports.  
Can arc speed problems be overcome using G2/3 codes instead of point to point for circles?  No.  The processing for G2/3 at the machine adds to the processing that needs to be done.  At high feed rates is too slow to generate fast, accurate arcs.  Point to point is better for arcs and fast speeds.  Modern High Speed NC machines use point to point for high speed arcs.  Less processing at the machine with no processing delays means faster overall performance.

Post processing time of this train boiler with Grid supports was almost 2 hours and gloves are needed. Very easy to get cut.   There is a lot of supports to remove and they don't remove easily even in PLA.  The longer to remove the supports, the more chance of damaging the part.  I printed the part on an MK4 in PETG using organic supports and it took 15 minutes to remove the supports.  No damage to the part or my hands. 


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Last Update Apr 3 2024