This all brings me back to @Monger_Designs comment about wanting a more thorough test print for our use and more importantly FormLabs product testing. How do people feel about making that a new thread? It does not cross me as a simple problem.
here are my laser spot tests:
laserspot-test-19122014.jpg - the test before I had to send my printer back for repair
And here are the laser spot test of the repaired printer. (Arrived yesterday evening):
laserspottest-13012015-1-4sec_5-6f.jpg - test with steve Johnstones pdf-file - exposure: manuel 1/4 sec f: 5.6
laserspottest-13012015-magenta.jpg - test with an old resin tank (silicon layer removed) and an old agfa magenta filter
Klaus
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@EvanFoss he printed the wrong one that is why it failed. However I am working on some better prints just don’t have much time at the moment.
@SachaGloor yeah that is why I made ky own version with the hole in the bottom filled in. Try the one from my post earlier and it should print fine at 0.025. Also if you have trouble getting it off the platform just pull it off. Pulling at an angle. It’s strong enough to take it.
Couple of thoughts on this…
The carrot flair looks like there is an alignment issue with the laser tube, am I correct on this? If so then I would think the laser should be replaced if it poses a problem. Are there other suppliers for this laser, maybe someone that manufactures them in Europe or the USA rather than if it is made in China? Wondering if there is a compatible laser from someone else that could be just plopped in.
Many show a glow around the dot itself when projected on paper, I think that could be the paper itself diffusing the beam.
Restricting the laser dot as Josh did seems like tricky business, changing the spot size seams so critical that it could leave a pattern on flat surfaces if restricted too much and if not enough you may have an over exposure where the beam overlaps. I have this pattern if I don’t have my focal point dead on and have the ppm to match the dot size when engraving large areas. Even cutting can cause saw marks if not set just right on my co2. It’s not like we have fine controls on the pulse rate, speed and intensity on this.
Someone else suggested positive airflow, I think this could be a nice little aftermarket item that if designed correctly could be put inside the machines, seems like there is enough room to put a small filtered fan inside to keep dust from resting. Dust seems to be the biggest problem outside of poorly mixed resin.
Again I do have a flair but it doesn’t seem to be hurting anything, recently printed out my makers mark to make a mold from and the total height of the smallest letter was .027" and perfectly legible. With a min feature size of about half of that this seems really good.
I even have a light haze on the mirror where you can see a square background. So the oddities of the laser spot and shape don’t seem that critical in most cases. Of course some have outrageously flawed beams that indicate something is broken.
And yes I do use Silly Putty to test impressions on parts before blasting through a bunch of mold material. Helps when touching up parts to see if there are flaws that may show up after painting etc. too.
Considerng @JoshK’s earlier post about the size of a 300um point and the underexposed shots taken by @Christopher_Eyhorn, I don’t think the 300um laser point is hitting the barrel. I think the laser has a lot of spread at different intensities and some of this spread is hitting the barrel. However more exploration will make this clearer.
Have you printed my rook at 0.025um directly to the bed yet? If so how did it come out? Anyway fine details and tiny minimum feature size will not in a lot of cases exacerbate flare problems. So your stamp print is not likely a very good test for flare problems.
Hi all,
I managed to print whack23’s Rook Sample on the 2nd attempt @ 0.025mm, in clear v1 resin.
To cut a long story short, there are loads of defects on the rear, some on the front, but the side were perfect. The part exhibits the exact same issued as in my previous posts.
I also got my wife, Sharon, to take some macro photos off the Tall Thin Calibration test peice.
For a more further details please see the video I’ve just uploaded -
Rear Face of the Rook
Rear Face of the Rook - Lower detail
Tall Thin Calibration test
This also seems mostly unlikely as @KevinHolmes blob test to show the flare exhibits the same glow around the dot itself, and no paper is involved at all with his method. It’s possible the resin diffuses the beam about the same way and amount, but that seems unlikely.
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Fantastic photos!
@KenCitron - it seems likely that most if not all F1+ lasers have some form of flare - as @CraigBroady effectively admits in post42 - and the FL line up to this point has been - “it’s too low intensity to cause issues”. And then - “it’s too low intensity to cause issues beyond special cases”.
I don’t agree with that. My parts from post1 are not special cases - they’re very plain small parts.
