Unfortunately, I didn’t have much luck getting help for my ooze problem in the Reprap forums. The only respondent suggested that the best way to fight it is to replace the hot-end, with a J-head nozzle.

While I do have a J-head spare, I’m not quite willing to give up on the Budasnozzle yet. I thought I’d sit down with the ‘daily branch’ version of SFact (which has more retraction-related settings), and battle my way through the various settings, see what the effects are.

Here’s my output from my tests:

Retraction settings:

v1 – Use Fixed Retraction
Retraction speed – 13.3mm / s
Retraction distance – 1mm
Restart Extra Distance – 0.1mm
Result – Corner bulge worse than SF default

v2
Retraction speed – 13.3mm / s
Retraction distance – 2mm
Restart Extra Distance – 0.2mm
Result – Even worse.

v3
Retraction speed – 13.3mm / s
Retraction distance – 0.1mm
Restart Extra Distance – 0.2mm
Result – Really terrible – filament everywhere. Did I save the second one correctly before skeining?

v4 – retry v2 again, slow down filament speed to 30mm/s just to get a better idea of what’s happening.
Retraction speed – 13.3mm / s
Retraction distance – 2mm
Restart Extra Distance – 0.2mm
Result – The same as V2. Notice that the Z-axis bars are moving around a bit. Probably need to tighten up X-axis bars again. Maybe print some Z-stabilisers.

v5 – Change settings again
Retraction distance – 3mm
Restart Extra Distance – 1mm
Result – Okay, it looks like the ‘restart extra distance’ is causing a lot of the blobbing. It’s the extra filament that gets fed into the extruder before starting the next section. Take this back to 0, I think.

v6 – Restart Extra distance at zero.
Retraction distance – 3mm
Restart Extra Distance – 0mm
Result – Much better. Internal blobs lowest of all prints. External still higher than default settings. Can you set a negative Restart extra distance?

v7 – Restart Extra distance at -1.5.
Retraction distance – 3mm
Restart Extra Distance – -1.5mm
Result –  Very good. Improved internal blobs even further. Corner blob improved but still larger than defaults

Here’s some of the results from the tests;

While I wasn’t successful in removing the ooze, I’d still call tonight a success. I’ve learnt a lot about SFact’s retraction settings, and feel like I have more control over the machine, in general.