Solved Z-Offset with Replacement Nozzle (Primary) Crappy Prints (Secondary)

Hi everyone. I recently purchased my second R1+ (I had to sell my first one and I just got around to replacing it). I apologize for the lengthy post but I am experiencing quite a few more difficulties with this printer than I had with my last one. I'm hoping I just need to make a few tweaks.

First, this printer seems to be jamming a lot, which I never had happen on my last printer. On two separate occasions I have had to do surgery on the hot end to get the filament out. As I was typing this, I realized that I'm using a roll of PLA that has been opened since 2016 that came with my first printer. So my first question is, does PLA have a shelf life? It has been stored inside my house. It was stored in the basement but that part of the basement has heating and air conditioning.

The second problem I am having is that it seems to take a very long time before you can even tell that there is something being printed. I searched the forum and found a post that showed what the first layer looks like when the Z-Offset is set correctly (mine looks nothing like that but I remember my other printer did), but I never found out how to set it correctly. I'm hoping that this will resolve the majority of my problems.

The third problem I am having is something that I had a little bit on the last printer and I never was able to quite resolve it. I am trying to make a very simple coin or a nameplate or anything of that sort with raised lettering and my logo on it (the type of object doesn't matter - this is something I want to include on just about anything I print for someone else). I have tried making all kinds of adjustments (high quality, high number of top layers, size of the object, etc) but the letters and the logo look horrible. I uploaded some stl files but they have to be resized and then merged. I used Selva to create my logo, then Autodesk Fusion 360 to make the coin. But it was easier to move the logo on top of the coin within Matter Control than it was to figure out how to embed it properly in Fusion. Anyway the files are down there if anyone wants to look at them.

I did find a post that said to try a smaller nozzle. I have had a very difficult time finding the exact (overall) sized nozzle as this printer but with varying opening sizes. I have a 6mm nozzle that a .12 guitar string fits in snugly (.30mm?) that I wanted to play with, but the distance from the seat to the tip is around 3/16" taller on the new tip. I have some others on order but I'm not certain of how the height compares to the original. I need to know how to correctly calculate the Z-Offset, considering the normal desired gap between the tip of the nozzle and the bed, and also the difference in the height of the tip as pictured below (I can get a measurement there but I need to know what to add to that for the air gap between the nozzle tip and the bed).

Any and all comments and suggestions are welcome (even RTFM, as long as you can tell me where the FM is). Thank you! Timothy E. "Timbo" Hamilton

 

Thank you Mark (for both replies)! I really appreciated the reference pictures, etc. I kind of figured out that they needed to touch when I heated it up to loosen the nozzle. For a moment I thought i had broken the hotend, as it suddenly started to swivel freely. I then observed that the two sets of threads have to touch to make the hot end so that it doesn't swivel.

So, if you don't mind, i have two follow-up questions:

1. I just want to make sure i understand correctly - So I don't have to worry about that extra nozzle height, because the z-axis is somehow able to detect when it is about to touch the bed? If so, (this is just curiosity) how does that work (just at a high level)? Is it just pressure that it senses?

2. What if any difference is there in just populating the Z Offset field in Matter Control (currently blank) and editing the startup G-Code?

I don't mean to be nitpicky, I just want to make sure I understand before I act.

 

This is what my start gcode is:

G28 X0 Y0 Z0 ; home all axes
G1 Z5 F5000 ; lift nozzle
M109 S[temperature] ; set the extruder temp and wait
G28 X0 Y0 Z0 ; Home Z again in case there was filament on nozzle
G29 ; probe the bed

Should I insert this line :

M565 Z-1.0 ; set the offset for auto-leveling mechanism

between the second G28 command and the G29 command, or after the G29 command? Based on the comment portion of the code, I would guess after the G29 but I don't want to add any variables
unnecessarily...

 

I don't know. The auto-leveling function appears to be working great. For that portion the extruder goes up maybe 1/4 inch and back down. But when it starts to do an actual print, no matter how I set the Z offset, it seems to drag on the glass, to the point I am worried that the bed will get damaged.(it makes a squeaking/scraping noise too.

I'm printing a test ring at low quality using a .20mm nozzle. I have set the layer heights etc to about 60% as was in a suggestion I read. Z Offset is -1,2. The test ring looks like it is going to take a little over an hour to print. Here is the print at around 16 and 23 minutes. Especially early on, I noticed that one side is printing less densely than the other. It just doesn't seem right to me. Thoughts?

 

Here is my startup gcode:

G28 X0 Y0 Z0 ; home all axes
G1 Z5 F5000; lift nozzle
M109 S[temperature] ; set the extruder temp and wait
G28 X0 Y0 Z0 ; Home Z again in case there was filament on nozzle
M565 Z-1.2 ; set the offset for auto-leveling mechanism
G29 ; probe the bed

This is how my coin looks in Matter Control:


Here are the prints before and after the nozzle change (from .40 to .20) and the Z-offset change to -1.2. The light blue is .20, and the darker blue is .40. The surface and thickness are definitely much better . I guess I just need to keep moving up, or do you think something else is at play?

 

And per your earlier statement, I have only used the g code to change the Z offset, not the macros.

 

I made a rookie mistake (coding 101 day 1, not 3d printing). I somehow deleted the semicolon after the Z-1.2 in my g code. I am re-printing now. The outline ring printed better, but I'm not sure how the rest of the print will come out. I definitely have a design and/or slicer issue. I used Matter control to place the logo over the coin and then lowered it along the z axis until it was at the height I desired (the reason I did this was because Auto Desk and Sketch up both did not like my logo as far as scaling, etc.).The first part of the coin prints beautifully, and although the logo still needs help, the lettering looks almost perfect. HOWEVER, the printer seems to think that it needs to print out the lettering and logo, then go back over the whole coin with a solid layer, then re-create the words and logo again. This started about half way through the print.

which slicer do you recommend?

 

It's definitely getting better. I've got it now to the point where I can keep tweaking the design and the slicer settings for incrementally better results. I've figured out that looking at the layers will save a lot of time in seeing how a print is likely to turn out. I'm thinking engraved instead of embossed might be worth a try. Anyway, I wanted to thank you, Mark, for all of your help!