Printer keeps pausing during prints

I'm having a rather strange issue in that the printer pauses randomly during prints. This was first noticed when printing a large and complicated model (from SD). Since then a 20 mm calibration cube has been printed (from USB) with no issues (paused briefly after printing the skirt), it was used in conjunction with M92 G-code command to calibrate the stepper motors. Now i'm trying to print a temperature tower but it pauses multiple times even on the first layer (tried USB and SD). How do i ensure that the printer does not pause during prints?

Here's a link to a video of the printer pausing (trying to print a temperature tower).

Slicer details:

• Ultimaker Cura 4.0
• Also tried slic3r 1.3 32 bit
• The temperature tower had a change temperature at Z injected into the G-code but none of the others did.

Printer details:

• Anycubic S
• Firmware 1.1.2
• filament PLA+
• firmware reprap/marlin
• Is the printer equiped with a optical filament sensor? I had similar pauses on a different printer and it was caused by filament sensor sencing false alarms. Jul 24 '19 at 12:38
• The printer does not have a optical filament sensor Jul 24 '19 at 12:54
• Does your gcode have multiple M109 (wait for new temp) commands?
– Davo
Jul 24 '19 at 17:33
• It does but the temperature on the printers screen does not change to indicate that it's trying to change temperatures Jul 25 '19 at 8:48
• Could it be the z-hop bug (at speed=c, yes c the speed of light)? It was a ridiculous cura bug. Jul 30 '19 at 12:40

I had a similar problem some time ago. The problem in my case was, that in the slicer I had a minimum layer time, which was pausing the printer until that time had passed. I can't remember the name of the settings and I'm not at home right now, but the slicer can either print full speed and pause or it can slow down, to maintain a minimum layer time. I guess the idea is to give the plastic time to cool down.

• Do you mean Cooling Thresholds > Slow down if layer print time is below: ?
– Davo
Jul 30 '19 at 11:24
• Yes. That will slow down. I have also seen that it will print full speed and wait. There was also a setting to make the hotend hover above the object. The problem is, that if you slow down, you will have the hotend melt the already printed parts. A pyramid, for example, will get the tip melted, if the hotend slows down. In that case, it would be better to print at full speed and move away and wait
– jkp
Jul 30 '19 at 14:05
• See ultimaker.com/en/resources/52674-cooling in the "Lift head" paragraph. Quote: "[...]The print head will wait until the minimum layer time has passed and will then move back to the print to continue[...]"
– jkp
Jul 30 '19 at 14:15
• This setting should just be removed, imo. What happens is melted filament will leak out of the nozzle during the wait time, and when you resume it's gonna end up in a bad place. Plus, the now the nozzle is short filament that will be needed elsewhere. Instead, they should estimate the time to print the layer, and if it's less than the minimum layer time scale the speeds (except travel speeds) appropriately so meets that layer times. I know some slicers have options to already do this. But this "wait in one place" setting is just not helpful and should be removed. Jul 30 '19 at 15:59
• Yeah. Scaling the time exists as well. Problem is, that if the head moves too slow, it will heat up the part that is already printed. I usually print other parts at the same time, if that seems to be a problem or I just add a tower. Somewhere I have an STL of a 10mm diameter disc with 1mm height and I just scale it to the same height as the object I'm printing. The time spend printing this cooling tower is usually enough
– jkp
Jul 30 '19 at 19:59