Throat Tube Diameter

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DeftCAD
Posts: 32
Joined: Wed Dec 20, 2017 11:15 am

Throat Tube Diameter

Postby DeftCAD » Thu Feb 22, 2018 3:12 pm

I've been trialling a new filled PLA filament (Nanovia PLA XRS) and it's not playing ball; I'm having real issues with blockages.

I recently changed to a 0.4mm hardened nozzle, which has done almost no work and I can't see any issues in the white feed tube. I think the issue is in the throat tube. I've had it apart probably a dozen times in the last 24hrs and I can't seem to get it properly cleaned out enough to allow filament to pass through smoothly. Even when I've just cleaned it and re-assembled, I load filament and the drive gear starts clicking and skipping when the load is almost complete - right about where the throat tube is. Also it feels like there's a small ledge in the bore of the throat tube at the threaded end. I can't tell if it's material build-up or it's supposed to be there. I checked the one on my right extruder and I can't feel the ledge...

What should the diameter of the throat tube be? I'd like to know so I can load it into my lathe and run a drill through it to make sure it's PROPERLY cleaned out!

zemlin
Posts: 297
Joined: Sat Oct 21, 2017 2:02 pm

Re: Throat Tube Diameter

Postby zemlin » Fri Feb 23, 2018 1:30 am

I checked my unused spare hot-end using number drills.
Looks like the nominal is 2mm. A #47 drill is 0.0785" which translates to 1.994mm. #46 was no-go.

Squenz
Posts: 140
Joined: Fri Dec 01, 2017 11:18 pm
Location: Stuttgart/Germany

Re: Throat Tube Diameter

Postby Squenz » Fri Feb 23, 2018 6:47 am

Just to add some smart-..s wiseness ...

I allways losen the knurled pressure screw on the BondTech and proceed a cold pull at 60 to 70 percent of nominal filament temperature. For loading i push the new filament down into the throat tube before securing/adjusting the pressure screw. Safes quite some time where the Hot End is without any material to heat up (= cooking up the remainder into carbon residue) and ensures proper adjustment of the pressure to the new filament.

DeftCAD
Posts: 32
Joined: Wed Dec 20, 2017 11:15 am

Re: Throat Tube Diameter

Postby DeftCAD » Fri Feb 23, 2018 9:08 am

zemlin wrote:I checked my unused spare hot-end using number drills.
Looks like the nominal is 2mm. A #47 drill is 0.0785" which translates to 1.994mm. #46 was no-go.


That's great, thanks. I'll give it a pass through with a 2mm bit then. I expect it'll only be clearing out carbonised material anyway.

Interesting regarding doing a cold pull. I have to admit that I've been leaving filament loaded in between uses. I suppose the material remaining in there is part of what's causing my issues?


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