text:
How to add menu options to the (Marlin firmware) LCD menu?
Where is the correct Marlin firmware file and location to add code that I want to shop up in the LCD menu of my printer, and then execute the function I write when the button is pressed?
For example I want to add a menu item that says "Preheat Custom" that is in the same menu as "preheat PLA" and "preheat ABS" and then runs code to heat to values I specify.
I'm running Marlin Firmware version 1.1.9 on a Creality Ender 3.

The answer to your question (baring in mind that the question is raised for Marlin 1.1.9) is the file ultralcd.cpp. Nowadays, you can also enable extra option through the Configuration_adv.h file, just enable:
#define CUSTOM_USER_MENUS

and edit the options beneath it to your needs (otherwise it will use the preset values from the Configuration.h file).

Add custom items using ultralcd.cpp
This is how I used to do it if you want to add items to the menu in Marlin Firmware through the ultralcd.cpp. It is best to first look at the current implementation of the menu items. As you already mention Preheat PLA, that would be the first to search for. Searching in files is easy when you go to the github website with the Marlin firmware sources, functionality is available for searching in the files. Alternatively, download a copy of the firmware and use a free "grep" utility to search in files.
Searching for Preheat PLA will show you a bunch of language translation files. These point to the use of a constant MSG_PREHEAT_1 which finds its presence in ultralcd.cpp. This hints to function lcd_preheat_m1_menu that is called by MENU_ITEM which adds menu items to LCD. You could start there to add your own option.

Demonstration
As a quick demonstration, I've added a CUSTOM PREHEAT item by copying the lcd_preheat_m2_menu function in ultralcd.cpp and renamed this lcd_preheat_m3_menu (a full functional item needs changes within the lcd_preheat_m3_menu as it now uses the constants from the ABS preheat option).
You then add the item to the menu by changing this part of the code:

      //
      // Preheat for Material 1 and 2
      //
      #if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 || TEMP_SENSOR_3 != 0 || TEMP_SENSOR_4 != 0 || HAS_HEATED_BED
        MENU_ITEM(submenu, MSG_PREHEAT_1, lcd_preheat_m1_menu);
        MENU_ITEM(submenu, MSG_PREHEAT_2, lcd_preheat_m2_menu);
        // ADD THIS LINE:
        MENU_ITEM(submenu, "CUSTOM PREHEAT", lcd_preheat_m3_menu);
      #else
        MENU_ITEM(function, MSG_PREHEAT_1, lcd_preheat_m1_e0_only);
        MENU_ITEM(function, MSG_PREHEAT_2, lcd_preheat_m2_e0_only);
      #endif

After compiling and uploading to the printer board, enter the Prepare menu and scroll down to see:

As Mark said, Marlin supports a number of menu items in it's advanced configuration. These items are meant to run custom G-code, which in this case (adding a preheat action with custom target extruder and bed temp) is enough to fill your needs. So, let's see that advanced configuration file: Configuration_adv.h. The section we are looking for is almost at the end of the file, you can ctrl+f for "CUSTOM_USER_MENUS" to find it.
#define CUSTOM_USER_MENUS
#if ENABLED(CUSTOM_USER_MENUS)
  #define USER_SCRIPT_DONE "M117 User Script Done"
  #define USER_SCRIPT_AUDIBLE_FEEDBACK
  //#define USER_SCRIPT_RETURN  // Return to status screen after a script

  #define USER_DESC_1 "Do the trick"
  #define USER_GCODE_1 "G91\nG0 z5\nG0 y10"

  #define USER_DESC_2 "Park"
  #define USER_GCODE_2 "G27 P2"

  //#define USER_DESC_2 "Preheat for PLA"
  //#define USER_GCODE_2 "M140 S" STRINGIFY(PREHEAT_1_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_1_TEMP_HOTEND)

  //#define USER_DESC_3 "Preheat for ABS"
  //#define USER_GCODE_3 "M140 S" STRINGIFY(PREHEAT_2_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_2_TEMP_HOTEND)

  //#define USER_DESC_4 "Heat Bed/Home/Level"
  //#define USER_GCODE_4 "M140 S" STRINGIFY(PREHEAT_2_TEMP_BED) "\nG28\nG29"

  //#define USER_DESC_5 "Home & Info"
  //#define USER_GCODE_5 "G28\nM503"
#endif

The source code downloaded from the official repo actually comes with some examples (the ones commented) and I added two more just for fun.
To get your custom preheat menu item working you'll make use of the following Gcodes:

M140: set target bed temperature (visit
http://marlinfw.org/docs/gcode/M140.html for some more data)
M104: set hot end target temperature (visit
http://marlinfw.org/docs/gcode/M104.html for some more data)

The supplement on how to proceed with custom menus in practice:
Enable (uncomment) this line in configuration_adv.h:
#define CUSTOM_USER_MENUS

Below there are 5 sample entries, later you can change them or remove/comment out.
You can add new, for example:
  #define  USER_DESC_6 "Home Z (0.2)"
  #define USER_GCODE_6 "G28 Z\nG0 Z0.2"

  #define  USER_DESC_7 "Fan on"
  #define USER_GCODE_7 "M106 S255"

  #define  USER_DESC_8 "Fan off"
  #define USER_GCODE_8 "M107"

Marlin currently (v2.0.7.2) supports up to 25 menu items (see menu_custom.cpp). There may be gaps in these numbers, so you can comment out some unnecesary options without fixing numbering of others, which could be really convenient.
Custom commands can be executed in runtime (when already printing). I could use the above "home Z" after manually tuning Z endstop to correct first layer's height quickly, without restarting the print. So you can actually make harm to ongoing print as well.

There might be a better solution.
Marlin supports custom user menus, in configuration_adv.h, you probably should try to keep your changes limited to the configuration*.h files.
The menu code is kind of ugly and you can easily break things.

Hi Mark and welcome to SE.3DP! That sounds like a good point to be made. Could you provide a snippet of the code? I haven't looked myself, and maybe it is too large to summarise, but if you could edit your answer and show a part of the code and illustrate how/where to insert, that would be a great addition to the answer.

Preheat Constants - Up to 5 are supported without changing the code just add a new one and then build
#define PREHEAT_1_LABEL       "PLA"
#define PREHEAT_1_TEMP_HOTEND 215
#define PREHEAT_1_TEMP_BED     70
#define PREHEAT_1_TEMP_CHAMBER 35
#define PREHEAT_1_FAN_SPEED     0 // Value from 0 to 255

#define PREHEAT_2_LABEL       "PETG"
#define PREHEAT_2_TEMP_HOTEND 235
#define PREHEAT_2_TEMP_BED    70
#define PREHEAT_2_TEMP_CHAMBER 35
#define PREHEAT_2_FAN_SPEED     0 // Value from 0 to 255

#define PREHEAT_3_LABEL       "ABS"
#define PREHEAT_3_TEMP_HOTEND 270
#define PREHEAT_3_TEMP_BED    100
#define PREHEAT_3_TEMP_CHAMBER 35
#define PREHEAT_3_FAN_SPEED     0 // Value from 0 to 255

