Enable prime blob

[LindsayPatten 1]

Under settings visibility the "Enable prime blob" setting has an i beside it that says "this setting is hidden by the active machine and will not be visible."  I think this setting is exactly what I need and I wonder why it is hidden for my machines (Anycubic Chiron, Anycubic i3 Mega S) and if it is possible to enable/unhide it?  And if so, how?

 

Right now at the start of every print I manually push in the filament a bit while it is retracted and moving to the start position.  Depending on how far I manually push it in the unretract at the start point creates a blob at the start of the print but the print then carries on very reliably.  Without doing that the print often doesn't immediately start extruding for some distance and often fails to adhere for some distance.  I almost always use a raft so the blob doesn't cause any problem.  My guess is that the Enable prime blob setting would do the same thing I'm doing manually so I would like to be able to use it.

 

Thanks in advance!

[Smithy 1,144]

The reason why you cannot select the prime blob is, that the prime blob is not generated by gcode. It is done by the firmware on newer Ultimaker printers and therefore only available there.

 

But you could do something on your own in the start gcode section of your printer profile. Just move the head the front, extrude some filament and that's it. I would recommend to raise the head 30-40 mm before extruding, so nothing can stick to nozzle.

 

Another procedure could be to extrude 1 or 2 lines at the front like the prusa printers.

 

Or just print a bigger skirt.

 

Which one you use doesn't matter, all of them extrudes some filament before the print. If you don't want to play with your start gcode, use a wider skirt, which you can configure in Cura directly.

[LindsayPatten 1]

Thanks for your response. I can try your suggestions but I'm not sure they will solve my problem which is rooted in oozing. Currently, a lot of filament oozes before the print starts which means that the first bit of the print is short on filament. Worse, during the initial period before it gets to full extrusion it is extruding a bit, but often not enough to properly adhere,resulting in strings of filament dragging behind the extruder.  Extruding somewhere away from the model would help but there would still be oozing during the move to the start point, which is exasperated by the large size of the Chiron build plate, and the problem with underextrusion resulting in unadhered strings would still be there.

Providing for Xmm of extrusion after moving to the starting point pretty much exactly solves the problem so it would be a nice feature to have, at least for non-ultimaker printers.  But since that won't likely happen in the short term I'll try your suggestions, so thanks again.

[geert_2 557]

Multiple lines of skirt (=an outline around the model, but a few mm away from it) do solve the underextrusion due to the oozing before printing. I usually do between 3 and 10 lines of skirt, depending on the size of the prints: the most for small prints, the least for larger prints. I don't have problems getting them to stick, even if the beginning stutters a bit.

 

Also, it gives you the opportunity to check if your bed leveling is okay, and it purges the nozzle and removes some of the dirt in the nozzle that often comes loose when starting a new print (=tiny black flakes in the melt).

 

See the photos below. This is on UM2 printers, but it should also work for other models.

(Note that these were testprints for trying-out bonding, overhangs and warping. Don't pay attention to any defects in these areas, but concentrate on the skirts, thus on the outlines around the prints: these are well printed.)