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Severe light bleed with FTD SW

Hey guys,

Yesterday we tried to print out the tower and it was designed inhouse.
And here are the results.

At a certain side there’s severe light bleed. Do you have any tips to how to solve this? We don’t want to pigment the resin because the white simply stands out.

Here are the specs that we have used for the tower:
xy=100u z=250u

Any tip is well received

Unfortunately, there’s no really good way to mitigate this and still stay white.

The problem here is that the photoinitiator in the resin is sensitive to visible light wavelengths, and white pigment scatters all visible light wavelengths, including curing spectrum ones. That bounces curing light all over and creates light bleed.

If you really need to print clear or white, the only thing I have found that works is to use Autodesk PR48 resin, which uses a photoinitiator which is more selective and mostly insensitive to visible light. That makes the UV blockers sufficient for preventing light bleed without affecting the visible color of the resin.

This resin, consequently, requires longer layer curing times since the photoinitiator reacts to less of the light being emitted.

James thanks for the reply :).

So the best solution would be to print with a different color and maybe airbrush it or paint it white after the print?

Also I’ve contacted you via youtube message. Do you happen to have FTD exposure times? As in I’ve read your post on the forum and you mention that for xyz100 you use 4-14s depending on the part.

In one of your posts you explain the how to extrapolate the exposure times in xy and I get that. But you do you calculate it in z? For example what would be for xy=100 and z=250? (FTD standard blend [deep black or snow white])

The Z scale factor is a bit trickier to compute because it can vary depending on the intensity and type of pigmentation used, and may have some nonlinearity.

Generally, you’ll see from the comparative examples at:

That the exposure time increases by 25-100% for each 100% increase in layer height, meaning that when you double the layer height, you may increase the exposure time by as little as 25% or by as much as double.

Given the wide functional range of FTD, if you aim in 18 second range for 250 microns, you’ll probably get something out that you can then tune in subsequent prints.

Looking at your pictures again, the way that you have flakes all one one side of the print is peculiar. That type of artifact is typically caused by “background cure”, where the black background areas are illuminated enough that they cause excess XY plane curing in the areas where the lamp is most intense, rather than light bleed, which occurs in all directions, but is most intense in the Z direction.

It is unusual, however, to see background cure artifacts in low XY resolution prints, they typically show up when you are at high XY resolution, like smaller than 50 microns XY.

For example, I would expect light bleed with white pigment to affect the sharpness of the windows in your tower, which with highly pigmented resin can be extremely sharp and well defined, but with white resin will likely always be somewhat soft and rounded. However, the flaking you see off to one side is probably caused by something different.

The first thing I would look at is your video card. If you have an ATI or nVidia video card, these cards are known to have issues where they digitally preprocess the output image and put out poor quality black that is over-illuminated. While it may be possible to fiddle with gamma and projector brightness settings to mitigate this somewhat, people have only reported consistently good results when using Intel video cards. The cheap on-motherboard integrated Intel chipsets are the best.

If you have Intel graphics, then there may be some other possibilities.

The first thing I would confirm is that your lifts are high enough and that you are fully release on every layer. If the orientation of your part is such that the artifacts are all on the flexible end of the vat, I would be suspicious that the part isn’t fully releasing on each layer, and that a portion of the part is left stuck to the vat for several layers before releasing.

Another less likely possibility may be that FTD SW is more reactive than the IB that I have used in the past, and 18s is far too much exposure, creating these kinds of artifacts. You could try reducing your exposure and see if that makes it difference.

Thanks again for the great reply James.

So I’ve checked the laptop which I use for printing has an intel onboard vid card.

Yesterday I’ve printed a smaller statue in xyz 100. And came out good without exterior artifacts. But the inside is a different story:

I’ve put on a print for another big tower. 7 more hours to go. I will report back so far so good.

Well darn it, after I left my office everything went horribly wrong. But where’s a problem there’s opportunity :D.

Now the big tear appeared just after i left. The thing that I’ve done around that time was pouring a lot of resin. I started to notice artifact forming on the side and saw also that the resin level is low.

Btw I’ve checked the design there are no flaws at the tear area.

Could the extra resin mess things up like this?

The pics:

The artifacts formed on the not bolted down part of the resin tank. Also the interior is filled it’s like a haunted tower :P.

Crap I forgot to export the config file …

Also I paid attention that on the roof to slow down the printing but that didn’t help either.

Good pictures, especially showing the print in relation to the orientation of the vat!

The big tear areas are most likely due to insufficient lift. The lift sequence didn’t life the part high enough to fully release the part from the vat until several layers later when the accumulated lift height was high enough that the part finally popped off and then started forming again.

It is interesting that you have the flake artifacts right at the gash.

1.5mm of lift is much less than I typically use for FTD IB. I find IB to be stickier than other resins (like MJ G+ or 3DM ABS) and requires > 4mm of lift to reliably release over the duration of a print.

Thanks again for the the insight.

The interesting part is that the lift hasn’t change since the 100th layer and the first tear is at 900 something.

Any ideas on the artifacts? They only form on one part of the print. It was really easy to peal off the those which were attached to the roof. Now around the wall and the windows it’s harder now. During the print it was much easier because they were fresh. I’ve left them there so I can photograph it.

In your experience the tear could’ve been caused by adding in resin? Cause I remember correctly that the resin level started to get low and the artifacts started forming and added a whole lot of resin it was around 50% with the print. Then I left and pow there’s the tear.

I have found that even when analyzing a reference layer with the same cross section for hundreds of layers, if I try to optimize the lift height too closely, I will have a failure to lift even if the setting seems to work initially.

There is probably some random variance from layer to layer and once a layer gets a little stuck on one end to the vat, it will get progressive more and more stuck until the height is high enough that the flex tension on the var gets very high. The flexing force from the vat, like a spring, is nonlinear. It is very small when flexed only a little, and progressively increases as the amount of deflection increases.

In my experience, adding resin in the middle of the print has not caused any artifacts like this and generally had no effect on the print unless I accidentally let the vat run dry.

I still wonder if the flake-like protrusions have something to do with insufficient lifting. The artifact is quite different than anything I’ve encountered, but it is likely that the white pigmentation causes artifacts to form differently compared to the darkly pigmented blends I usually use.

Thanks for the reply. Uhum I see ok going to test out a higher lift and see what happens. Maybe praying next to it as long as the printing goes on :slight_smile:

During my first few months printing, I generally only printed while monitoring the print (not necessarily watching it visually, but being close enough that I could hear the “slap” sounds of the vat dropping on each layer and notice if they stopped).

There are a lot of things that can go wrong in a print and it took a while to get a feel for what settings constitute “conservative” estimates for unattended printing.