Issues with printing the last few parts

Hello! This is a question related to my 3D printer so I’m sorry if it’s not within the scope of this forum.
I’ve tried Makerbot support but I’m not getting much help.

So far I’ve printed 32 of the MPCNC pieces with some occasional issues (I will explain them later) but the prints eventually worked after a couple attempts. I mostly have the longer prints left to do: C-Roller, C-Roller M, XY_C_Burly, Tool_Mount_C_6-32.

The first problem that I had early on was bed adhesion but I fixed it by increasing the number of external brims and lowering the speed + disabling the fan on the first layer. Changing from hexagonal to linear infill also helped with some other printer issues.


Now onto the 2nd, persistent issue.
It seems that on the longer prints it gets to a point where the filament begins to under-extrude.
Always happens at a different Z-height. Most of the time it’s after ~60% but has also happened earlier.

Makerbot Replicator 2 (enclosed)
Hatchbox 1.75mm PLA
Retraction distance: 1.3 mm
Print speed: Solid 90 mm/s | Sparse 80 mm/s | Shells 35 mm/s


Changes/inspections I’ve made but did not fix the problem:

  • Was printing @ 230, decreased to 220, 210, and 205 with no improvement
  • Checked hotend fan
  • Replaced SD card
  • Checked tension on filament
  • Replaced nozzle + cleaned old one
  • Re-sliced STLs
  • The print speeds listed above used to be faster but I decreased them with no improvement

I really want to get this working but the last few days have been very frustrating. I’ve probably “wasted” over 500g of filament :frowning:
Any advice for a beginner? Thanks so much everyone!

I have no experience with that printer. I can tell you I print at 30-35mm/s maximum. I suggest slowing things wayyyyy down. As you start to consistently get working parts slowing increase each subsequent up 2-3mm/s until you hit another issue than back down a bit. Slower is better for layer adhesion and any underlying printer issues you may or may not have. I think CNC Kitchen did a good video on print speed vs strength.

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Thanks for the reply!
I’ll try slowing it down to your recommended speed and let you know how it goes.

Searching through CNC Kitchen’s channel I coudn’t find one on print speed - only vidoes discussing cooling, temperature, and infill but those are probably beneficial to watch as well.

I’ve run into this issue after I’ve built an enclosure for my printer. The extruder motor would slowly heat up over time, and eventually put enough heat into the extruder gears to soften PLA filament. This resulted in severe under extrusion very similar to what I see in your pictures. Sometimes it would recover for some layers and then go back into under extrusion. It does look suspiciously similar to your second picture.

The issue occurred only with PLA filament and only after 5ish ours of printing.
I easily solved it by adding fans for air circulation.
I’m not familiar with your printer, but it is sold with an enclosure right?
That makes me doubt that this is the issue.
Does your enclosure have any fans?

Do you have an option to print with the enclosure open?
Might be worth a try if you can’t think of anything else that causes this issue.

What is the exact nature of the extrusion failure? Is your drive gear chewing the filament? Is the extruder skipping steps? Is your filament snagging in the spool? Are your nozzle temps consistent throughout the print?

Just a general Slicer setting comment: I only see two perimeters on those prints and you’ll probably be happier with three. You could also drop the infill percent a bit and not compromise the strength of the parts to shorten your print times.

The printer has an acrylic front panel, two side panels, and a lid that can all be removed (not 100% sure about the side panels, I’ll have to check when I get home).

There are only two fans: one for cooling the print and the other for passing air through the heat sink.


I’m not 100% sure what the exact cause of the failure is. I’m certainly not an expert and I’m going off things that I’ve read online.
When I pull out the filament I’m not seeing any rough gashes on it, no clicking from the extruder motor, and no tangling in the spool. As for the temperature, I’d say it fluctuates +/- 1 or 2 degrees during the print.

If the extruder was clogged you would hear your stepper motor missing steps (clicking sound). If something was killing the heat to the hotend and the extruder was shut down for mintemp reasons you would see that in a temperature graph. If it was grinding filament and not extruding you would see the spot that was ground off. Given all of that I suspect there may be something weird going on with the firmware or the driver board.

Are you using up to date firmware? Is the failure repeatable? (that is, if you print the same model does it fail in the same place). If it is a consistent failure then you are probably hitting some sort of firmware bug.

When the extruder stops again, check to see whether the extruder motor is turning at all (or is, in fact, even energized. You could be having an intermittent failure of your wiring or the stepper driver.

Yes the firmware is up to date.
The failure always occurs at a different Z height and on different STLs.

Thanks again for the tips everyone!

I started a new print last night with these changes:

  • All print speeds @ 40 mm/s
  • Removed all enclosure pieces
  • Added a large fan to blow air through the printer (I think this caused very poor bed adhesion, but I caught the part lifting up early on in the print so I taped the edges down, lol)
  • 3 shells (not necessary but it definitely feels a lot more sturdy)

I should have tested the first three changes independently, but I only had enough filament to do one more part.
Another spool is on the way, so pretty soon I’ll find out if I was just lucky with this last print or these changes were the real solution! :slight_smile:

Well, I printed the C-RollerM part with the exact same method (except I slowed down printing of the first layer) and the problem has returned. :frowning:



Looks like it’s either not hot enough, or a clogged nozzle.

It was another brand new nozzle and I’ve been having this problem with PLA at all of these temperatures: 220, 215, 210, and 205 degrees.


I think you have an extruder issue as well. Maybe some pictures of your exrtuder and we can spot something. But if it is an all metal hotend you might ant to try PETG instead of PLA to see if it is heat creep.

My pla prints at 225c. Your spool should have recommended temps.

I’ll try to take some pictures tonight. I can disassemble part of it to get some clearer pics.

My Hatchbox PLA recommends 180 - 210

I used to print hatchbox at 198. In your case I would start at 185-195 and take away that large fan. If you are having heat creep issues lower print temps will help, also make sure your extruder fan (not print fan) is functional and not clogged with lint/dust.

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Thanks again for your continued support with this, I know it’s not 100% MPCNC related and more of a printer issue but I really appreciate your time.
I didn’t get around to disassembling the extruder to take pictures, but I was able to successfully print one of the C-Roller M parts yesterday.

I’ve found somewhat of a “sweet spot” by running the 3D printer without the enclosure panels and turning on the large fan after 30-60 minutes. On the second C-Roller M this morning, I must have waited too long to turn on the fan and the filament started to under-extrude again.

I’ll try your suggested temperature tonight

Okay, that sounds like your extruder fan isn’t working. That would cause these issues. The fan that blows across the hot end should always be running, this is different than the part cooling fan, which for pla also should be running most of the time, just not as hard.

I printed C-Roller M last night @ 190 degrees with the large fan turned off and I did not have any extrusion issues! :slight_smile:
Still some problems with bed adhesion but I taped down all of the external brims after I caught them starting to lift up.

Is it better to use rafts for these parts? I’ve been using 7 to 9 external brims.

I was constantly checking on the printer during the build and I never noticed the fan stopping or slowing down.
The fan + heat sink was recently cleaned and it is dust-free.

Lol just when I thought it was printing perfectly another problem came up.
I’ve never seen anything like this before, and it was so close to completion :frowning: