Strange problem with base of print

[nc42]

If you do a bit of digging on the site you will find quite a bit of info, Unfortunately it's not curated especially well. My best advice would be to look through all the sub forums and the threads of any length.

I just wrote a tutorial about making a mask which can be found at viewtopic.php?f=5&t=3684

[jon_bondy]

After evaluating which parts of the build plate made the best prints, I made one print and it came out perfectly. Another in the exact same spot came out OK, but with a small defect on the bottom. Since then, three attempts have all been total crap. One print fell off of the build plate. Two of them had such horrible bases that I killed the prints. I swapped in a new petri dish, wondering if the coating might be the problem (I could see a faint ghost image of the print on the old plate), but that did not help. Sanded the build plate, but that did not help.

At this point, I would describe the printing process as erratic and unreliable. I have obtained a few very nice prints, but it is really hit or miss. Mostly miss.

Could the projector bulb be changing with use? I am not sure how many hours I have on it: probably around 75 or so.

I understand the idea of a Mask, but if the prints change from hour to hour and day to day, I doubt that a Mask would resolve the problem.

Frustrated.

[jon_bondy]

Tried rotating the build plate in each direction: no joy. Tried a new petri dish. No joy. Tried a new bottle of resin. Joy.

Frustrating that I have half a bottle of resin that seems to be contaminated (no idea how), but at least I'm printing again.

No need for the Mask at all.

[jon_bondy]

Here is the last test print using the old/bad/red resin and the new test print with the green resin. Both Maker Juice SF. Notice that with the good print, I was able to print beyond the edge of the build plate, because the print was one huge piece. The red print had one entire section that just dropped off; the remaining section was only attached to part of the build plate. The green print was attached to the build plate almost uniformly.

Lesson? Contaminated resin can make you crazy.

[DanOrgan]

Jon_bondy, do you keep your resin away from light? Do you mix it before printing?
By the way, I don't think its possible to get all your sections perfect without Mask, no matter what resin you are using

[jon_bondy]

The resin is kept in the original dark plastic bottles between prints. I shake/mix the resin just prior to pouring it for each print. I printed a funnel with a sieve at the bottom in PLA and use that when I'm pouring the resin back into the bottles; it is possible that the PLA has been contaminating the resin I suppose. Light exposure is possible but unlikely. I marked the build platform with a magic marker, only to discover that the resin dissolved the marks, so that is a possibility. I suppose I could have introduced some IPA into the resin by accident. Not sure what else could have happened.

A pity, because that bottle is only half full

[jon_bondy]

The folks from Maker Juice believe that this probably was due to contamination with IPA.

[jon_bondy]

So, the first print using the fresh bottle of resin was perfect. The second and third were defective.

At this point, I'm back to feeling as if I cannot predict whether the next print will be OK or not. I must be missing something

[goopyplastic]

Is your build plate sanded at all? The rougher the better almost for adhesion.

[jon_bondy]

It is sanded. There is no problem with adhesion for the first 10 layers. It is after those layers that the defects begin.