#define PREHEAT_4_LABEL       "NYLON"
#define PREHEAT_4_TEMP_HOTEND 260
#define PREHEAT_4_TEMP_BED     65
#define PREHEAT_4_TEMP_CHAMBER 35
#define PREHEAT_4_FAN_SPEED     0 // Value from 0 to 255
```

Hi Bruce welcome to 3DPrinting.SE! Thanks for revisiting the question, yes, it is much easier now in Marlin 2.x as other answers have already pointed out. The question is raised for Marlin 1.1.9, so this answer doesn't technically answer the question for the OP, please [edit] the question to include that in Marlin 2 it is much easier to add custom preheat menu items. Also link to the code section where the preheat examples are found. Thanks!


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PVA support with small tolerances
I am at the moment designing some in place mechanical parts. Something like two cylinders that rotate with respect to each other. I need in my design some overhangs that cannot be printed and I was thinking of using soluble supports to be able to print these overhangs. I am afraid that by using something like PVA the PVA will end up between the two parts and glue the together.
Does anyone have any experience with this? Can something be done about this apart from 'not using PVA'?
Edit:
Here is an (minimal) example of an object I would be worried about. The blue and red cylinders are supposed to turn around each other and there is a cutout in the blue cylinder that will need support (the bridge is to long to print without support).

Maybe you can add an image of the print design or printed object?

Are you planning to have support in between your cylinders, or does the support need to be elsewhere and you're afraid it'll go between your cylinders unintentionally?

@DanHulme support should be somewhere else and I am afraid that it will go in between the cylinderspenscad

You know the PVA support comes out solid, right? It doesn't just ooze into places like squirting PVA glue out of a tube.

Yes I do know, but I am afraid that once you start to dissolve it in water the PVA will start to ooze into the crevices.

Do you need to print both cylinders in one go, i.e. no way to remove supports mechanically prior to assembly?

Yes, I did not draw it here, but the two cylinders are inseparable. They can only rotate around each other. This is not the model I want to print, but a minimal example of the thing I am worried about.

You've not stated this, but one must presume that you have a dual or multi-material extruder equipped printer.
Because PVA dissolves in water, the supports will be eroded on contact when the part is immersed. As the PVA dissolves, it increases the concentration of PVA in the water, but only slightly. You would have to agitate the water, change it if you feel it is becoming too concentrated. At some point, you should be able to rotate the cylinders, creating more turbulence, causing more PVA to dissolve into the water.
If you are determined enough, you can cause all of the PVA to dissolve, followed by a rinse with clean water. This would remove any residual PVA.
The water containing the dissolved PVA is somewhat sticky, but would not glue parts together if the parts were thoroughly rinsed. It's not out of the question to use an ultrasonic cleaner with plain water to provide sufficient turbulence, again changing the water periodically to keep the concentration low.
If you use an ultrasonic cleaner, test a sample of your print filament to determine if the heat generated will soften the plastic. I've had success with PVA to the extent that I have not had to use an ultrasonic cleaner to remove it.

Out of curiosity, did you try to print something similar with PVA supports? I do have the feeling that this procedure would work, essentially trying to keep the concentration of PVA in the water low so it won't stick the parts together. At the moment I do not have a multi material printer, so I cannot try it out. But in the past I tried to have these kinds of models printed (through a printing service), which failed miserably, therefore I want to know if anyone has any (real world) experience with this. I am happy to provide a model if that helps.

The smallest PVA print I've done is one that required a 2mm gap.

With moving parts? and 2mm is way to big for 'smooth' motion in the system I want to print.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Retraction Causing Skipping
I am trying to get rid of stringing on my prints, to do that I have tried turning on a retraction in Ultimaker Cura, and reducing flow.
When I turn on retraction it causes the extruder to skip on the filament. the extruder pulls the material out as it should, but when it pushes back in as it prints the next parts it goes part of the way then it skips making the bumping sound, it seems to do this almost every time that it retracts.
To stop this from happening I have tried changing the retraction distance from 10mm to 5mm, the retraction speed from 60 mm/s to 40 mm/s, the flow from 100% to 90% and the temperature from 200 °C to 220 °C.
I am using the Ender 3 running Marlin 1.1.9 with an aluminium Bowden extruder upgrade and BLTouch.

How do prevent this skipping due to retraction?
Update:
After changing the setting to what has been suggested in this answer the result of the retraction print resulted in:

It has almost completely solved the stringing problem as well.

Fighting stringing will not work by increasing the temperature of the hotend.
There could be 2 possible causes for your problem,

the first is that you still have a too high retraction speed, too high for your stepper to follow (do note that the default value in Ultimaker Cura is 25 mm/s),
the second is that you retract too far and the cooled "hot" filament tip is deformed and causes extra tension/friction in the extruded liner.

I have set the retraction speed to 25 mm/s and the retraction distance to 5 mm, and everything seems to be working, the skipping has stopped. Thank you

@Liam You could benefit from some extra part cooling to improve the top of the print.

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text:
Flashforge Adventurer 3 Filament feeder loud thumping noise, not enough filament extruded
My Flashforge Adventurer 3 is not printing properly.  Filament feeder makes repetitive loud thumping noise and not enough filament is extruded.  Resulting print (if completed) is not solid.
Results vary with filament. Flashforge brand (red) PLA works best.  Any other filament fails completely unless I print at High quality, with head temperature at 235 degrees.  Nozzle has been un-clogged repeatedly, but right from the start, when  feeding filament in, it does not flow through properly.
I had used the included tool to clear blockages in the extruder several times before now, but after posting this question I tried again. Ordinary use of the tool made no difference. So I applied more force, and, pushed filament through by hand directly into the extruder and used a pin to try to clear the extruder. It now appears to be working adequately Not perfectly. I am able to print with default settings. It still thumps -or ticks- a bit. I am alarmed at the amount of force I had to use to clear the extruder blockage.

Welcome to 3dPrinting.SE!

Possible duplicate of Extruder clicks and Extruder clicking Tronxy x5s.

Wait, you print PLA at 235°C?! That is ridiculously high for PLA.

Had same issue, did a color transfer with same reel but cut off the filament that was in the printer, worked fine after that.

Advice from another source suggested thoroughly cleaning the feed gear on the bowden extruder.  When I looked closely there were plastic flakes all over the mechanism.  I used compressed air and a brush to clean it.
I also discovered expert mode in the FlashPrint software, which enabled me to slow down the speed at which fill is laid down.
Now I have good printing results with any filament.
EDIT AND UPDATE::
I have continued to have problems with PLA.  For most of the last year I printed using ABS with no similar problems.  I guess that PLA is simply rougher, scratchier than ABS and catches in the tube.  I found a comment that putting olive oil on the filament fixes it.  I used Vaseline.  Things were fine for a while, but a retailer said this would lead to other problems.
So far, no permanent answer to this question.

@0skar Thanks, but in fact my answer to my own question turns out not to be complete.  I have since worked out that PLA filament is rougher than ABS and seems to catch in the tube.  I have printed with ABS with no similar problems for most of the last year.  I found some advice suggesting to put olive oil on the filament.  I did not do this, but I did use a bit of vaseline.  I was then advised this was not a proper way to deal with the issue.  So the question doesn't have a suitable resolution.  However, I will close the question.

My Flashforge Adventurer 3 showed similar symptoms at the start of a print.  I found that the z-axis was out of calibration, causing the print head to touch the platform, meaning that the filament could not extrude. The solution was to calibrate by slipping a piece of paper under the extruder and adjusting the z-offset until it was just touching. Worked fine after that. Hope this helps.

This has also solved my "thumping" issue in the past as well. I use a thin piece of packaging tissue for it.

After a couple of hundred hours of successful (mostly) prints, I heard weird thumping of the feeder and though it fed filament it would not extract it completely for a color change. Tried a number of tricks to fix that without success. Then I read here about just using compressed air to clean the wheels and the feed channel. Voila! Success. Maybe that won't solve it the next time but it cleared this problem.

I had this problem and thought I'd put my solution here.
The nozzle (at least my nozzle) is not actually an 0.4 mm nozzle. You can tell just by comparing it side by side to another one. Mine seems to be a 0.3 mm nozzle, despite being sold as 0.4 mm.
Once I set the Path Width in FlashPrint to 0.3 mm, my thumping noise (extruder skipping) and subsequent under-extrusion were completely gone.

PLA should not be printed at 235 °C. If your printer requires such high temperatures to make the filament very fluid, you have too much friction in your system, e.g. this can be caused by clogs or too low layer height printing the first few layers. Note that such high temperatures are also a cause for obstructions as the filament can carbonise creating clogs. On the other side, too low temperatures also cause too much friction or resistance.
The sound you are hearing is often referred to as "clicking" and can be caused by steps being missed or the extruder hobbed gear to skip back as a result of the friction/resistance.
Now that clicking is introduced, please look into this answer and this answer to answer your problem.

Thank you for this information.  It confirms I was not missing something basic.  I had done everything I could to address the problem.  That being the case, I took it back to the store and exchanged it for another one.

I had an identical problem, flashforge provided me with a setup that helped (mostly going much slower) but I still needed high temperature and had a lot of failures.
Eventually I dismantled the extruder hot end and found that there is a tiny metal ferrule that secures the plastic tube the filament feeds through to get to the hot end.  This had failed and been drawn into the tube.
The high temperatures and slow speeds were basically just softening the PLA enough to squeeze past the blockage.
I cut the piece of metal out of the side of the plastic tube and reassembled without it.
The printer now works fine at high speeds and with any filament :)
I’ve not yet seen adverse any effect from removing this ferrule, I guess the extruder may fail eventually at which point at least I know I just need a new extruder.
There are four plastic clips you need to push in with a screwdriver if you want to try this, I was able to open it up without causing any damage as the clips are quite strong.

Hi and welcome!

Thanks for that information.  Since I posted the original question, my printer developed more problems.  The plastic tube was no longer being held in the collet.  And of course, the thumping ('clicking' if you will) and blockages.  Now I see the ferrule had failed on mine too, and probably had been dragged into the tube.

I had a lot of thumps lately after I moved my printer location.
