text:
Anet A8 ignores extruder temperature?
I don't understand what's wrong with my G-code. I have set the printing temperature to 195 °C but when I try to print, the target temperature is always 0 °C and printing never starts.

I have tried changing material preset to different PLA profiles but that didn't help at all.
G-code:
;FLAVOR:RepRap
;TIME:1736
;Filament used: 0.676205m
;Layer height: 0.1
;Generated with Cura_SteamEngine 3.4.1
T0
M190 S50
M104 S195
M109 S195
M82 ;absolute extrusion mode
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G1 Z15.0 F9000 ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F9000
M117 Print0ng...
M83 ;relative extrusion mode
G1 F1500 E-6.5
;LAYER_COUNT:96
;LAYER:0
M107
G0 F600 X90.425 Y93.152 Z0.3
;TYPE:SKIRT
G1 F1500 E6.5
...

In addition, the extruder and heat sensor are working. An older G-code file correctly sets 200 °C as the target temperature for the extruder.

This G-code prints just fine
;FLAVOR:RepRap
;TIME:4628
;Filament used: 1.44191m
;Layer height: 0.15
;Generated with Cura_SteamEngine 3.4.1
T0
M190 S60
M104 S200
M109 S200
M82 ;absolute extrusion mode
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G1 Z15.0 F9000 ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F9000
M117 Print0ng...
M83 ;relative extrusion mode
G1 F1500 E-6.5
;LAYER_COUNT:80
;LAYER:0
M107
G0 F4800 X72.96 Y99.484 Z0.3
;TYPE:SKIRT
---

Note, I have never modified the firmware or changed anything except what I can change with the frontpanel.

What do you mean by "Target temperature" --> the displayed value on the screen?  Will the extruder start to move if you edit your code to M104 S0 M109 S0 ?  Have you tried more recent versions of Cura?   Oh, and what printer are you using, what firmware, etc.?

No, the extruder reads 25/0 on the A8 screen. As said in title, I have an Anet A8 printer. Target temperature is the temperature the extruder should reach before printing.

For troubleshooting further, I suggest to connect to the printer directly (What is a printer console/terminal?) and send M104 S200 or use the UI to set these. We also could help you in [chat] further.

I got the same problem today and after a lot of troubleshooting (following the answers here) I found out that the issue was the connection to the hotbed. After I clean out the connection to the hotbed the printer started working as usual. The debugging logic was that the printer heats up the hotbed before setting the extruder temperature.
Looking to your LCD the issue seems to be the same, since 33 degrees is a normal ambient temperature.

There is nothing wrong with the G-code, M109 S195 sets and waits for the temperature to reach the set point. There must be a different reason, other than G-code, why the temperature is not set correctly.
After updating your question by adding another G-code script, the conclusion is that there is nothing wrong with the G-code itself. The problem is that the printer cannot set the 195 °C temperature.
Could it be that the minimum temperature is 200 °C and that it doesn't set a temperature lower than the minimum value?
If you are comfortable enough to flash a new firmware (which you should always do with an Anet A8 as it has no thermal runaway protection) you could try to see if this is a firmware problem.

The thermistor is working, it's reading room temperature. The display shows 25 / 0 °C. The target temperature is wrong (0°C).

I never had any problem with lower temperature. I can try to set the temperature in Cura  to 200 but I know that I printed with 195°C before.

I have now loaded a gcode that has 200°C as target temperature and it shows 0° as well. As another test, I copied the starting gcode of the working file to the file that doesnt work and it still shows 0° ... I am out of ideas now on what to try.

@user6329530 sure looks like a flaky control board, leading to intermittent errors.  Just in case, clean and re-engage every connector -- especially the thermistor and heater cables.

How can that be a flanky control boad when the one gcode works and the other doesn't... where is the difference?

@user6329530 I thought you wrote that you retried a working file and it failed.  if that's not the case, then you may need to look at your gcode files in a good text editor and look for invisible (but bad) characters

Yeah that's what I was trying to say. I wonder why one gcode works and the other wont. I loaded the same model into Slic3r and had the same result (0° target). That's why I am lost. I can print the thing when I set the extruder temp to a fixed value in the control pannel but that results in overextrusion...

Double check the physical connection to the heating element and the thermistor that go in the hot end. Those wires and crimps aren't great. I had one fail on me out of the box with my A8. Re-crimping did the trick.

Be sure that you are using the version of Cura (14.07) that comes on the SD card provided with the printer.  I ran into this same thing after updating Cura, largely because it prompts you to when it starts.

You don't mention printing via a connected computer over USB, so I assume you're printing from an SD card. I think the most likely cause of your problem is a corrupted filesystem on the SD card, or bad SD card. I've had many occasions where my printer (Ender 3 with Marlin, stock and upgraded to 2.0) fails to see files or correctly read files despite them being readable when the SD card is put in a PC; I suspect the microcontroller library implementations of FAT filesystem reading are less tolerant of errors than real filesystem drivers on Windows, Linux, etc.
Try backing up all the files you care about on the SD card, reformatting it, and repopulting it with known-good files and see if the problem goes away.


text:
Monoprice Maker Select v2 stops extruding after about 200-300 mm
I've done a fair bit of looking around for an answer and have yet been unable to find one.
So here is my problem, after about 200-300 mm of extrusion, the PLA stops coming through the nozzle. When I pull the PLA out it looks like this. There are teeth marks going up the PLA and end with a small divot. The head of the PLA is slightly thicker than the rest of the PLA; approximately 1.9 mm.

I first noticed this when I thought that only the bottom layer was being printed. I moved to printing a small bullet and I got about halfway through the print before it stopped extruding.
Next I raised the Z position to about 100 mm to give me some room to work and I manually moved the PLA through the extruder with the dial. No problems until I hit the 200 mm mark or so. I've done this test 4 times now and failed at the approximate locations: 208 mm, 280 mm, 250 mm, and 325 mm.
Settings:

Nozzle: 200 °C
Bed: 60 °C
Layer Height: 0.15 mm

Other things I have tried with seemingly no effect:

Turning off/on print cooling
reducing retraction to 2 mm from 6 mm
yelling out in frustration
reformatting the SD card (because who knows?)
brand new filament, older filament, middle aged filament

Welcome to 3dPrinting.SE! Definitely a +1 for yelling at your printer/print :o)

Good that you have told us how much you managed to extrude each time... When you pushed to these points, what did happen? Can you show us a photo of a print-result where it?

Does the extruder stepper try to move? Did you try to push the filament by hand?

Looking at the tread pattern on the filament, I think it's getting stuck. Note that the teeth marks get closer together as you go up the fillament, and the last one is a big divot, that looks like the gear trying to grab at it, and being unable to move it.
Are you seeing any drops in nozzle temp? I had a cooling fan kick in and drop temps low enough to prevent extrusion before.
Edit
From the discussion in the notes, heat creep was identified as a possible culprit, and seems most likely.

good point... clog?

@Trish clog wouldn't have the consistent behavior of working for some amount, then stopping. It's something about the printer's behavior that kicks in.. there's nothing repetitively cumulative about what it does otherwise.

true... a broken nozzle that generates blockage (similar to a clog) or bad heating behavior?

No temperature drops that I was able to notice. It stayed pretty consistent while I was doing the test.

My money's on the heating behavior. A nozzle that misbehaves wouldn't generate FOD, so it should still continue to extrude.

Alternatively - it could be heat creep. If the filament gets too soft by the gear, then it gets harder to push the filament down, and at some temp, impossible.

so, i might have just fixed it. Im doing a test print to see. I think the culprit is heat creep. When I put the print head back together I put the heat sync on backwards. (smart, i know). I think because the heat sync was on backwards it wasnt dissipating the heat as well, so i was getting melt higher up the PLA, which made it too fat to be able to continue extruding. This explains the pattern on the PLA as well.

That would definitely do it.

Did a few test prints and they came out successful! Thank you so much. I guess the heat creep softened the PLA which made it bunch up on one side and made it so that the teeth couldnt push the PLA down.

source: Stack Exchange

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sort: votes


text:
Is this hot end salvageable?
Kicked off the second long print in a series (printing Lack enclosure components). First 10 hour print was flawless. Started this one, saw the first layer laid down well, went to bed. Woke up to this (you can see the successful prints in the background):

The whole heater block and nozzle is entombed in PLA. The leads to the heater and the thermistor are too. I'm assuming there's no solvent for this, and I'm better off just buying a new hot end.
Thoughts?

