High temp resin printing problems FORM 2


#1

Hi
I’m having an issue printing with the high temp resin. Ive done a a lot of printing on the form 2 with a number of resins including high temp before… but ive never encountered this.
My print is a mold with a hole through the center of the mold cavity “for an ejector pin, also printed” the pin came out fine but the mold itself did something weird… the inner part of the cavity seemed to smear or something it looks like maybe the resin could not escape? I’m kind of at a loss. I have printed very similar designs using the flexible material without any issues.
I am using a brand new high temp resin cartridge, and a brand new LT long life tank. …thoughts?
two pics attached are the part and what I got.I also wanted to add that I got this result twice. The first time was the same build including two ejector pins. I had the resoullution at .025mm. I the saw the suggestion to only use that setting for small parts “the pins are small and printed ok”. So the next.print I changed the resolution to .050mm without the pins, and I got the result pictued below.



#2

Is the model firm or squishy? I had a problem where the fill of thick bodies are too under exposed with the gray 4 settings in 2.19. Another user had a problem with the durable basically collapsing from the same problem where fill is too under exposed. There are 2 exposures used to print the slices. First is outline of the slice that creates a shell, the second is the fill which is less of an exposure to extend the life of the tanks. This is where a laser based system has some advantages over a dlp based system as well as uniform x,y resolution over the tank (not pixel based).

My thoughts is you have the raw or semi raw resin creeping out of the shell of the model.


#3

Hi the model is firm." When you say squishy…how squishy?" I wonder if I changed the orientation? I wanted to avoid supports in the hole that passes through. Ok one other thing, I had forgotten that I got a print using grey pro that did something similar a little while ago. The weird thing is twofold. 1.ive printed bigger and more complex things using high temp. And 2. I’ve successfully printed this kind of model many times using the flexible resin. I’m starting to suspect the printer… thanks for the info…if you think of anything else I’d appreciate any ideas.


#4

I typically used the Clear 02 resin with OpenFL and almost never had any issues. Recently with FL no longer selling the clear 2 and out of stock on the other versions. I jumped ship and picked up Applylab works Black 2. That particular resin uses gray 3 or 4 for it’s exposure so I had to update to 2.19. The prints detail is phenomenal but the inner part of the model the resin was nearly uncured. It seems this is happening to the FL durable resin as well so I believe that in general 2.19 has some issues with the profile where the fill is not cured enough. This can cause problems where if the model was compressed it could have a leak and raw resin could come out of the model. A good exposure profile will have a nearly fully cured outer perimeter and enough of a fill cure to keep the inside in a green state but still solid. This would maximize the life of the tanks and still have good dimensional stability. Hopefully they can further investigate and patch the profiles OR maybe someone has the newer resins in a profile for OpenFL.


#5

Interesting, I hadn’t thought of the latest software patch. Perhaps I’ll roll things back… Too bad since i had been excited about the smaller point sizes offered with that update. I’ll take a look


#6

One other thing I noticed with the larger high temp prints was the print adhesion… I had a really hard time removing the raft. I wonder if this could.also be a function of 2.19?


#7

How small is that ejector pin hole?

I would try tilting it as far up as possible that doesn’t result in supports on the printing cavity.

But you may be looking at an optical issue.


#8

The hole itself is fairly big… about .25inches across. When you say an optical issue, you mean in the printer? I’ve printed smaller parts in this tank with no problems. And I have had this happen once with the grey pro resin. And that part wasmon the larger side as well.


#9

that doesn’t obivate an optical issue, as the issue might only affect a small - or several small areas of the build plate area- that is- you may find issues whenever a detailed part happens to coincide in its positioning on the build platform with the optical issue.\

Also- you have to consider what you are printing- that die cavity has planes that form prismatic angles that can refract the light path. Have you tried printing this in a resin that is more opaque?

Once more- I would try repositioning the model to a much steeper angle that does not end up generating supports on the die or separation plane faces- and repositioning to a different area of the print bed.

Also- just look at the optical window and mirror to see if you can spot any smudges, dust, or other issues that might cause a localized scattering of the laser path.


#10

Yes I’ll take a look at the optical window. I hope you are wrong on that count as the effect happened on two parts in two different locations. I have printed very similar almost identical parts using the flexible resin with no trouble at all. Which makes me wonder about prismatic effects. I did have a similar problem occur using grey pro resin. And that problem happened on a largish part. I will definitely look at the optical window when I return.


#11

well I returned to work today. I checked the optical window and mirror usinga strong flashlight…I didnt see anything on the mirror. I did have some very slight streaking on the window which I cleaned with PEC pads. Id like to note that I have printed allot if successful prints with the window in its former state “which was probably acceptable” but is now much cleaner.
I am making another attempt today on the same part with a steeper orientation, Ill have results around 2:30EST. will update.