Turns out my printer wasn't level and the extruder was pushing harder (further down) on different places, causing thumps.
This really shows because the calibration is only in 1 spot.
I used some printer paper and a bubble level then recalibrated.
Not a single thump since.

Note that bubble level says nothing, it is all about levelling the bed with respect to the X-axis. But indeed, an inconsistent bed shape and a nozzle close to the build plate can cause this.

Your nozzle might be blocked. Check that.
My printer worked fine for the first ~500 g ABS. Then I started to hear the clicking/popping when the print required high material flow. The hose connector that attaches to the top of the extruder ended up giving up the ghost and it released the PTFE tube, creating spaghetti in the printer before I got a chance to stop it.
So, I replaced the hose connector, but the printer was still popping when material flow was high. I followed the steps for clearing out the nozzle. I wanted to clear it until I could see light coming through the nozzle, so removed the nozzle and used heated needles to poke through.  This is where I figured out that there was something stuck in the nozzle...
I looked at my broken hose connector, and sure enough, the clamping/retaining ring inside of the hose connector was broken and fragmented. It would appear that a chunk of the ring got lodged in my nozzle.  I couldn't figure out a way to clear the nozzle so I just bought a new one.

I have had the same issue with mine. And the clicking was indeed calibration. When you're doing the paper part, I make sure I move the axis up one point from the bed allowing enough room for the filament to lay and adhere. If it still thumps after, check for a clogged nozzle (which you’ll have to do anyway if you have attempted countless failed prints from not being calibrated correctly) I can guarantee there’s a blockage at that point it’s just a given if you think about it. Also, I did read above that someone experienced the nozzle being in fact .3 mm instead of .4 mm.
I believe this to be true as well. All of their models seem to not be sized right. Therefore, path extrusion needs to be adjusted as well when all is said and done. Good luck

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Extruder doesn't retract on inner wall lines thereby causing stringing
I am trying to stop the stringing that occurs on one of my prints, I have set it so that it retracts the filament which does stop it during the extrusion of the outer wall layer, however when it comes to print the inner lines of the section it does not retract at all (the extruder gear does not move back).

I am using Cura as my slicer and I cannot find any setting that would change this. My current retraction settings are as follows:
Enable Retraction - On
Retract At Layer Change - On
Retraction Distance - 7
Retraction Retract Speed - 40 mm/s
Retraction Prime Speed - 30 mm/s
Retraction Extra Prime Amount - 1 mm3
Retract Before Outer Wall - On

I am not sure how to stop this from happening, any suggestions that you can make will be greatly appreciated.

Cura has a setting called Combing that is enabled by default. This stops the printer from retracting if the travel is contained within the walls. It does this to speed up the print but you get oozing during the travel since the plastic is still in the melt zone. You can change this setting to no skin which will stop it from combing on the skin layers or turn it of completely.

In addition to being able to turn it off completely, Cura has a setting called "Max Comb Distance With No Retract" (retraction_combing_max_distance) which you can set to a really low value rather than turning it off entirely. This lets you avoid retractions at each top/bottom layer diagonal fill line and similar while still not moving distances where the oozing potential would be significant.


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Heatbed PID vs Bang-Bang - which one is more stressing on components?
I recently switched from Bang-Bang to PID controlled bed heating. The stock firmware pulsed On/Off with about 5 seconds each cycle. Now with PID, my bed keeps its temperature much more stable, the frequency is around 7Hz.
Although the total amount of energy used for heating should be less now since the heating is more efficient and doesn't waste energy by cooling down, I am a bit concerned of the fast pulsing of the rather high amperage (around 13 Amps in my case).
So I was wondering, do the faster cycles cause more stress on the components (I am thinking MOSFET on the board and components inside the PSU) or is this negligible? I am particularly curious since this is a rather low budget printer (Anycubic i3 Mega, $350 printer with a generic unbranded PSU) and I don't want to push its limits too much.
The only thing I can observe is a very faint noise with the same frequency as the pulses. Might have been the same on 5 second cycles, I was just not paying attention to it back then.
I'd be very glad if somebody could chime in on this.
Thanks in advance.

Although I understand where the question is coming from, isn't it best to ask this at the Electronics Stack? That community must have more knowledged people in the electronics department to help you find a correct answer. Good question, I'm very curious to learn from the answer!

mosfets can switch in the megahertz, so long as they are rated for the amps you're fine.

I'm voting to close this question as off-topic because it is better on the Electronics.SE

The frequency of the cycle shouldn't affect the efficiency as such, however more might be lost due to physical properties.  Fast should cause less stress on the printed part, unless it hits a resonance frequency, which it unlikely.


text:
Marlin Firmware Manual Mesh Leveling
Why am I seeing two different versions of the way to enable manual leveling?
One option says to enable:
#define manual_bed_leveling
#define mesh_bed_leveling

And the other says to enable:
#define probe_manually
#define LCD_bed_leveling
#define mesh_bed_leveling

How is it that they both work? One is from the official marlin github and the other is from a tutorial that is confirmed to work.

Which revision of Marlin are you working with?

@Pᴀᴜʟsᴛᴇʀ2 Good one, clearly not the latest source!

I am using the latest non beta ................................................................................................................................................... I now realize that this tutorial from the github wiki (which lists no version #) is old. I would have thought they would have updated it seeing as how it is the official repo for Marlin.

If you look into the most recent version of Marlin you will find in file Marlin/SanityCheck.h:
elif defined(MANUAL_BED_LEVELING)
  #error "MANUAL_BED_LEVELING is now LCD_BED_LEVELING. Please update your configuration."

This implies that constant MANUAL_BED_LEVELING is obsolete. It is not found anywhere else except for the file linked above. So, no, the constants are not supposed to do exactly the same. Instead an error is shown on compiling to update your configuration to exclude the constant MANUAL_BED_LEVELING.


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Stepper motor for CR10-S5 Y-axis
I need to replace this stepper motor with the following product identification:

It’s a Y-axis for CR10-S5 and labeled as JD42HS60-1500A-02F. What type of stepper motor is this?

Hi Peter, and welcome to 3D Printing.SE!

I have found the motor in Ebay, check the following link:
https://www.ebay.com/itm/Creality-3D-Two-Phase-42-60-RepRap-60mm-Y-axis-Stepper-Motor-For-CR-10-400-500-3/163335682211?hash=item260790b8a3:g:lE0AAOSwlxxb0kqd

This is a NEMA 17 motor. It is virtually identical to the NEMA 17 motors Creality uses in most of their 12V products.
In contrast to other companies, Creality uses a different connector with a flat ribbon cable instead of color-coded wires.
The upper line of the label identifies it more clearly:

JD Identifies the factory/manufacturer
42 identifies the faceplate size as 42mm square, so a NEMA17
HS identifies how the holes are shaped
60 is the height of the motor as 60 mm.
1500 identifies how much power is OK for it, here: 1500mA = 1.5A
A specifies our motor has a maximum safe temperature of 104°C
- gives us no voltage for this motor, but as you have a CR10, it should be 12V
02F is supposed to tell us something about the wiring and steps per rotation, but I can't find out what.

Side Note: the Creality Ender3 uses 34mm high stepper motors.

Would a voltage rating be relevant ("gives us no voltage for this motor")? I thought that for magnetism it is the current which matters.

@Andrew, yes current matters in magnetism. Any voltage specified on the datasheets is "Tested at" voltages.

@AndrewMorton operation voltage does matter. If you run a machine designed for 12V with 24V you burn it out. If you run it at 6V, you might not operate it at all.


text:
Z axis: Stepper motor and lead screw torque calculation
I am trying to figure out some calculations regarding stepper motor and lead screw.
These are the things need answer:

Selection stepper motor to lift given weight?
Amount of load threaded rod can handle?

I found a this topic how much weight can my stepping motor lift?

where,

p = pitch of the screw
Se = screw efficiency = Standard lead screw will be between 20% (.2) and 40% (.4)
Sf = static force. This is the force that is needed to start the movement. The number may be eliminated, but it is good to use a number in the 5 N to 20 N range.
Load = the expected load that the effort will need to carry (i.e., the router and the included axis assembly that the motor will need to lift)
R = radius of the lead screw

Based on this equation with following data

Load: 5 Kg = ~25 N
Thread rod specs;

Pitch : 1.25 mm = 0.0492126
Dia : 8 mm = 0.314961 inch

Motor :

Nema 17
Datasheet

Calculated Effort = 6.22 N = 1.4 lbf = 22.4 ounce
Radius = 8 mm = 0.315 inch (using Pitch conversion table)
So torque = 22.4 * 0.315 = 7.056 oz-in = 0.0498 Nm
As per data sheet Motor can provide an Axial force of 10 N. I'm using two of such motors, so this motor is enough
However, based on this calculator, Lead Screw Torque and Force Calculator, with following information:

Torque required to raise in 0.0252 Nm.

Which should be used for calculations?
How to find the running torque of stepper motor?
I know it will be less that Holding torque, but what percentage?

Nema 17 that I've given Holding torque is 5.5 Kgcm or 0.55 Nm. My second calculation gives the calculated torque to lift is 0.0252 Nm.
Also from this Threaded rod load table, load capacity of 8 mm rod is somewhat around 270 Kg.
Looking for further inputs.

5 kg is about 50 N, maybe change Load: 5 Kg = ~25 N to Load: 5 Kg  ~ 50 N => 25 N per stepper

Possible duplicate of Ball screw: Maintaining Z axis position when motor is OFF - Same problem, different values

I've closed as a duplicate as the previous 4 votes had aged away, but this question doesn't seem to garner any answers, and I don't know how to finish my answer off. If you believe it isn't a dupe then feel free to vote to reopen, explaining why it isn't a duplicate...

This is a work in progress - I'm still plugging in the numbers

A couple of issues:

You appear to be mixing Force (effort) and Inertia and comparing them directly - this mistake seems to have come from the first link;
You used 8 mm diameter, instead of 4 mm radius, to calculate the torque
You haven't calculated the holding force, which would provide the holding torque required, which can be easily compared against the specification of the stepper motor;
I can't see where you obtained the value for axial force of 10 N, from the datasheet of the stepper motor.

Regardless of these issues, tackling each question separately:

Selection stepper motor to lift given weight?

First equation
Your first equation, for effort, is
$$F_{effort} = S_f+\frac{Load}{2*\pi*\left(\frac{R}{P}\right)*S_e}$$
where,

Starting Force, from linked article, worst case scenario, $S_f = 20$ N
Radius $R=4$ mm$=0.004$ m
Pitch $P=1.25$ mm$=0.0125$ m, and
Screw Efficiency, from linked article, worst case scenario 20 %, $S_e=20=0.2$

So filling in the numbers, for 25 N:
$$effort = 20+\frac{25}{2*\pi*\left(\frac{0.004}{0.00125}\right)*0.2}$$
$$effort = 26.22$$