Wow, that's just ugly! ;-) I think this is going to be situation dependent solution ... If I were you, I'd just see if I could start removing filament a chunk at a time. If you can get them cleared, all the better. If you can't without destroying the hot end parts, back to the drawing board. You'll need to get the mess cleared before you can get new parts on there anyway, so might as well have at it. The real question here is, why did it putz up?? ... I guess the tape is a good indicator here.

i think the tape looking that way is a consequence, not the cause. not pictured is a piece of the print that was on it originally, found next to the bed. whenever it got knocked off, it took the tape with it.

Pull out the Dremel and have at it, I'd suggest?

@Pᴀᴜʟsᴛᴇʀ2 Only if you don't value your hotend... or know exaclty where it is. Heat and pull down.

Next time put a sock on the hot end so this doesn't happen.

@user77232 you mean like a silicone cover?

@kolosy, yes a silicone sock.

@user77232 yeah, had one. it's inside that blob.

@kolsy, wow make it even more amazing. Wish we had time lapse of that blob forming.

Yes
I had a somewhat similar clog once, and I could fix it back up. However, it is a lot of work.
Hobbyist Way
Step 1: heat
As long as the heater cartridge is still ok, just fire up the printer, move up the print head by 50 mm and wait some two or three minutes till the goop is warmed enough at the core to melt. Set the hot end to 200 °C and no cooling fan.
Step 2: rough clean
Check the cables for your hot end and thermistor as long as the plastic has not yet softened up around them and especially surrounding the thermistor: When the glob is removed in one swoop, you might tear the lines! It's better to use a sculpting tool or exacto-blade on the softening plastic and make an opening that allows the glob to be pulled away safely with minimal pull on the cabling.
When the blob has softened enough, you can just pull at the outer of the blob to pull it down. Use a tool like pliers and pull off the worst that still sticks to the hotend. Pulling the blob free can take a while, so be patient and careful.
If you have a soldering iron, you can use that as a heated scraper from the outside and skip on heating from the inside. If you have no temperature control (as if your thermosensor is shot) outside heat is the only safe way.
Step 3: Cool down
After having made a rough clean up from the outside, let it cool down so you can dismantle it.
Step 4: dismantle and clean the hotend.
This is actually rather simple, and I will point to a question where I outlined that for a broken thermistor cartridge. You have a working thermosensor at least, so less problems on that front.
Shortcut
If you have a hot air gun for hot air soldering, you can be much faster! Skip step 1 to 3, dismantle the hotend and go straight to Step 4, dismantling it and cleaning it out of the machine with the hot air soldering tool as a heat source. Heat and scrape away, and get out the thermosensor and thermosensor as soon as possible to prevent destroying them.

Can a hairdryer substitute for the hot air gun? In my experience it's plenty hot to soften PLA to let you deform/reshape it, but I'm not sure how helpful that'd be in removing it. I would think a hairdryer would be safer to avoid damaging the printer in the process.

@R..GitHubSTOPHELPINGICE In a pitc, probably, but you want to melt an awful lot of plastic... a typical hairdryer gets 140 °F = 60°C, enough to make PLA somewhat malable on the surface. A hot ar gun gets considerably more - 350 °C is usually a given.

Careful application of a hot air gun, along with mechanical prodding (pliers, pokey sharp stick tool) will soften the PLA. It will soften on the outside but the heat transfers inward rather easily and quickly and is retained for some time.
When heating and poking, force the mass downwards and then away from the heater block. If the outside becomes liquid, too much heat is being applied and may damage other components.
An SMT soldering station with adjustable temperature and airflow rates would be ideal, but a garden-variety hot air gun with a concentrating tip could be used effectively.

hot air... is a solution but not while the printhead is installed - you'd burn the other parts to smithereens.

Yeah, I have an SMD rework station 2 feet left of the printer :)

@kolosy If you use that, first dismantle the hotend.

If you can remove the hot-end it is easier.  If not, carefully use hot air to soften (not melt) the PLA so you can more easily pull away chunks.
When the hot-end is removed from the other plastic parts, you can get more aggressive with hot air.  BUT, be careful of the thermistor and heater wires.  They are fragile, and can easily be broken or pulled out of their devices.
Heat and patience is the key.  If you do break a heater or thermister, they are pretty easy to replace.  Depending on the hot-end, the heater and/or the thermister may be locked in place by a set screw.  That set-screw is probably locked in place by plastic, so use the hot-air gun to melt that plastic and allow you to back out the set-screw.

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text:
MKS 12864OLED Display setup
I've bought MKS 12864OLED and connected to my DIY 3d printer with Mega/RAMPS combination. In Marlin's configuration.h file there are these lines to uncomment:
// MKS OLED 1.3" 128 × 64 FULL GRAPHICS CONTROLLER
// http://reprap.org/wiki/MKS_12864OLED
//
// Tiny, but very sharp OLED display
//
//#define MKS_12864OLED          // Uses the SH1106 controller (default)
//#define MKS_12864OLED_SSD1306  // Uses the SSD1306 controller

I'm not sure to choose between 'SH1106' or 'SSD1306'... either way, the LCD module is not working.

Maybe you need to set more constants? E.g: #define U8GLIB_SSD1306? Also post a picture of your module front and back, e.g. is it exactly the same?

if I uncomment that too,it says: #error "Please select no more than one LCD controller option."

Are you aware that your module is different than the MKS from RepRap.org? You have a 0.96" display, the MKS is 1.3".

AFAICT, he has a https://www.reprap.me/mks-12864-oled-0-96in.html

First of all let me state that I do not own the module! The analysis below is based on old patches that worked in a version of Marlin in 2015, and translated to the latest version of Marlin of the 1.1.x branch. This is 1.1.9; this is the last version of the 1.1.x branch, all new development takes place in branch bugfix-2.0.x (dated May 2019).

The reported patches are compatible with an earlier version of Marlin Firmware (a version from 2015). Clearly this doesn't work anymore, but that should not be a problem, if it worked then it should work now provided we configure it correctly. The display you have requires U8GLIB_SSD1306, so the U8GLIB library need to be installed in your Arduino IDE!
Let's follow this installation guide for the older version as an example.
First, from patch 1 it becomes clear that you'll need to define that you are using a display that is identified by its name/type, you should uncomment the following line in your configuration.h in the section:

//=============================================================================
//======================== LCD / Controller Selection =========================
//========================   (Character-based LCDs)   =========================
//=============================================================================

//#define MKS_12864OLED_SSD1306  // Uses the SSD1306 controller

to:

#define MKS_12864OLED_SSD1306  // Uses the SSD1306 controller

as you are using the SSD1306 controller according to this reference.
That is about the only thing you add in the configuration.h file! You only activate the name of the controller type (as in defining a constant) so that it is caught in other source or header files to do/trigger something.
With this change, you automatically activated the rest of patch as that is implemented in Conditionals_LCD.h!
Next, we need to address patch 2. This is addressed in ultralcd_impl_DOGM.h; here you will find:

#elif ENABLED(MKS_12864OLED_SSD1306)
  // MKS 128x64 (SSD1306) OLED I2C LCD
  U8GLIB_SSD1306_128X64 u8g(DOGLCD_SCK, DOGLCD_MOSI, DOGLCD_CS, DOGLCD_A0);      // 8 stripes
  //U8GLIB_SSD1306_128X64_2X u8g(DOGLCD_SCK, DOGLCD_MOSI, DOGLCD_CS, DOGLCD_A0); // 4 stripes
which clearly differs from the patch:

U8GLIB_SSD1306_128X64 u8g(23, 17, 16, 25); // SW SPI Com: SCK = 23, MOSI = 17, CS = 16, A0 = 25

as such that it uses numbers instead of constants. So we need to define these constants first. These constants are defined by the board you are using, more specifically the pin layout.
Looking at the pin layout of your RAMPS board:

      #if ENABLED(MKS_12864OLED) || ENABLED(MKS_12864OLED_SSD1306)
        #define LCD_PINS_DC     25   // Set as output on init
        #define LCD_PINS_RS     27   // Pull low for 1s to init
        // DOGM SPI LCD Support
        #define DOGLCD_CS       16
        #define DOGLCD_MOSI     17
        #define DOGLCD_SCK      23
        #define DOGLCD_A0       LCD_PINS_DC

you'll find that the pins are correctly configured with the fore mentioned:
U8GLIB_SSD1306_128X64 u8g(DOGLCD_SCK, DOGLCD_MOSI, DOGLCD_CS, DOGLCD_A0);      // 8 stripes

