02-18-2021, 07:44 PM
Nighteagle,
I don't have a Mars 2, but I've spent a lot of time trying to improve Z accuracy on a Mars. My run parameters are not directly related to yours but I can tell you that I have seen more than 1mm thickness difference on a 5 mm thick part just by varying run parameters. Light delay time is important and adding say 13 seconds may be helpful. Every single trial (maybe 50 or so on a simple open rectangle 95 x65 mm x 5 mm thickness) I've made produced thicker parts than the design by at least 0.155 mm. You are apparently seeing only thinner parts than design, so maybe the Mars 2 has different factors affecting the thickness.
Early in my testing I had weak indications that slightly increasing the lift distance from the recommended 5 mm to 5.5 mm might have made a slight improvement, but that might have just as well been caused by replacing the FEP film and having a different amount of tension. I currently run a 7mm lift but only because it was the high end of a design of experiment that I initially ran. One can definitely hear the part release from the FEP film well before it reaches the lift limit.
Whatever parameter changes you make, I'd suggest at least 3 replicates each with a minimum 5 thickness measurements. This way you can run a statistical test to see if the parameter really might have made a change. The standard deviations have varied on a given trial from 0.068 to 0.108 mm at the low end to well over 0.200 mm at the high end for a part with 5mm design thickness.
I haven't even looked into the gcode yet, but the print precision I'm seeing suggests you may be chasing a ghost (I mean that maybe the problem is more parameter settings and lack of print precision due to machine design than the code itself).
You also seem to have an issue in Chitubox as those numbers are odd. I'm running a lot of trials with mostly 0.020 mm layer thicknesses and in Chitubox my layers are stepping that amount (in the Chitubox run window). I've switched to the latest version 1.8.1 but I don't recall seeing any odd numbers in the previous version ( I think it was 1.7.3). It might be worthwhile testing the latest release.
For what it's worth my lengths and widths also vary with parameter settings but generally are less than 0.5%.
Hopefully somebody with a Mars 2 can try to replicate what you are seeing.
Greg
I don't have a Mars 2, but I've spent a lot of time trying to improve Z accuracy on a Mars. My run parameters are not directly related to yours but I can tell you that I have seen more than 1mm thickness difference on a 5 mm thick part just by varying run parameters. Light delay time is important and adding say 13 seconds may be helpful. Every single trial (maybe 50 or so on a simple open rectangle 95 x65 mm x 5 mm thickness) I've made produced thicker parts than the design by at least 0.155 mm. You are apparently seeing only thinner parts than design, so maybe the Mars 2 has different factors affecting the thickness.
Early in my testing I had weak indications that slightly increasing the lift distance from the recommended 5 mm to 5.5 mm might have made a slight improvement, but that might have just as well been caused by replacing the FEP film and having a different amount of tension. I currently run a 7mm lift but only because it was the high end of a design of experiment that I initially ran. One can definitely hear the part release from the FEP film well before it reaches the lift limit.
Whatever parameter changes you make, I'd suggest at least 3 replicates each with a minimum 5 thickness measurements. This way you can run a statistical test to see if the parameter really might have made a change. The standard deviations have varied on a given trial from 0.068 to 0.108 mm at the low end to well over 0.200 mm at the high end for a part with 5mm design thickness.
I haven't even looked into the gcode yet, but the print precision I'm seeing suggests you may be chasing a ghost (I mean that maybe the problem is more parameter settings and lack of print precision due to machine design than the code itself).
You also seem to have an issue in Chitubox as those numbers are odd. I'm running a lot of trials with mostly 0.020 mm layer thicknesses and in Chitubox my layers are stepping that amount (in the Chitubox run window). I've switched to the latest version 1.8.1 but I don't recall seeing any odd numbers in the previous version ( I think it was 1.7.3). It might be worthwhile testing the latest release.
For what it's worth my lengths and widths also vary with parameter settings but generally are less than 0.5%.
Hopefully somebody with a Mars 2 can try to replicate what you are seeing.
Greg