It is worth noting that this running torque only comes to 6.22 N, much smaller than the worse case value of the starting force, of 20 N:
$$\frac{25}{2*\pi*\left(\frac{0.004}{0.00125}\right)*0.2}$$
$$ = 6.22$$
and plugging in the numbers, for 50 N:
$$effort = 20+\frac{50}{2*\pi*\left(\frac{0.004}{0.00125}\right)*0.2}$$
$$effort = 32.44$$
Again, it is worth noting that this running torque only comes to 12.44 N, much smaller than the worse case value of the starting force, of 20 N:
$$\frac{50}{2*\pi*\left(\frac{0.004}{0.00125}\right)*0.2}$$
$$ = 12.44$$
It should be noted that these values are for a force, in N, not torque, in N•m, and I can't see on the datasheet were you obtained an Axial force of 10 N. To convert these to a torque, you must multiply by the radius of the M8 x 1.25 spindle - M8 is 8 mm, therefore the radius is 4 mm, which is 0.004 m:
$$T_{raise} = F_{effort} \times 0.004$$
Thus reducing the values for the Torque (derived from the effort) even further, by a couple of orders of magnitude, to 0.104 and 0.12976 N•m, for loads of 25 N and 50 N respectively.
So, the estimated value of worst case starting force would appear to be the dominant factor in selecting the stepper motor.
Regardless of all this, if, as you say, that the holding torque, $T_H$, is higher than the running torque, $T_{raise}$, then the holding torque would be the deciding factor in selecting a stepper and the running torque can be discounted.
It is unclear whether the equation that you found is the appropriate equation for calculating the holding torque. This equation appears to be for moving the load, whereas you need it for merely holding the load. For completeness both the holding and lowering torque values should be calculated.
Second equation
Your second equation apparently from Wikipedia - Force, via Lead Screw Torque and Force Calculator,
$$Torque_{raise} = F*D_m/2*\frac{L+\mu*\pi*D_m}{\pi*D_m-\mu*L}$$
where,

Force, $F$
Diameter, $D_m$
Pitch distance of square thread, $L=\frac{1}{D_{Thread}}$, where $D_{Thread}$ is the thread density given in the table.
Coefficient of friction, $\mu$

Whilst I can not see that equation on Wikipedia's Force page, I did manage to find the equation for raising, and the equation for lowering, on the Wikipedia page for Leadscrews - Mechanics1:
$$T_R = \frac{Fd_m}{2}\left(\frac{l+\pi\mu{d_m}}{\pi{d_m}-\mu{l}}\right)$$
and
$$T_L = \frac{Fd_m}{2}\left(\frac{\pi\mu{d_m}-l}{\pi{d_m}+\mu{l}}\right)$$
Plugging in the numbers for 50 N of load:
$$T_R = \frac{50\times0.007375}{2}\left(\frac{0.00125+\pi\times 0.25\times0.007375}{\pi\times0.007375-0.25\times0.00125}\right)$$
$$T_R = 0.1848 \times 0.308$$
$$T_R = 0.0568$$
Plugging in the numbers for 50 N of load:
$$T_L = \frac{50\times0.007375}{2}\left(\frac{\pi\times 0.25\times0.007375- 0.00125}{\pi\times0.007375+0.25\times0.00125}\right)$$
$$T_L = 0.1848 \times 0.193$$
$$T_L = 0.0357$$
NOTE: As the link to the calculator states, there are two different torques - one to raise, $T_R$, and one to lower, $T_L$. As the lowering torque, $T_L$, is less than the raising torque, $T_R$, then it isn't really necessary to calculate it, or consider it when selecting the stepper, as the raising torque is the dominant factor.
Again, if, as you say, that the holding torque, $T_H$, is higher than the running torque i.e. $T_R$, then the holding torque would be the deciding factor in selecting a stepper and the running toque can be discounted.

Amount of load threaded rod can handle?

This would appear to be much simpler to answer, as a value is given in the specifications for the rod, depending upon what you actually mean. It could be:

The weight that the rod can support before slipping, or;
The weight that the rod can support before slipping before mechanical failure,

I would imagine that, the specification given is the weight supported before the threads give way and break.

Footnotes
1 These equations only account for the friction of the thread and the term for the collar appears to have been omitted.
From Torque Required to Raise Load (TR) Calculation, the full equation, for both thread and collar, is given by:
$$T_R = \frac{Fd_m}{2}\left(\frac{l+\pi\mu{d_m}}{\pi{d_m}-\mu{l}}\right)+\left(\frac{F\mu_cd_c}{2}\right)$$
where,

Torque required to raise load, $T_R$
Load, $F=50$ N
Mean diameter of square thread, $d_m = X?$ m
Mean diameter of collar, $d_c = X?$ m
Pitch distance of square thread, $l = 0.00125$ m
Coefficient of friction for thread, taken from the Solved Example, $\mu = 0.25$
Coefficient of friction of collar, taken from the Solved Example, $\mu_c = 0.25$

As the mean diameter, $d_m$ is not provided, it can be determined from the pitch, $l$, and nominal diameter, $d_n = 8$ mm, by
$$d_m = d_n-\frac{l}{2}$$
$$d_m = 0.008 -\frac{0.00125}{2}$$
$$d_m = 0.007375$$
The mean diameter of collar, $d_c$ is not given...
Plugging in the numbers for 50 N of load:
$$T_R = \frac{50\times0.007375}{2}\left(\frac{0.00125+\pi\times 0.25\times0.007375}{\pi\times0.007375-0.25\times0.00125}\right)+\left(\frac{50\times0.25\times{d_c}}{2}\right)$$
$$T_R = 0.1848 \times 0.308+\left(6.25\times{d_c}\right)$$
$$T_R = 0.0568+\left(6.25\times{d_c}\right)$$

You made a mistake. Pitch is 0.00125

Hi @VaidotasRastenis and welcome to SE.3DP. Ah yes, so I did...many thanks... I'll convert your answer to a comment to my answer. Thank you again. :-) Also the radius of the spindle should be 0.004, not 0.04. Fortunately, that means the answers to the first equation remain the same. The result to second equation changes though.

oldy but goldie - still WIP?

@Trish - ah yes, wow, I'd forgotten all about this. Hmm, I wish I'd never attempted to answer it... it's a nightmare of a question... lol. Would you like to finish it off for me? :-)

@Trish - Apparently,  this comment on my question over on Engineering.SE sort of implies that either: the question can not be answered (which I'm not sure is correct), or; I was going about it the wrong way and using the wrong equation. Maybe it should be closed as a duplicate then, if your linked question is the same thing.


text:
Adding a custom printer to Cura
I'm trying to enter the settings into Cura for the printer.
The manual has a screenshot of what they should be:

However, when I run Cura and try to enter the settings I'm presented with different options:

How do I translate the settings from teh screenshot into the settings I have available?
Should I be concerned about the settings that aren't available to enter?

Are they important?
Do I need to enter them somewhere else?

Your manual is in another Castle!
The manual you look at is for Cura (1) 15.04. You are however using Ultimaker Cura 3, most likely the most recent 3.6.
Quick references
The machine setup is for the physical settings of the machine - build volume, nozzle diameter, coordinate system and such.
The other settings you refer to are all set in the right bar, but you will have to switch from simple to advanced mode, and possibly activate the settings you need.


text:
Silicone spray as a release agent?
I've just printed my very first part and it did not want to come loose from the build plate, it fact, it just broke instead.
I can heat the bed up again and work it off, but I wondered if a release agent would be better?
I have a silicon release spray (like those use with molds).  Could I spray the base with that before starting printing?

no, you want the surface clean and dry and non-greasy. i've had prints fail to stick because of fingerprint smudges before, so spraying something would be even worse.

It may help to know what type of build plate you are using. Glass, PEI, bare aluminum, or others would have different solutions. I use hairspray on glass, and my prints almost always self-release within a few minutes as it cools. Before that I used blue painter's tape on the aluminum plate which worked well but took more time.

I would highly recommend getting one of those magnetic flexable built plates, you can get them for around $10 from China. It saves a lot of trouble with sticky prints.

@Ezra I haven't heard of those.  Have you got a link?  I have read people saying to get a glass plate.

The problem with using a release agent is, you really run the risk of the print not sticking to the bed at all. Sticking to the bed is uber important, because if it's not there, the piece isn't going to come out right. Having it stick to the bed is a good thing (something which I struggled with for a while!!).
I believe what most people do to get the piece unstuck from the bed is to use a putty knife. Wedge the flat part under the piece and twist slightly. Continue doing this around the print until you can get it to release. Your best bet is being careful by going easy with it though. Also, if the print is sticking well to the bed, ensure you're not using a raft. This will make it even more difficult.

not a putty knife, a sharpened spatula. However, I have seen woodworking tools used too...

Plastic shrinks when it cools, usually, print come loose when you cool down the build plate. If you print on glass, you could put the plate with print in the refrigerator.
If you can't put the build plate in the refrigerator, wait for the plate to cool; the print part sometimes pops off, if not, prying up a corner with an artist palette knife or a razor blade scraper will be enough to pop the print off.

Note that release agents can be used (from experience), but not what you suggest. E.g. when you print PETG on PEI it almost fuses, to release those prints you can use 3DLAC or any other PVA based spray or glue (which normally would increase the adhesion!) to be used as an intermediate less sticking release layer.
Do note all the questions here of people not getting the filament to stick to the build plate, do not grease up the plate, else you won't have a print to get off!

upside down spray dusters (canned air) can be used to cool the glass in-situ, which prevents re-leveling.

@dandavis When using auto leveling, re-leveling will be automatic, but you are right, if you manually level this may require a re-leveling session.


text:
How to fix Y layer shift on Creality Ender 3?
While printing a simple model, my printer starts to layer-shift the build in a direction suddenly. I used the default setting for ultimaker Cura 3.4.1. It has done this same thing for multiple different prints. I would guess it is the software.
How do I fix the issue?

Terminology: that is not offset, that is layer shift

Please specify if it is X or Y, it is clearly not both as shown in the image. Considering the markings on the bed, this appears to be a Y axis layer shift. Please acknowledge!

You have a case of layer shift. Layer shifts happened to me in 3 ways:

The movement of the axis is hindered. Check if all cables run freely and without any chance to catch! improper cable chains can cause binding and stop the printhead or bed in movement and thus induce a shift.
The acceleration might be too fast. Shift the acceleration of the printer movements down a notch. Don't print faster than ~60 to keep the acceleration in check, as the printer will try to reach the top speed as fast as possible, thus limiting top speed also limits acceleration.
The model might be broken. Re-slice the model just in case.

In addition to the other answer to complete the overview, your stepper motor may not get enough power and misses steps, increasing the current by adjusting the stepper driver voltage could also solve the issue (when the current is too low that is! never just increase this to try out, you could damage the stepper, the drivers or the board, so beware).


text:
Considerations when pausing a print job
Some prints take a long time and, as I'm not in a workshop, I need to pause the print sometimes.
Are there any special considerations I should take when pausing, or can I literally just click pause, leave it for twelve hours or so, and it'll continue without any ill effects?
I'm using PLA at present.

If you keep the head hot during the pause, and over the print, you will melt the material already deposited.
If you move to X0 Y0 (like on a layer change) and pause there, you can cool off the head (or not), but will want to prime (advance) some material before resuming your print - or risk an initial void, as the heated material will expand and drip to some extent.
If you move to X0 Y0, retract, and cool off for your pause, you should be able to heat up, advance, and resume with few issues. You will probably still need to some manual cleaning where the resume was, as there is likely to be some buildup.
