Rep2 Filament not touching/connecting

[Florian Harr]

Hi everyone,

as a new Makerbot user, I'm starting to have lots of problems with my filament or better said with my Replicator 2 in general.

My rep2 just started to do strange things or more particular, strange things with different kinds of filament. I'm trying to print a spool holder (tower) with yellow filament from Makerbot. I already printed two of the same model with translucent blue filament from the same vendor (Makerbot) without a flaw, but somehow yellow and a few other colors never work with any of my prints. As I'm running a rep 2, all filament is PLA used with a spring loaded drive and sailfish 7.7. All my models are exported with the latest Makerbot/Makerware software in High resolution settings or the settings mentioned on thingiverse.

So attached is a picture of my problem. Basically the filament which is extruded doesn't touch the edges/isn't connected which makes the layers strange and weak. I already tried to tamper with different temperatures, which didn't help much. The strange part which bothers me, is that I can't find the right settings to fix this as it feels the Makerbot is doing strange things when loaded with different filament.

Any help is highly appreciated.

[Dan Newman]

You measured the filament's diameter and input that into the slicer
before slicing? (Also helps to calibrate the feedstockMultiplier,
but using the correct filament diameter is the first step.)

Dan

[Jetguy]

Looking at that picure you are invoking the shells bug!!!!!!

 

Everyone should educate themselves on this. It applies to nearly every slicing software out there.

Too many shells = gaps in infill.

 

Again, this info has been around since 2011.

http://www.makerbot.com/blog/tag/extra-shells/

 

Again, the link info is Skienforge in Replicator-G and the terminology for Makerware is slightly different but the PROBLEM and UNDERSTANDING are the same.

 

Makerware doesn't call it "Extra Shells" it's just "Shells". Minimum is 1, no more than 3 for 99.999% of all prints.

You used 4 shells on that print (simply count the rings like a tree). 4 shells doesn't allow proper infill in the thin section in the upper portion of your photograph.

 

Assuming a typical Skeinforge setup, the extruder will first draw the outline of a layer in a part before filling any of it in with more plastic. That outside trace is the “first shell.” The “extra shells” setting will add additional interior traces of the outline of the layer for each additional specified. This picture should explain it better:

2 extra shells, 0 extra shells

Pretend the lines are the paths of the extruder as it lays down plastic. The figure on the left has the extruder drawing the outline, then draws two extra shells, and then fills the center of the object with plastic. The figure on the right has the extruder drawing the outline and then filling the object with plastic.³

The “extra shells” setting is probably just as important to part strength and structural integrity as plastic “infill” or the amount of plastic printed inside the object. It is probably pretty intuitive that an object that is 100% filled with plastic is going to be stronger than an object with 0% filled with plastic. But what if you don’t need the strongest part possible? What if you just need an object that is purely decorative, doesn’t need to be strong at all, that just needs to be only just strong enough for a particular application, or prints quickly?

It depends. Generally speaking, a higher infill ratio will lead to a stronger and sturdier object that will use more plastic and time to print. Whereas, a lower infill ratio will lead to a lighter, less sturdy object that uses less plastic and time to print. When I don’t need a part that is super-strong, I typically print with about a 20% fill ratio. I find this makes for parts that are very strong and durable while still being quick to print without using a ton of plastic.

However, infill isn’t the only concern. Laying down extra shells can result in an object that is strong on the outside, while still being sparse on the inside. However, more shells isn’t always better!

• Thin Parts. When you have extra shells on a thin part, a current bug in Skeinforge will cause your thin parts to be hollow. Basically what’s happening is Skeinforge looks at the thin section of your object, figures that it cannot fit the required number of extra shells in there, and then skips the shells and the infill. ⁴ So, if you’ve got a small or thin part or a part that has small or thin features, you will want to turn extra shells down to 0.

 

 

[Jetguy]

I also question if beyond the shells problem that you don't have some backlash in your belts.

 

That would be an easy mechanical explanation for the gaps between the infill and the perimiters/shells.

Honestly, I think your first layer height/AKA leveling looks ok.

Given that the perimiters and the infill separately also do seem to merge correctly and form a smooth connection indicates this is not an extrusion diameter issue IMO.

 

I would sheck my belts for tension, and also, check and ensure the X carriage belt clamp zone has not distorted from heat and results in backlash of the belt in X.

That is a rare but known Failure on the 2 and 2X models.

