Bad prints out of brand New Form 3


#310

Thanks for the fantastic analysis and explanation. This is entirely consistent w/ my own observations on my Form 3, and your logic seems sound to me.


#311

I think that it might be helpful to have this post here as it helps explain some of the reasons for “bad prints” Those reasons are something that we address on a daily basis as part of our work…

Earlier post:

Welcome to our working world - at work we spend a lot of time configuring resins to operate with different printers (often directly for the printer manufacturers). Those include Masked LCD, DLP and other printers that use a laser as the light source. The reality is that most resins (in fact almost all) are chemically configurable to work very well with different printer types. The base formulation for the resin remains consistent, its simply the components that alter how it cures (speed and depth of cure) that are varied between different types of printer.

In general terms a resin can be adopted to almost all printer types chemically. However the process is time consuming and lengthy. Utopia for us is when we can also alter the printer settings for time of exposure and the power is variable. Formlabs certainly is able to do that inhouse.

If we look at the resin cure then two things influence it, the first is how reactive it is, the second is how well it allows the UV energy to penetrate through the cured / uncured material (at a certain wavelength).

If the energy penetrates too far then different chemicals can be used to stop the penetration (we know these as light blockers) There are also available things known as light “absorbers”,

Light “blockers” and “absorbers” work in very different ways, generally the absorber takes the UV energy and changes it to heat (Remember the principle established by Émilie du Châtelet in about 1730, that energy cannot be destroyed or created, it can only be transformed or transferred from one form to another) The transfer from UV energy to heat energy is an undesirable effect for us as it leads to the warping of prints and effects the adhesion of the print to the build platform.

Light "blockers work in a very different way, that relies upon the fact that different photoinitiators work at different rates of efficiency dependent on the amount of energy at a set wavelength (in the case of the Form 2 and 3 around 405nm)

If that light was at a wavelength of say 450nm then the resin would not really cure.

Light blockers work by taking the energy that remains after the cure (polymerisation) has been effected at a certain depth of penetration and they fluoresce That takes the form of taking the 405nm energy and then transferring it form a visible glow at a different wavelength (in this case around 435 to 460nm) which is beyond the range for the photoinitiator to work efficiently.

Unfortunately the chemicals used to create colours (the pigments) are made up of materials that show very different characteristics (some absorb UV, some fluoresce, some do a little of both)…In practical terms this generates unique problems for each colour (and often varies dramatically from one pigment manufacturer to another - due to factors such as particle size, suspension or material used for the pigment) .

The chart below gives a little insight into just how complex this is:

The reality is that black is a particularly difficult colour (as is white - but for slightly different reasons), black generates a lot of heat when exposed to the UV energy source (due to the black pigment) and the depth of UV light energy penetration is much less than say a clear resin (or a blue pigmented resin). Its good to see that black now works well, that demonstrates that mechanically the Form 3 is a sound design (accurate).

I realise that the Form 3 uses a different laser (higher power) than the Form 2 and wonder about Formlabs intention to make all resins cross platform compatible (so they can be used on either Form 2 or Form 3) in reality thats unlikely to achieve best performance from the Form 3 (you would need to run the more powerful laser at lower speeds and power - which results in longer print times)

Hopefully Formlabs will see the light and optimise both the resin formulation AND the Form 3 profiles to take maximum advantage from its higher power laser… Rather than simply trying to match the Form 3 to Form 2 performance to suit the existing amounts of photoinitiators, light blockers / absorbers used in their resins for the Form2.

So to summarise:

To fully optimise a resin requires both alterations to the laser settings (and thus the amount of energy entering the resin at a point per unit of time) and also chemical optimisation. (pigment, photoinitiator and also the use of various light blockers.

For correct optimisation of the resin for maximum performance, the light blockers are a very important part, and a very small alteration (normally in the range of a few hundred parts per million of the actual light blocker chemical) can make huge differences in how the material cures. Of equal importance is the correct amount of photoinitiator, too much and the material becomes brittle and may suffer with uncontrollable light bleed (the overgrowth, especially in the Z plane), Too little photoinitiator and the print is soft and often with very poor adhesion to the build plate. Both have an interaction dependent on timings and speed at which the UV is applied (at a certain wavelength or range of wave lengths). (think units of UV power x area applied to times the length of time the energy is applied - we normally measure that as (mw/cm2) x time to achieve desired cure )


#312

Not being able to get good quality out of the Gray V4 at 50/m and 25/m a few days ago I finally broke, went out and bought Black V4 and a new tank. Today I see there is a new software update which, besides other things is good for Gray V4 to be run at 50 and 25/m… of course…
If you guys do some test can you post them here…

Thanks


#313

An update for Preform dropped yesterday:

Grey Resin: Improved print quality at 100, 50, and 25 microns

Anyone try one of the problematic Grey prints on that version yet? I’m hoping this is the refinement we’ve been waiting for to do for Grey what they did for Black.


#314

Can you go into explicit detail (or show pictures) of the symptoms? I have an early rev Form 3 and I experienced a lot of issues that might be similar.

Are these rings angled at all off-axis to the build platform? Why do you print them with this orientation?