Also, if you let the bed cool during your pause, your print may become unstuck from the bed.

All good points.  Sounds like it's much better to design smaller pieces and print individually then.  I don't know if the printer will move the extruder head to 0,0 if I press pause or not.  I'll have to test it.

Pausing a print: A vital aspect to anyone who tries to do something advanced with 3d printing.
There are three (3) things:

Never pause over the print. Your pause "script" should lift the head up from the model and rapidly move it over to a parking region, which is clear of the bed (ideally).
Keep the bed warm, but retract the filament. Ensure that the filament gets retracted prior to the pause. Also the bed must stay hot/warm to ensure the part doesn't loose adhesion, and doesn't begin to warp out of shape (in the case of ABS).
Do not shut off the motors. If you are pausing so that you can insert objects into the print (screws, washers, electronics etc) then touching the print can cause the bed to shift. Keeping the motors running will help resist any movement of the build plate during said operation. If you are pausing to do a filament change then keeping the motors energized will help resist the back driving of the lead screw (or belts or whatever is moving the z axis) so that you don't accidentally push the z axis out of position.

Of course the most important thing is the resume command. It should "undo" the movements of the pause command and return the machine to a printing state.

This procedure the Prusa MK3S is doing exactly

It is not recommended to pause prints a considerable amount of time as the printed model will shrink and might warp during the pause. Also, layer bonding between the old and the new art after resuming will be weak, but this can be used to induce planned breaking layers.
On the other hand, if you have set up your printer properly, it is quite safe to leave the room even during the print:

Maxtemp and Thermal Runaway Protection need to be set
a smoke detector over the printer should be installed
the printer should be placed in a way that no flammable objects can get in contact with it

What use is a smoke detector if you're not there to hear it?

What use is a smoke detector if no one is around to hear it? Get a IP camera instead.

@user77232 it warns people in the area. An IR Camera does warn nobody. and you can use a smoke warner that calls you.

There are smoke detectors that will cut power to your printer.


text:
Ambient Temperature Range for Printer Storage/Usage
I've just joined the 3D Printing world and am patiently waiting for my printer to come in next week. I've been thinking about keeping my printer in the garage so that it stays out of the way of every day life.
Since I am in the Midwest, I was wondering if this is the best plan. Is it okay to store and use my printer when the ambient temperature can get as low as 10 °F (about -12 °C) and as high as 120 °F (about 50 °C)? Would the cold affect my prints substantially, mainly using PLA, PETG and some TPU? Would larger prints, spanning days, affect the filament on the spool?
Note that I am solely talking about the printer. I plan on keeping the filaments inside the house so they won't be bothered by the temp extremes.
My google searches came up with nothing and I didn't find anything on the supplier from which I purchased my printer. I doubt that it matters, but in case it does, my printer is the Creality CR-10S

Printers are electrical machines. They don't like water, so they also don't like condensation in them. If you can keep your garage dry and prevent a sheet of metal inside it from rusting, then your printer might survive the problems the shifting temperatures induce by condensing water vapor on the electronics.
Another thing to consider is, that at negative degrees Celsius, your printer might trigger a mintemp error, as the minimum temperature allowable is usually defined as 0 °C or higher. On the other hand, low temperatures might allow to bridge further than other days, as the cold air absorbs the heat from the prints faster. It could cause other problems like clogging or under extrusion due to low temperature though.
High summer temperatures might impact the print quality, causing quite some extra sagging.
The Filament on the machine in a garage might be impacted because of the humidity changes, but might be mitigated with a drybox.

I didn't even consider the condensation aspect and using metal currently stored as a metric. That's pretty handy.


text:
How to make physical buttons send G-code?
I want to hook up an Arduino to my Creality printer running Marlin firmware, such that I can have a few physical buttons mounted on the machine that will execute commands such as preheat, home, disable steppers, and so on, so that I don't have to navigate through the clunky LCD screen.
Ideally it would work in addition to the normal LCD and serial functionality, so it would not impede me from using Ultimaker Cura to print via USB, etc.
What is the best way to do this?

How many pins are still free on your Arduino Uno)

All of them....

One option would be to have your printer controlled by an Octoprint server.  You would then use the Octoprint Api plugin to use your arduino to send commands to octoprint - and from there, your printer.  Octoprint has a fairly fully-featured rest api that allows you to send arbitrary GCODE to your printer (see here).  You would then hook up your buttons to some code that sends the gcode commands to the printer when pressed.  It's certainly not as simple as installing a plugin - you'll have to write some interface code, but it looks like those APIs should be able to do what you want, without interfering with the standard controls at all.

Thanks, I will definitely look into that ...................................................................................................................................................  Would there be any way to do it without a raspberry pi? Like using the Arduino to send serial commands the same way we do with the serial console in the Arduino IDE?

Yeah after looking into that I would not want to use octoprint. There are still way too many bugs.

There's already Arduino inside the printer (to be precise: the printer board with spare pins). Im sure its possible to hook up a switch then change firmware to send G-codes; 1 pin per series of commands?

Are you sure, or are you asking?

Where would you add the code? In which file(s)?


text:
Stepper motors making noise after steps/when idle
Why is it that if I execute a gcode command that causes the stepper motor to turn in reverse (any negative move on the X axis), after the step it will emit a high pitched whine until it gets another command to rotate in its forward direction?
Executing multiple reverse commands will cause the tone to vary in frequency each step, and always it goes away after another step in the opposite (forward) direction.
Sometimes.
And other times it does it in both directions, but only on every other step. One step +X its there, next step its gone, next step its back, and so on...
Then they also make a different noise when idle, before I disable them with the "disable steppers" command.
What are these noises?
And is it bad to leave the motors in this state? Will it burn them out?

what kind of printer you got? Does the sound really originate in all or just one steppers?

Ender 3 pro, late-2018 model (only 3d-printed part is the power supply lower cover)

Mainly the X and Y, but not at the same time. It is random

that would be... desing 3 or 4, one of them has a detatchable magnetic printing surface (which I am not a fan of as you can't print ABS without demagnetizing it)

When idle, the stepper is stationary, no rotation.
Normal standard electric motors will start spinning as soon as you apply power to them. However, steppers only rotate when a magnetic field is applied1):

Stepper motors effectively have multiple "toothed" electromagnets
arranged around a central gear-shaped piece of iron. The
electromagnets are energized by an external driver circuit or a micro
controller. To make the motor shaft turn, first, one electromagnet is
given power, which magnetically attracts the gear's teeth. When the
gear's teeth are aligned to the first electromagnet, they are slightly
offset from the next electromagnet. This means that when the next
electromagnet is turned on and the first is turned off, the gear
rotates slightly to align with the next one. From there the process is
repeated. Each of those rotations is called a "step", with an integer
number of steps making a full rotation. In that way, the motor can be
turned by a precise angle.
The motor's position can then be commanded to move and hold at one of
these steps without any position sensor for feedback (an open-loop
controller), as long as the motor is carefully sized to the
application in respect to torque and speed.

When you power the printer and energyze the steppers there is no movement, but, the magnetic coils in the stepper are activated to hold the rotor in position. This is controlled by the stepper driver. The creation of the signal for the magnetic coils is causing the noise. It is a function of the driver type, micro-stepping setting, the stepper motor inductance, current setting and supply voltage.
If the stepper motor, stepper driver and power supply can take it, increasing the current setting of the driver may lower the noise.
Turning off the steppers (disabling them with G-code using M2, M18, or M84 depending on your firmware) will stop the noise, but you will easily lose the current position as it is not hold into place anymore.

1) source Wikipedia

this is normalISH for stepper motors. they have a fair ammount of current pulsing through them at relatively high frequencies, coils and other parts that will vibrate. if it quite loud you can look into the boards that drive them, depending on your printer they are replaceable, and better 'drivers' send cleaner signals that make less noise. however: if your motors get hot or start making clicking noises, or stop randomly, or acting up more significantly, you should look adjusting how much current they are getting. search for stepper motor calibration, basically you need to adjust the ammount of current the motors are getting, but if the machine prints normally, then this is not something you want to play with. you can also probably find the data sheet for your motor, they are usually rated to operate up to about 50C

Would you please look onto this again, [edit] and fix up your grammar?


text:
Steps to setup a new 3D Printer
I hope it doesn't get closed since my question is widely open:
I got recently a Geeetech Prusa i3 Pro B as a DIY kit, the assembly took a lot of time since the package did not include a building instruction. However the booklet contained a link to YouTube where I found almost all steps (based on the video names, some videos where missing and two steps had the wrong order).
I'm still wondering how I can put the (much too long) cables to prevent that they will touch the heat bed. Are there any hints or best practices?
However now the axes can be moved from the top panel however I'm not sure how to adjust the printer. I already found out the deltas of each stepper (I just excluded the extruder for now). How can I enter those deltas?
When done the next logical step is to do some test print. However how!? I found no exact steps. What kind of kind of printing software do I need? (I'm running Windows OS) The device is detected as com port when I plug it in my computer. Where do I find an ideal test 3d model?
Sorry for so many questions, however I hope this can get a introduction for newbies like me.

Try to split the questions into multiple questions. This might help to get answers.

Please split this up, leave this question to answer the deltas question. What do you actually mean by that? Please expand by [edit]. Furthermore , the latter 2 question already have an answer at 3D Printing.SE. A valid substitution may be (in a new question): "I found this model, is this an ideal test model to test my new 3D printer".

As a side note, please provide the part of the construction manual you have problems with.


text:
Trying to control temperature of hotend using PWM signal and MOSFET
