Barrel mod for printing flexable filament

[mlr53]

I recently tried to print Ninjaflex flexable filament on my Rev E M2 with no success. No matter how slow I fed the filament, I never could even get it to load. As soon as the filament hit the nozzle, the back pressure caused the filament to flex and it would get wrapped in the drive gear. Upon closer inspection after pulling the extruder apart multiple time to unwrap the filament, I notice that there was a fairly large gap between the top of the barrel and the drive gear/bearing, which allowed the filament to bend instead of pushing down and thru the nozzle at the other end of the barrel. I brought the filament to work and tried it on a Makerbot Replicator 2 we have there. The filament loaded first time with no issues, printed perfectly each time. I pulled the fan to look at the barrel and drive set up and noticed that the barrel conforms to the shape of the drive gear/bearing and there is almost no gap to allow the filament to bend. See picture attached. Is there a way to have a barrel made for the Rev E that would contour to the drive and adjust to the close the gap in a similar manner?

extruder photo

[mlr53]

Here is the picture with comments on it.

[Jules]

That's an interesting idea worth pursuing. If you want to take a crack at it, you can modify the STL file for the drive, since MakerGear posts them for just that purpose.

https://github.com/MakerGear/M2/tree/ma ... 4%20Hotend

[sthone]

I a lot of people run flex without any problems.... it can be challenging but if you want to take a crack at modifing the filament drive the step files are on the Github Site.

[mlr53]

How do you'll convert the stl file to be able to modify it? I'm using Inventor Fusion or Auto Cadd. The file you referenced above seems to open in Fusion but nothing shows up. My experience with stl files is that once you open it, you can't modify it. The file does open in S3D, so I could print it as is. but that doesn't offer an option to fix the issue.

[willnewton]

You can modify them in several ways depending on your software package.

Meshmixer can work directly on STL meshes, for example.

More likely is that you import the STL into your design software, then you design the additional parts or make cutters to trim away/enlarge holes, etc. using your CAD package. You can then convert your designed objects into meshes and use mesh Boolean functions to unite, subtract, etc. from the original mesh.

You can also do a fair bit of reverse engineering if your measurement systems match to convert meshes back into polylines/surfaces/solids.

This depends on the mesh handling abilities of your software and your willingness to learn how to figure it out. Sometimes it is a snap, sometimes it's a pain. Meshmixer is free!

One hint is to match mesh densities when Boolean-ing. You can also use meshmixer to unite tricky meshes and heal bad areas, etc.

[Jules]

You can modify the STEP files in Auto-CAD, can't you? (I'm not sure - I've never used Auto-CAD.)

If not, they can be modified fairly easily in Fusion 360. (Which is free for enthusiasts, and a great little program.....highly recommending it now.)

[willnewton]

How do you'll convert the stl file to be able to modify it? I'm using Inventor Fusion or Auto Cadd. The file you referenced above seems to open in Fusion but nothing shows up. My experience with stl files is that once you open it, you can't modify it. The file does open in S3D, so I could print it as is. but that doesn't offer an option to fix the issue.

After reading Jules' post and yours and mine and others, I wonder if there is some slight confusion as to the file type you might prefer to be working on, since folks are referencing different file types.

There are STEP files and STL files of the hotend. The STL files are meshes that can be tricky to modify. The STEP files are the vector/NURBS surfaces that you can import into your CAD software and work with directly.

In terms of preference, get the STEP files if you want to mod it and the STL file if you want to print as is.

[sthone]

Man... No one ever listens to me.

[Jules]

Yeah, that's partially my fault for suggesting the STL file first. Force of habit.....they are a bitch to modify. (I've done it...it ain't cool.)

Go with the STEP if you want to make changes.