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Version 1 Mini Extrusion Issue

Posted: Sat Dec 22, 2018 7:14 am
by Dabme
I purchased a version 1 Lulzbot Mini about a year ago. I have only ever printed PLA. I have averaged 8 hours of printing a day over the last three months.

The extrusion is now having issues. The extrusion is very slow. When I extrude 20 mm very little filament comes out. Manually applying a little pressure on the filament does make it extrude more normally.

Here are somethings I have tried...

I made sure the tensioners were fully screwed tight.

I put in a fresh spool of Hatchbox 3mm PLA and made sure the settings were correct. Filament width 3mm and extrusion heat 210.

I then bumped the temperature up to 215.

I totally took the print head off to closely inspect both the gripper wheel (teeth seem good) and the pressure wheel (spins freely). I checked for cracks but both seems to be in good condition.

Any advice? What do I try next?

Re: Version 1 Mini Extrusion Issue

Posted: Sun Dec 23, 2018 10:47 am
by IDEngineer
When you give it the command to extrude 10mm (or some multiple thereof) and it doesn't extrude very much, release the clamp and pull out the filament. Do you have clear marks on the filament where the "hobbed wheel" (the knurled part that drives the filament) has deformed the filament? If that wheel is actually turning but your filament isn't moving the same amount, you shouldn't have clear marks... more likely you'll have a scrubbed-looking region where the wheel is spinning against the filament.

Remember, there is significant backpressure on the filament when it's being forced through the print nozzle. The drive system has to overcome that. If the backpressure is too great, the wheel can spin instead and grind against the filament. Excessive backpressure can be caused by low temperature, contaminated nozzle, dirty "hobbed wheel", insufficient pressure on the idler pulley, etc. You've checked several of those things (good job) but the answer may still be in there somewhere.

As a big next step, you might try unscrewing the nozzle and then testing extrusion again. If the filament can move freely through when the nozzle is missing, I'd inspect the nozzle very carefully for damage or foreign objects.

Hope this helps... report back!

Re: Version 1 Mini Extrusion Issue

Posted: Fri Dec 28, 2018 3:48 pm
by zachah
With the hexagon hot end, the first thing we will want to do is to check your heat sink fan. This is the middle fan pointed directly at the heatsink (The horizontal hexagon metal plates.)

This fan is on a dedicated 5v connection and should turn on full blast whenever the printer is turned on. Please turn off the printer, and turn it back on while keeping an eye on that fan. If this is not functioning, it can lead to heat creep issues making printing much more difficult.

If the heat sink fan checks out, let's look for an obstruction in the hot end. Bring your hot end up off the build plate and up to printing temperature. Once at temp, open your idler and using a 2.5mm hex wrench, manually push the filament through the hot end.

Your filament should extrude in a solid consistent line. If nothing is able to extrude or it comes out like a "pigtail" it will indicate an obstruction and it will need to be cleared. We recommend a procedure called cold pulls, and you can find a write up on it below.