I have a 40 W, 12 V resistance heater in the hotend. It also has a 100 kΩ thermistor built in. I am using an Arduino to read the temperature on the LCD. This is working fine.
I want to use this temperature using a MOSFET and the PWM signal that is generated by the ARDUINO.
So I connected the PWM signal to the Gate of the MOSFET and connected the 12 V, 3 A supply to the drain of the MOSFET. And connected the Resistance heater of the 3D printer to the source and ground.
But the problem that I am facing is that the Current is flowing from drain and the source even without the gate signal to the MOSFET.
I am not able to control the current to the resistance heater.
Mosfet: IRFZ44N
and the AC to DC adapter is 12 V, 3 A.
PWM signal is max 2 V.

please add a wiring diagram

As a side note, 12V at 3A is only 36W. Using that with a 40W heater is asking for trouble.

connected the 12 V, 3 A supply to the drain of the MOSFET. And connected the Resistance heater of the 3D printer to the source and ground.

The MOSFET is damaged. If the gate is at $0V$, no current should be able to flow.
You're trying to use an N-channel MOSFET as a high-side switch. This is a bad idea, because it would require more than $12V$ at the gate to turn the MOSFET on properly. It would be better to set this up as a low-side switch so that the microcontroller can drive the gate directly. The MOSFET should go between the load and ground, not between the load and $+12V$.
The fact that you connected it like this is the very reason the MOSFET has been damaged. When the MOSFET is OFF, there is $0V$ across the heater. When the microcontroller starts to turn the MOSFET ON (by applying $5V$ to the gate, thus increasing $V_{GS}$ to above $V_{th}$), current starts to flow through the load and the voltage across the load increases. This in turn decreases $V_{GS}$, causing the MOSFET to turn off. You will end up with approximately $3V$ across the load and $V_{GS}=2V$. You've got $9V$ being dropped across your MOSFET and with a current of approximately $800mA$, the $7W$ of heat produced will quickly kill the MOSFET.


text:
Hotend does not reach set temperature
If I set the temperature of my hotend with pronterface to 200 °C, the temperature never reaches that value. For instance, it almost reaches the target with a temperate of 196/197 °C and then starts to drop to 184/85 °C before it starts to rise again to 196/197 °C. It remains in this loop forever and thus I'm not able to start any print because the temperature never stabilizes enough.
I've tried to configure the PID (M303 E0 S200 C8) with 8, 12, 15 intervals not help the issue continue.
I've tried to change heatblock and thermistor not help
Its important to refer this behaviour occur in any tempurate if I fix 150º it never reaches 150º it go to 146/147º and then drops again 10/15º and restart the loop. Same thing if I fix the tempurature to 210º.
Also I've tested this in multiple versions of marlin 1.1.8 and 1.1.9.The version of marlin 1.1.8 have worked in the same print in the past.
I'm have not clue about what can cause this issue, maybe its a board malfunctions (mosfet) or a powersupply malfunction.
Somebody can help me on this?

Did you change the Heater Block (square metal block) or the Heater Cartrige (the actual heating element)? What is your Printer? What kind of hotend you use? Did you save your settings after PID tuning?

Can you go higher than 200 °C when you set the temperature to 235 °C for instance?

Yes my printer could reaches higher temp then 200º easy. I've a heat cartrige of 50w the problem is stabilize that temp. I'm using 3dv6 clone with Trianglelab Thermistor Cartridge 260 from ali

Your description sounds indeed as if the PID is not correct. You can try autotune with M303 only if your heating cartridge is not absolutely overpowered. However, in such a case you typically also have an overshoot, which you don't mention in your description.
In that case you need to lower your duty cycle (by the BANG_MAX parameter in the firmware) a bit. Otherwise autotune fails, because your heating cartridge overshoots even at small gains.
Out of the box I would suggest you to increase your D-term and decrease your I term if it cycles like that. For most printers, I used, a ratio like that is sufficient: 4/1.5/25.

Many thanks for your reply I not mention but have update my termistor (Trianglelab Thermistor Cartridge 260) and heat Cartrige to a new 50w aswell as the heat block. How I can check if the PID routine was failed? Because I'm using the value that came out of that routine.

When heating up, do you have overshoots? Typically, in such cases and after Autotune you will just get PIDs leading to overshoot-undershoot-loops which indicate that the D-Term is too low. At least it was like this for me. Just set your Bang_MAX to 64 and try again.

During autotune PID I'm seeing overshoots, tempurature raise over the setted temperature. But in print's never get overshots only undershoots. In case never have overshoots should I increase or decrease D-Term in PID parameters?? I'll set my bang_max to 64 now its setted 255. I'll drecrease

your tip have solve my issue I reduce the BANG_MAX from 255 to 240 and them I've run the M303 whiout any parameters that have run the PID with round temp of 160 and gave me parameters which work for me. Many thanks for your help


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Prusa i3 pro W - not extruding
I'm trying to do my first ever print with my Geeetech prusa i3 pro.
When I try to print that printer seems to work, x,y,z axis all moving ok.
What isn't working is that little to no plastic is being extruded.
The nozzle appears to be getting to temperature, and some plastic comes out whilst it's heating, but then when it starts to move and print, no plastic comes out.
My thoughts are:

Have I not loaded the plastic properly
Is the extruder engine not working i.e. not pulling the plastic through

Any hints on what I can try would be appreciated.

What did you do to troubleshoot already? What exactly does not happen? Do the Gears turn or not? Is the motor connected?

I've wired the motor in as per the build instructions. How would I know if the gears are turning are they not internal ? I suspect this is the case - it does not look like it is feeding the filament in at all.

There is exactly 1 gear on the extruder stepper motor: the one that tries to push the filament. As a good test, remove the filament.

OK, I've removed the fan and heatsink so I can get a better view of what is going on. Using the repetier-host I'm trying to drive the extruder motor - but I'm getting no movement.  If I've wired it in correctly (and I think I have) does this imply an issue with the motor itself ?

Is the extruder gear turning into the right direction?

Problem identified.
I took of the fan and heat sink so I could see what was going on in the mechanism that should pull through the filament.
Using repetier-host software I tried to manually drive the motor - nothing happening.
I swapped the A4988 stepper motor driver for the extruder with another (and my x,y,z axis motors work) to see what would happen - and it worked!
So just a faulty A4988 on the extruder motor.
I also manually pushed filament through the hot end to ensure there was no blockage and it worked fine.
So hopefully GEEETECH can send me a replacement and I'm good to go!


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What the adjective "downstream" is used for?
I'm working with a project involving 3D printing's terminology, but I'm not such an expert... so I was asking myself if someone can explain the meaning of the "downstream" adjective in this field.
More precisely, I'm dealing with this sentence: "Handle any downstream task", which I really can't understand because it has a very poor context.
I also have this sentence with the adjective that I'm having trouble with:

Confidently send your surfaces downstream knowing your results are usable design surfaces.

A link to the page would be useful, in order to fully understand. That said, this question probably belongs on ELL.SE.

Without more anymore context "downstream" could be in reference to a print that would be sent to another machine for post-processing. The post-processing machine is "downstream" from the machine used to make the print in the first place.

Imagine an assembly line and the flow of the material along that line. That flow is analogous to a river, and therefore any machining/processing following on from any point along that line is considered to be downstream of that point.
From Wikipedia - Downstream (Manufacturing)

Downstream in manufacturing refers to processes that occur later on in a production sequence or production line.


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Calibration print shape
To check my leveling etc. is correct I was going to print a wide and thin cube.  My theory being that I should be able to spot any obvious separation of the layers.
Does anyone have any better shape that they print as a dry run?

Your calibration shape depends on what you want to calibrate on. Among the most popular:

Benchy as a general "overall" test.
Lattice Cubes for retraction/stringing and overall quality.
Two pillars to test for stringing and temperature/cooling control.
Spikes for retraction, stringing and temperature/cooling control.
Bridges for cooling control.
Cubes for sizing. They also allow seeing if the printer is skewed in X or Y.
Circles, crosshairs, and squares of just a couple layers high to determine the correct center of the print area and measure sizing.
Cylinders in each other to check the achievable resolution and clearance.
Overhang tests to test just overhangs.
Temperature towers for temperature and overhang.
Impact1 & Bend & Tension test pieces for filament properties - if you have the setups needed.

1 - I couldn't find a proper model for an ISO 148-1 Charpy pendulum impact test in thingieverse

Great list, although one not mentioned is a calibration square to measure diagonals in order to test the skewness. This is typically a large square only a few layers tall.

Lots of useful stuff there.  How doe the bridge to test cooling control work though?

@BanksySan If the bridge fails or sags too much, you need more cooling.

@Trish and print slower.


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Moving Extruder Gear Assembly
So I am getting a Creality CR-10S which has a similar print frame with a lot of other printers. Eventually I'm sure I will want to print using flexible materials, but the bowden system is not optimal since you're basically trying to push cooked spaghetti through a tube. I could replace the bowden with a direct drive but that can be expensive (and potentially shave off 15 mm from one of my axes). Not to mention that the print head is now heavier which can affect print speeds and quality.
That's when I thought about moving the extruder gear and motor from the side of my printer to the top. The tube then goes down the Z axis so the flexible filaments are pulled by gravity and controlled by the gear instead of just being pushed by the gear. (Please refer to my wonderful sketch)

I can't be the only one to think of this, but I've only seen one website that has talked about this issue and thinks that the solution is a second gantry to follow the hot end. If you're interested, here's the link.
Are there any potential issues with this new setup? Though I would mount the servo above the cross beam instead of to the side so that there's full range of motion along the z axis. (sadly that thought came to me AFTER making the picture in paint)

Hanging up the Bowden system won't fix the problems with printing flexible filament: the filament will still press into the bends of the tube and thus lead to under extrusion. Another issue is, that the flexible filament can compress - and the longer way it has to the melt-zone, the more filament it can "store" on the way to it. These bunched up zones will release suddenly, resulting in pulses of high output and between those under extrusion.
Direct drive (like in a Prusa i3) is pretty much the only way to reliably print flexible materials. You could, with some engineering, move your existing motor to the carriage and turn your Bowden into a direct drive.

I don't see bends happening, or as extreme at least. At least as long as prints stay below, say, 200mm. I don't think that I've seen anyone print anything substantially tall so the bending would be nominal maybe? A capricorn tube could maybe resolve that issue? (I think it's called capricorn, that really slick blue tube)

