I have a ticket opened with support already but the replies are very slow so I wanted to see if anyone has any experience dealing with this issue. Below is exactly what I have on my support ticket and I am at wits end trying to solve this issue.
TLDR: We got a H2S, outside dimension’s can be good on square blocks but holes are all over the place (0.3-0.5mm with no consistency on sizing in both X and Y so off setting doesn’t help) Have tried both PLA and ABS, external slot and in our AMS 2 with no luck. Have ran through the H2S wiki help and have done the belt tensioning step and tightening the hot end bolts as requested by support (Still waiting to hear back) with no luck on problem. Problem does not exist on P1S with same model.
Any help or insight would be appreciated. Thanks
Support ticket info:
We recently received a H2S unit and have been having issues achieving good dimensional accuracy when compared to the p1s. Attached in the image is the print we have been using to test. On the p1s we are getting a consistent accuracy of ~0.1mm, while on the H2s the accuracy is anywhere between 0.3-0.5mm with no consistency.
The same model was used throughout and we are using the bambu labs slicer.
The following has been attempted:
Multiple calibrations including the high temp calibration
using Bambu lab PLA and ABS filament
Ensuring the filament was dried in the ams pro 2
utilising the external spool holder instead of the ams
cleaning the bed surface
checking the nozzle for clogs
Printing parts in different orientations (as seen in the image)
doing the recommended belt tension step
restoring the bambu labs slicer to default settings
Doing a flow calibration test
Testing prints with bed levelling and flow calibration turned on and off
we have moved the printer to a more solid table and repeated the above
As mentioned the P1s prints the model fine in both ABS and PLA. We are lost as to what to do and don’t want to continue wasting filament.
Response from support asked to do belt tensioning, calibration and tightening of hot end bolts. Did not resolve issue.
It will depend on the hole diameter being measured for instance the first 6mm hole was reading 6.4 but the 5mm was reading 5.5mm, the 6.2 was reading 6.4 and the 4.7 reading 4.4 etc. The next few prints had the same sizing issue but completely different to the first print i.e 6mm was now reading 5.8 etc. This is what has been driving me crazy, the complete lack of pattern.
No actually it stays consistent in its randomness. My 6.9 mm hole is reading 6.44 in x and 6.61 mm in the Y. The 5.9 mm hole is 5.3 mm in X and 5.73 in Y
No I havent looked into each setting to compare the two which now typing it is a stupid thing to not have done. The only real similarity I have is that both were using default settings. But actually one thing I have noticed is during a cold pull on the H2S the extruded PLA comes out very Lumpy?. As in its very inconsistent and kinda stop starts and is non-uniform unlike the smooth uniform nature of the P1S extruded filament. I dropped the H2S nozzle temp to 180°C at which point it was similar to the P1S filament. I redid the print and the top surface quality was better and the raised numbers sharper but the hole diameter issue was still there.
If you have deviations of 0.4mm in X and Y you ether have an issue with your motion system (but your square block outside dimensions say otherwise) or you are measuring a seam in one direction. You could try to rotate the caliper a bit to avoid the seam.
You could try to add a scarfed seam. Make sure that the filament settings have scarfing enabled on inner and outer contours.
It is a known phenomenon that small holes tend to get smaller, and the deviation increases, the smaller they get. Imagine pulling an elastic band around. It tries to take a shortcut.
But some of your holes are bigger and others are smaller. That is really weird. Unless there is some excessive correction activated for holes.
It would be interesting to test a similar model, but now with square holes to see if you are measuring the same deviations.
Yes I initially thought it was the seam but those measurements are with rotating the callipers around and getting the average diameter. I have tried the random, aligned and back seam options with no luck. I will double check but I think I have tried with scarf enabled and disabled.
yes I know about the smaller holes, typically if I want a smooth bore anything under a 4mm hole I will print a pilot hole and drill it out. Otherwise this test block was to check sizing for should bolts and threads so we could size them in cad to what the printer is capable of.
Yes this is what is annoying me. There doesn’t seem to be anything obvious as to why these deviations occur and how. Each print is not accurate to the previous one so there is almost a randomness to it so maybe it is a correction factor but I don’t understand why it only occurs in the H2S and not the P1S.
Good point. I will need to test this and see what happens.
I have yet to receive any additional reply from the support ticket in two days. The second live chat agent has told me the ticket has been marked as urgent (…which the first agent allegedly also did).
I want the H2S to work but this is really delaying our R&D projects. I’m putting it down to early adopter bugs but management isnt too pleased. Im currently looking at the H2D now…
Measure the outside perimeter (x and y dimensions) of the printed rectangle test part (also check those x/y dimensions in the slicer), and compare those x/y dimensions to the CAD x/y dimensions.
You may or may not find that the model dimensions (in the slicer and/or printed model) are not the same as your CAD dimensions.
I’m mentioning this because I’ve had similar problems driving me insane until I finally found that some of the CAD export models were mis-sized somehow - and the problems were resolved by correctly re-sizing the perimeter dimensions in the slicer.
I was really hoping this was the case. I just checked my CAD (Solidworks) against the slicer and they are the exact same well 47.5667 in Cad compared to 47.57 on the slicer but you get what I mean.
I’m currently waiting for a square hole version to finish as recommended by @Gerrit so I hope that highlights somethings
At the risk of pedantry, maybe try cleaning the nozzle camera with a microfiber cloth? There could be a filament wisp or something interfering with the camera’s view, causing these weird inaccuracies…
I have swapped the nozzle out this morning thinking that but the nozzle camera? the lidar unit beside the nozzle or is that actually a camera?
At this stage I’ll try anything.
Thanks for mentioning it. I saw the box sticking out but thought it was the LIDAR module. Anyways it has been wiped down with a microfibre cloth. I havent seen anything on it but hopefully itll fix something with it
Update from Bambu Labs:
This precision falls within the normal range. The movement accuracy of H2S is 0.1mm. Considering factors such as filament shrinkage, an error margin of 0.3-0.5mm is considered normal.
They are allowing a refund as long as we cover shipping so we are going to do that. Probably pick up a H2D instead, we might revisit the H2S when it has had more time out in the wild.
Surfaces look smooth internally. Im pretty sure this was printed with default settings aswell.
Im using elegoo PLA from an external spool. I was originally using Bambu PLA but that was getting expensive fast, plus we are seeing the exact same range and issues so I am fairly certain its in the slicer.
Not sure if I will get the chance as we want to do the refund process but I’ll try to squeeze a test in.
Also to note this was bambu labs response:
This precision falls within the normal range. The movement accuracy of H2S is 0.1mm. Considering factors such as filament shrinkage, an error margin of 0.3-0.5mm is considered normal.
While I understand what they are saying and I would agree a continuous 0.3-0.5mm deviation is expected I cannot accept that you are getting 0.3-0.5 mm random deviation across holes. In reality that is -0.3 to 0.3 so 0.6 to almost 1mm in some extremes if you really want to argue it.
But hey I don’t make the calls, I’m just happy they are letting us do a refund at this point.
I wouldn’t expect the H2D to behave much differently. The toolhead is different, but the motion system is mostly the same. So you may be in for another disappointment if this is really caused by the motion system and not by a slicing issue.
Perhaps it wont but I haven’t seen any complaints about this issue on the h2d in a while. I’m chalking these issues up to early adopter problems. Plus looking at multi material print times the h2d looks way faster for what we need. Probably should’ve just got it first day but hind sight and all.
Just be aware that the H2D is also quite new and is not as mature as the P1 and X1. There are still many reports of issues with the H2D. It’s not a bad printer, but also not a 100 % sure bet.
