I think the calibration sheet for the laser should have marks like on a reticle so that you can more easily measure from photos.
- Print the calibration sheet.
- Measure the width or height of the box on the sheet you printed.
- Display any photo of a laser test that uses the same sheet.
- Measure the same dimension on the box as seen in the photo, that you measured on the printed sheet.
- Compute the ratio of the chosen box dimension as measured on your printout to the same dimension seen in the photo.
- This is a scaling factor.
Measure any aspect of the laser flare as seen in the photo and multiply by the scaling factor and that’s the actual size of the feature you’re looking at! (well, with some provisos on accuracy which will be a function of camera lens induced image distortion, which depends a lot on the camera used).
Well, here’s my result of the cross test print. Unfortunately the cross on the PEEL SIDE failed after a couple hundred layers. But I let the print finish because that might be caused by an issue related to the laser flare??
Here we go:
OUTSIDE THE PRINTER:
(this is the front side of the broken part (on the peel side)
AFTER CLEANING AND RINSING IN IPA
My apologies for the many photo’s. Normally I would have captured both in one single picture, however, since on part failed I decided to take seperate photo’s as this might help.
Looking forward to your comments!
Alex
P.s. This seems to be a common issue lately…
@Alex_Vermeer hmmm - certainly not obviously drastic flaking that I can see - but you do have peeling bases and I think I see bubbles in those parts? and the one that failed - it looks bad - a bit swiss-cheezy?
I used to get those same issues - but I’ve changed two things (edit - actually 3) that I can think of since then - lowered the build platform, and heated my lab. Previously I thought it was due to the build platform height, but with @Steve_Johnstone results I’m thinking those are typical symptoms of resin that’s too viscous - it makes sense, the extra suction of more viscous resin causes layer separation in the bases, and sucks bubbles under the part during peel.
You say your resin is kept against the heating - and the room is 21degC - if you’re certain, perhaps its still viscous resin, but not because it’s cold.
How old is it your resin? I had to wait 6 months for my F1+ upgrade (even though I ordered it on the first day!) and when I tried to use my remaining resin - parts pretty much all came out swiss cheezy or total failures. New resin improved things a lot, and then things improved again when I put the heating on. I still get heavy flaking and solid corrugations on flare oriented faces near the hinge - but no bubbling.
I totally agree will everything @KevinHolmes says above & your results look very similar to mine.
I would be really interested in how fresh you resin is and if you filter between prints.
@KevinHolmes and @Steve_Johnstone,
I wouldn’t say it’s the temperature as that is regulated and it shouldn’t drop below 20 degrees Celcius. However, my grey resin was purchased on 30 September and delivered on 20 October. This means the resin is between 3-4 months old (not taking into account the amount of time it’s sitting in the Formlabs warehouse. Therefore, this could be an issue.
Unfortanately I don’t think it can be proved that this is the proper reason for these kind of bubbles/scars as I have the same issue with my Clear resin V2 which I purchased on 19 November and was shipped to me a week later (+/- 2 months old). If this would already be “old” resin, then I have a problem as I still have two unopened clear resin bottles as I ordered three together.
I can print the crosses in clear resin as well to show resemblances/differences to ensure that it’s not the age of the resin that is the case.
I shall not lower the build platform as of yet, to check one difference at a time. Otherwise we’ll never be able to pinpoint different symptoms.
I do not filter my resin often (enough). I do use a comb to find small cured parts, however, most of the times I cannot find any cured parts in my resin. I have filtered my clear resin a few days ago when these problems started to occur, but that didn’t have any noticable effect.
@Alex_Vermeer - well I’m pretty much stumped, all I can add is to use decent resin filters. I used to just use a kitchen sieve, but now I’m using paint filters like the one pictured in the OP up top, and I can see they pick out a lot more. Oh and if the temp never drops below 20 then why keep the resin against the heating? maybe it’s bad for resin to be constantly heated? but I’m reaching there…
I use several layers of mosquito netting to filter my resin. Does take an hour or so for it to filter it. However, I’m pretty sure it filtes every single piece of cured resin. (I cover the filter and bottle to ensure that it’s not fully exposed to UV light during the process).
The reason the cabin which holds all my resin is against the heating is that’s pretty much the only way I can fit it in the room without it taking up unwanted space. So yes, you might be right… Maybe it’s bad for resin to be constantly heated. If, however, that is the case, it’s impossible for me to test that (right now), as I have all my resin stored there. I will be buying some more resin the coming weeks, and I’ll ensure that these bottles are stored outside the cabin at normal room temperature without influence from the heating to see what happens.
Well @KevinHolmes,
Here is my second batch. This was printed in clear resin V2 (2 months old) with a layer thickness of 0.2mm. I know you suggested using 0.05mm, however, I wanted to speed up the process a little, and looking at the results, I won’t need to print another one at 0.05mm as the results speak for themselves.
