There seem to be quite a number of people having issues with undersized internal holes/features on the H2 platform, especially compaired to the P1 and A1 series. The following posts are some of the ones that have highlighted this issue:
In my testing I’ve just printed a load of 10mm cubes to rule out belt issues. The accuracy is astonishing, the worst was 0.02 out, and most are exactly 10.00 on my calipers.
When test printing for internal features, I’m 0.2mm undersized on square holes at 10mm and 0.4mm undersized on circular holes. Testing the same models on various P1S printers deliver perfect results on internal holes.
Feedback from bambu is to use auto hole compensation, but this is limited to a very few materials and so far has not made much difference to my testing other than manually changing dimensions.
If you’re looking for parts that can and will fail, the fans in the H2D are the most vulnerable. They tend to fail during prolonged prints when you run the chamber and nozzle near their upper temperature limits. I actually lost mine yesterday, and that wasn’t even at maximum heat — just a continuous seven-day, 24-hour print cycle with very little cooldown time in between. That alone was enough to kill the hotend cooling fan (the one that’s especially inconvenient to replace).
I also encounter various strange errors during long, high-temperature prints. In the middle of a job, the printer sometimes claims the bed is misaligned and pauses the print, which ultimately causes the entire job to fail. So there are definitely issues that show up when you push the machine close to its limits, even in situations where it should technically be able to handle the load.
But the accuracy is genuinely good — I haven’t had any issues so far, whether printing normally or after running the Vision Encoder calibration for physical accuracy.
Imagine being this angry over someone elses feedback/experience when comparing one bambu printer to another bambu printer. Imagine gaslighting people and saying all holes are oval from all printers ever
no, it’s more like playing stairway to heaven in a guitar shop. Repeating something over and over and over again that is simply limited by nature of the technology is just… not interesting to say at least.
oval holes are nothing new, under sized holes or undersized pegs are nothing new,
Just learn some basics of FDM and how slicing works and why dimension accuracy would always be a problem, yes, it’s a tool for everyone no it’s not a tool for everyone.
Let me quote myself again here:
fully calibrated but no compensation is turned on, so no scaling would be applied.
2mm hole: I got 1.85mm
3mm hole: I got 2.88-2.90mm
4mm hole: I got 3.93mm
All measured by using a mitutoyo caliper.
So does this make sense? I think yes, a Δd=0.1mm ish error is well expected. It’s just how slicer works for FDM, as it’s already below 1/4 of my linewidth.
Now, with using Classic wall generator, also without precision wall turned on:
2mm hole: I got 1.6mm
3mm hole: I got 2.67mm
4mm hole: I got 3.7mm
This is again well expected. The 0.3mm-0.4mm range of error is basically the width of 1-2x half width of a line.
You can’t expect a 0.4mm nozzle to have sub 0.1mm level of accuracy anywhere, it’s just not physically possible. Round holes are just exposing it better than most of other shapes.
I printed the same test model (holes from 1mm to 3mm in 0.1mm increments) on my H2D and my i3 with the same roll of filament with the settings as close as I could make them given the different slicers. Flow calibration was performed on the H2D.
The i3’s holes were all less than 0.1mm smaller than the model, while the H2D’s were all 0.4-0.6mm smaller than the model. I don’t think it’s unreasonable to expect a brand new $2k+ printer to be at least as accurate as a several-year-old printer I built from a kit.
Flow rate calibration, precise wall, outer/inner, and report back. This is very common in fdm and the Genesis of these features is related to the problem you describe.
Oval z in holes is a different problem than small hole diameters so plz don’t conflate them
Yes I’ve generally had to compensate on small holes, but only seems like sub 5mm territory. H2D user. I usually expect to compensate on small holes with any machine tbh.
Well if you did all that then yes you have a problem. Each of those are not in the default profiles so nearly every user doesn’t manage to find them.
I first noticed this issue on a production part that we print on a variety of P1S printers. The part holds an 8mm stainless dowle, it’s a tight clearance fit at 8.1mm and at 8mm it can be lightly pressed in by hand. This is the case on all of our printers in house. On the H2D the hole had to be scaled up to 8.45mm to fit the same dowel. All print setting the same and materials calibrated. The outer geometry of the parts are perfect. We can’t use the H2D in production alongside the P1S if it needs models customised to it’s limitations.
Additionally I’ve found that accross the bed, the hole size seems to slightly vary, on the right side the holes have to be 8.5mm, on the right we can get away with 8.4mm.
I printed this test model by the way. (1372173-hole-size-calibration-blocks from makerworld - can’t post the link) I tried both Classic and Arachne. Arachne was slightly better, but still 0.4-0.5mm undersized.
Have there been any updates to this situation? The vertical holes in my parts are still ~0.3-0.4mm undersized when printed on my H2D (latest firmware version), but almost perfect when printed on my X1C using the same material and print profile. I’ve also noticed that while the sliced part holes look correct when viewed on the slice preview screen, the actual printed parts have noticeably smaller holes than expected just based on visual comparison to the preview. This makes me wonder if the issue is deeper than the slicer. Could there be a firmware bug causing this? The outer dimensions of my parts seem fine.
I ran into this when making a wheel for a dishwasher and the internal hole was to tight.
all measurements in millimeters;
The hole in the STL, was 9.6, printed parts 9.3 So I used Auto circle contour-hole compensation with 0.3 added and got parts that where 9.9 ?!?
So it seems like suddenly the printer gets the holesize correct and then add the compensation.
So next experiment I used 0.01 and got 9.6
So I agree with @banderies that it seems like a firmware bug