[Dan Newman]

On 14/11/2014, 12:06 PM, Jetguy wrote:
> Looking at that picure you are invoking the shells bug!!!!!!

Note that he wrote that the same model was working fine previously and the
difference was that he changed filament. So, unless he changed slicer
settings (or upgraded), the difference is likely elsewhere. Possibly
in not measuring filament diameter before slicing (or even calibrating
feedstockMultiplier).

Dan

[Enginwiz]

Hello Florian,

maybe your nozzle is too far away from the blue tape when printing the first layer

and the single noodles of printed plastic don't fuse together properly.

Start a new print and cancel it after the outlines and most of the first layer infill is printed

just before the outline of the second layer starts. Carefully pull off that first layer from the blue tape.

Use a digital caliper and measure the actual thickness (= height) of the printed first layer.

The thickness of the printed first layer should be in the range of 60% to 90% of

the specified layer height of your print. So if you sliced your part for a layer height

of 0,2 mm your printed first layer should be 0,12 mm to 0,18 mm thick.

The first layer of the print has to be pressed down tightly onto the build surface

to make it stick properly and to close the gaps between the print lines to give

you a closed bottom surface.

Makerbots levelling procedure with a business card or a piece of copy paper

between the nozzle and the build plate is not very accurate. Measuring the first

printed layer gives you a better Information about the real gap between nozzle and

build surface. Use the three levelling screws below the build plate to adjust

the first layer height until you are in the 60% to 90% of the desired first layer height.

[Florian Harr]

Thanks everybody for all the great answers.

I am aware of the "Number of Shells" problem. I tried it with different numbers of shells already, but as I said, with translucent blue everything works (same x3g file) while yellow, blue and black totally suck. 

I have measured the diameter of my filament and it seems to be pretty stable and actually fits my Makerware slicer settings. I haven't changed anything on the feedstockMultiplier yet.

The next step will be to tighten the belts on my rep2 again and then remeasure my prints. I will let you know my results later today.

Thanks so far

[lassi kinnunen]

try with less diameter or feedstock multiplier to cause more extrusion.

the diff color filament may shrink differently(especially opaque vs translucent). it doesn't look like the shells bug since the infill path is there, theres just not enough plastic at the ends..

-lassi

[Florian Harr]

It took me a while to fully investigate and try all the suggestions everyone made and a few improvements where a success. White and Translucent Blue print now as expected, though I still have problems with my Black and the other blue. 

The change which helped with the other colors was adjusting the speeds and the feedstock multiplier in my slicer settings.

Though, all these things helped, I'm not completely where I should be with my replicator 2. The pictures attached show two of yesterdays prints. You can clearly see that there are massive problems in the infill as the filament strings are not really touching and it's doing some kind of double wall thing. In addition to that, the outer edge has the same problem as it looks like the extruder didn't go fully to the edge.

I try to fix that through the feedstock multiplier, unfortunately without much luck. Currently printing at 225 Degree Celsius.

Any Ideas how to fix this?

[Jetguy]

Note where the problem is (the far right picture), it's all in the Z zipper which means it's all about controlling retraction.

But worse than that, I see an obvious backlash problem because that Z zipper seriously gets wider in some places indicating nozzle positioning is changing, above and beyond any restart after retraction issues.

So, that is belts in some way. Either a belt is loose, OR the belt to the extruder carriage clamp is failing- a known failure from heat and molding defects of the Extruder carriages.

Classic test:

Using the control panel, enter jog mode and jog X axis if even just a mm. That locks ALL the motors.

Now attempt to move the extruder left and right by hand (don't make it skip a step) just ensure the belt is holding the extruder and it cannot move left or right even a fraction of a mm without a lot of force. If it can move, that's the belt clamp area of the X carriage failing or an insanely loose X belt.

Same thing in, Y, but in that case, the most likely candidate is the short belt between the motor and the upper shaft pulley is loose.

[Ryan Carlyle]

Agreed, looks like backlash.

[Florian Harr]

Okay, but how do I fix this? 

The Y belt is really tight and seems to be good. The X belt seems to be fine as well, I just re-tightened it several times and I doubt that I can make it tighter ...

Thanks

[Ryan Carlyle]

Which axis has the gaps?

[Florian Harr]

I would say Z and Y

[Ryan Carlyle]

Z? Really? That would be a separate issue. Backlash only happens when you reverse directions, and the Z axis is typically a one-way trip during the print.