We move on to patch 3. This patch deals with the reset/initialization of the OLED display. This is also already taken care of in ultralcd_impl_DOGM.h:

  #if PIN_EXISTS(LCD_RESET)
    OUT_WRITE(LCD_RESET_PIN, LOW); // perform a clean hardware reset
    _delay_ms(5);
    OUT_WRITE(LCD_RESET_PIN, HIGH);
    _delay_ms(5); // delay to allow the display to initalize
  #endif

Next to patch 4, in pins_RAMPS.h you see that pin 25 and 27 are correctly defined (apart from the name LCD_PINS_RST, now without T, but that is fine!):
  #if ENABLED(MKS_12864OLED) || ENABLED(MKS_12864OLED_SSD1306)
    #define LCD_PINS_DC     25   // Set as output on init
    #define LCD_PINS_RS     27   // Pull low for 1s to init

The only difference is that pins
    #define LCD_PINS_D5
    #define LCD_PINS_D6

are not set to -1, so to be consistent, you should change pins_RAMPS.h to:

      #if ENABLED(MKS_12864OLED) || ENABLED(MKS_12864OLED_SSD1306)
        #define LCD_PINS_DC     25   // Set as output on init
        #define LCD_PINS_RS     27   // Pull low for 1s to init
        // DOGM SPI LCD Support
        #define DOGLCD_CS       16
        #define DOGLCD_MOSI     17
        #define DOGLCD_SCK      23
        #define DOGLCD_A0       LCD_PINS_DC
        #define LCD_PINS_D5     -1
        #define LCD_PINS_D6     -1
      #else
        #define LCD_PINS_RS     16
        #define LCD_PINS_ENABLE 17
        #define LCD_PINS_D4     23
        #define LCD_PINS_D5     25
        #define LCD_PINS_D6     27
      #endif

A conclusion from the analysis above is that you enable the display in your configuration file and add the 2 values of -1 for D5 and D6, but I don't think they cause problems if they're not initialized to -1. Be sure that the cables are connected correctly. Some modules have reported upside down connectors.


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Ender 3 print is skipping and dragging up base print lines

I have only been able to get my prints this far. They just can’t stop skipping pulling material up towards the nozzle which then melts pulls of another random bit. At first I thought it was motor skipping, so I strengthened the spring, but even after that and calibrating the bed, I couldn’t figure out exactly how to fix this issue. Hopefully someone has some idea what is wrong.

Your question comes down to insufficient bed adhesion, there are a lot of questions related to that issue. You could start with proper leveling and nozzle to bed distance or using a glue stick.

Don't overlap the blue tape, that is REALLY bad. Some lines do seem to overlap. And I was much happier with the BuildTak clone than I could ever be with the blue tape. Plus,if you really want to work with blue tape, pay it down in the Y direction, so the edges don'T scrub at the frame and induce layer shifting.

It's probably bed adhesion, and that can be related to bed temperature, accuracy of Z-axis zeroing, correct extrusion rate for first layer...

@Trish - Most things I've read suggest putting the tape at an angle to the bed. Definitely should NOT be overlapped, though.

What temperatures/type of plastic are you using?

I’m using PLA at 205 with a bed heat at 60. It’s what I was told I should use, so I figured that would work.

Thank you guys for your input, I will try your fixes as soon as I get some free time and let you know which of them was the right fix

It's all black magic, and best settings are machine-dependent.  I've heard from other forums that any temp above 50C will reduce the adhesive strength of the blue tape.  It depends a lot on the accuracy of the temperature sensor and the uniformity of temperature across the print bed.

So, contrary to what people were saying, my problem came from my spring that controlled filament flow. There was too much tension and it caused motor skipping. I did get rid of the overlap with the blue tape, but otherwise I had to clamp down my spring and that fixed the issue.

I would get rid of the blue tape and go with glass and hairspray. Glass gives you more of a flat surface. You are printing with the aluminum build plate which over time c
an warp. The glass with give you a much flatter and level surface to print om. Blue Tape is actually not a great surface to print on. Hairspray using a chemical compound that actually is related to a PLA makeup. This compound in Aquanet Hairspray will bond to the PLA and release when cold. Using both the glass and hairspray will give you and even build plate and a clean smooth surface that it will stick to better than blue tape.

Hi Aaron, and welcome to SE 3D Printing! Whilst your answer may be technically correct, it is rather terse, and, as such, it has been recommended for deletion, unfortunately. If you could expand it then you may get a more positive response. I would recommend that in addition to reading some highly voted answers to gauge the standard expected, that you take a look at the help section relating to answering questions, in particular [answer], and take the [tour] for more information on how stack exchange works. Thanks :-)

the "chemical compound" in hairspray is PVA, which is the same material as in PVA filament, wood glue, glue stick and 3d Lac


text:
OpenSCAD editor font is unreadable
I am a new OpenSCAD user. My screen editor window is using a very strange font that I cannot read. How can I fix it? I just installed OpenSCAD on my Linux Manjaro computer.
This is a screen shot of my screen for the first example in the examples folder.

Have you tried to change the font via:
Edit -> Preferences -> Editor -> Change to a different font using the combo drop down box?


text:
Delta Printer: After Calibration X and Y Axis are slightly different
I noticed that my x axis is slightly longer than my y axis (~0.6%) if I print an object. What parameter in Marlin can be tuned to correct such issues? The rod length parameter seems to rather influence the overall scaling of the object. The other parameters such as Txyz and Exyz influence the flatness according to the bed. I noticed, on the firmware of the Duet there is a gcode command for this particular issue, which I haven't found in Marlin yet.

I have the feeling (after reading the config file) it might be DELTA_DIAGONAL_ROD_TRIM_TOWER in https://github.com/MarlinFirmware/Marlin/blob/bugfix-2.0.x/Marlin/src/config/examples/delta/kossel_xl/Configuration.h#L626
I guess there is no info whether this value can be tuned via menu ..

This might be a duplicate of Delta printer nozzle not moving square with a perfectly level bed (as if the bed is bent... but it isn't), but I'm not sure. Is yours a different issue?

I think that you probably need to adjust the following two parameters in the Marlin firmware, in configuration.h:

MANUAL_HOME_Z_POS, and;
DELTA_SMOOTH_ROD_OFFSET

See my answer to Delta printer nozzle not moving square with a perfectly level bed (as if the bed is bent... but it isn't).


text:
False "Object does not fit into print volume" warning from OctoPrint
Octoprint warns me that the objects do not fit into the print volume. I noticed that this happens after a power-off cycle. Since I was overly anxious until today, I always uploaded the GCode file again and it didn't complain any more.
Of course, always uploading the files again is also error prone. So today I gave it a try and simply started to print the object. As far as I can tell, it prints nicely.

Image: Octoprint saying something like "Object does not fit into print volume" in German

Is this a known bug in OctoPrint? Are my files really damaged after a power off cycle?
The values (0.00, -3.00, 0.00) seem to be constant in this error message, no matter what object I want to print.
I'm using OctoPrint in the PrusaPrint flavor and I'm running version 1.3.10 (hopefully a recent version, since I usually update). I generate the G-Code with Slic3r.

The chance of corrupting a gcode file during upload is extremely small.  If you are in fact getting errors there,  you may want to check your connectors and the quality of power supply for the printer circuit board.   But as the answer points out, you don't actually have a problem with volume dimensions.

That's the purging that Slic3r PE adds, the broad line of filament at the edge of the sheet. That is outside the official print volume, which triggers this error.
The G-Code generated by Slic3r PE at the start of the file contains the following lines:
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 X60.0 E9.0  F1000.0 ; intro line
M73 Q0 S174
M73 P0 R173
G1 X100.0 E12.5  F1000.0 ; intro line
G92 E0.0

You can see that it explicitly goes to -3 on the Y axis, and then extrudes two times on a line along the X axis.
The model size detection is labeled as beta in the settings dialog. It's not very reliable at detecting stuff like this purging line outside the boundaries.

This answer is correct, it's normal for Prusa printers to purge at -3 mm on the Y axis.
This answer is an addition that describes how to get rid of the error.

