Printing Reliable functional parts with From4, truth to myth?

[eaglechen]

Evening! Couple of things; first please do read this thread in detail, I document the core issue of warping during formation of the first 2-3cm of the part here:

My experience with the Form 4(B) so far/ Semi-Review from a Semi-Industrial User Perspective

Hello there. I would like to start a discussion for the Form 4 for some perhaps necessary feedback to hopefully make this product better. You may have been like me, couple months ago, scouring the internet for reviews and experiences for the Form 4. I am here to offer you a perspective from a semi-industrial user. If you are shopping for a resin printer as your hobby, this probably should not be a consideration – the material I have thrown in the trash as failed prints over the last 2 months wo…

The orientation approach you have described is common knowledge and probably what Formlabs should be recommending of 30-45 degrees upwards from each axis to avoid steep overhangs (instead of the current guidelines of insufficient 10-15 degree: customer_v2). Pretty much anything remotely square or straight can benefit from this approach and this is probably the best way to go about printing this for the reasons you have stated. I have pretty much fallen in line with orienting flat things like this. I took a closer look at your pictures and notices some things:

This orientation will create pulling forces indicated by red arrows during printing, warping will probably occur with will the middle of the part sinking down. The corners should bend upwards and provide stability. This image below with exaggerated red lines show what I mean, you can see the warping in the image:

Some additional warping observable here:

Furthermore, this image illustrates perhaps the weakest point of Form 4, which is the first part of the corner which first attaches to a supports (a “V” like part) will contain non-straight edges that curl. I think I see this with the top of the model not completely perpendicular to the bottom edge. I discuss this more in my own thread as well:

Curious as too how the pillars at the bottom of the part looks as well, wonder if they are straight.

Of course, I am not going to speak for someone elses experience, and if this is a useable part for someone, that’s great. However, I don’t think you will disagree with me that this model does not achieve the +/- 0.15% or 0.2mm guidelines Formlabs advertises.

Do you have any other suggestions or practices we are not aware of? Unfortunately, seems that supporting is more like triaging on this printer to make sure everything bends together rather than counting on the printer to produce a straight edge. I am pretty sure Friedl also made a thread where he showed some FDM parts off a $500 printer with near perfect straight edges and finish/ accuracy better than anything I have seen from the Form 4 including these pictures, I am sure you can find that on this forum as well.

Also @Friedl_1977 I am going to have to backpedal on my advice on precision model resin, seem that it is not significantly better than another general purpose material after more recent testing…

[Friedl_1977]

Hi -

I have a couple of “areas” I need to put more work into solving.

• “Layer lines” - I am not oblivious to the fact the SLA is still printing in layers, just much smaller ones, but I die not expect to see layer line (in some areas) comparable to my very much out of date UM printers. To date I have not been able to solve this issue in any other way than to print directly onto (and perpendicular to) the build platform., Of course this is not always possible and even when it is, it comes with it’s own drawbacks.

• The second part is dealing with warping. I am been able to improve the prints by adding A LOT of support in the areas that do warp. This of course leads to more extensive post processing and increased part costs. Another fix (again) was writing directly onto the build platform.

• small threaded (or non-threaded) holes. I did some M2 threaded holes today with 0.1mm face offset and 2.5mm wall thickness. They simply shattered the part when I screwed them in. Printed in Clear V5 resin.

• cleanup - aside from media blasting (or spending a lot of time manually cleaning up) it seems there aren’t many great options. Personally I would have to approach a 3rd party service provider for this as I do not have the equipment to time to post process to this extent.

I have not given up yet… I will keep posting my findings, hopefully it saves some other new users some effort

Regards,
Friedl.

[Friedl_1977]

Hi -

I started on two new enclosures and am still having some issues with the sides attaching to the supports closest to the build plate, warping.

Further to this, I am struggling to make sense of the 10-20º ‘rule’… I mean if you have two sides perpendicular to one another, one will be at eg. 20º and the other one will be at 70º along the opposing axis.

I then found an interesting video which I am, about to put to the test, here is a link below:

* Video

It uses the pixel size of the printer and the layer hight to want to print at. The formula then calculates the ideal print angle. From what I could find the Form 4 pixel size is 50 microns. This has a benefit that if you have a model with perpendicular sides (eg a cube) you can print both the “tilted sides” at the ideal angle of 45º when print at a layer height of 50 microns.

I will put this to the test on a print I need to do and will post my findings.

Regards
Friedl.

[br4n_d0n]

Lychee was the other I couldn’t remember. You can look into that as well.

[Friedl_1977]

I actually have Lychee as I was playing around with various slicers when I was still considering the Uniformation printer as apposed to the Form 4

[eaglechen]

The issue detailed by the video is pretty separate from the warping I have experienced on Formlabs printers in my opinion. The gist of that video is to reduce overhang angles to reduce stairstepping and pixel artifacts on prints:

Pretty much all of these mSLA/ LCD printers are optimized when printing at a 30-45 degree orientation anyways. Your calculations will reach pretty much the same conclusions, a few degree difference won’t be different.

The warping you are talking of I can probably say is more so related to the warping issue I discussed in my thread I have linked above. This is related to the Form 4 being not particular good at printing those steep overhangs, expanding areas where the part attaches to support materials initially, as well as additional warping from high internal forces which do not anneal properly (especially with like Grey V5). The only true fix so get the printer printing close to its claimed accuracy guidelines that Formlabs have told me is settings changes through software updates from their side. Currently there is no timeline for this.

I have bashed my head against this problem endlessly as well with many people telling me how to reorient parts or just print with this one Preform/ curing trick (that usually is public and common information and do not really work or fix the core issue). So far no success

[Friedl_1977]

Hi @eaglechen -

Sorry for not being clear in my post.

I am just trying everything I can to make my prints look as good as they can be so I am actually comfortable selling them to clients

You are correct, the video above addresses surface finish issues, which I have had to deal with as well most likely due to me knowing how to orientate parts (and the somewhat confusing docs IMHO). What I have started doing in the meantime to address the warping of the side that attaches the to the support closest to the build platform, is to to print a sacrificial “tab” that can be snapped off after printing. Very much like I used to on corners of large flat prints of FDM (when printing with engineering materials eg CPE or Nylon).

I then attach the bulk of the heavy support to this area and I must say, it works really well No more warped “starting layers”. The next challenge is an enclosure shaped as a cube, I will implement the finding from the video together the the “warp tab-thingy” and hopefully get some good prints. Below is the first attempt without these, not great so hoping these will help this issue.

Regards
Friedl.

[Friedl_1977]

Hi -

As promised, below is a part I printed using a combination of the guidelines from that video and the “breakaway tab” I mentioned earlier . For this particular part I DID NOT rotate on two axis, but only one and the results have been far better than anything I have had so far.

Based on the the pixel size of the the Form4 (from what I could find 50 micron) and the fact that I was printing on 50 micron layer height, the “ideal angle” based on the calculation was 45º. This made it easy to orient the part in such a way that two perpendicular sides were both at 45º angles to the build platform. See image below:

Below is the result:

I can confirm, all sides are at 90º (or VERY close) and free from any layer lines with the exception of one small area indicated by the red arrow. No warping at all on the 25 parts printed.

I know this is early days, will try the same logic on another model and see if it holds true.

Regards, Friedl.