I'm not sure if the way that the Cube Print software causes blobbing is unique to the Cube Print software or if anyone else has come up with a similar solution. Even though I am calling it a blob shield, it technically isn't shielding anything.

When the software generates a print file for the left extruder, it does retraction on the left side of every layer, and vice-versa for the right side. Retraction (pulling the filament back a bit so it doesn't ooze out and cause stringing) is normally only needed when the print head is stopping on one part and moving through a non-printed area then it undoes the retraction (pushing the filament back to the tip so it doesn't leave a gap) before printing again.

Unfortunately, Cube Print software tends to put retraction on every layer even if you are printing a simple cylinder for example. The problem with that is that the retraction causes a slight pause to retract, then undoes the retraction and continues printing in almost the exact same spot. I have tried modifying the .bfb code to remove retraction entirely, but that can be very tedious and if it is too small of an object, it doesn't have time to cool between layers and will warp or twist.

The best solution I have found so far (besides using better software) is to create a blob shield. The idea is to create another object next to the main object. As an example, if you print a cylinder, when it gets to the end of the circle it will perform retraction and then move to the other object and undo retraction before printing again. This eliminates that pause and then continue in almost the same spot. You will still get a slight line, but not the blob of plastic that the pause causes. Also if you create the shield .2 mm taller (assuming you are printing at 200 microns) than the main object it will eliminate or reduce the blob you get on the top at the end of the print.

You could make a thin cylinder around the entire object, but it is only needed on the side of the extruder being used.

BlobShieldExample1.JPG

A cylinder all the way around would cover either side so it doesn't hurt.

BlobShieldExample2.JPG

Also a cylinder is not necessary. A simple flat wall would do as well.

The reason why the print head I designed http://www.print3dforum.com/showthre...ll=1#post42476 needs to have the rounded side away from the extruder is that even with the blob shield, you will still get a slight line. It will still work with that line but this way it is a nice clean print.

To show what I am talking about I included the BFB file for a small cylinder here >>> https://drive.google.com/open?id=0B6K745kRy16-dUtLTXE0TFdjQ0k

Cylinder.JPG

This was sliced with Cube Print software and converted to BFB with Mythandar's tool.
It has 41 layers and 87 retractions.
The comments at the top (starting with ^) have the details of the object.
The code for retraction is M103 so if you use a good text editor like Notepad++ you can count them.