Video: How to determine exposure settings using a working curve


#21

Now I know. Thanks a lot


#22

If you mean the values in yellow, you’re supposed to adjust them to match the curve to the data points. It’s all pretty manual.


#23

OK - I added sliders to my excel file to make this easier… :smile:


#24

Sliders?! Is this a new feature?! :open_mouth:


#25

I hope you guys are using a micrometer vs a calliper, for consistency between measurements.


#26

@Yannis_Vauthier
Mititoyo drop gage with 5 place (inches) readout

@OwenSmithyman
To lazy to keep typing in numbers… Added form control slider’s to do the work for me.


#27

Also, I’m exposing on a glass slide and leaving it in place for the measurements.


#28

Hi all,

I just wanted to reopen this discussion.

I have been working through this and I am unhappy with the way the fitted parameters are dealt with. Mainly because fitting these three parameters to minimize the residual often causes unrealistic plot shapes.The way I found best to fit this data, is to:

  1. Make Dp0 the maximum thickness measurement you observed, which if you wish to accurately
  2. Make Ecrit the dosage at which the first cured layer was observed minus ~5-10 mJ/cm2.
  3. You should be able to adjust dDp/dE only then to fit the data.

I guess the point I am making is that you can vary these things to obtain the best fit, but Ecrit (and Dp0 to some extent) are properties which are defined by a specific value and obtaining the mathematical best fit to the data may give you something that fits perfectly but the actual values are meaningless.

Also I have done this for a few resins, how can we share it here?

Martin


#29

I haven’t been able to get back to this area of research for a couple of weeks, but here is what I have done:

I created a fixture to mount a glass slide from an old tray. STL file is too big to attach… a common problem I find. @OwenSmithyman
I created a custom calibration file that includes some features that I hope to use to determine precision vs mJ/cm2


I then reformatted the spreadsheet to include sliders to control Dp0,dDp, and mJ/cm2.
Made it look a bit 'nicer’
Plotted a value for exposure time vs layer / cure depth.

Here is the spreadsheet. Ember Working Curves.xlsx (291.3 KB)


#30

@scott_chabineau Wow, I love what you’ve done with the spreadsheet! Particularly the sliders and the suggested exposure times. Very nice.

Unfortunately my hosted plan for this forum doesn’t allow me to change the upload size. I’m asking them if they can make an exception, but we’ll probably have to use Dropbox/GDrive for larger files. Sorry about that. But very cool fixture.

@mapadebe I would just attach the spreadsheet to your post. If it would be useful, I can start adding people’s spreadsheets to a list in this thread’s first post so that they’re all in one place.


#31

Remeshed the STL with a lower resolution. Looks like all the features are still there…
Working Curve assembly for 45.75x70.75x1.87mm glass slide revNR.STL (5.8 MB)

I highly recommend printing this with FormLabs Tough. PR57-K is too brittle and cracks after a few days


#32

Great Fixture :ok_hand:. I printed with formlabs, but the supports were too much and it took a long time to break. them. it will be great if the file does not contains the supports and the slicer software create its own the supports.


#33

I have attached the individual part files here. I didn’t have success with auto generated supports. If you do, I would like to know the settings used. Creating my own support structures is very time consuming!

Working Curve Upper Frame (no supports) 45.75x70.75x1.87mm glass slide rev1.STL (67.6 KB)
Working Curve Lower Frame (no supports) 45.75x70.75x1.87mm glass slide rev1.STL (1.6 MB)


#34

You are a life saver. i will let you know my results.


#35

Printed on mark forged using Nylon. but in the lower part the curves around the holes don’t allow the glass slide to be seated in the rectangular groove. i have to cut it manually.


#36

Looks good - too bad the glass didn’t fit. Did you check the final part dimensions and the glass slide? The glass slide I pulled out of my ember resin tray (new version) measures 70.78mm x 45.79mm. The old tray glass slide measures 73.10 x 47.95mm.
I have a SolidWorks configuration for the larger slide too if you’re interested.


#37

I’ve have to ask - how do you like the Markforged printer? I’m looking for FDM style printer to fab jigs and fixtures - and since we usually use aluminum it seems like an interesting alternative.


#38

yeah i use the old broken trays’ glass slide, didn’t break a new tray yet :smiley: it already worked for me. Thanks for your great support.


#39

Here’s the larger slide STL just in case anyone wants it.
Working Curve LowerFrame 48x73x2,04 slide .STL (4.1 MB)


#40

FYI - here are the Working Curve ZIP files that I use. I print each file starting at 0.64 sec until I get most of the print to be less than 200um. This helps fill in the lower thicknesses for the working curve spreadsheet. I am finding however that even though the cure depth may be close to the desired layer thickness, layer adhesion requires the final exposure value to be significantly higher. It would be nice to have a calibration file that allows this value to be determined as well.

PatternMode Working Cuver ver2 0,08sec.zip (257.8 KB)
PatternMode Working Cuver ver2 0,16sec.zip (257.8 KB)
PatternMode Working Cuver ver2 0,32sec.zip (257.8 KB)
PatternMode Working Cuver ver2 0,64sec.zip (257.8 KB)

PS - don’t forget to reset your printer for detect jams - since these file disable it and it’s not part of the normal print settings files created by Print Studio.