Valve open material...
Clear all

Valve open material gap

Juan Barbini
Trusted Member
Hi Guys!
I have noticed that with the filament I am using (3rd party petg) there is a "groove" of filament when the valve opens in the outer wall. This is very consistent with each part I print.
I tried calibrating the head several times, always waiting the small part of filament on the nozzle.
I also tried changing eject volume, changing the filament diameter (in this case i measured 1.72mm), and now I am testing with flow rate and feed rate.
But as you can see the problem is only when the valve open in the outer wall, otherwise makes the outer wall very well.
So I think it is a problem when the valve opens, but I dont know what other parameter to set.
Mike suggested that the groove is under extrusion, editing the gcode in the parts of "G1 B1 F150 E0.30" could improve, but I would like to know what AM parameter do I have to edit to improve this. 
Any suggestion?
This topic was modified 2 months ago by Juan Barbini
Topic starter Posted : 6th July 2021 2:48 pm
Former USA Robox Support Moderator

Check the filament multiplier. Print a box using the spiral print mode and measure the walls with calipers or micrometer. Adjust the extrusion width up and down until the measured wall thickness is the same as the extrusion width. 

That usually fixes this type of issue for me. If not, during a print type M999 and see what the bDelta values are. It may be the head is starting to fail and the valves aren't moving correctly.

Posted : 7th July 2021 2:33 am
Juan Barbini
Trusted Member

Hi ben!

Thanks for the replay.

I made a 10x10x10 cube with Spiral mode with my actual config.

I measured the walls and they marked arround 0.43-0.44. 

Now I lower the feed rate to see if the wall prints more fine. 


Other thing, I used the M999 command and I received values from 0.124 when the head was cold, and 0.118 when it is printing. 


What are these values?

Topic starter Posted : 12th July 2021 1:43 pm
Former USA Robox Support Moderator

@juan15pablo If the wall is thinner, change the filament multiplier by adding 0.01 or 0.02 and testing again. If it is thicker than the extrusion width, subtract 0.01 or 0.02 and test again. Don't change the feed rate.

BDelta is a measure of the position accuracy of the nozzle actuator. Large values indicate a failure to position. Yours are on the high end but still within operating limits. If it exceeds 0.150 the actuator is failing.

Posted : 12th July 2021 2:16 pm

This community page and the content inside is publicly visible except in restricted groups. A registered community member is able to post content. Because of the open nature of this forum the content posted may not represent the views of CEL. While we do regularly read the content posted, in some cases the content may not be appropriate for the reader or may cause offence. Please help us by reporting such content. Technical advice provided in this forum may be provided with good intention and a belief that is is correct but may not be applicable to all hardware, software or user ability. In some cases content may not be relevant to newer or older revisions, conflicting or incorrect advice may be contained within conversations, community moderators will attempt to add to this or make corrections but to preserve the thread this may be on following pages or be missed as the forum evolves.

For official advice users should contact the CEL support team via and follow the provided advice to preserve safety, warranty and function of Robox hardware or software.
This applies to any use or alteration which is not specifically described in the officially supplied guides from CEL. Community content should not be considered official even where posted by CEL employees. Only advice provided via the CEL support portal should be considered official.
Robox is a complex machine with many potential uses, to help preserve the good working order of both hardware and software please be patient and note that many common fixes for other 3D printers do not apply to Robox and may cause irreversible damage or compromise safe operation.
Images and content placed on this forum may be used by CEL and in related media without reward or attribution.