Dealing with build lines in resin prints

[cv_acr]

From the CMR thread in Product Discusssions. Didn't want to totally derail that thread with a technique discussion...

Any printing experts have insights on how you deal with build lines coming up in the print like this?

I purchased their N-Scale 3D printed Alco C430 shell.  It went in the garbage.  Build lines were horrific. 



Scott Lupia

I've been experimenting on printing some freight car projects and the last run ended up with some regular horizontal lines (not quite as bad as this, but weirdly noticeable regularly spaced lines. I haven't done a second re-print on the same project yet (I've been too busy with other projects to get back to the printing) so I'm not sure if there are tricks to try in designing/supporting the print, or just a fluke sort of thing and just try to reprint.

I'm looking at "somewhat" mass-producing some specific ore cars for the club layout, and working on little print issues like this.

[Chris333]

The z rail must have some unwanted play in it. Some machines now have dual rails.

[cv_acr]

This is the result I was getting BTW. (Models were printed at 45deg, supported from the top of the car.

The consistently regular spacing of the horizontal creases I thought was odd.

[cv_acr]

The z rail must have some unwanted play in it. Some machines now have dual rails.

I'm using an Elegoo Saturn, single Z axis rail.

So basically, kind of try it again, making sure everything is REALLY tightened down well and see if results vary?

[Chris333]

I don't have that machine, but:
https://www.reddit.com/r/ElegooSaturn/comments/omls62/just_got_a_saturn_and_seeing_some_major_layer/
https://imgur.com/gallery/PPU8kJ7

There is a bunch more if you search, but I really don't know how it is with your machine. Looks like it already has dual rails and those are much better, but still seams like a bunch of complaints.

I was getting lines like this:
https://photos.app.goo.gl/kYQi617wsxjVxxzNA

Swapped out the lead screw
https://photos.app.goo.gl/be35G1zdx6tX7fBBA

and got this, much better
https://photos.app.goo.gl/bNzarmwzJ9VfxQFG8

So in my case it wasn't the rail slider bearings. It was the screw.




Some of those bigger deeper lines in your photo look like just a change in FEP tension between layers from the ribs under the car.

[chessie system fan]

That CMR shell is suffering from two rookie Photon mistakes.

There are consistently regular \ lines

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

This is caused by the model not being exactly 90 degrees on the build plate.  When the user imported the model into the photon software, he needed to rotate the model 90 degrees so that the shell would fit on the build plate... so he *eyeballed* it.  The lines are there because it's really 86 or 87 or 88 degrees.  And this only matters in flat areas.  Do you see how the curve on the cab isn't affected one bit?  That's my main clue.

This mistake isn't as dumb as I'm portraying it.  I have the original photon software.  I recently downloaded the most recent version to see if it was an improvement.  It turns out that that feature we need disappeared! Or it's so hidden I can't find it. In the old version I can type in exact degrees to rotate a model. In the new version I can't do that anymore.  After searching around I gave up after about 30 minutes and went back to using the old software again.  But if I didn't have the old software I wouldn't even know how important that setting would be.

The other mistake is the / lines.  Notice how irregular they are:

..........///////................/................///

The important clue is that in addition to being irregular they are *parallel* to the build plate. And there's nothing special about where they happen, like an undercut or something. To me, this means that each time a line appears the machine got bumped. And it doesn't take much. I discovered this because I've done it too.  I keep my photon in a bedroom closet. Similar lines appeared, and I realized they happened whenever I opened the closet door to check up on how the print was going. Since then, I leave it alone and the lines have gone away.

Prediction: the CMR guy started the print before going to bed.  The big lines are from the family getting ready for work/school and the next big band is when everyone arrived home for the day. And I wouldn't be surprised if the machine is located near a set of stairs.


Your lines are different, but I don't have experience with lines like those.

[Ed Kapuscinski]

That CMR shell is suffering from two rookie Photon mistakes.

There are consistently regular \ lines

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

This is caused by the model not being exactly 90 degrees on the build plate.  When the user imported the model into the photon software, he needed to rotate the model 90 degrees so that the shell would fit on the build plate... so he *eyeballed* it.  The lines are there because it's really 86 or 87 or 88 degrees.  And this only matters in flat areas.  Do you see how the curve on the cab isn't affected one bit?  That's my main clue.

This mistake isn't as dumb as I'm portraying it.  I have the original photon software.  I recently downloaded the most recent version to see if it was an improvement.  It turns out that that feature we need disappeared! Or it's so hidden I can't find it. In the old version I can type in exact degrees to rotate a model. In the new version I can't do that anymore.  After searching around I gave up after about 30 minutes and went back to using the old software again.  But if I didn't have the old software I wouldn't even know how important that setting would be.

The other mistake is the / lines.  Notice how irregular they are:

..........///////................/................///

The important clue is that in addition to being irregular they are *parallel* to the build plate. And there's nothing special about where they happen, like an undercut or something. To me, this means that each time a line appears the machine got bumped. And it doesn't take much. I discovered this because I've done it too.  I keep my photon in a bedroom closet. Similar lines appeared, and I realized they happened whenever I opened the closet door to check up on how the print was going. Since then, I leave it alone and the lines have gone away.

Prediction: the CMR guy started the print before going to bed.  The big lines are from the family getting ready for work/school and the next big band is when everyone arrived home for the day. And I wouldn't be surprised if the machine is located near a set of stairs.


Your lines are different, but I don't have experience with lines like those.

Well here's a fun realization: 3D printed objects now contain a source of intelligence information about our movements.

[MK]

They can be our personal seismic machine!

[chessie system fan]

Speaking of movements, want to test the theory, Ed?  I'll set up the photon in my bathroom, send you a print and then see if you can guess my daily patterns. For science, of course.    






Might as well have fun with this.

[Chris333]

Lots of fiber in your.    .    . Resin.

[Erock482]

The lines definetly seem like wobble of some variety in the Z screw mixed with unequal layer tension.

The other thing I see is a poorly supported shell, which happens at these steeper angles.

The higher angle seems not super productive here. I generally print perfectly flat with excellent results, and 22.5 degrees prints wonderfully without being ridiculous to support.

So I'd check the mast for tightness, re-orient the print to be a bit flatter and try again. If I didnt see improvement I'd explore replacing the Z screw