It now seems obvious that there is a large degree of variation in flare intensity, and hence in part quality between printers. Compare my tall test pieces from post3 and post26 with @SachaGloor’s from post47.
Perhaps your flare is as benign as his.
I suspect most printers including mine will pass basic tests - but stretch the ones with more intense flare - like printing close the hinge side - and the parts are no good.
I think it is @RocusHalbasch’s contention that pretty much any flare at all causes observable issues (on certain parts) - and that the 25micron rook will print with quality issues on most F1+ printers.
This may well be the case - I don’t know - no-one’s posted perfect 25 micron rook yet and I haven’t managed to print anything at all at 25 microns, I gave up and focused on 50 microns where I could quantify flare effects. Personally I would be happy enough with results like Sacha’s - and to be able to use my entire build platform - which I can’t currently.
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Hey @KevinHolmes could you try the rook at 50um? I would like to see how it compares to your test print.
I haven’t had a chance to find the file through all the posts, I also have been using a 3rd party resin that is friendlier for printing flat objects but it seems to be limited on printing tall objects since the blockers tend to settle quickly so I am doubtful it would be a good comparison. Reason I tried another brand is because the resin is much thinner making peeling much easier on the machine. So far this is working out really well. The other resin also hasn’t given me any blowouts on objects with rims such as coins when printing flat.
The parts are also semi flexible so they are not nearly as fragile as the Formlabs resin which did give me some issues when making molds where the parts may crack.
I will be ordering some more Formlabs resin along with a tank soon and will test your rook on that.
Here is the first of my simpler test prints this is a replacement for the Rook. It is smaller, has way less volume and is simpler so you know more clearly what the problem is. Still print it at 0.025 with no supports. I haven’t tried this version yet I printed one with a different rotation and thicker walls and it worked so this one should work even better. Anyway this should probably be used instead of the rook from this point forward,
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I have taken down my variant of the rook as it is no longer needed and is not my work. If you need my version which was modified for the Form1 let me know and I cand give it to you.
This first pic is of the side where my rabbit ears are. You can see the rough and bumpy texture.
This second pic is of the opposite side where I have a small defined carret. You can see the carret causes the spirals to bulge.
This third pic is of the side in between the two it’s mostly clear and what artifacts it does have are attributable mostly to the bad sides.
Oh and lastly the big line all the way around it near the bottom is from formlabs going back to over curing the bottom of the print. They have varied the amount of the print they do this to across versions. In different versions I’ve seen it be anywhere from 0mm to 2mm of the bottom of the print but now it is 5mm. Unfortunately formlabs doesn’t give us control over this setting so when they have it over 0mm it messes up all prints done with no supports. I’ve requested user control of it but it has been ignored.
Printed the helix out at 50% with 25µ layer thickness. Front and back had failures which is parallel to my flair but I don’t think in this case the flair has anything to do with it because I have waves which is typical of the particular resin I am using in which the blocker settles too quickly during the print. Reason I say that is because the early part of the print is fine. In this case with this resin I am sure the flair doesn’t help matters though.
There might be a mix issue with the FL resin and flairs but not nearly as severe as the resin I happen to be using. I think the blockers in the resins all settle as prints progress, why thicker is better on bigger prints. As blockers settle the laser will refract throughout the resin and part causing blobs, blips, partial cures and eventually layer failure from poor adhesion. I guess until resins can be designed not to settle with the print time it is the nature of the beast with these machines.
When I get more FL resin in I’ll re-run the test. I’m sure it will be much better than this one.
Hi
i switched to clear 02. The Tower was print perfect @0.25mm. The first try in black failed. Will post the pic later. Black is new for me. I think black is not made for printing @0.25mm.
Sacha
It’s possible that the clear resin doesn’t require much power from the laser, vs the black and grey resins, and therefore the flare doesn’t really affect it as it does with the other resins.
Add me to the list.
Less than a liter put through the machine, parts are usable by us as at the moment fine details are not required, but the surface finish has always been poor.
Thought it was something we were doing!
Marks in the pic are cm
Dave
Actually, no, the exact opposite happens, although the end result is as you describe it.
As the pigment settles on the PDMS, it blocks the laser more, so the resin doesn’t cure completely (or at all in extreme cases).
Which is something that might be possible to solve in software, actually, for resins with known settling times - all you’d have to do is gradually increase the exposure time and/or laser power as the print progresses.