anybody know, Why my printer is creating little blobs on printed object's surface?
what are you using to slice it?
Consider changing filament before trying anything else, tthis could bee just some bad filament with water in it.
that is because the arduino is not capable of processing that quantity of sqrts.
I assume you are using marlin firmware. Your problem It's because you "DELTA_SEGMENTS_PER_SECOND" value is too high. You may define a value close to 100 or slow down the printing.
Adjust your jerk settings. If you're getting artifacts like this, the setting's too low. Roughly 20% of your max print speed.
mmm too much moisture in the filament ...... campia Filamente with a just opened and try again
I have had similar problems when wrong filament diameter calibration in my slicer. (non delta)
What s the measured diameter of your filament vs the set in your slicer?
For me the blobbing is all retraction based. Delta's (or any bowden extruder) need ALOT of retraction. On my 3DR with a belted geared extruder the perfect setting is 7mm Retraction with a E3D v5 clone. On my Core XY with direct drive extruder the magic spot is 6mm.