My Prints Are Getting Better - Still Some Z Ribbing

As I continue to adjust my settings and my components my prints get better, but I think I should be able to get even better. Below are attached two pics of the same item; the 25mm test cube. I don't currently have the cube with me at work, but I seem to recall it was about 25.06mm in the x/y direction and about 23.xx mm in the z direction. Obviously I have some z adjustments to make.

The only modifications I have made to my printer were adding ball bearings where the threaded rod touches the stepper motors inside the couplers and the couplers themselves there was a lot of play and squish when you moved the rod, so I adjusted that.

I did notice that my heat bed sags in the middle (as others have also mentioned), so I'm not sure what to do about that. The only idea I have would be to buy some of that boro glass and place it on top of the heated bed, and then add spacers between the glass plates to make the top one level. Anybody have any thoughts on that?

I have the R1 with the auto level feature and I'm running the R4 firmware applied from within MatterControl. Does anyone see anything obvious from the following pictures? My goal is to create smooth edges.

 

That looks really bad.... is this really Z-Ribbing? For me it looks more as under extruding and or over heating...?
Maybe you should provide some additional informations. Which material, temperatures, speeds for extruding, etc., etc. So far one can only guess...;-)

I just got in now a 3rd party hobbed bolt to eliminate the slipping of PLA material during extruding - as it looks now during the 2nd test print my ROBO prints wonderful!

Please provide more informations...

Br,

Matthias

 

Sorry, I could have (should have) given a LOT more information. I am using PLA with a heated bed at 55deg and an extruder temp of 195-210deg (played around with diff temps no real change that I could see). Speed is the default speeds set in MatterControl for the PLA dropdown material selection (not at home at the moment, will update later when I get home). I *think* it was like 60mm/s or something, but I could be way off on that one.

Can you send a link to your hobbed bolt upgrade? I would be interested in that. My hobbed bolt is kind of dull and I tighten down the two spring bolts to hold the filament against the hobbed bold. I often wondered if I had it too tight or not tight enough. ?

Can you post a close-up pick of the 25mm test cube found on thingiverse? I would like to compare to mine. It is relative as well, because that picture I posted above is zoomed in a lot.

 

Today this hobbed bolt arrived after 3 days shipping from Slovenia in Germany ...! - click.

It seems to work perfectly with a very strong grip!, I currently just wait for the 2nd print to get finalized. So give me some ore days/printd to confirm... - on the other hand - at below $1o,- incl. shipping no big risk/loss if it does not perform finally.
I´m leaving in 4 hrs. for a business travel to Norway, but can print the test cube on Sunday.
I print PLA from Amazon currently - but this on modest rates:

Speed all kind of layers at 30mm/Sec. Retract at 0,8mm, Layer 0.2mm, Extruder Temp at 205 degree celsius, bed at 65 d degree.

Hot End E3D V6 with PTFE? Tube installed...

 

I have the exact same problem (using the earlier version of the printer, not the auto-level one), it also appears that it has gotten worse over time since its purchase and first print. In an older topic of mine (hotlink), I addressed this problem as well (just scan through the topic for pictures related to your/our problem). I was told to look for Z-ribbing solutions, adjusting the flow / extrusion rate, that it might be caused by cheap filament or that I should try an other extruder bolt.

It doesn't matter what material I use, be it ABS or PLA (I am using stock hotend).
I have tried the new aftermarket bolt, adjusting the flow rate and trying different temperatures. But without any results.
I haven't tried other, premium grade filament. Neither have I had the time or energy to look up for Z-ribbing/wavy-Z solutions, as I fear it might involve some hardware upgrading like the rods... So I don't have the solution for you, but I hope some useful information will be posted in this thread.

It really is an annoying problem, especially when your need to print precision parts. But for the aesthetics as well.

EDIT
I have found this post (hotlink) with some useful information in the attached file. Worth reading.