Walls not touching

[eestelles 1]

Hello,

 

I recently bought an UM2+ and I'm printing with Fiberflex 40D, so far so good but the external walls do not seem to touch. I have increased extrusion % but still nothing. See photo attached. 

 

What do I need to change on Cura so the walls are joined? I have successfully printed using Fiberflex 40D on other brand of printers so I'm sure is a matter of getting the right setting. 

 

[gr5 2,265]

You have pretty bad underextrusion.  I'd say you are underextruding by about 20 to 30%.  So if you are going to increase extrusion try 20% but I think if it's underextruding that badly then going to 120% will just cause the extruder to fail even worse.  In my experience 10% is about the max you can compensate for.

 

I'm wondering if someone took apart the feeder and put the tension screw back in wrong.  There is a tension sensor on the side of the feeder.  Make sure it's half way in the window.  Or maybe someone printed some carbon fiber and ground down the feeder.

 

But the most common cause of underextrusion BY FAR is worn teflon part.  There is a teflon part in the print head.  It is considered a "consumable" by ultimaker.  So they are nice and sell it quite cheap (around $18?).  

 

You can get them from any reseller in your country.  If they are all out, 3dsolex sells a 3rd party version.

 

I'd look in the maintenance menu and see how many hours of printing the printer has done.  You have to replace this part every 500 hours or so.

 

The teflon gets soft at the hot end over many weeks and the pressure makes the hole in the center squeeze the filament hard enough that it can add several pounds of resistance.

 

If this isn't the issue I have a list of about 30 things to check.  Most of them only take a few seconds to eliminate.

[eestelles 1]

Thanks so much for the swift reply. 

 

The printer is brand new and I have only printed with Fiberflex so far. The tension screw, I have tried in different possitions, same results and I can feel the filament going in ok but will have a double check just in case. 

 

Please let me know about those 30 things to check as the printer is brand new so not even 10h print time. 

[eestelles 1]

Ok, so I had a look at the extruder, the filament looks pretty bad (see photo)]

 

What I noticed is that with the pressure off from the feeder, still the filament felt tight inside the transparent tube. Definitely not smooth as I have noticed before in other printers.  WD40 inside the transparent pipe?

 

[gr5 2,265]

The name of the tube is the "bowden tube".  Or just "the bowden".

 

OH!! Fiberflex 40D!!!  Oh I saw that but wasn't familiar.  That is similar to "Ninjaflex".  I think that is also 40D.  maybe?

 

Okay so Ultimaker has is a bowden printer and has more trouble with filaments that are so flexible.  But you can do it.  So yes absolutely put oil on the filament (to get into the bowden).  Here are some steps you need to do:

 

1) Print maybe 10C hotter than they recommend or if they have a range print at the top end of the range.  Higher temps means less viscosity.

2) Print extra slow.  I like 10mm/sec for Ninjaflex filament.

3) oil the filament.  This part is weird.  People think it will mess up the finished part but it doesn't.  WD-40 might work but it's mostly a cleaner - not a lubricant.  Ideally use some light oil: 3-in-1 oil or sewing machine oil.  Probably even baby oil would work fine.  You want a peteroleum based, light weight oil.  Then you put one drop on the filament before you insert it into the printer.  Then what I do is hang the back of the printer over the edge of a table and unspool until the filament almost touches the floor (don't get any dust on the filament).  Then I add one drop up near the feeder and the oil runs down to the "U" in the filament.  Then every hour or two (every meter of filament printed) I unspool so it almost touches the floor again and add another drop.

 

This oil makes a huge difference.

 

4) Set the feeder tension to the minimum (at the top).  When the feeder squeezes the filament it is feeding less than the feeder thinks it is feeding.  So because of this,

5) Also increase the flow.  On the UM2+ you can change the flow rate live from the TUNE menu.  Go in there and try 105% "flow".  it's called flow.  If you overextrude too much it will just bunch up inside the feeder and make a mess.  I'm not sure what ideal flow rate is.  Maybe 110%?  Maybe 105%?

[gr5 2,265]

Ninjaflex is about 30D.  40D is still difficult but should be significantly easier.

[eestelles 1]

Making good progress! Now the walls are much tigher and haven't put any oil yet. I can separate them with a bit of force but as they are, they are together. 

 

Will keep tinkering and update this thread with  my findings. Thanks for the tips!

[gr5 2,265]

The oil will make a HUGE difference.  🙂