Open Octoprint web UI
Go to Settings -> Printer Profiles
Find active profile, click on the pen icon next to it (Edit Profile)
Go to Print bed and build volume
Tick Custom bounding box
Enter -3 to Y Coordinates Min input box
Hit Confirm


text:
Main board heated bed connectors aren't powering up
Flsun 3D Cube; Marlin 1.1.1; main board: Makerbase MKS Gen_L V1.0; running from either Repetier or OctoPrint.
I was recently obliged to replace the main board when it stopped powering the heated bed. I got the new main board - same make, version, etc - got everything setup just as it was before, but the bed still doesn't heat. Multimeter shows zero across the board's heat bed contacts, whether using G-code from the terminal (in both Repetier and Octoprint), G-code in the print file, or the control panel on the front of the printer. The thermistor works: if I shine a heat lamp on the bed, it registers the temp change.
Bad board? Something in the Merlin config I missed? Is the board smart enough to not power it on if the bed heater itself is bad?

Welcome to 3dPrinting.SE! You state "Marlin 1.1.1" ... is that correct? Marlin 1.1.9 is the most current stable version. You might try loading it and seeing if the issue still exists.

One of the prime rules of problem-solving: don't assume a cause.  In this case, that means don't replace a board until you know it is actually the reason you're not heating.

Do any other outputs (e.g. xyz drives) work?

@CarlWitthoft 1. Good advice for any situation. Not replacing the board (in other words: spending more money) until I'm sure.

All other outputs work: the printer functions normally otherwise. My prints are curling on the corners, so I am motivated to fix the bed.

have you solve Your problem? I have the same issue with bed heating in the same printer. Everything works great till today. When I set up heating the LED on board turn on, but I don't have any voltage on pins.

I solved it by switching to an MKS GEN L v1.4 with an external mosfet. The MKS boards just don't have the oomph to drive a heated bed for any length of time.

Considering:

Multimeter shows zero across the board's heat bed contacts

this implies that

If you measured resistance, the heated bed has no resistance. Basically this implies that the bed has a short. This might be the reason why it is not working. If you would power it as such you create a short. Instead of replacing the board, you need to replace the heated bed. Typical values for a heated bed of about 200 x 200 mm are in the order of 1.2 Ω (measurements between 0.9 and 1.5 Ω are reasonable to be expected).
If you measured voltage, the heated bed does not receive power for heating, or the power does not reach the bed (not turned on or broken wire?). It would then be wise to measure the resistance (of the bed and the wires). If the resistance is in the order of about 1.2 Ω (see above) for the bed, you could try to connect the heated bed directly to the PSU to see if it gets warm, if so, please disconnect immediately to prevent damage. From this experiment you can find whether the heated bed is broken (or the cables), or that the board is not functioning correctly, this is, however, strange as you tried 2 boards. A possible suspect could be the MOSFET that schedules the powering of the heated bed if you use an external MOSFET board that it.
If you measured current, then you found out that no power is delivered to the board, but you also might have broken your board in the process, as measuring current is a (close to) 0 Ω connection and has to be done in line of a circuit.

Perhaps the multimeter was in voltage measuring mode. The question doesn't say they were measuring resistance.

@TomvanderZanden Good point! Updated the answer to include both.

But it's unlikely the same MOSFET would be bad on both boards  (if the power MOSFET isn't on the board he replaced, then ignore this comment)

@CarlWitthoft The question does not state the use of an external MOSFET, good to make that clear

1: The MKS GenL is a purpose-built board, nothing external.
2: With the bed (supposedly) heating (issued M140 S60, response OK), I measured DC voltage on the board's heated bed connector, as shown in this image: postimg.cc/jD5Sbhtj

More info: put 12V to the bed and it began heating. Multimeter on 200Ω measured .5. Anything higher than that was zero.

Since the bed was warm when you connected to 12 V that means the bed and the wiring are good. It sounds like your multimeter is not too accurate, with a reading of 0.5 Ω (or you measured accidentally some other circuit), but no worries.
Since both boards do not power the bed, it seems like it could be a firmware setting. To help with that, a look at your config file, and possibly the pins_ramps.h file can help.
As a first check, your mks_gen_L.h file should look like this;
    #if HOTENDS > 2 || E_STEPPERS > 2
  #error "MKS GEN L supports up to 2 hotends / E-steppers. Comment out this line to continue."
#endif

#define BOARD_NAME "MKS GEN L"

//
// Heaters / Fans
//
// Power outputs EFBF or EFBE
#define MOSFET_D_PIN 7

//
// CS Pins wired to avoid conflict with the LCD
// See https://www.thingiverse.com/asset:66604
//

#ifndef X_CS_PIN
  #define X_CS_PIN 59
#endif

#ifndef Y_CS_PIN
  #define Y_CS_PIN 63
#endif

#include "pins_RAMPS.h"

Now all you need to confirm is that your bed is hooked to D7.

the main part is good, but I have experienced a lot of people just having problems how to measure the resistance correctly.

@yellow I'm grateful for the firmware comment: when I upgrade to the latest version of Marlin (in about a week when I get new stepper drivers; I'm going to do everything at once) I may well have to know that. However, the original board WAS powering the bed, and then stopped; I can see on the board where the connection failed. At the time it was still running the original firmware, and no other changes had been made.

@Trish This is quite likely. I'm currently attending the University of Google, and the class content isn't always clear. "A Beginner's Guide To..." articles are rarely vetted by actual beginners.

@BillinKansasCity how about having a talk about that in [chat]?

@Trish At your convenience. I'm back at my desk and available.


text:
Upgrade main board or straight-across replace?
Flsun 3D Cube; main board, MKS GEN L V1.0
I think I need to replace the main board and I don't know enough about 3D printer components yet to judge whether a 1:1 replacement would be better than selecting a different board, or keep the same board but with upgraded stepper drivers?
I've been able to do everything I've wanted with the printer as it was out of the box, so I have no complaints about the main board (aside from no longer heating the bed). I don't need the biggest-baddest board out there. I just don't know how to judge the pros and cons of my choices here.

Are you asking about replacement of the board or seek troubleshooting advice to conclude that you need to replace the board? You wrote a lot, but I guess the most interesting part is that the heated bed is not working anymore.

The heated bed is being dealt with in another post. I'm thinking about upgrading or replacing or something regardless. I just don't know how to make my choices.


text:
The BLTouch is hitting the bed on the double-probing
When double-probing, sometimes the BLTouch will hit the bed before the z-axis goes down:

The BLTouch deploys
The bed goes up
The sensor triggers
The BLTouch stows
The BLTouch deploys and crashes the bed before the z-axis goes down for the second probe

It happens only on the second probe of double-probing (slow speed) - the bed can't move out of the way fast enough.
This happens in 2/16 probe points.
Probe Accuracy Test result:

Mean: 0.023075 mm
Min: 0.018 mm
Max: 0.027 mm
Range: 0.008 mm
Standard Deviation: 0.002584 mm

Hello David, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept (after 48 hours) your own solution. Thank you!

Sounds like the height the printer is supposed to go to before second probe is too low.

First, make sure to check if stow, deploy and the trigger are working correctly.
Second, check the pins files to make sure you put it in the correct pins. Black and White probe pin might need to go to Z-min or probe pin depending on. Make sure to check that.
Third, add "BLTOUCH delay". It might be triggering too slow or too fast for the next one to react. So after the first trigger, there should be a time for it to "re-setup" for the second. But if there is no time to do that then it won't trigger.
To add examples: If you have SKR 1.4 Turbo, then use BLTouch probe pins (black and white) on the board. IT will NOT recognize. You have to use Z-min endstop pins. Reason for this?:
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN

If this has been used, Z-min probe will use Z-min endstop pin instead of Z-min probe.

In case someone still has this problem I have a solution for what happened in my case.
I am using a 3DTouch and I also encountered the same problem and it was solved by commenting //#define BLTOUCH_HS_MODE

The High Speed mode is not recommended, so indeed this line must be commented out.

Welcome, and please take the tour.

I solved the same issue.
I had the same problem, just send the G-code M502 to your printer through Cura or whatever it is you use. The reason is that you already did an auto bed leveling and you more than likely send the G-code M500 which saves your auto mesh data so that you don't have to auto home for every print.
So M502 restores everything to its factory settings after you reset don't forget to send M500 to save the default settings or else your printer will be fixed up until the next time you turn it on and you'll have to start all over again hope this helps.

