Brittle support plates


#21

If the support plates are too brittle but the rest of the model is fine then there is an issue with the exposure settings where the resin is over cured on the initial layers.

Try an earlier version of Preform that supports that resin version and see if the problem still exists.

I wish there where some simple editing for the exposures in Preform without going through major hoops. Something that would allow users to tweak settings for the following:
Build Layers
Height Adjustment
Base exposure (perimeter of model)
Fill exposure

Ability to adjust these would allow users to mix their own resins and achieve an optimized profile.
Going through OpenFL seems pretty cumbersome and I honestly don’t have the patents or the time to fiddle around.


#22

@KenCitron I don’t think this is the issue because it’s intermittent and correlated with the number of subsequent prints. I’ve since been lightly sanding the build plate down in between prints and parts are popping off nicely.


#23

Hey Leonhart88, what grit are you using to get the best result?. I sanded a few and it “helped” but still gave me quite a lot of brittleness around some of the peninsula area.


#24

You shouldn’t have to sand the build platform between prints. If the build platform is cleaned with IPA between prints and the print profile is correct then you should have consistent results all the time.
If the prints don’t stick to certain areas of the build platform then make sure it is flat and not worn down from sanding that would cause recesses. Even a worn pdms should not cause the first compression layers not to stick if the pdms is marginal.
A marginal profile will cause havoc with prints and not be stable enough whereas prints may or may not work. This can be from compression layers being too weak and/or exposure too weak to get a solid and consistent layers to hold the rest of the layers.

I have had issues with the latest preform where the initial layers start to peel up from the build platform, I have never had that issue in the 5 years or so of running my machine. I actually had to lower my build platform .070 to squeeze out a print for a job, the print came out fine but the build platform still wanted to peel up.

I am looking to roll back on a version but not sure where changes were made that are causing the issues. I used to use OpenFL without any issues and nearly flawless prints every time. Unfortunately the resin formulas changed and I do not have a material setting to match and was forced to update to 2.19.


#25

I can’t speak to whether you shouldn’t HAVE to… but you definitely OUGHT to. Because every single resin I have tried will gradually result in increasingly robust adhesion with accumulated print runs…

When I sand the Build plate, I can clearly see the areas where the resin is worked into the microscratches because the grey dust from sanding sticks to the trace resin and leaves a discolored surface. This discoloration correlates perfectly with the footprints of prior builds.

And my resin sticking to the platform problem disappears when I am careful to keep sanding until I can get those discolored areas to wash off clean.

The resin CAN get into the tiny surface scratches and it can definitely get cured inside those scratches and the first few layers Are over cured and compressed to ensure a bond.

ergo- the cause is not the optics, its the build up of traces of resin that do not pop off with the rest of the raft- but that fracture and remain stuck behind.

The resin is Not becoming more brittle… grey and clear and rigid resins are Already pretty damn brittle- its just that when they stick to the platform hard enough, trying to pry them loose snaps them rather than popping them loose. Durable and Tough do the same thing- but both of those tend to not snap as suddenly- when they stick to the platform , prying them loose will bend and crack them or cause them to tear, more than fracture.

I would point out that Formlabs Does list the build platform as a ‘consumable’ and about the only thing on it that I can see getting consumed is the fact that I have to sand a little bit off of it regularly to maintain usability.

I keep an orbital sander to hand with a pad big enough to cover the whole platform- with 200 wt sandpaper on it.
After getting the parts off, IF they are tending to stick more than normal, I clean the platform with IPA- dry it- hit it with the sander for about 15 seconds or so- then wash it again with IPA. If I still see the grey areas that look clogged, I sand a little more. Then clean with IPA
works great.


#26

I have never had a part not stick to the build platform until I changed to Preform 2.19. I had used OpenFL since it was released. I never had to sand my build platform and the only thing I always did between prints was pop off the part, scrape the extra resin back to the tray and wipe the platform down with ipa.

Even if you had build up the resin should stick to it as it does the build platform. This would be the same as adhering parts together with raw resin.

I keep saying there are problems with the new software where as initial compression layers are under exposed, inner fill is way under exposed making the parts incredibly fragile because the entire form is dependent on the outer perimeter exposer like an egg shell.

The new support system also seems marginal, I am guessing there is not much difference on the exposure on the supports probably the same as the perimeter exposure.

I do like how the supports pop off but that was not a huge deal to replicate in OpenFL by simply reducing the point size.

I am only comparing the latest version to OpenFL since I had not changed software until recently.


#27

I am not running 2.19

You are saying that in this version the form2 only fully hardens the OUTSIDE of the model volume and does not fully cure the interior resin?

Has Formlabs confirmed this?

