Blobbing, again...

[dreyfusduke]

I still have blobbing issues. It does not seem to be coming from any retraction setting or "coast to end" settings. No matter how much I change these settings, I get a bumpy part. The bump seems to come while the printer is doing the shells. It is precisely when it goes from doing the inner shell to the outer shell. There is always a bump there. The only reason I purchased this software was because Makerware always seems to leave a vertical "zipper" on the part and there isnt much of a setting to change this. This software, expensive software I might add, leaves my part looking like it has warts all over. Any help?

I am using a flashforge creator pro with brand new Makerbot PLA.

[lkeppner]

Without pictures I am left to assume what you are describing one of two problems I have finally understood and overcome. If you are referring to little "bumps" of plastic that correlate with every retraction then do you have vertical lift after retraction set??? If so, I found that this leaves a little blob right at that spot. If this is on the surface (or close to it) it is very visible. I found turning off this retraction resolves the issue. There are times this lift is needed and I have found I can adjust the other retraction settings (such as minimum length before retraction) which help to balance this effect.

The other problem I have observed which happens precisely at the junction of either inner/outer shell or transition from infill to perimeter is due to the speed change. Any change in speed requires the pressure in the nozzle to reach an equilibrium with the new flow rate which corresponds to the new speed. This will manifest itself in extra plastic being left at any point that decreases speed. I have eliminated this in models that are sensitive to this effect by maintaining the same speed for both infill/inner/outer shells. Again, it is a balancing act but this same/same/same speed approach is one way to tackle it.

Don't know if I've covered what you are seeing....

[dreyfusduke]

I will see if I can get some pictures of this. It is the same problem most people are having. Some call it blobs, some call it zits, or some call it bumps. It seems to be a common issue. My problem happens exactly when it goes from an inside shell to the outside shell. I do not think there is any retraction that happens during this process, but I could be wrong. It does do the outside shell at a slower speed than the inside though.

[lkeppner]

Then just for troubleshooting purposes, try setting the outer perimeter speed to 100% of the printing speed and see if your problem goes away. In fact, set all speeds the same for the moment to eliminate the same problem when moving from shell to infill.

See if that proves any improvement.

[jimc]

If you are having blob issues after a rapid movement and your finding it very hard to control with the different ooze controls then a possibility is that the moisture content of your filament is too high. Just throwing that out there as a possibility. Other than that its all over in your ooze control settings.


to add to this.... excessive blobs all boils down to one thing, pressure in the hot end. relieve the pressure and get rid of the blobs. things that cause excess pressure is as i said...moisture in the filament and keep in mind that extrusion width will play a part as well. i know that the higher my extrusion width the more i have to turn up the ooze controls. i run a .40 nozzle which has a normal extrusion dia of .48. if i have something i need a real fat width and i turn that up to say .60, now the extruder has to push that extra plastic out between the part and the nozzle to make it wider. this all causes the pressures to be higher. you will need extra ooze control on something like this. i tell everyone to think of it like a caulking gun. if you dont press the button on the back of that and pull the plunger back then the crap just keeps oozing out of the tip of the cartridge and you get caulk all over the place.