This sounds like the firmware setting for your BLtouch is not set up properly. Look at the line in Config H where it deploys the BLtouch. make sure nothing is commented out and that the 2nd deploy is shown.

"2nd deploy is shown", Can you be a bit more specific about this?

Could you expand upon your answer please?

If the 2nd Deploy is shown on the line make sure that line is not commented out. Remove the "#" in front of the 2nd Deploy to activate that line.


text:
Connecting OLED 128x64 LCD; dogm_lcd_implementation.h is missing for patching
I'm trying to install a MKS 12864 0.96 OLED for my DIY 3D printer (see this other question).
It's not listed in Marlin's LCD section of configuration.h and according to some instructions, I need to do some modification to a file  named dogm_lcd_implementation.h which is missing in Marlin 1.1.9!
Where is it? How can I install my LCD module?

Question History
An answer on your previous question discusses patches for installing the LCD module in your Marlin printer firmware. Note that these patches are very old (around 2015). Many things have changed since then (as is acknowledged there). That answer does not work for recent versions of Marlin source code!
Answer
Yes, your observation of the dogm_lcd_implementation.h file being missing in the 1.1.9 version of Marlin is correct. But, I believe it is not lost, all code and further development can be found in ultralcd_impl_DOGM.h. There are some older versions of the file wondering over internet, e.g. here or from this older Marlin cloned repository.
I believe that your 2nd patch:

/*---------------MKS OLED patch_2-----------------------*/
#elif defined(U8GLIB_SSD1306)
U8GLIB_SSD1306_128X64 u8g(23, 17, 16, 25); // SW SPI Com: SCK = 23, MOSI = 17, CS = 16, A0 = 25
/*---------------MKS OLED patch_2-----------------------*/

should be placed in ultralcd_impl_DOGM.h just under:

#elif ENABLED(MINIPANEL)
  // The MINIPanel display
  //U8GLIB_MINI12864 u8g(DOGLCD_CS, DOGLCD_A0);  // 8 stripes
  U8GLIB_MINI12864_2X u8g(DOGLCD_CS, DOGLCD_A0); // 4 stripes

and before:

#else
  // for regular DOGM128 display with HW-SPI
  //U8GLIB_DOGM128 u8g(DOGLCD_CS, DOGLCD_A0);  // HW-SPI Com: CS, A0  // 8 stripes
  U8GLIB_DOGM128_2X u8g(DOGLCD_CS, DOGLCD_A0);  // HW-SPI Com: CS, A0 // 4 stripes
#endif

to create:

#elif ENABLED(MINIPANEL)
  // The MINIPanel display
  //U8GLIB_MINI12864 u8g(DOGLCD_CS, DOGLCD_A0);  // 8 stripes
  U8GLIB_MINI12864_2X u8g(DOGLCD_CS, DOGLCD_A0); // 4 stripes
#elif ENABLED(U8GLIB_SSD1306)
  // SW SPI Com: SCK = 23, MOSI = 17, CS = 16, A0 = 25
  U8GLIB_SSD1306_128X64 u8g(23, 17, 16, 25);
#else
  // for regular DOGM128 display with HW-SPI
  //U8GLIB_DOGM128 u8g(DOGLCD_CS, DOGLCD_A0);  // HW-SPI Com: CS, A0  // 8 stripes
  U8GLIB_DOGM128_2X u8g(DOGLCD_CS, DOGLCD_A0);  // HW-SPI Com: CS, A0 // 4 stripes
#endif

Do note that there already exists an entry for U8GLIB_SSD1306! This has to be deleted, or you need to put the code in that section (un-commenting existing code)!
E.g.

#elif ENABLED(U8GLIB_SSD1306)
  // Generic support for SSD1306 OLED I2C LCDs
  //U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE | U8G_I2C_OPT_FAST);  // 8 stripes
  U8GLIB_SSD1306_128X64_2X u8g(U8G_I2C_OPT_NONE | U8G_I2C_OPT_FAST); // 4 stripes

could be altered to:

#elif ENABLED(U8GLIB_SSD1306)
  // Generic support for SSD1306 OLED I2C LCDs
  //U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE | U8G_I2C_OPT_FAST);  // 8 stripes
  //U8GLIB_SSD1306_128X64_2X u8g(U8G_I2C_OPT_NONE | U8G_I2C_OPT_FAST); // 4 stripes
  // SW SPI Com: SCK = 23, MOSI = 17, CS = 16, A0 = 25
  U8GLIB_SSD1306_128X64 u8g(23, 17, 16, 25);

There are several lines in "ultralcd_impl_DOGM.h" where 'U8GLIB_SSD1306' is mentioned... Should I uncomment all of them or only your E.g?

with your new instruction for patch 2, I get this error:   #error "Please select no more than one LCD controller option."

@2012User That could imply that you have another LCD controller enabled in your configuration file.

I've uncommented every line in "lcd/controller selection" part of configuration.h!


text:
My 3D prints don't end up the same as the model
I'm trying to print a very simple item that I created in blender:

However, the print always ends up being a simple "plane" with some scribbely stuff on top

Please add (by [edit] of your question) an image of the stl in a slicer software and a photo of the end-product. Please note that Blender has proven (from other questions at 3DPrinting.SE) to be not a very good tool for designing parts.

I will add the requested parts when I get back home. Can you recommend software for designing parts?

This is not a recommendations site, but if you are prepared to learn how to use Blender, maybe you should look at Fusion 360.

@Anton Let me reevaluate 0scar's note a little: Blender has been proven to be at times  problematic when it comes to creating non-manifold objects, but if used carefully can be perfectly fine to make modeling. However, for dimensional designing, you may want to use something like a CAD Program. I personally like Fusion 360, which is at times a little complicated, but have worked with Design Spark Mechanical, which is a little simpler and liked it. also, angus has one more https://www.youtube.com/watch?v=Cuqao90C76U&t=0s

@Anton If Fusion360 isn't your thing and you're into programing, you may feel comfortable with OpensCAD.

Sorry I did not intend to break the rules, but the conversation was going that way. My primary question really is though, that the 3d stl file that I've created looks the same in all visualizaiton softwares, and even the printer software. But the outcome is not what is represented in these programs.

Anton, you should view the results of your slicing tool in "Layer mode" . That will at least show you whether the slicing algorithm was able to interpret your STL model correctly.

"Scribbely stuff" sounds like you have a layer adhesion problem with the printer, rather than a problem with your STL file. Can you [edit] your question and include a photo of the print, and details about your printer: what printer, what material, what slicer, slicer settings, etc.


text:
Is there proof that 3D printer made nanoparticles are dangerous?
Facts:

Breaking down (or melting) plastic creates nanoparticles.1
3D printers melt plastic.2
Therefore, 3D printers make nanoparticles.3
Nanoparticles are evil.[citation needed]

Wait, What?

1. Plastic waste disintegrates into nanoparticles
2. How do 3D printers work?
3. Characterization of particle emissions from consumer fused deposition modeling 3D printers

I know that 3D printers make nanoparticles. But is that actually a safety concern? There are multiple products on the market today that will suck up your nanoparticles for you. However, I can't see an obvious danger in the particles themselves. Who decided that these nanoparticles are bad for your health? 3D printers put out plenty of heat too, but nobody thinks that's dangerous.
So my question: Does anyone know of sources/research articles of the possible harmful effects of nanoparticles created by 3D printing? I'm looking for real scientific research. Thanks.

Your fact three isn't really a "therefore" in the deductive sense. The paper you link to is about measuring the emissions empirically.

@DanHulme, you can read it as: Therefore, 3D printers make nanoparticles-(proof 3D printers make nanoparticles)

After answering, re-reading, editing, re-reading again, and re-editing, I wonder if this is relevant to this SE group?  Perhaps the red herring of 3D printing could be removed, and the question moved to a more appropriate SE site?

The dose makes the poison.

I'm voting to close this question as off-topic because this belongs on some health or hazmat site.

@CarlWitthoft, the question refers to the nanoparticles created from 3D printers.

It's also good to keep in mind that lots of things will melt plastic, and therefore there's a certain amount of background nano-plastic in any modern society. So even if nano-plastics turn out to be just awful for human bodies, and 3D printers do create them, you haven't shown that 3D printers will appreciably increase the "normal" background concentration.

@JoelCoehoorn, look at my 3rd link. 3D printers definitely increase background concentration. We do not really use any other devices that intentionally melt plastic. However, you may be right that the increase may not be an appreciable health risk; that was part of my question.

