Second Extruder wil...
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Second Extruder will not feed to Nozzle! Brand New Robox Dual!!


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The above says it all. The only way I can get filament to through the second extruder is to run a purge (it was interesting that the new printer had filament still in the nozzle both red and white).


When I try and eject the second filament it only moves and inch and shuts off. My guess is there is a bad switch.. but it has been impossible to get through to support...


Any ideas? Could it be firmware...

All Robox print heads are tested at the factory with red and white (usually) filament. This is to ensure that you have a working print head. The packing clips for your printer were printed on your printer before it shipped.

Can you give more detail on what happens when you attempt to load filament? There are a couple of possible causes but without a complete detailed description including any error messages it is really hard to determine what the issue may be.

Sure! Thanks for the response. So the first extruder loads fine.. and takes the filament to the nozzle and registers as full. However, when I try to push material through the second extruder (I follow the instructions and push in until the material grabs) and it stops after about 1 to 2 seconds. When I attempt to eject the material.. same thing the extruder only runs for a second or two then shuts off. Sometimes it takes several pushes of the eject button to get the material out.

What is interesting is if I run the "Purge " procedure... the extruder operates and will push the material out of the nozzle and pull the new stuff in. I ran a few purge cycles and managed to get the filament to the nozzle. The printer recognized it and would use it to print. However, when i tried to eject the filament, it would again.. only run for a second or two. I do not receive any error messages.. it just simply stops. Makes me think the sensor is not operating properly.

The printer is brand new but i have heard nothing from support. I have also noticed my filament recognition is intermittent but i suspect that is due to the contacts..

Any help would be much appreciated.

If your filament detection is intermittent that is why it won't load the filament. There are two sensors on the extruder. The first tells the extruder that filament is moving and this is what triggers the extruder to turn on when you insert filament. The second identifies if the filament is loaded. This is a continual observation of the filament status. What is happening is that either the filament you are using is not in spec and isn't triggering the second sensor or the second sensor is faulty. A third option is that the cable between the mainboard and extruder is faulty but that is extremely rare and is caused by user damage.
Where are you located? Did anyone respond to your support ticket? Do you know whom it is assigned to?

1 Answer


I recommend replacing the extruder or returning it for repair. 

I do not know what is happening with the warranty support for US buyers. You may contact Circuit Specialists to see if they are able to assist you. They are the US reseller and may have some options or know more about the warranty support.

I suspect that the filament movement sensor is jammed, probably due to either an assembly problem or a small burr on the sensor wheel. If you want to preserve any warranty you may have, don't take it apart on your own. If you prefer to attempt to resolve it, there is an instruction to disassemble the extruder on the support site. 

That is about the limit of what I can provide without actually seeing the extruder. 

I didnt realize support for US owners was so terrible... I love the printer and it looks like if I use the purge function to load the second material it all works fine. Is there some negative impact from running purge cycles?..

@atsparkinson US Support underwent a change at the beginning of July and I don't know what the current arrangement is. I wish I could help more.

There isn't a drawback to running purge cycles except time.
I suggest contacting Circuit Specialists to see if they can sell you some parts.

So I took the extruder apart and saw no visible signs of any damage.. the sensor wheel rotates freely and there dont appear to be any blocks. Any way to reset the status of that second sensor? Where is that located? Anyway to just replace that sensor?


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