How tight are your three Y belts? Try plucking them. The short one should make a medium-high pitched twang, and the two long ones should make a low strum. (Don't kill them, but yeah, tightness is required.

[Joseph Chiu]

Can you explain with more details, or show with pictures?

The gap you show in the infill is huge - easily 0.5 mm from the looks of it - if your belt is tight all around (including the belt from the stepper to the Y drive shafts), you might want to see where else there might be play in the system.

Run the job mode and put the extruder in the middle of the printer.  Then grab the (cold!) nozzle with your finger and wiggle it back and forth, left and right.  Look at the various belts, pulleys, shafts, etc. as you do this and see if you see any movement.  Ideally, there should be none.

[Florian Harr]

Here are some more pictures and a video which hopefully gives you a better idea of what's going on.

http://www.youtube.com/watch?v=aiRfkjBGRQE

Also, what I don't get is why there are soooo many string in between the hexagons which shouldn't be there.

Again, thanks for your help.

[Joseph Chiu]

Hmm, that almost seems too tight.  Does the Y move smoothly?  Or can you feel it bind when you move it with the steppers off?

On Thu, Dec 4, 2014 at 11:46 AM, Florian Harr <evilsre...@googlemail.com> wrote:

Here are some more pictures and a video which hopefully gives you a better idea of what's going on.

http://www.youtube.com/watch?v=aiRfkjBGRQE

Again, thanks for your help.

Am Donnerstag, 4. Dezember 2014 14:30:12 UTC-5 schrieb Joseph Chiu:

[Florian Harr]

I never touched(tightened) Y, I only adjusted X. 

Y moves smoothly. 

[Joseph Chiu]

Can you indicate the X and Y axes just to make sure we're looking at it the right way?

[Florian Harr]

I used this video on how to tighten the belts 

https://www.youtube.com/watch?v=l1FWj-ZHEVA

Or how would you like me to indicate which one is which?

[Ryan Carlyle]

Infill stringing like that is actually normal, Makerware does that on purpose.

Something is loose in your printer. We don't know what. Your job is to wiggle stuff until you find it.

My money is on the little belt attached to the Y stepper.

[DonaldJ]

On Thursday, December 4, 2014 9:44:03 PM UTC-6, Ryan Carlyle wrote:

Your job is to wiggle stuff until you find it.

That's a wonderful phrase.  Mind if I borrow it?

It can be applied to many endeavors...

 

[Florian Harr]

I did everything which was recommended here and also disassembled quite a lot around the Makerbot.

I also tightened/aligned the Y Gantry again as shown in a Video from Makerbot on youtube as I felt like this is the loosest part on my printer. When doing this I found a weird spot on the left gantry, see pictures attached. I don't know if that's a problem, maybe some of you know if it is. Anyway, after realigning my y gantry/belts I did the test as shown by makerbot and my makerbot had quite a bit of friction on the left side. Here's a video of me demonstration that: http://youtu.be/5bS2JLx343I

Is this normal or how can and should I fix it? 

Thanks

[Jetguy]

Well, the question is does that part of the belt go around the pulley? If yes, it must be replaced.

If no, then no big deal. That looks like horrific chewing on the belt from from something.

[Florian Harr]

Unfortunately this part goes through the pulley. 

Any idea where I can get a replacement?

Additionally, did you see the video? It seems strange how I can move the extruder carriage even after I realigned everything

[Ryan Carlyle]

You could unclip the belt from the X-ends and rotate the belt until it's between the two X-end clips.

[Florian Harr]

That's a really good idea! Thanks!

Anyway, all belts look really brittle, so I might want to exchange it anyway. Any idea where to get replacement belts?

[Jetguy]

It's GT2 2mm pitch belt 6mm wide. You can get it from nearly anywhere.

This one can be cut to length and probably have enough for both sides. http://www.adafruit.com/product/1184

$10

[Jetguy]

Note though, that first belt I linked is just a large belt of the correct pitch width and would work for Y axis.

For X you need a specific belt of an exact http://www.sdp-si.com/eStore/Catalog/PartNumber/A%206R51M424060

2 mm (GT2) Pitch, 424 Teeth, 6mm wide Single Sided Neoprene Belt with Fiberglass Cords

[Florian Harr]

Okay, for now I moved the y gantry belt so that the "broken" part is no longer going over the pulleys.

Did three test prints which all had the same failures before and it seems to be fixed! 

Just wanted to let everyone know, it seems to be working! Awesome! Thanks a lot for you help again everyone