@LuxClaridge the bowden tube will not hang straight, it will always bend to the left and right in some way to accommodate movement of the print head, thus the flexible material will rub against the inside. Even Capricorn tubing is not frictionless.

Regarding your second paragraph and comment. I'm trying to avoid added extra mass to the carriage. Unless I'm mixing up the terms "carriage" and "print head" as they seem synonymous to me.

@LuxClaridge they are. but you can't have light and flexible materials. Just like the engineering mantra: Engineering mantra: cheap, good and fast, choose at most 2.

At the risk of turning this into an extended discussion, what if I forewent the bowden tube altogether (maybe engineer a short funnel into the hot end)? There's nothing to bunch up in. Granted, I've never heard of a tubeless design so it's probably a really bad idea. :)

@LuxClaridge Tubeless Bowden? impossible. Without pressure from the extruder, nothing will push the filament into the hot-end. Without the tube, the extruder does not apply pressure on the filament.


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Z Axis Cannot Move
I've got a Geeetech Pro B i3 printer (my first 3d printer) and after I've assembled it I started testing the axis. X and Y work well but Z cannot move.
If I disconnect the couplings the motors move by themselves and they move in the same direction.

If I help a little bit the motors, by turning with my hand, they move and sometimes move without helping anymore but it stops after a few seconds.
I don't know what do to. I've measured the rest of the setup to make sure there aren't any big differences that could create tension.
What do you suggest?

Check if your Z-Rods and motors are exactly vertical. If not, adjust as needed.
Check if the brass nuts are perfectly aligned with the rods in the position they are forced in by the screws. Shim to adjust if needed.
If they are ok, then your brass nuts might need a little oiling/grease if they stick to the lead screw.


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Evidence of a warped build plate?
The first layer is very patchy indeed.  I've calibrated the build plate pretty accurately but even if it was a badly calibrated build plate I don't think it would have this effect.

It doesn't seem to have a negative effect on the print.

Should I be concerned about this?
Is this due to a the build plate fault?

That's some strange warping. Usually, glass plates will have a slight U shape when they're warped.

It looks like a Buildtak clone

First things first:
Don't Panic
Your heated bed is made from metal with some sort of Build-Tak-Clone surface. It is not broken from what I can see. Your print is not failed, however, the quality does suffer a little bit.
Your bed does warp a little under heating. That is perfectly normal, and you should actually calibrate your layer thickness against a hot heatbed, not a cold one as metal that is heatbed extends - especially over the heating elements. The main heating element is usually in the center, so it "bulges" a little there, and if the heat has not equalized everywhere, it can show a dimple around it. So it warps slightly. The extent of the warping is determined by a couple factors, but from what your print looks like, it is not in a worrisome amount - the second and third layers will even it out.
I can't tell how much time passed between reaching the print temperature of the bed and the start of the print, but you might want to make sure  the heating behavior heats the bed first and the hotend second, allowing the heat energy in the bed to spread more evenly. A tiny G4 P20000 ; wait 20 seconds (see here)` in the pre-print code, before cleaning & priming the nozzle might also help.
You can try to get more even first layers by positioning the parts in areas that do not suffer from warping.
As Tom mentioned, you might get better base layers if you increase the first layer thickness. I usually print with about 0.15 to 0.2 mm for the first layer, regardless of the following layer thickness to even out small miscalibrations and unevenness in the heating.

Good piont about calibrarinbg against hot parts!

It looks like your first layer is way too close to the bed. The printer is trying to squash the plastic down very thinly, resulting in inconsistent extrusion. You will likely see better results if you move the nozzle away from the bed a little bit. Increasing the thickness of the first layer might help as well (this is a setting in your slicer).
Keep in mind that if you're trying to print (e.g.) a first layer with a thickness of 0.05mm then a 0.025mm variation in the height of the build plate will result in very strong variation in the thickness of the extrusion on the first layer; in some places it will only be half as thick as in other places. If instead you used a 0.2mm first layer, then the 0.025mm variation barely makes a difference.

If that were the case wouldn't I see a different pattern?  The calibration screws are triangular with one at the front and one at each far corner.

The pattern is determined by tiny variations in the surface of the build plate. It doesn't have anything to do with the way it's mounted.

the instructions said to use a piece of printer paper for the final measurement (first measurement was 1mm).  I favoured the point before the paper snagged rather than after.

@BanksySan that... actually is too close: you want to use the point where the paper binds on pull or starts to bend if you push.

A piece of paper gets the bed level and set at approximately the same height. Not all pieces of paper are the same though. You might still need to make small adjustments. Try raising the first layer nozzle position by around 0.05-0.15mm - this will probably make a large difference. If you enable babystepping in the firmware you can finetune the position of the Z axis while the first layer is being printed.

@TomvanderZanden This printer doesn't have an autoleveling thing, just three screws to manually turn.

@BanksySan Babystepping is not the same as autoleveling - it is sending less than 0.1 mm movement commands, which are usually what you can send via the movement tab.

@Trish I can raise and lower the whole plate by very fine amounts, but the corners only by manually adjusting the screws.

@BanksySan that is babystepping. babystepping is "adjust the general layer height by a tiny ammount" not "Fix a skewed build platform"

I'm having the same problem but worse.
Some parts of the print are squished and towards the middle I will have bad or no bed adhesion. I always have to print with a raft or else the first layer will fail.
Borosilicate glass
From what I've read online the best solution it to replace the build plate or add a pad on top of your build surface. The most recommended one is borosilicate glass. It has good heat conductivity and is very stiff.


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Filament Leaking During Automatic Bed Leveling
Before the print has actually started I have set up Auto Bed Leveling using a BLTouch sensor, during the period that this runs I find that material leaks out of the nozzle and curls back onto itself and by the time it finishes it is substantial enough to cause problems when the nozzle is primed  drawing the line to the left of the print. The material that leaks out catches on the material extruded to prime the nozzle, before printing the model so when the first line of the model are extruded to very quickly pulls up off the bed and becomes a massive tangle of material.
I try to catch it my self using various thin instruments to scrape it off the nozzle as it starts the priming but this isn't always successful and is far from ideal. I have also tried adding a retraction before the bed levelling starts suing the gcode commands added to the beginning of every print, at the moment however I find that a retraction large enough to stop the leaking material also means that material doesn't come out for the priming in time so the first lines of the print don't work.
The gcode at the beginning of the print is as follows:
; Ender 3 Custom Start G-code
M104 S{material_print_temperature_layer_0} ; Set Extruder temperature
M140 S{material_bed_temperature_layer_0} ; Set Heat Bed temperature
M190 S{material_bed_temperature_layer_0} ; Wait for Heat Bed temperature
M109 S{material_print_temperature_layer_0} ; Wait for Extruder temperature
G28 ; Home all axes
G1 F1800 E-3 ; Retract filament 3 mm to prevent oozing
G29 ; BLTOUCH Mesh Generation
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X0.1 Y20 Z0.3 F5000.0 ; Move to start position
G1 X0.1 Y200.0 Z0.3 F1500.0 E15 ; Draw the first line
G1 X0.4 Y200.0 Z0.3 F5000.0 ; Move to side a little
G1 X0.4 Y20 Z0.3 F1500.0 E30 ; Draw the second line
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed

I am using an Ender 3 running Marlin 1.1.9 with BlTouch Auto Leveling, With slicing done by CURA 3.5.6
Any suggestions you have that would help to stop this would be greatly appreciated.

What do you mean by material doesn't come out for the priming in time? It is you that defines the priming in your "start G-code", do not solely rely on the skirt for priming.

The oozing is due to hot-end getting hot before the bed leveling procedure: if you move the hot-end warm up command after the G29 line you avoid that oozing
; Ender 3 Custom Start G-code
M104 S{material_print_temperature_layer_0} ; Set Extruder temperature
M140 S{material_bed_temperature_layer_0} ; Set Heat Bed temperature
G28 ; Home all axes
G29 ; BLTOUCH Mesh Generation
M190 S{material_bed_temperature_layer_0} ; Wait for Heat Bed temperature
M109 S{material_print_temperature_layer_0} ; Wait for Extruder temperature
G1 F1800 E-3 ; Retract filament 3 mm to prevent oozing
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X0.1 Y20 Z0.3 F5000.0 ; Move to start position
G1 X0.1 Y200.0 Z0.3 F1500.0 E15 ; Draw the first line
G1 X0.4 Y200.0 Z0.3 F5000.0 ; Move to side a little
G1 X0.4 Y20 Z0.3 F1500.0 E30 ; Draw the second line
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed

The above code will activate the heating elements but starts homing and leveling procedure without waiting for the elements to get up to temperature. Only after the bed leveling is finished the printer will pause and wait for the heating elements reach the desired temperature.
This will prevent oozing on a cold start, but you will still be affected if you start a print right after another print, when the hot-end is still close to  melting temperature.
If you prefer to avoid that condition you might want to also move the M104 and M140 commands after the G29 bed leveling command.

I have noticed that leveling with a heated nozzle and bed is different than leveling cold. If you want to level with a hot plate and nozzle, another more simple solution is to retract more filament at the finishing of a print, you could add an increased retraction of filament in the "end G-code" script of your slicer.
As an example, an "end G-code" script  could look like:

M140 S0       ;heated bed heater off
M104 S0       ;extruder heater off
G92 E0 ; set extruder value back to 0
G1 E-5 F300 ;retract 5 mm filament speed 300
G1 X0 Y210  ; park the machine

Be sure to update the "start G-code" to counteract this retraction in your additional priming section of the nozzle.

...
; Prime the nozzle
G92 E0 ; set extruder value back to 0
G1 E5 F300 ; extract 5 mm filament at speed 300
; additionally, extract more at elevated height and wipe the nozzle...
...

Alternatively, but less accurate (as it does not compensate for layer height) is to have a minimum length of your skirt (this will work if you always use the same first layer height, just calculate how many millimeters you require for the skirt to compensate the retracted volume, you could add some extra distance to the skirt).

The best solution would be to heat the bed, but not the nozzle at startup.   If you level with a cold bed, your ABL mesh is going to be off, since the aluminum heated bed plate expands considerably once the heat is applied.
You could also issue a retract command before leveling, and then add a counteracting filament feed command after ABL is complete. I have no idea how that code would look though.   Just my 2 cents.


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Weird surface thing