At the time of this writing (March 2019), I don't think theres any study on the health effects of nanoparticles emmitted by 3D Printers. The general consensus seems to be right now that those particles are potentially harmful, as they build up in the lungs, and therefore precautions should be taken.
The reason why nobody has yet determined if and how harmful they are, might be that those adverse health effects are probably long term, and hard to isolate. Plastic is everywhere today - it's not that easy to just study harmful health effects caused by 3D printers.
But we can say for sure that plastic in our bodies isn't ideal and can cause damage, so we should avoid it.

Perhaps FDM 3D printing does emit nanoparticles during the process of printing, but the syllogism does not prove it or even suggest it.
Parenthetically, your headline is not actually addressed by the body of your question.  As an answerer, I have been misled by other questions which seemed clear enough from the headline, but where the question body actually posed a completely different question.
Double parenthetically, your final question does align with your headline.  The discussion of 3D printing and the assertion that it is dangerous is not actually relevant to the question at all.  It might be better to remove the references to 3D printing and post this in another SE group focused on human health.
The first point, that breaking down or melting plastic produces nano-particles is not supported by your reference.  The reference refers to the mechanical breakdown of particles in a simulated oceanic environment and does not mention melting.  The reference is silent on the possibility of melting producing and emitting nanoparticles.
In an FDM 3D printer, the melting takes place in an enclosed capsule, the hot-end.  The plastic is heated to the point where the viscosity is low enough that the pressure of the unsoftened plastic filament pushes the softened material out of the hot-end through the nozzle.  Upon exiting the nozzle the temperature falls, and the plastic begins to recrystallize.
I have seen no evidence of outgassing during printing with dry filament, other than an odor.  Usually melting joins separated objects, pellets, and larger particles in a unified liquid state.
Without specific testing, one can not say there is no risk of nanoparticles emitted by FDM 3D printing.  Ventilation remains a useful method of reducing local exposure to nanoparticles and odors.  Airborne risks are one of the many risks to be considered, but I have no evidence that they are more serious than the burn risk, the fire risk, or the risk of a stroke from high blood pressure induced by failed prints.

I'm not really sure how this attempts to answer the question? The first part of your "answer" is a rant against the question. I'm not sure how that is useful to the reader in general?

Not intended as a rant, the parenthetical bits were added after re-reading the question.  Pointing out that the syllogism contains a fallacy seems appropriate, but perhaps it is not.  Discussing the mechanism through which nanoparticles may or may not be emitted is responsive to the teaching of the question, although I understand (and later commented) that everything about 3D printing was not relevant to the question which was actually asked.  Feel free to delete as you find appropriate.

Just look at the definition of the 'health' tag on this site. 'For questions about the long-term effects of 3D printing.' My question seems to fall into that category. As for migrating the question to another site, my question refers specifically to nanoparticles created through 3D printing. I'm sorry if that's not clear, I'll edit my question.

@Pᴀᴜʟsᴛᴇʀ2 I like the point made in the fourth paragraph, that the article does not mention melting at all... While the answer starts off as a bit ranty, I think that it is actually (justifiably) dismissing (some of) the arguments made in the question, and in doing so, make the question itself a bit of a non-starter. If the question had better references, then the question might be more "acceptable" or, to put it better, "unassailable" as a 3DP question. But as it stands the question does seem to be based upon a few false premises... even though the points raised by it are valid...

@Rafael ... i.e. "Are there nano-particles?" and "Are they dangerous?" would seem to me to be valid health related questions to ask w.r.t. 3D printing, as a lot of people (especially students) have them set up in their bedrooms, and have prints going all night long...

In your 4th paragraph, you are correct that my first reference does not directly support the fact that melting plastic creates nanoparticles. However, if you would read my 3rd link, you will see it is very clear that 3D printers do indeed make nanoparticles. In your 6th paragraph, you say "I have seen no evidence of outgassing during printing". You misunderstand. Outgassing refers to the emission of VOC's (which definitely happens anyways), but my question refers to nanoparticles (which are also made but not the same thing).

@Rafael - good point. Third link does state that, sorry, I hadn't read it.

@cmm, if you like this source better, I can replace it as my 1st reference: Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic

@Rafael, I like your third reference.  The title of the reference immediately above doesn't seem relevant.  Your third reference is squarely on-point.

@cmm, as you have clearly noted, the other references aren't really necessary. However, the 3rd reference certainly covers for them. The reason I put in the other references was to demonstrate the logical leap I have seen a lot of articles perform when discussing 3D printer emissions. They spend time demonstrating how many np's they make, but they don't go in depth about why these particles are dangerous.

authors: เอาที่ เธอ สบายใจ


text:
How do I calibrate temperature control in a Repetier firmware?
I have built a 3D printer using RAMPS 1.4. I am trying to raise the hotend temperature over 180 °C. But I can hardly get to 100 °C in 60 minutes. I applied power directly to the heater and I was able to get to 220 °C in about 15 minutes. What am I not doing right? Currently I think the PID isn't correctly calibrated. How do I do that with the Repetier firmware?
P.S. I tried PID tuning but end with an error on timeout.

Welcome to 3DPrinting.SE!

You have problems with your sensor or is selected the wrong type sensor; is possible to reach the temperature in less than 5 minutes if settings are correct.

When applying a voltage directly to the heater element, it should heat up very fast. You could measure the resistance of the heater element. A 12 V heater element of 40 Watt should have a resistance of about 3.6 Ω; you could test that with a multitester. If the resistance is a lot higher, the heater cartridge could be a 24 V heater element. Operating such element on 12 V would imply that the power output would only be 10 W. Heating of the hotend is much slower at low power output.
Incorrect PID settings can indeed prevent the heater to heat up fast enough to trigger errors during tuning. The trick is to heat up the element a little prior to performing the tuning, or upload new PID settings to the firmware prior to tuning.
PID settings can be set not only by uploading a modified firmware version (configuration file), but also by sending commands to the printer over serial terminal connection (e.g. Repetier host, OctoPrint, Pronterface, etc.) or stored in a G-code file and executing it ("printing"). The G-code command to set the PID values is M301. The relevant parameters are:

Hnnn heater number Pnnn proportional (Kp) Innn integral (Ki) Dnnn
  derivative (Kd)


text:
Why is 2 / -2 / 2 equal to -2 in OpenSCAD? (Mathematical Order of Operations)
Recently I have been doing more complicated math in OpenSCAD and I have run into something that I find strange. Take a simple math expression: 2 / 2 / 2. By any programming language this will equal 0.5 (1/2), and OpenSCAD agrees. Something like this: 2 / -2 / 2 should also be -0.5 for the same reason. However, OpenSCAD thinks this is -2. That is echo(2 / -2 / 2); gives ECHO: -2. My calculator, other programming languages (and myself) all say its -0.5.
Is this a quirk of OpenSCAD, or am I missing something obvious?

Check what (2 / -2) gets you

I suspect the behavior you are seeing is an undocumented feature (aka, bug) of OpenSCAD. I've found in the latest stable release that if the - is placed on either end, the result is -0.5, but in the middle, my results are the same as yours. Surrounding the -2 with parentheses results in a correct answer, however.
It appears that the parentheses turns a mathematical operation into a signed integer. It follows that the operations without the parentheses is right to left:
2/2 = 1, negative 1 with the minus, 2/-1 = -2

Filed: https://github.com/openscad/openscad/issues/2894

And there's now a fix for the issue merged into master. Nightly builds should handle this correctly from here on out.

I filed this issue as a bug with the OpenSCAD project, and there is now a fix merged into master, as well as a test case to prevent regression. The latest nightly builds should handle this correctly from here on out.


text:
Prusa i3 MK3S Z axis moving down in calibration wizard
During recalibration of my printer (due to the nozzle catching on the prints), the Z-axis went down where it used to go up, damaging the heatbed steel sheet in the process. It then failed calibration.
I didn't change the wiring since previous print although I re-adjusted the PINDA probe.
What can I do to fix this?

From the information you gave, it could have been anything. Some other possibilities would be the probe not working at all or the wires not working.

