Blobs in specific angles of a (round) print

Hello everyone!

I'm printing a filigree vase on my rostock delta printer and above a certain outer shell speed (>15mm/s) I'm having random blobs on almost every layer.
I noticed that the blobs only occur in certain sections/angles: Every 60° – it's always the section witch is aligned to the delta's towers. The other 3 section are proper!

Does anyone encountered similar problems or has any idea what's causing these blobs?

Thanks for helping!

After some print observation, I noticed very short pauses while printing and I think this is where these blobs occur!
These pauses seems to occur quite constant after every 7 seconds. Because of the complexity of the G-Code I thought it could maybe a buffer issue and I increased the buffer size to 32 but no improvement so fare.
Does anyone experienced similar problems or has an idea what could cause these pauses?

I'm printing on a reprap rostock delta printer, driven by an arduino mega 2560 and ramps 1.4, an E3D v6 hot end. Printing PLA at 190°C with 25mm/s.

A delta is the printer, that suffers the most from a slow 8 bit cpu.
15mm/s is Prusa speed. A Delta should go much faster, independent of complex gcode and what not.

Do you know, how many "segments per second" you've set in marlin? ( If it's marlin you are using...)
It's worth trying to reduce them and/or disable LCD support in FW.

#define DELTA_SEGMENTS_PER_SECOND 200

should I reduce this value? how far can I go, without getting visible corners?

This has been discussed already, try to search for it. I don't know what the outcome was. Maybe 40 segments, maybe 100??
In some cases, the reduction was helpful, other claimed there was no difference...

Biggest problem is IMHO, you have to find a general compromise or have to flash FW every time.

Yes, this eliminates the pauses completely! I decreased DELTA_SEGMENTS_PER_SECOND to 100 now I can print at 40mm/s or even faster without pauses.
Thank you for the hint o_lampe!