I mean, I can’t see how doing so would in any way be of benefit.
I’ve broken models before and their interior volume is always just as hard and just as brittle as the exterior. If not more so because they are sealed off from oxygen,


#28

Yes there are multiple settings for printing a model. It is in the ini files if you read through for OpenFL.
There are probably other settings for the Form2 as it has more features than the Form1’s

First thing that happens is there are compression layers that make up the base. The machines will go slightly lower on z and compress the layer. Those initial layers are usually exposed more so they are harder and will stick to the build platform.
Next there are the supports that are printed and those I believe have solid exposures so they are strong.
Then finally the model itself. The laser will print a outline of the model and then do a Fill exposure which is less leaving the resin in a green state.

By filling the model with a lesser exposure you save wear and tear on the pdms layer which extends the life of the tank. It also speeds up the printing time. It also makes the model somewhat forgiving during the peel process so there is less of a chance of a failed layer.
The outer perimeter of those layers are like an egg shell.

This is a big advantage having this type of control over a typical dlp type printer.

Make sense?


#29

I definitely agree with @Sculptingman based on what I’m seeing empirically. I’m running 2.19.1.

I’m extremely careful in removing parts and always clean the build platform diligently with IPA after before another print. Even doing so, I’ve noticed exactly what we’re describing above, where subsequent prints result in rafts that increase in brittleness (I typically print with Tough resin). Once I sand the build platform, it goes back to normal. I’ve since been sanding lightly with 120 or 340 grit paper after each print (clean with IPA, sand, clean with IPA) and I have yet to see another annoying brittle raft.


#30

I have not seen any difference between the exterior and the interior of any printed model when I have broken a print. I have also sanded well into clear resin parts and never encountered any interior materials that show any less rigidity than the exterior.

It makes little sense to expose the interior at a lesser energy that would not fully cure the resin… because Formlabs makes a big deal about the Isotropic qualities of the parts their printer produces.
Differentially polymerized layers would result in the part showing Anisotropic results in testing and it would result in less predictable warpage and distortion that would vary with the shape of the profile being drawn.

I agree that the laser draws the outline first- but this is not to create a shell but because in drawing the outer edge of the profile the laser is running OFF the actual line so that the very rim of the laser spot is following the rim of the actual layer profile…that is, the center of the laser spot is actually running INSIDE the profile by half the diameter of the spot. This is HOW laser SLA’s achieve a finer surface detail in X/Y than the the measured resolution of the laser spot. ( and why the size of a printer’s laser spot is not an accurate description of the detail achievable by the printer. )
The rim of a profile is drawn as a precision path.- and slower for the higher energy to ensure that the very rim of the laser- where a certain amount of diffusion is present- still fully catalyzes the resin.

The interior fill is NOT a precision pathway, and is run such that the laser spot OVERLAPS adjacent paths by as much as a quarter or third of the laser spot width. Because all of the fill area will be exposed twice due to the overlap, the laser can run faster reducing the exposure of the laser… but still totaling the amount of exposure needed for full polymerization.

Again- this is what makes sense to me if the goal is a resin part that has isotropic characteristics.

With 2.19 are you actually SEEING interiors of resin parts that are not fully cured?


#31

I notice the problem with the interior of parts being under cured. There is a chance the problem is with the Black v3 and v4 settings in 2.19 on the Form1+ since it has a lower wattage laser.

You would not see any difference in the layers internally once the model has been properly post cured.

The fill just goes back and forth, how much that overlaps would be difficult to tell, typically they are right to the edge of the spot so the offset is the spot size. Overlapping laser passes is not a typical practice as I have ever seen and used on my CO2 as it causes overburn.


#32

I think this is the key here, but it does raise the question of proper post-curing in very thick parts.


#33

Post curing does not really allow the UV to penetrate to the interior in any resin other than clear.
In my experience- it is the Outer layers that are less well cured because of their exposure to oxygen,

The UV lamps in post curing on opaque resins only really penetrate a couple or 3 millimeters with any strength.
What post cures the interior is the HEAT- because the interior is already sealed away from oxygen and therefore cures more completely with laser exposure alone.

Because of light diffusion thru the liquid, the laser spot HAS to overlap slightly to improve Isotropic properties in the final material. And if you feel the interior laser exposure is LESSER- then that drop in exposure would have to be compensated for by additional exposure. Once again, otherwise the cured parts would not test as isotropic.

I am still unclear on what you are saying… are you saying you think the form-2 has Always undercured the interior of parts? or that this is a NEW issue you are seeing with 2.19?

I have been resisting updating to the new version until I hear good reports of results, and if you are seeing a drastic change in the internal cure of parts as a result of the update then I don’t want to update.


