bulge after z seam when printing outer layer first

RedMachine

I finished building my first machine a couple weeks ago and I am still trying to dial it in. It uses a Titan Aero. I am having a problem I can't seem to shake.

When I print the outer walls first using cura on a round object printing with PLA, the start of the move at the seam bulges, which gradually tapers off and looks good after about an 1/8 of the way through the turn.

The problem starts shortly after the base is done.

I have tried changing temp down to 185, pressure advance from 0 to 0.100, retraction up to 1.5, outer wall speed down to 10 and up to 50, cooling from 40-80%, minimum layer time up to 15s.

I think it must be overextruding at the start.

I am running out of ideas, any input would be greatly apprecitated.

Thanks!!

SteveYYC

@RedMachine
Have you tried adding a small negative value for unretract distance? If there's a bulge after an unretract that can sometimes help - especially with the more ooze-prone filaments like PLA and PETG.

Keep the value small (5% -10% of your retract distance is a good place to start) or you might wind up starving your hotend for filament for models with frequent retractions.

DIY-O-Sphere

@RedMachine
Witch kind of machine, CoreXY?

RedMachine

I set "extra prime amount" to 0.5mm3 for a quick first test, and it definitely under-extruded the seam. This is the first thing that has effected it at all, so I will see if this can dial it in.

The setting is in mm3 and I am trying to retract 1.5mm printing with 1.75 filament, so I I will try 0.18mm3 which should be about 10% of the volume.

SIam

have you try to print a cylinder in vasemodus? if not please do it and post the result

RedMachine

It is a plane Cartesian that moves the gantry in the Z axis.

DIY-O-Sphere

How was the orientation on the bed?
I would print a cube, setting the seam to the middle of one side.
That would it make easier to relate to the axis. For me it looks more like slack or lose parts.

RedMachine

I actually did try changing belt tension some. It looked at first to me like it was overshooting with the Y axis.

It was oriented with the seam facing the front of the Y axis.

I will try a cube as you suggested.

RedMachine

RedMachine

@SIam What would this help disambiguate? Would it indicate if it is over-extruding in general or just at certain points?

DIY-O-Sphere

As the spiralized without prime looks good for me, why are you using prime?

SIam

the cylinder looks good so far
your extruder runs smooth without any clicking noise?

RedMachine

It does make a soft noise when it is retracting, but i wouldn't describe it as clicking. More like gears turning.

Since I haven't had a Titan before, i wasn't sure what to expect from it. I have it set at:
400 jerk mm/min
5000 speed mm/min
2000 acc

DIY, i was testing prime in the regular print also, so I thought I would just point out the conditions of the two different tests.

DIY-O-Sphere

@RedMachine
Your jerk and acc is very low. On my BMG I use much higher values.

RedMachine

@DIY-O-Sphere
What are your settings?
So I can know a range to start messing with.

DIY-O-Sphere

@RedMachine
Depends on the size of the motor.
In you case I would take the values of Phaedrux. They were pretty similar to mine (Pancake BMG direct) Currently I'm back on a bowden setup with a bigger motor.
https://forum.duet3d.com/topic/5982/typical-titan-extruder-settings/5?_=1578786524923
You also can increase your max. speed. The linked value is very high and only nessary for high speed printing. I would set that to 8000 mm/min

DIY-O-Sphere

@RedMachine
From that base you can try to increase jerk. But at some point your extruder will start skipping.

RedMachine

it's 1.8, but I think they are similar. 17hs08-1004s.

Thanks for the link, I missed him saying that in that thread.