Does it sound like it's skipping steps when retracting for example? This usually gives an awful sound. If not, chances are that acceleration isn't the problem 25mm/s^2 isn't that high.
If it isn't skipping steps just keep bumping it up until it does then back it off until it starts working properly and reduce it some more to be safe. That should be the maximum your setup is currently capable of. You can increase motor current and bumping up acceleration even further.
The quicker the retraction the faster the nozzle moves on, the lower the dwell time on that point, which cannlead to blobs because of back pressure. You can of course use pressure advance to try to reduce this but may complicate matters more. For my 3mm 600mm long bowden it wasn't working. The filament kept moving in and out at lengths and speeds which were too much, it wears away the filament by the hobbed bolt. For a 1.75mm and direct drive it should perform better..
--
Kind regards
Imqqmi
NFAN CoreXY printer:
[
reprap.org]