#12

Ok well i have some “results” between yesterday and this morning I tried two more prints. Both got the same results ,both had the same problem as before". I’m trying to eliminate variables, so step-by-step…

  1. I cleaned the optical window with a pec pad, and confirmed that the mirror is clean.
  2. I moved the print to a different part of the print bed.
  3. I adjusted the print to the steepest angle i could, I even allowed a few supports into the hole that runs through the dice cavity.
  4. I confirmed that on the x/y avis I had the print at a 30 degree angle to the wiper face.
    “all produced the same results”
    On the second attempt I made one change “just for fun”. I oriented the model on a almost flat angle, which eneded up producing exactly the same problem.
    So It looks like im experience prismatic effects? Im having trouble with that possibility, mainly because I havent seen this problem before in the high temp and I’ve printed lots of parts with similar and more complicated geometries. Also The weird smear effect cropped up on a print i dd using the grey pro resin. AND I have printed upwards of 30 molds of almost identical design using the flexible resin. I know the flexible resin is totally opaque so no prismatic effects should happen, but i cant explain the gray pro. Very troubling. any thoughts?

thanks


#13

one other thing… Ive wondered if this print is just o big?


#14

have you never gotten a good print of it?

You might need to check the model. Its possible the geometry is corrupted or flawed in and around those facets.

When the printer seems to ADD material that isn’t in the model, or have material missing that IS in the model- there’s a good chance the model has com issues regarding proper solidity.
It could be co-incidence polygons of points or line segments left over from an incorrect boolean operation, it could be two line segments that are not connected in opposing directions- violating solidity. It could be faces that appear to be part of a properly defined volume that are in fact not connected to the rest of the geometry.
Or it could be that one or more faces have flipped normals- or even that you have two or more points that ended up so close together that the resolution level of your modeling app Averaged them to the same coordinates in export.

Run an object doctor on the model and try to determine if it has any geometry errors.


#15

Hi

Specifically of this exact model? no I have not gotten a good print yet… I have gotten many prints of something very similar, designed using the same software and formatted in the same fashion as my other models that did work.
I can’t speak to the model solidity issues, Ive never had to use object doctor before. I will say that preform needed to make repairs to the model, but this happens for every model ive ever loaded into preoform. I draw all my designs using solidoworks and save off as a .stl file. I put in a ticket with formlabs “i dont have allot of hope there, but why not”.
I am currently attempting to print this using the rigid resin as a test. Ill also take a look at using object doctor. But the model itself is pretty simple Id be surprised if that was the issue, at this point though it could be anything.
I appreciate the advise hopefully something will work… as an aside, I wonder If I could dye the hightemp resin opaque to cut down on any prismatic effects? I know its not reccomended with that resin, but who knows?.

thanks


#16

ok so i printed the same model using the rigid resin and I got the SAME results! pretty much the exact same flaw as with the high temp resin.
So there must be something wrong with the model. Ill have to take a look at redesigning the model. Formlabs dosent really tell you what its repairing when it says a model is broken. I looked up object doctor but i dont have auto desk. anyone know how i can get it? Anyway At least I think i eliminated the prismatic effect, and possibly any flaw with the printer although i guess that is still possible. I also wonder about the presence of the ejector pin hole, that is the real differnece between my old molds and the new mold… could that possibly be an issue? Ive printed lots of parts with deep holes before without issue.
Any urther thoughts?


#17

Its almost certainly Not a prismatic effect if you get the same flaw at different orientations.

I am pretty confident that its a flow in the model geometry.

If you added the numerals and other features, those alone could be the source of incorrect geometry that is causing these issues.

For example… if the numerals are separate models that simply intersect the facets of the die… then they contain geometry below the surface of the cavity and Preform can not always correctly discern to ignore this geometry.
If you modeled this in a surface modeler- you may have surfaces that are NOT stitched and therefore violate solidity.

Preform thinking the model needs repair is not a good sign… although I have seen preform give the same error message on geometry I know for a fact to have been flawless.

What it comes down to is modeling expertise. While CNC milling does not require solidity- all printer, do. and while some software, like Preform, has been written to try and correct for the most common forms of non solid geometry… the possible ways in which differing software can potentially export bad geometry is multiplied by the possible ways import filters can incorrectly interpret or try to correct that geometry

In short- a computer can only tell something is solid when it has only ONE SIDE. an outside. With ALL its normals pointing OUT. Flip one normal on one polygon and that object is no longer a solid.
A proper model form printing should have NO internal, non-printing geometry. Every polygon and every point should be on the surface of the volume the model describes.

You can try a model doctor… or you can try importing the model into a voxel modeler like Freeform.

But I think this is the crux of your issue. You may want to consider using different modeling software.


#18

I agree.
The big change i mede form the last mold to this is the numerals… the last mold I used Solidworks type face function adn a custom tff file to put in the numerals. But they had flaws that would not allow me to put drafts on them…kinda a must with solid molds but not necessary for rubber molds. So i hiton the idea of manually tracing each numeral and saving off eatch sketch…I then used that sketch to extrude cuts into the mold cavity, this gave me cleaner numerals for solidworks to use and allowed e the drafts i needed… i wonder if thats the trouble in continuity flow… or maye the tiny fillets i added later to improve mold release qualities.


#19

every one of those operations has the potential to violate solidity.

Especially fillet operations, which often result in adjacent patches that are not stitched into a continuous surface.

Looks perfect- might even mill perfect- but gives a 3d printer conniption fits.


#20

ok small update
as i said before the numerals I cut in hat additional “manually placed” fillets in the base of the numbers. when i removed those fillets from the model Preform no longer gave me any error messages tellig me the model has errors that needed correcting… I also fed the model to Makeprintable.com using their free trial and it didnt find anything wrong either… ill run a new print today to try it out. will advise when i have some results.

thanks