#34

As far as overlap… you may be right- the laser may very well not overlap to get the final cure of the interior of the profile-
However, when a new layer is being exposed the laser likely penetrates to the surface of the prior layer, providing additional exposure to the prior layer.

This would make sense as a partially cured prior layer- being finally cured with the UV bleed thru partial curing of the next layer would improve the polymer crosslinking between layers and result in a more isotropic properties in the direction of the laminations.

That is- the form cure has to ensure each layer properly crosslinks with subsequent layers or the part would display a ‘grain’ across the layers of weaker performance.

?


#35

You are correct that the layer exposers do stack but if the exposer is just too low then the print will have problems.

I can confirm that on the Form 1+ and Preform 2.19 the Black versions 3 & 4 are under exposed. I printed the FL butterfly at approx. 1/2" wide and the thinnest parts of the wing were too thing and breaking up.

My wild guess the genius’s at FL didn’t thoroughly test the exposures for the F1 machines when they dumped the profile out and may have only tested the F2 profiles.

Seems like there is 0 support now on these machines and they seem to be deliberately forcing the F1 users to go elsewhere. If that is the case then I believe FL is not a reliable business partner for any professional work.


#36

I dunno about that-
I don’t see any other SLR printer maker even close to as survivable as Formlabs. They did offer Form 1 users a chance to upgrade for less…
But beyond that, I have not seen any cutting edge technology that remained consistently supported by ANY company. Floppy discs gave way to CDs- and now even CD readers are getting harder to find on computers.
Serial gave way to firewire and firewire now to USB. I have software that will not run under new operating systems, and will not get updated.

They don’t even make parts for my car anymore since the body style was discontinued 8 years ago.

Back then I had to hire companies to scan sculptures for me… because I could not justify the $85,000 a decent scanner cost. Today I own a scanner that cost 4 grand and does a better job, and the scanning companies I used to use went under, still making payments on that expensive equipment.

And before I got the Form 2, I used service bureaus, and from one year to the next I never saw the same printer twice, because newer, better printers were coming out every year and the service bureaus had to invest in the new ones or die.

I don’t think you can get away from the fact that in every field in which change is happening quickly, early versions of all new technologies are going to be supplanted by more mature versions pretty quickly, too.

I am already saving for the machine that will replace my Form 2- and I have no idea yet which machine that will be.
It might very well be another Form 2 if they are still the best, most automated printer on the market.


#37

What it looks like is Formlabs is making a proprietary system by continually altering their resins as to make them incompatible with the older machines such as the case of the gray resin which is now at version 4. They are pushing their resins to use the higher laser wattage leaving people with the older machines forced to seek supplies elsewhere.
By doing so they are forcing owners of older machines to use OpenFL and they are now required to program their own print profiles where none exist.
To me this seems unethical.

I was quite happy with the clear resin and when I attempted to re-order there were no more tanks and the resin was out of stock. How does a company of that size not have minimal inventory of their product line at all times?

Many Service Bureaus tend to lease their equipment for short periods of time and take advantage of section 179 allowing them to offset their entire purchase in the first year rather than an outright purchase and then need to try to sell the equipment off down the road or get stuck with it.

Small shops and individuals don’t have the luxury of making $500-$3000+ monthly payments each month and tend to buy rather lease and go for either used, refurbished or smaller desktop units. This was the market that Formlabs targeted and soon forgot where their customer base came from or were ignorant how that market tended to keep their machines over a longer period of time and not a 36 month lease.

I was offered the lousy deal for the Form2. I turned it down because I did not feel confident in the machine as Formlabs has a reputation of pushing equipment out that still has some flaws or issues. I owned my Form1+ outright and it serves me well. The machine owes me nothing and still has plenty of life to it. Why would I want to have to dish out another few grand and start over? Also Formlabs DID NOT inform me that the machine was going to be discontinued when they offered the upgrade program. Instead the offer ran out and I was then cut off of supplies and parts. They offered OpenFL for the tinkerers with little or scattered documentation on creating print profiles and left it for the people that have the time to tinker and not the average Form1+ user.


#38

While i appreciate the replies, can we keep the posts on topic? There are some great tips in here for brittle plates and I’d hate for them to get buried.


#39

I agree and apologize.
Back to the topic, brittle support plates are usually an over exposed resin. More exposure the more brittle the supports. You could try nudging the Z offset up a click and that may help as this will make the initial layer thicker and less over exposed.
Too much offset and the layer won’t stick.


#40

I just want to hop back in here and say again - that since sanding the build plate in between each print, I am no longer seeing this issue.

I’m running the latest PreForm version and firmware on the Form 2 and using Tough resin.