I apologize for the wall of text that follows. Bold text throughout to mark the most important stuff.
First, my question. So far, 3 of 23 eggs have hatched. Five more have pipped normally, three have pipped the wrong end but are making at least some progress. I'm curious about the cause. With such a high percentage pipping the wrong end, I'd like to figure out why.
Some background info on the process I used. I'm hatching Swedish Flower Hens, which I've heard can be difficult in an incubator. Dry hatch seems to work best for this breed, so that's what I attempted. I received my incubator Saturday, May 21st and set the eggs three hours after setting it up. Bad, I know, but I work full time and really wanted them to hatch on Saturday/Sunday when I was home. I took a chance and it paid off. I had been collecting eggs for roughly 2 weeks and had 3 dozen, so I set the 27 newest and let it run. Two hours later, I went out to the coop and found that my two favorite hens had laid so I made space for those two eggs, even though the capacity should be 27. Bad again, but that also worked out.
The incubator has held temp reasonably well, although my two additional thermometers drifted by two degrees each over the first week. First the digital one began to read two degrees high, then the analog began to read two degrees low. Both were calibrated correctly in the beginning and have stayed consistently off since. I fiddled with the temp at first, but never went more than half a degree in either direction. After that, I calibrated a meat thermometer, verified that the incubator temp was correct, and mostly relied on that from then on.
The turner lays the eggs flat and moves along the floor to turn the eggs. This is mostly effective, but the trays are fairly large and some of the smaller eggs rotated as well as turning. Those did still turn somewhat (the eggs were marked front and back so I could tell), but not fully. I repositioned them occasionally if I felt the need.
Humidity hovered around 40% I think, for the first 10-12 days, due to excessive rain. My hygrometers both calibrated perfectly using the salt method but there was a difference of 10-15% between the two when dealing with the lower humidity in the incubator. The built-in hygrometer doesn't have numbers, just highlighted sections on the dial for target humidity for incubation and lockdown. That usually read at or just below the minimum humidity recommendation for incubation. I was shooting for 25-35% as recommended by many experienced SFH breeders. Humidity dropped to around 35% for days 12-ish until lockdown. Wednesday evening (at the beginning of day 18 according to the timer on the bator, which shows days and hours), I removed the turner and bumped the humidity to 40-45%-again following the recommendation of experienced breeders.
Tuesday, my air conditioned began to freeze periodically, and the temp in the bator went up to 100.5 before I caught it. I'd had some problems the previous week with the temp in the incubator room and the temp was a little high one day when I got off work-somewhere between 100.0-100.5. Both issues were corrected promptly once found, and I was able to compensate for the a/c problems this week by adjusting the bator settings related to the room temp.
Early last night (early day 19), I saw the first pip. That chick hatched this morning, followed by one in early afternoon and another this evening. We've just ticked over to day 20, and as mentioned above, I can confirm 5 more normal pips (two zipping), and three pips in the wrong end, all of which are large enough to see some chick down through the hole. There may be more pips that I can't see due to the chicks rolling the eggs around the bator.
My hypothesis: Since the chicks are hatching early, I understand that means that the temps were a little high. Not sure whether to blame that on room temperature or improper incubator calibration. The a/c is now fixed, so I guess future hatches will tell. I'm wondering if the issue of the chicks pipping the wrong end could be due to the fact that the turner was running too close to hatching. If that's the case, then this is a problem I can address by monitoring the temps.
My other idea is that incubating the eggs on their sides may make this more likely. If that's the case, then it's an unfortunate incubator design and I'm not sure how to proceed.
Thanks in advance for your input!