Workhorse Stringing/Under Extrusion Issues

Hi I have some issues with stringing and under extrusion (top and bottom layers) on my new machine. I have a Lulzbot Mini as well and don’t have these problems.

I have tried nearly 10 times adjusting various settings and the stringing won’t stop. I am printing PPE for donation but this is really slowing down the production.

Any ideas would be appreciated and help others!

Filament is: MH Build PLA
Printer: Lulzbot Taz Workhorse

Things I have tried:

  1. Temperature - I usually am around 205 C but when I put 205 into Cura, the printer seems to print at 195 (even though 195 is no where in any of the temperature settings). So I put it at 210 which brings it closer to 205. My initial Build Plate Temp is 55 C.

  2. Retraction - I have experimented but landed at a Retraction Distance of 2mm and speed of 40 mm/s. It was initially at Retraction 1.75mm and a speed of 20 mm/s.

  3. Speed - I have tried a slower speed but it doesn’t seem to make a difference. I am currently printing at:
    Infill Speed (20%): 40 mm/s, Wall Speed 30 mm/s and Top/Bottom Speed: 30 mm/s. Travel Speed is 175 mm/s and the initial layer speed is 15 mm/s.

Top View

When I do a temperature tower for PLA on my Workhorse (I’m using PolyMaker “PolyLite PLA”) I find the best temperature for printing with the least stringing is at 230°C … which is quite a bit warmer than typical for PLA.

But the Workhorse has a hardened steel nozzle and it doesn’t conduct heat as quickly as a brass nozzle … so it typically does need to run a bit hotter.

Try changing your top/bottom layers to “concentric”.

I don’t know how you’re running retraction speeds as fast as 40mm/sec and not stripping your filament at the hobbed bolt, but good for you.

I’m printing PLA at 220c with a Brass nozzle.

For under extrusion, you have an extrusion multiplier you can mess with.
Assuming you’re using Cura.

I’ve had to decrease my extrusion to cut down on strings and pimples, but perhaps you need to increase yours to fill in the gaps.

First thing I’d try if I were you is my suggestion for concentric top and bottom layers and see what that does for you. It’s helped me a lot.

I had major stringing issues in the beginning with my Workhorse. When I raised the heat the stringing would go away but then id have some oozing. For me, I will use a copper plated nozzle on the workhorse…always. I did purchase some brass nozzles but I have yet to try them on my machine.