Help With Print Quality

Hi all,

I built a Prusa I3 a few years ago. Now I have been in 3D printing for quite a while. I have been trying to improve my print quality and am happily looking for suggestions on what to do. Here's what's going on:
I am getting great looking layers. My extrusion rate is calibrated nearly perfect. However, I am getting what I will call banding, or visible lines that look almost like z wobble. I have been trying everything to fix this, but I can't track down what it is. The prints look good ONLY if you look at them STRAIGHT on. Any other direction, it is VERY obvious they are not very good. Can I have suggestions please?

Things I have tried to fix:
Upgraded to T8 lead screws
Printed bracing for Z axis
Leveled bed
Leveled x axis
Re-squared y frame
Recalibrated extruder and z axis
Checked for z wobble
Checked for noise/vibrations

Can anyone recommend any ways to test for anything else, or suggest things in my fixes I may have missed? Please look at pictures of sample print.

Thanks,

Levi

1) there is a whole forum dedicated to printing, you might want to look in there
2) none of the samples links works.

I also built a Prusa i3 about 3 years ago. I worked on print quality until I was out of ideas and finally came to the point where I think my machine was printing its best. These things helped with print quality, although not specifically with banding.

Here are some ideas.

1. Mount your filament off-board. Mine is now mounted on a wall fixture that looks something like a paper towel rack. I also mounted the LCD display on the side of the filament rack to take as much weight as possible off of the printer to minimize any movement or cycling in the frame due to inertia.
1a. Print spool centers for your filament, if needed, so the filament spools rotate on their rod as smoothly as possible.
2. Upgrade your hot end and extruder if you have not already done so. I replaced my J Head with an E3D v6 hot end and Titan extruder. My prints were better, although some of that was because my J Head nozzle was rather worn.
2a. Just install a new nozzle if the old one is tired and you don't want to spend big bucks on the upgrades.
3. Replace the steel rods with chrome-plated hardened steel rods, and maybe new linear bearings. This is probably not necessary on the Z axis. This also costs some bucks. In this case the quality of the rods is the most important issue. The old ones can wear out and make the bearings run gritty. I doubt if there are any good quality direct-replacement linear bearings available, but they will run better on better rods.
4. Print new frame parts that carry your linear bearings if the ones you have now give the bearings a loose fit.
5. Make sure your belt tensioning is optimum. I made belt guides for the Y axis that tweak the bearing on one end and the gear on the other. The guides keep the belt in the center of the bearing and keep the other end from dragging on the edges of the drive gear. Figure out a way to add shims or otherwise center the belt on the X axis, too.

That is about as much as I can think of. It is a lot of work, and the results might be modest, but improving print quality based on reduced mass, friction, and vibrations is quite a time sink.
I can show you some pictures if you are interested. I can't end this without complimenting you on the effort you have put into getting the most out of your machine. I have put in what seems to be coutless hours and I appreciate the work you have done - and I am a bit envious of the 8mm lead screws!

Edited 1 time(s). Last edit at 04/29/2017 03:37PM by drgrs.