#315

Hi
They are not angled , Formlabs support recommended (to me at least) not to angle rings - but I suppose that it’s all about the design, so different structures will need different adjustments . Mine were pretty simple


#316

Is the layer shifting now a problem of early form3 printer or have this issue the complete serie??? I have a early form 3 and also the problem with the layers??

What did the support mean to this problem?? can they fix the problem with the many updates in last time??

Thank you for your answers!!


#317

The problems that were present that got me to start this thread in the first place are still present an o updates to date have fixed it. It seems the updates to the black resin have eliminated most of the original issue but all other resins still suffer the same problems.


#318

Hi everybody!

I looked at my first print and… saw all my grids are look damaged. Which reason can it be?

The second question. I reduced walls thickness to 0,3 mm. Is it too thin? Shall I choose lower temperature for Form Cure? I have selected 60 degree.
May be I have washed too long (13 minutes 70% concentrated IPA in the Form Wash… )
Or wrong placed on the platform… I don´t know…

Thank you for your answer


#319

Looks like damage from too-long IPA exposure. IPA is very hard on features that are long and very thin, like your grills.

Recommend trying 7 minute wash in 90% IPA.

Hope this helps.


#320

Form 3 black V4 at 50 microns is working much better for me than Form 3 gray V4 at any resolution including 100 microns.

Form 3 print quality with black V4 at 50 microns is as good as Form 2 print quality in gray V4 at 50 microns. Form 3 black models are sellable in this quality.

But will my customers buy black models? So far, customers prefer gray for easier painting.

Still hoping for a fix to gray V4.


#321

Today new version of preform/firmware was released noting grey resin improvements. Can you check it on your models?


#322

Thank you Stephen

Ok. I will try 7 minutes wash in 90% IPA.

I thought if a take 70% IPA, I can wash little bit longer as by Formlabs recommended… (10 minutes for black V4, 90% IPA). But it looks having not the same result…

Another phenomenon: there are very fine accuracy details on the roof. The handle on the picture has a diameter only 0,3 mm. It is much more accuracy than in Z-direction…


#323

I was having a lot of failures (around a 72% success rate), and on most of those failures the raft would either incompletely adhere to the platform, or the first several layers of the raft would be on the platform, but then about where the lip of the raft would start, it would just cut off, and all subsequent layers would be stuck to the bottom of the tank.I eventually had a set of parts that just wouldn’t print at all, no matter what I did. I was talking about it on the forum, and someone from Formlabs urged me to call support. When I did, they swapped out my machine.

My original machine was from the first batch of orders, pretty much ordered as soon as they announced the machine. The new machine is not having the same problem, and is so far running at an 85% success rate, with most of those failures coming from one difficult part I finally got printing correctly with some work.

There’s not much to see, but this is what one of my failures would look like in clear resin.


#324

I just finished a test of rings with new firmware and update form software- grey V4 looks MUCH MUCH better then any other result I got in the past.


#325

Just printed off a WW2 Russian howitzer with the latest PreForm software upgrade. Printer is the Form 3, with Gray v4 resin at 25um layers setting. Here is the user-visible surface of the model. The base is 30mm x 30mm, just to give you a sense of scale for this 1/285 model. The details are excellent, bearing in mind that a standing figure is only 6-7mm tall:

Here is the top surface, nearest the build platform. You can see the scalloping effect of extra curing between the support connection points. Not an issue for my models but would still be an issue for others:

Robert


#326

I might be wrong - but I think what you see on the bottom is not over curing- was your model parallel to the build platform? Is so- you should angle it slightly and that will prevent this situation along with adding more support


#327

‘Over curing’ was just my interpretation of previous reviews of the potential cause for this phenomenon. Happy to be corrected on the terminology as this is a specialised area. The top surface issues are not a problem from my perspective but thank you for the reminder about angling. I think the bigger issue is that, for some prints at least - for example where there is no surface that is out of view to users, any problems of this nature with the top surface rendering will continue to affect the quality of the prints.

Robert


#328

Here is the top surface, nearest the build platform. You can see the scalloping effect of extra curing between the support connection points.

This is due to the peel forces that “pull” on the thin first layer when it is parallel to the build surface. The support touch points do not pull because the supports are much more resistant to the peeling forces. These slowly equalize from layer to layer and the surface eventually becomes flat. Hence the “pillow button” effect.
Note that this effect is a lot more pronounced on the form 2 ( higher peel forces ) and is one of the main reasons why the Form 3 can get along with smaller touch points.
The solution is to tilt the part.


#329

@lmlloyd - very interesting post. Similar to your experience, late last year, I had an early Form 3 that did not fully print models. It would only print the rafts. The rest of the model was just a thin wafer stuck to the bottom of the resin tank with other debris swimming about the resin. This required wafer removal and resin filtering after each of the first three prints I attempted and a call for help from Formlabs. Removing the wafers stuck to the tank damaged the tank. Formlabs quickly swapped that machine out and replaced the tank, too.

The replacement machine does not have that problem. It sounds like Formlabs was able to correct whatever was going wrong with our early machines.

New tech is high adventure.

The problem I am presently experiencing with the Form 3 printing in black V4 is that it takes a considerably greater force to remove black models from the build platform than gray V4 models. So much more force is required to remove a model from the platform that I am breaking 1 out of every 3 models trying to free them.

This has been talked about in other threads.

I’ll be contacting FL support. Hopefully there is a fix.