Unresolved Print Quality after Leadscrew Motor Upgrade (Non-official kit)

Hi all,

So this weekend I did Leadscrew stepper motor upgrade using locally sourced parts (Australia). Apart from a few issues along the way with things lining up (new leadscrew motor was not lining up to the solid rods correctly causing the motor to jam due to the pressure - I used washers to re-align the motor) - I have now developed some verticle lines that run throughout the print on both the X and Y axis. The Z axis is now alright, no more ribbing but it does seem that each layer has a small amount of misalignment to each other, but this might be related to the X and Y issue.

Below is the imgur album containing 20mm calibration cube print after the install.

Notice the verticle lines that run through the print.

- I have checked belt tightness on both axis
- I have made sure the solid rods are screwed in firm
- I have made sure my e3dv6 hotend has no wobble/movement
- I have ensured the bed is fixed properly to the tray

I have tried printing at slower speeds and this helps a very minimal amount (I use to be able to print 95mm/s but have reduced it to 70 for the attached print.

I have had a browse through the visual troubleshooting, but usually these issues are across a single axis?

- Using Cura 15.04 (can't remember exact number)
- ABS at 235c
- BED at 85c
- Extruder feed at 100%

Any ideas??

imgur album: http://imgur.com/a/vkA3T

Cheers
Krish.

 

Thanks for the reply!

So I get that that could be the case. I had seen those visual trouble shooting guides and that's why I lowered the print speed and checked for any loose bits.

What fascinates me is that the vertical lines appearing are pretty much the same distance apart on both the Y and X axis. Often when there are vibrations/ringing it would be something that moves/shifts throughout the print.

I also wasn't saying that the z axis motor/rod upgrade itself is causing the issue, more so this is what I noticed after the upgrade and it could be due to the disassembly of the printer for the install, hence asking for help on how to fix it if anyone else had come across the same issue previously.

In the mean time I have also ordered LM8UU bearings as a 'I might as well try replace everything on this printer' measure.

Any other help would be great, just can't seem to find a concrete cause and a fix for this issue.

 

Well it appears to be worse on the Y-Axis, but still noticeable on the X-Axis. I feel new bearings (both X and Y) may solve some of this if not all. When I had to replace my Y-Axis bearings, my problem was similar to yours except only happening on Y-Axis and they were smaller. On larger prints it would only happen in certain areas of the print, which is why I got replacement smooth rods too.

Have you tried placing the Cube in a different area of the bed rather than center to see if it still happens? Maybe you just have a bad spot in the smooth rods?

 

When replacing you linear bearings, make sure to clean and lube the new ones prior to install. I have found new ones come either dry, dirty, or both. Either one of those scenarios will reduce the life of the bearings.

 

Thanks for the reply! Well, I will explain what I've done below - but to answer your question, no, I have not tried printing it in a different bed location. I will give it a try this afternoon. Also it could very well be the bearings, have a look at what I've found below.

So I made changes to the firmware, reduced acceleration by a great deal (from like 9000 down to 800 on the X/Y and the other acceleration I reduced too). It prints in a very slowish manner now and is about double the estimated time given in Cura. Also reduced jerk settings. None of this seemed to have any effect on the print.

So I cut open the cubes to see what was going on. I suspected that the infill pattern was somehow showing through. My shell thickness is usually 0.8, but even at 1.2 I would see this pattern.

Look at these images - http://imgur.com/a/XCnjz

What I think is happening is, there is still some sort of wobble to the hotend and/or carriage. When the hotend runs in a particular heading, then changes direction, it shoots a bit wide because of some sort of wobble/slop.

The e3d hotend seems tight when I try move it by hand, but I will investigate it in the coming days by pulling it all apart and putting it back together. I do know that my z offset has changed a couple of times recently and I am leaning towards hotend movement when it is at temperature - but not when cool.

Thoughts?

 

A couple weeks back I had ordered a new belt and pulley set to keep as spare. I only had time to replace the X drive cog/pulley this weekend but I ran a print, wasn't the calibration cube so can't 100% say just yet but appears the issue is still there.

My LM8 bearings should be here this afternoon so before I swap them in I will replace the Y drive as well as run a calibration cube print to get a base line before the bearings are replaced.

Any further tips on replacing the bearings? is lithium grease good for lube @danzca6 ? do I need anything special to pull them out?

 

There seem to be some that believe in using a heavy grease and done that prefer a light machine oil. I use just a 3 in 1 machine oil. Another member here that does a lot with making machines over the years recommended Tri-flow oil that is also a light weight oil. I've recently gotten some and haven't had time to try it out for comparison.

I also have an ultrasonic cleaner now that is heated and I run new bearings through it to really get them nice and clean before lubing and installing. Dirt is an enemy of bearings.

As far as pulling out the bearing, honestly never have. I've printed new parts that I've used new bearings in do far and haven't had the need to remove old ones yet. I did find someone designed a puller, but no idea how well it works. A long thin screwdriver and hammer might work as well for the first side. That would probably be the tougher side.

http://www.thingiverse.com/thing:734449