One of the crosses failed near the end of the print. This time it was the cross on the HINGE SIDE. I do not have an explanation why it failed though…
Here we go again:
AFTER CLEANING
Strangely, the rough sides seem to be on the front and rear side of the print now… and not the hinge and tilt side… Which makes this all the more confusing…
Furthermore, you can really see the difference in quality when holding it against the light:
It seems that the age of the resin can be ruled out. Unless the resin can only be kept for +/- 1 month…
I cleaned the large mirror with IPA and pec-pads again before printing, so that isn’t the issue as well.
I shall strain the clear resin once more to see if it has any improved efffects… having the issues on opposite sides compared to the grey resin does make little sense though…
@Alex_Vermeer I don’t think its the resin. Your results look exactly the same as mine, but a lot worse. Your front and rear surfaces are horrendous!
Looking again at your laser test just confirms your test print results. The worst surfaces are the front facing, followed by the rear facing. The side surface seem to be OK.
Have you raised a support ticket yet with Formlabs?
I’ve just switched to clear v2 so will run the test again a 0.2mm. After seeing your pictures I wounder if the v2 resin is going to make the effects of laser flare worse, especially if they have increasing the laser power or slowing down the exposure time.
I will also revise the laser spot test paper template to include the reticle pattern that @EvanFoss suggested. I will set the center dot at 300 microns as the minimum feature size from their specifications.
I guess I just want to ensure that it definitely isn’t the resin. I will print another cross after i’ve filtered it.
I haven’t opened a support ticket yet, but will do tonight. Hopefully the support team will be able to help improve the prints.
Here’s a photo of my laser flare. I didn’t exactly do it like @EvanFoss said, but I believe the results are the same.
I created an image (w x h): 35mm x 40mm. resized the image I took to fit exactly in this box. Set up a grid of 5x5mm.
Here’s the result.
the width of the laser (including the spike to the left side) is 11mm. The height of the laser is 19mm
EDIT: Just submitted a ticket with the support team.
@Steve_Johnstone what problems are you still having? Your last pics of the cross test looked fantastic. The little bit of waviness is to be expected, every Form1/Form1+ I have had has had some, and it’s always been worse at higher resolutions. Those shots look in line with what I would expect from a good printer. It looks, just from those pictures, like your real problem was just temperature and now that is fixed.
@Alex_Vermeer you grey prints of the cross are not at all consistent with the was flare presented for most of us. Looking at your laser spot your worst side should either be the front or the back, not the sides. Except @Steve_Johnstone I don’t think anyone has had holes form inside the prints from flare, instead we get build up of extra resin on the surface of our prints and flaking. Your later clear prints look more like flare but being as your grey prints didn’t show normal signs of flare, I don’t think your case is so clear.
@RocusHalbasch, I agree. My case seems to make no common sense towards blaming the laser as the (only) issue… I’ve filtered my resin very slowly the last hour and have refilled the clear resin tank. I’m printing one cross (0.2mm) as we speak and shall post the results of this one once it’s done. hopefully the print will come out without rough spots, or at least consistent to the last one. Otherwise it’ll just get even more complicated 
The result after straining the resin (new thorough method):
As @Steve_Johnstone mentioned. The resin can be ruled out as the cause… This is the result after washing in IPA again:
In case you’re wondering how I filter my resin; I use these two items simultaniously to filter the resin. It takes some time, but atleast it’s thorough!
Apparently this was a shape that was needed by someone (Kevin?) and exhibited a problem, thus it’s being passed around as a common .form to show similarities/differences in prints - correct? Ostensibly, this is to highlight the laser flare effect, but is it also possible the shape and orientation are also playing into the surface quality anomalies? e.g. the position and shape incur a specific type of stress from peeling that may exacerbate the issue.
Q: why does it need to be that tall? seems like it’s using a lot of resin for minimal additional informational benefit. I fully understand the need for a common form that exercises the device and can provide a comparison - just not sure this is the best shape for that.
Also, has anyone tried printing this (shortened, ideally) with the 'X" rotated 45-degrees in the z-axis?
-C
Could a fume hood have the unfortunate side-effect of working to pull dust into the machine at all @EvanFoss?
@ChristopherBarr this shape was arrived at by @KevinHolmes possibly out of necessity but really it just demonstrates the issue with the minimal amount of resin wasted. For the back story on this go here. The tiny cylinders with the double helix in them were also from this thread. They are for the same basic function.
The point for the group was not that we needed this shape it was that it shows a common issue for a lot of our print failures goes back to this laser flare. The tall aspect means that the same areas are retraced over and over by the flare causing it to fully cure resin that otherwise would be uncured or gelled by less optical power.
@ChristopherBarr The airflow in our fume hoods is such that it would only do that when the printer’s cover is open. To do that I have to lift the fume hood window way above the safety limit. Meaning that the airflow is so low around the machine it might as well be squat. Plus I would have to expose the mirror which would require taking the resin tank out. I have had really one 1 occasion to do that because i was scared about cracks in it leaking resin.
Dust prevents laser light from curing things. I have things I don’t want being cured getting cured.
Besides our employee safety people have insisted that I use the fume hood as have my coworkers. It was giving me and my office mates headaches.
OK, I see. Now I understand how the height was part of the test. Thanks. re: the 45-degree question: anyone see what that produces?