Pulsar erratic flow rate

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Corrado Steri

Mar 10, 2023, 2:09:24 AM3/10/23
One of our machines has a pulsar head mounted. We are encountering problems of erratic flow rate. Once every hour or so the head prints a layer with very little material, making the print useless.
We are printing PETG in 2mm diameter cilindrical pellets. The temperatures are set as per manual and it does it at slow flow rate and fast flow rate.
We are at a loss at the moment.

Would i get an improvement using spherical pellets? 

Technical Support

Mar 15, 2023, 3:41:31 PM3/15/23
to corrad...@gmail.com, DYZE DESIGN
Hello Corrado, I see that you have already opened a ticket with our technical support email so I have answered by email.

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May 16, 2023, 2:39:02 PM5/16/23
to DYZE DESIGN, Technical Support, DYZE DESIGN, corrad...@gmail.com
I had the same problem. 
With the nozzle of 5mm for globular pellet of PLA @ 200°C I get a flow rate that is not constant and predictive. 
I'm trying with different extruder motor speed and constant standoff distance and scanning speed but there are tracks where the material is "liquid" and  the tracks are wider others where the material delay to come out and the flow rate is low... 
I checked that the screw speed correspond to the motor command and it seems perfect, the only variable I suppose is the temperature measured which is not correct...

Technical Support

May 16, 2023, 3:41:42 PM5/16/23
to FEDERICO INSERO, DYZE DESIGN, Technical Support, corrad...@gmail.com
Hello Federico,

What is the brand and name of the PLA pellets that you use ?
Some PLA can have a bridging problem where the material melts too fast and too soon near the feeding area and causes a jam, resulting in inconsistent extrusion, especially over time and during long prints.
You can try cleaning the screw to see if pellets are melted and stuck together too soon at the top of the screw. If that is the case you can try lowering the top heater temp to lower than 200C or even disabling the first heater.

Micheal Torrey

May 16, 2023, 4:09:15 PM5/16/23
to DYZE DESIGN, Technical Support, DYZE DESIGN, corrad...@gmail.com, FEDERICO INSERO
See attached 

This has been a big problem for us! 


Technical Support

May 16, 2023, 4:26:58 PM5/16/23
to mtorr...@gmail.com, DYZE DESIGN, Technical Support, corrad...@gmail.com, FEDERICO INSERO
Michael's photo shows exactly the problem described indeed, definitely try lowering the top heater temp as much as possible or deactivating it altogether.
This takes some trial and error but every material can be quite different even if it is the same type.

Micheal Torrey

May 16, 2023, 5:13:29 PM5/16/23
to Technical Support, DYZE DESIGN, corrad...@gmail.com, FEDERICO INSERO
We've actually tried this! I guess more trial and error! 
Check us out on youtube - We live stream some of our prints
Micheal Torrey 

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May 16, 2023, 5:22:27 PM5/16/23
to DYZE DESIGN, Micheal Torrey, DYZE DESIGN, corrad...@gmail.com, FEDERICO INSERO, Technical Support
The brand from which I buy is FiloAlfa, I have used before with a very small extruder called mahor XYZ. I will try tomorrow to lower the higher heater to see if this problem will solve! The other pla suggested in the documentation require the same trick for the temperature?

Technical Support

May 17, 2023, 9:16:55 AM5/17/23
to FEDERICO INSERO, DYZE DESIGN, Micheal Torrey, corrad...@gmail.com, Technical Support
Federico, The NatureWorks PLA 3D700 requires the same trick of deactivating the first heater but the 3D850 works fine with all 3 heaters at the same temp.

Michael, what material do you have difficulties with and what is exactly happening ? Corrado started this thread so I suggest opening a ticket with us would be better here to keep track of the issue. Do you still have the bridging problem even with the 1st heater off ?
I have seen your Youtube channel but very close up videos or photos of the print would be better to diagnose the problem, even better if you happen to have a video of the problem when it happens.


May 17, 2023, 1:25:01 PM5/17/23
to DYZE DESIGN, Technical Support, DYZE DESIGN, Micheal Torrey, corrad...@gmail.com, FEDERICO INSERO
Thank you so much. Today we tried to modify the temperature of top heater and effectively the results improved. Shutting down the temperature of top heater created bubbles inside the tracks but the track width it was almost constant and repeatible. Hence, we tried to increase the top heater temperature up to 150°C and It seemed improved. We will try to measure quantitatively the flow rates for different ranges to check the effective flow rates. I will write updates of the experimental campaign.
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