New Prusa i3 pro B extruder faulty.

[russellz]

Picture of throat

DSCF2689.JPG (278.54 KiB) Viewed 9573 times

I have received this printer kit a week ago and built it up. Now I find that the extruder doesn't work.

The filament will not enter more than 7 mm into the nozzle throat. I have removed the hot end and find that the throat has a sharp step about 7 mm down and that the filament gets caught on that. Is this normal? It looks as if either the throat is wrongly made or that there is a bush missing from the end.

See picture attached.

I have asked Geeetech via Ebay to send a replacement part but they just refer me to the forum. Can anyone help please?

Russell

[William]

Hi,Russell
You can remove the entire throat from the hotend,and it's easier to check if it has a problem or there is a PTFE tube inside it.

[russellz]

Thanks William,

Yes, there is a PTFE tube in the throat at the bottom end. I assume this is to provide a seal to the nozzle?

However, as I stated above, there is a step about 7mm down from the top end and the filament gets caught on it and cannot be fed through. This is clearly shown in the picture I attached. Perhaps there was a mistake in machining this part with both ends machined the same?

Russell

[William]

Hi,Russell

Sorry i can't get your idea completely.

You mean you can't plug the filament into the extruder successfully when heating up your extruder?

[russellz]

You mean you can't plug the filament into the extruder successfully when heating up your extruder?

Yes. I push the plastic lever down and try to push the filament into the extruder. It enters past the gear and into the top of the throat but then it gets stuck on the step in the throat.

I ask again - should this step be there? It serves no purpose and I believe it to be a manufacturing error.

Regards
Russell

[William]

Yes,it should be that.
You can try plugging the ejector pin(a metal rod in the package we send),if the pin could be plugged in(it means the filament could be plugged in),then the throat is OK.

[russellz]

Yes, the ejector pin enters O.K. but of course it is straight and rigid. The filaments are not straight and are flexible so the situation is different.

As you have been unable to help I have modified the supplied throat as shown in the attached drawing by chamfering the step (fortunately I have a precision lathe). The filament now enters easily.

Throat.jpg (47.06 KiB) Viewed 9542 times

I would suggest that you make the throat part like that in future as other purchasers of the kit might not have access to a lathe!

Regards
Russell.

[William]

I guess you can sharpen the filament and strighten it to make it easier to plug.