Answer taken from OP's comment

the issue has been resolved (the PINDA probe was too high)

@helpme - If you care to submit your own actual answer, I will delete this Wiki answer, thanks.


text:
Trouble printing small thin pole
3D-printing newbie here. I have a Geeetech's Prusa i3 mk2 B.
I'm trying to print this: https://www.thingiverse.com/thing:1358311
That's a mold, with 2 external parts and a core. The exterior prints wonderful. But the core is too messy. Take a look at this:

What riddles me is that the side parts, and the pole's base, print fine; so this does not look like a bad calibrated printer, but something else entirely. My guess is this is some precise tuning I don't know yet.
I've been trying to print that little pole without success for over a week now. Tried all this:

Changing the slicer program (I've used Ultimaker Cura and Slic3r prusa edition)
Tuning the e-steps for avoiding over-extrusion.
Tuning the z-steps, so the nozzle doesn't melt the last layer when printing a new one.
In the same sense, changed the nozzle heat.
Tried lots of different layering, speed, walls, bridging, and quirks configurations.

So far, the best I got is a little pole not-too-deformed so I can make my part anyway, even when the pole is not well printed. But after seeing lots of videos and reading lots of tips online, I still don't understand how to tune my print for that simple little pole.
Other that tips, what I would really like to ask is if somebody has a name for that problem I'm facing, so it would be much more easy to search for my tuning options.
So... any clue how to fix this?

Try printing it at 1/10 the speed that you normally do, or switch to a smaller nozzle, re-slice, then try again. What material are you printing in?

Basically, you print too hot (and fast) without enough cooling. The deformed small pin in your image is a perfect example of depositing new layers onto too hot (not cooled down enough) prior layers.
You can easily solve this by printing two identical parts spaced apart from each other. This allows the layers to cool before the next is deposited.
From mastering Ultimaker Cura:

When printing a series of small parts, print them all together. The
  travel time between the parts is often enough time for the layers to
  cool without changing your settings.

If you do want this to print as a single piece, you need to:

tune down hotend temperature (use the minimum temperature that gives good print results, printing a temperature tower will help to determine this),
increase minimal layer time (may not always work as speed will not be lowered under the minimum printing speed) and
increase part cooling fan percentage (or print a better fan duct that allows for more cooling air to reach the print; many fan ducts are too convergent, the pressure increase is then too big for the fan to effectively push air through it).

The thin core gathers too much heat in the printing process. If you need to print slender objects, either:

Print several. This is the most simple solution and best for beginners.
Increase cooling. A better cooling solution or increased fan speed often can help to get thin or delicate objects printed.
set minimum layer time to slow down the printer automatically on layers with low cross-sections. If too small, it could pause on the edge of the print, which could leave scorch marks.
If you know a little more about your printer and got your retraction dialed in, you can go more advanced: set minimum layer time to 10 to 15 seconds and activate the accompanying Z-hop. This will prevent the scorch marks, but you might need to make sure you don't string.

This way the part has a chance to cool down between printing layers.

Although you are correct, adding Z-hop introduces the chance of a leaking/oozing hotend or filament not being extruded in time, that would not be my personal preferred solution for people starting using 3D printers for the first time.

The other answers have addressed the heat problem.  The other risk is that a rod printed vertically like this is prone to snap, because the weakest axis is between layers.
I often rotate pieces like this and print with the rod horizontal.  You then have to remove the support and/or brim material, and probably do a bit of sanding to get it properly round, but the final part will be much more reliable (not break).

Yes strength can be a problem, I've printed such parts with room for a screw to strengthen the part. But if that is not possible, a change in print orientation might be very helpful!

I'm sorry for the long time I took to answer, but the ammount of NEW problems I faced since started this question was so big that wanted to write a list of them before answering my own question. I've finally also desisted from the list, as the problems tends towards infinity.
Simple version: printing more than a single item did the trick, as several people proposed here. But then the piece broke when tried to remove it from the hot bed, as somebody else also warned me here. By that time I tried a temp tower, had to recalibrate almost the whole printer, had to also relubricate it, had to learn some tricks about sticking and de-sticking pieces from the bed, tried several different glues, started to fine-tune my slicings, and so on and so on... man, 3D printing is laborious.
But I wanted to let this link here for all the fellow newbies out there reading this.
https://all3dp.com/1/common-3d-printing-problems-troubleshooting-3d-printer-issues/
That was exactly the kind of document I was looking for online as a newcomer to this world, and I'm sure it will be useful for a lot of people.
Thanks everybody.

another good source for print troubleshooting: https://rigid.ink/pages/ultimate-troubleshooting-guide


text:
Temperature fluctuations, is it normal?
I have an Anycubic i3 Mega-S and when I'm printing something (especially when it's hotter) the temperature increases and decreases by around 3 degrees during the print. Is this normal?
I was worried this is a loose thermistor and if it comes out during a print my house will probably catch fire! I have no idea how to tighten it though.

Welcome to 3dPrinting.SE! While I'm no expert, I've seen the same fluctuations while using my Anet A8 clone printer. I've not seen any detrimental effects due to it.

:O after reading this question I went to print, then the temperature  started to fluctuate from 175° to 215°, then temp error, so I found the sensor connector was loose, temp error was fixed, then fluctuation temp was only on preheat only, but suddenly the PSU burned out!!! The PSU was shorted circuit.

All printers will have some fluctuation and it's not a concern. This is similar to the fluctuation you'll see in your home temperature around the thermostat setting.  There are a couple reasons. One is that the feedback loop (thermistor to control board to heater to extruder block) will always have some lag. Another is that most systems have built-in "hysteresis," i.e. set the "turn off heat" a couple degrees above the "turn on heat" thresholds. This avoids "chatter" from on to off right at the setpoint.
Some thermistors (e.g. my AnetA8 clone) can be held in place with a setscrew. If yours doesn't have a similar capability, use Kapton tape to hold it in. This tape is designed for high temperature operations so it won't age or collapse, and it has good holding strength.


text:
da Vinci 1.0 cannot print PLA filament
I bought new yellow PLA filament from XYZ (1.75 mm).
Over the past I have printed many objects with my da Vinci 1.0 (ABS only). I found that while the brim is being printing (using default configuration of XYZWare; the da Vinci machines give the user very little control over print parameters, if I remember correctly the temperatures are controlled by the chip in the filament cassette), filament stopped extruding from my extruder immediately. However, ABS can be printed properly.
Could anyone tell me how can I work around ?

Have you reduced your temps (extruder and bed) for the PLA? ABS prints at a much higher temp than does PLA.

My colleague has the da Vinci 2.0 duo, he also cannot print PLA (results in clogged nozzle), this looks like a design feature. I guess this is related to the hotend (probably all-metal) which are prone to heat creep problems. You must ensure that the temperature of the hotend is as low as possible and that the cooling of the hotend is optimal, maybe open the enclosing while printing? You need to add some details on how you print PLA, e.g. hotend temperature, bed temperature, cooling, etc. else it is very difficult to be answered.

Please let us know if the teeth of the drive mechanism of this head are getting clogged with softened filament (heat creep).

Also, a thorough cleaning of the nozzle/hotend might also be a good idea to get rid of all the stuck ABS residue inside.

@TheThriftyEngineer - Be that as it may ... what are they?

The problem solved !, my abs is stuck in nozzle !!!

@3ORZ: You should add that as a self-answer to close the question.

The answer to this specific instance appeared in the comments:

Also, a thorough cleaning of the nozzle/hotend might also be a good idea to get rid of all the stuck ABS residue inside. – 0scar Mar 26 at 8:44
The problem solved !, my ABS is stuck in nozzle !!! – 3ORZ Apr 25 at 6:52

That looks pretty bad for a number of reasons. If you've got an all-metal hotend, you can be pretty sure that your PLA issues are probably at least partially cooling-related. I'd recommend you try and find a better fan duct design for your hotend, if possible, and possibly upgrade to a better fan.
You can temporarily skirt around cooling issues with PLA in all-metal hotends by printing more material, which typically means one or all of the following:

Faster print speeds (if your printer can move quickly enough and has good acceleration)
Thicker lines! Surprisingly useful. If you don't want to sacrifice print detail, then make the infill lines ridiculously thick, the inner wall lines fairly thick, and the single outer perimeter "normal" thickness.
Thicker layer height. Normally I printed at 0.2mm like everyone else, but with PLA in my all-metal hotend, I had to up it to 0.3 with fatter lines as well.

