Failed Broken Prints.

[Argyle]

I'm having a difficult time understanding the cause of my failed prints. After several hours of decent printing the parts will suddenly break apart, frustrating to say the least. Brand new film, using the recommended resin profile. Any ideas from the community?

[reify]

Pretty good chance it's due to that overhang on the back. Best to add a support there or change the angle on the design.

If it's improperly supported, just because it printed fine once doesn't mean it will always print fine.

[Argyle]

The ridge on back was supported I removed it when removing from the build platform. If you look closely the larger more complete print is broken as well. There is a failure on the back side in a relatively flat area, for that reason I don't feel it's a support issue.

[reify]

The other break (chip) seems to start exactly where that upper overhang starts. Can you email me the stl?

[Argyle]

I suppose that's possible. I didn't really consider it since the overhangs on the front are more substantial and printed just fine. I'll get the STL to you. If .25mm overhangs are an issue support structures are not going to be viable. I'll need to add more draft.

[reify]

Such a small overhang should be fine but it seems like too much of a coincidence. The pigment/dye could be settling after a few hours and causing trouble too.

[mongerdesigns]

Printing such a tall object can be a gamble if it's not steady and supported well. Minor amount of shrinkage from the resin, or flex and sway during printing can cause a fail. Also, like Mark said, the pigment settling. How toll is it exactly? Can you position it on it's side instead?

[Argyle]

Its far too large to be placed on its side. The problem isn't unique to large prints either.

[Argyle]

Got some feedback but nothing I haven't already tried. Back to the lab. I was finally able to printed this 80mm tall beast. My photo's are crap but the print is silky smooth without any visible grow lines. Here are a few things that could be the cause of my previous problems:

1. Model rotation. I slightly rotated the model. Really this was to reduce the print time. It's been recommended that I try angling the prints by a few degrees, I've been there done that. Angling may increase the success rate but it will also result in more visible grow lines and a substandard surface finish. This was printed straight up and down at 90 degrees. Supports were nearly identical to what I've done in the past & the same default resin profile was used.

2. CPU throttling. I noticed that my CPU temps were slightly higher than usual, turns out the CPU fan was failing. There my have been some CPU throttling occurring but I never noticed any lag. Since I caught the problem early I doubt the fan had anything to do with the failures but you never know with this stuff.

3. Sticking. With large prints there is a tendency for the print to stick at points. Rather than gently peel away it snaps. If you've done large prints or multiples you've probably heard this. To me It sounds as if the sticking occurs closer to the hinged side of the peeling mechanism. This time I oriented the side with the most mass away from the hinge. The print cycle was very smooth, no sticking/snapping sounds. I can only imagine the sticking causes more stress to the print. Over time it may have caused the fractures.

The left side of the hinged platform separates a lot more than the right, I'm wondering if the distance can be increased. If so how? What is the max?

[Wdshea]

Everytime i've started to have failures, i change the film and the problem goes away. There arent many avenues for problems, sure sign is when you cant print a model you have had success with. I'd change your film before you spend too much time troubleshooting. (Even of the film looks good)

But, i've also attributed some of my problems with bulb age. 538hrs now, and These are mercury vapor bulbs. Mercury vapor are at about 90% output at 2000hrs. The lumens maintenance curve is rather linear to 90% so i estimate i've lost ~2.5% intensity.

Translate 2.5% to exposure time and there ya go. Maybe throw in some extra exposure for good measure.