I have a 3D printer at home, the Colido Compact, and for some reason when I 3D print big flat surfaces a really weird thing happens. I'm using some PLA from Colido too I think

It almost seems as if the bottom layer does perfectly but when it starts printing out the top surface this happens, because the one on the bottom left is in two parts because the upper part is the bottom one and that one is perfectly flat, then I took them apart and the weird thing just stayed with the top part... and also on the weird warps there are bits of brown goo or something? I don't know it looks as if the filament was burned...
It only appears on pretty big surfaces because smaller ones don't seem to have the problem.
Anyone knows what is happening?

I mean, how many layers do you print for horizontal surfaces.

I dont know i just get a model, slice it with options: Support, Cooling, Layer Height, Infill Density, Infill Pattern and Solid Infill Pattern... i have a really simplified slicer for beginners

Trough a modified version of slic3r for the Print-Rite Colido Repetier-Host

But i also have a modified cura slicer but i dont use that

If the left bottom part is printed like displayed, your first layer is far from OK.

If you hear some "clicking" during the print then you are experiencing filament slipping inside the extruder gear.
I had a similar issue on my Geeetech i3 and I fixed it by replacing the extruder tooth gear, the one that pushes the filament inside the hot-end.
Also, I advice to double check your filament is not getting stuck and your Spool spins freely.

Ill check on that, i never actually saw it in action

It could be over extrusion.
Since I do not have physical access to your prints I cannot make sure. Please check if the thickness of the part is actually higher than what it supposed to be. Also, check the printing process during the print. Is the object taller than the nozzle at any time?
I generally have the same problem at the first layer, as sometimes I squeeze the first layer too much, causing extreme over extrusion. But unlike your case, upper layers kind of fixes the issue. In your case, the issue is amplified as you get higher. Walls turn out to be ok as there is room for flament to grow around, it is the flat surfaces that will got hit bad.
I strongly suggest you to print calibration pieces to ensure correct setting. If you have caliper you could try this or if you don't this one might help.


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Material extruded to prime the nozzle doesn't stick to bed at first
When the material is extruded to prime the nozzle before the print starts it doesn't always stick to the bed for the first 20 or 30 mm of the line, causing the material extruded just after to peel off the bed as it is pulled up by the nozzle, eventually it does stick down to print a line but the parts that are not stuck to the bed can get caught by the nozzle as it comes back down to draw the second part of the line, this then ruins the first layer of the print of the actual model. On the occasions where the material does not get caught by the nozzle, there is stringing between the nozzle and the end of the line which itself can cause the first part of the bottom layer to have problems.
should I include a retraction after the priming has finished as it travels to begin the print or would this cause under extrusion of the start of the model thereby defeating the purpose of the priming in the first place.
The gcode that makes the nozzle prime at the beginning of the print is as follows:
; Ender 3 Custom Start G-code
M104 S{material_print_temperature_layer_0} ; Set Extruder temperature
M140 S{material_bed_temperature_layer_0} ; Set Heat Bed temperature
M190 S{material_bed_temperature_layer_0} ; Wait for Heat Bed temperature
M109 S{material_print_temperature_layer_0} ; Wait for Extruder temperature
G28 ; Home all axes
G1 F1800 E-3 ; Retract filament 3 mm to prevent oozing
G29 ; BLTOUCH Mesh Generation
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X0.1 Y20 Z0.3 F5000.0 ; Move to start position
G1 X0.1 Y200.0 Z0.3 F1500.0 E15 ; Draw the first line
G1 X0.4 Y200.0 Z0.3 F5000.0 ; Move to side a little
G1 X0.4 Y20 Z0.3 F1500.0 E30 ; Draw the second line
G92 E0 ; Reset Extruder
G1 Z5.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed

I am using an Ender 3 running Marlin 1.1.9 with BlTouch Auto Leveling, With slicing done by CURA 3.5.6
Any suggestions you have for how to stop the priming problems will be greatly appreciated.

Does this happen regardless of the part being printed and the location of the initial line?  If so, consider just raising the hotend temperature 3 or 4 degrees.

Have you tried using a raft
I had the same issue on my mini delta when I first started printing with it. After checking and double checking the bed level I ended up discovering that using a raft base in Cura solved the issue.
It does use more plastic however I have had absolutely no issues with respect to sticking in the dozen or so prints since then.
Additionally it makes removing the print from the bed really easy as I'm not worried about damaging the print with a scraper.

The print for the main model does stick quite well to the bed because i use the Brim setting, its the line that extruded on the left before the main part is printed that makes sure there is enough filament in the nozzle, that I am having trouble with. One thing that might help you not have to use a raft base is to try using isopropanol alcohol to wipe down your bed, it massively improved how my prints stick to the bed. I was previously using window cleaner which I thought was good but after a while, prints wouldn't stick at all.

I use this:
https://www.amazon.co.uk/gp/product/B003D8QFQO/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1        and this:      https://www.amazon.co.uk/gp/product/B016Y59W4E/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

@Liam  My Cura code does a pre-extrusion just after doing the Z-axis zero and before moving to the start of the print, and not intended to touch the platform bed.  This priming extrusion happens 3 or 4 mm above zero, so the material just "floats" away.

What's the benefit of not touching the bed? I find that it massively increases the chance of the parts that aren't stuck down getting caught on the nozzle on the way back.


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How could I print a large sphere-like object?
I have a STL file with a rather large roughly-spherical object. I'd like to 3D print it to be fairly large, and hollow inside. Since the printer I'd be using has a max size of (18–20 cm)^3, I'd have to print this in pieces and then reassemble them into the sphere-like shape. The textured surface of the object is important, but small seams would seem unavoidable.
My Question
How could I 3D print a hollow sphere or sphere-like object that's too large for the available basic 3D printer?
Because this would need to be done in parts, it's more complicated than the designs I've made. Because the final product is roughly spherical and hollow (i.e. nothing is nicely angular), it's trickier than some other designs.
(I have little experience with 3D modelling/CAD, so I'd somewhat prefer solutions with minimal advanced steps such as designing my own joints and whatnot...but advanced steps are definitely okay if part of a great solution!)
My Ideas So Far
I know I could cut the sphere roughly in (e.g.) eighths via planar slices, print the eight pieces individually, but then the question is how to attach them. I am also concerned that the seams might be too noticeable. (Perhaps there's a better way?)
I could just glue the pieces together. My fear then is that it would lack internal structural support if they were attached only at the outer layer (unless the skin thickness were excessive, at least near the boundary).
I imagine I could give the pieces internal supports with dowel joints or snap-fit joints (e.g. these), but I lack knowledge of how to do that and don't know whether that would even work well.

You can also look around to see if you can find bigger printers available for use. Depending on where you live, you might find a Fablab with printers free to use on a first-come first-served basis, or fond a shop that has a bigger printer and would let you use it against a fee.

A sphere can be put together quarters easily, but those need support in the center. However, there is a slightly different cut is more economic:

Cut a top and bottom "plate" off, print them separately, the lower one "upside down"
Cut the remaining piece into quarters

For more equal printing, maybe even cut them along the equator too and print the lower half "upside down"

This way, the support material can be reduced to a minimum - only the top and bottom will need any support, and it is easily accessible to smooth it away.
If the walls would be something like one millimeter thick, any good glue should work. If you want to reduce the visible seam, you might bevel the faces, so that the wall has a little gap on the inner wall. As most glues shrink as they harden, it will flatten into the "gap", evening out the internal face.

I don't really understand what you mean by 'plate'?

@Sava I added a picture what I meant

Upvoted, very smart way of printing a big sphere!

if the sphere is really big, more divisions might be needed. My cut keeps the print orientation the same for all parts, no "turns"


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Dramatic failure of calibration print
I printed out this calibration shape from Thingiverse with an unexpectedly catastrophic failure.  It looks like there are a lot of things wrong here.

I used the Normal profile in Ultimaker Cura.
There's so much bad in this print that I'm not sure where to start.

It appears that walls weren't printed at all.
Resolution is way below par.
Overhangs are collapsing (not sure if that would be expected at those angles)
The in-filling is inconsistent and "blobby".

What printer are you using? Before going through all the steps outlined in the answers below, I would first do a thorough maintenance and cleaning of the printer, following the instructions provided by the manufacturer.

@Sava I've done that, it's a brand new printer.  I found a pre-configured version of Cura for this printer and using that made everything OK.  I'll figure out what is actually wrong at a later date.

The failure you are faicing is underextrusion. Underextrusion can have several reasons. Among the three most common I encountered in my printers:

The nozzle could be clogged, hindering flow (Very crushy, squishy prints after it worked fine before)

Dissemble the filament path till you can push an acupuncture needle through the hotend, heat it, press out all filament, reassemble.

The extruder might be skipping steps or shredding filament

check if it is just not gripping the filament, not turning at all or clicking.
real Troubleshooting might be needed

The g-code might have a bad setup for the filament you are using - try upping the higher extrusion multiplier/flow rate and print at least 2 walls!

In Ultimaker Cura: Custom > Material > Flow

If not there yet: Gear > Material > hook Flow

What's the extrusion multiplier?  Is it something I can set in Cura?

I've got settings for wall thickness, wall count and some for specifically top & bottom (https://imgur.com/s1mqhK0).

I have Material > Flow.  That's a 100%, should I up that a bit?

@BanksySan Yes, that is the setting. Try 105%. if that does nothing, your nozzle most likely is clogged.

On some printers there might be a spring or similar to push the filament towards the extruder. An untightened spring can also cause this behaviour (happened to me quite a few times)

The best thing that you can do first is find out whether you extrude the correct amount of filament before trying all sorts of things. You clearly have an under-extrusion problem. Please look into question: "How do I calibrate the extruder of my printer?".
The reason why you aren't extruding can be found in e.g. this answer. Note that the list in the answer excludes the stepper driver. If the current is too low, the torque is too low to push the filament (see this similar answer for stepper torque).

Side note:
Note that a properly setup extruder never has a need to adjust the flow unless the extruder is calibrated for 1.75 mm filament and the used filament is of different diameter.