Blobs

Hi everyone,
I have perfect surface quality prints, except blobs on retraction spots.
I am using e3d v6 bowden, tube is about 450-500mm, retraction settings:
[onedrive.live.com]

I am using simplify3d software. Extruder is direct drive mk8 gear.

Any suggestions how to get those blobs gone?
Thanks

Edited 1 time(s). Last edit at 11/10/2015 10:03AM by Capinho.

Your image link doesn't work so I can't see your settings. I am using an E3Dv6 with a 600mm long Bowden tube, and I need 8mm retraction to avoid blobs. 6mm was not enough.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Your image link doesn't work so I can't see your settings. I am using an E3Dv6 with a 600mm long Bowden tube, and I need 8mm retraction to avoid blobs. 6mm was not enough.

Fixed. What are your retraction speed settings?

I currently use 100mm/sec retraction speed and either 1000 or 3600mm/sec^2 extruder acceleration, depending on which extruder drive I am using.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

My stepper motor cant reach such high speeds, it stutters when speed is set higher than 75 mm/s

I use the same extruder and length bowden tube and have very little blob problems with PLA and ABS. Check if the bowden tube connectors don't have any play in them moving up and down on retractions. They should be very light. I use a piece of thick single core insulated wire to fix them in place. I've also seen thingiverse printable things to do the same.
Also make sure the temperature isn't set too high and the nozzle doesn't stay in one place for longer than a third of a second.