If you can consistently keep the filament going through the hotend instead of lingering inside of it, you can basically "push" the melt zone back down into the heater block where it belongs, instead of it creeping upwards and resulting in a jam.
As a side note, the rippled surface of your brim there looks very similar to what used to happen to mine; the ripples are usually indicative of some form of over-extrusion on the first layer. I'd maybe look into checking your Z offset to make sure your print nozzle is far enough away from the bed, and maybe also check your flow rate is accurate for that particular filament. Check the filament diameter in a few places with a micrometer if you have access to one, and compare to your ABS prints to see if maybe you should adjust the flow rate down a few percent in your slicer.


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Can I dry PETG filament under sun?
At the moment the outside surface temperature is around 30 °C. Can I put my PETG spools outside with a fan in order to dry them cheaply?

Put it in a car parked out in the sun.

The simple answer is: No
There are two basic reasons for this:

The sun will not get the filament hot enough to evaporate any moisture which has been absorbed.
While sitting out in the sun, it will continue to absorb more moisture, which defeats the purpose.

On Matter Hackers, they give a very reliable way to dry filament:

Preheat your oven to 160-180°F  (or 70-80°C).

Place spool in oven for 4-6 hours

Remove and place in an airtight container, preferably with desiccant. 5-gallon buckets with airtight lids from local hardware stores work very well for filament storage. You can use uncooked rice as a cheap desiccant.

Filaments with lower glass transition temperatures (Tg) like PLA, use lower temperatures to dry. Lower temperatures also require more time to thoroughly dry.
That’s really all that’s necessary to dry out your filament and ensure optimum material performance and surface finish.
So if you have some spools that have been sitting out for a while and aren’t printing as well as they used to, dry them out and try again. Chances are they’ll be like new.

You can see in the write-up it states you need to get the oven up to 160-180°F (or 70-80°C). The sun will never provide that level of heat. It also states at lower temps it takes longer to evaporate all of the moisture. Placing the filament into an oven at the proper temps will ensure the best results short of buying a purpose built system like PrintDry which is also mentioned in the article.

the simple answer is correct for most of the way, but there is a way to set up a sun-powered drier for filament... which pretty much comes close to a building a specialized solar cooker. the closed top variant of solar cookers can reach 200°C...

WARNING Try lower temperatures with your filament first. I put a spool of PETG for 4 hours at 170 and it ended up basically ruining the spool. The filament is melted to itself and breaks apart very easily. I'm lucky to get a strand as long as 10 yards from this spool before having to pause the print because it breaks from being so brittle now. Maybe that's just an issue with the 3dSolutech brand PETG. Better a little "wet" than this

Here is my suggestion for a cheap, well and temperature accurate drying manner of a filament. I've done it several times for PETG that is actually a very moisture absorbing filament and pops it up when using by ruining the job. Why not using your own printer's heat bed to dry the filament (PETG about 6 hours in 65 degrees of Celsius)? I can guarantee that it works:

Hi Pekka, welcome to 3DP.SE! Although this is a very good proposed method to dry the filament, it actually does not answer the question. Note SE sites are driven by questions and answers, this answer is more something you would post on a forum. Please look into the [help] to learn how SE sites work and please take the [tour]. Thanks!

Ok, sorry :( I hope you destroy my comment cause I don't know how...

@PekkaKoivumäki you didn't do anything wrong.  We do allow answers that challenge the premise of the question, i.e. "don't do that, try this instead", as such your answer is perfectly valid, and encouraged.  Please don't let the feedback you've had put you off from contributing to the site.


text:
Will this MOSFET allow the heat bed to run at a different voltage than the control board
I am currently running my Tronxy X5s with a MKS Gen L board. So far I have not ran the heat bed over 50 degrees C since I have only printed with PLA so far. I plan to try PETG and/or ABS in the near future and I have a spare power supply 12V/360W laying around.
When I first got my printer I purchased this external MOSFET board after reading about X5s "upgrades", but so far have not used it.

My plan is to now run the heat bed using a separate power supply than the one running my control board using the external MOSFET to switch it. Since this power supply will only be powering the bed, I would like to bump up the voltage, via trim-pot somewhere from 12V-15V, to gain some watts per square inch on my heat bed.
Will this MOSFET isolate the heat bed circuit from my control board to allow it be ran at a higher voltage? Is it safe to run the power supply/heat bed at a higher voltage than it is rated for a significant amount of time?

Short answer YES. You can run it from a different power supply at a higher voltage. Also it has a PC817 Optical isolator (for some reason) therefore the second power supply and your main board should not be electrically connected at all.

Where did you find the information on the PC817?

I looked up the board online, zoomed in on the image then googled the numbers. This resulted in a link to the datasheet.

Yes you can, but you should be aware that running at higher voltage implies that the current also increases. Your wiring and connectors to the heated platform have to be able to transport that extra current (e.g. the wires, the ones I got where very low quality, and connectors that came with my Anet A8 where not even rated for the standard load, let alone an even higher load). You need to properly solder the leads to the heated bed and use proper terminal clamps (C-clamps or forks) to connect the cables to the MOSFET module. Even running the basic voltage this can happen:

Let's assume the heated bed has a resistance (R) of about 1.4 Ω. A voltage (U) of 12 V would result in a current (I) of $ I=\frac{U}{R}=\frac{12}{1.4} = 8.6\  A$ (Ampere). Running the same bed at 15 V would result in a current of $ \frac{15}{1.4} = 10.7\  A$. The power would increase from about 102 Watt to 161, which is a 60 % increase of a 25 % increase in voltage.

...and so long as the thermistor is working nothing should catch fire.

@user77232 The working of the thermistor has nothing to do with that, connectors and wires could burn anyway due to not being rated for the current. There are examples where it did go wrong.

You'll have that problem no matter what voltage you run at. Bad connectors are bad at any voltage.

... and good connectors become bad connectors when you are overpowering them.

For reference,I done tracing this module as shown.

So you can use isolated power supply for load.
Also you can use up to 24V without any problem.
Edit:
This module still work with higher voltage up to 24V. But according to question. Using higher voltage supply more than rated is same as my question here.
For summary. Adding more voltage to resistive load results to higher current flow. Recheck your wire and connectors for current rate so you will know the limit of voltage you can go with.
One more thing, mosfet can fail like short circuit. At this situation the temperature of bed cannot be controlled.
At normal voltage rate even we left the bed connected to power supply the temperature will rising to about 100C if you add more voltage it will go higher than that can the heated bed will broken or burned or start to fires

That doesn't seem to be a wise answer: "use up to 24V without any problem" Although you can supply 24 V, you need to make sure all connectors and cables can handle that current increase. I know it is possible as I have turned a 12 V bed into a 24 V bed, but that is only possible when you do more changes than just upping the voltage to 24.

@0scar My bad. I mean if we supply 24V to module the module still working fine


text:
Adhesion issues using AmazonBasics PLA
I am a neophyte at 3D printing. My Ender 3 is now 4 days old and I modified it out of the box with a glass bed.  My first print was a fairly complex item, but a mere 90 x 160 x 3.5 mm. Used the sample filament that was included with the 3, first print was a keeper.
Today I was trying to use the AmazonBasics PLA 3D printer filament.  I am not amused. I'm using the identical setup and glass bed as before but poor adhesion prevented a print.
I cleaned the glass with acetone followed with 90 % IPA...  No joy.  Another cleaning using a dishwashing detergent and IPA, boo hiss!
The glass bed is a Creality for the Ender, purchased separately For the first print, no adhesive was used, just the glass (cleaned the glass prior to the first print as described).
Your suggestions are solicited.

Coat the bed with sevaral layers of Elmers white glue, or gluestick.

Out of the box ender-3 does not have a glass bed. at least mine doesn't have one. Did you swap it? Do you use some adhesive?

More information is found here, here, here, here and here.

I used AmazonBasics PLA filament for a print and wasn't too impressed with it. I was able to get it to print, but the quality of the print wasn't up to par with other PLA filaments I'd used in the past. I realize different colors of filament have different print qualities and you have to tune your printer each time you change a color or manufacturer, but really, the print was mediocre at best. Previous prints were of much better quality. The only reason I used the AmazonBasics PLA was because it was a specific color. I doubt I'll go back to it unless absolutely necessary.

If you fixed it, post an answer, the fix should not be in the question, this is not a forum. Besides, printing on a raft is not really a solution when you have such a great upgrade like a glass slate. An adhesive on the glass is usually the way to go, but if you are happy, we are happy :) p.s. I did not know you could clean with beer

@R.Ogburn The fact that you have modified the machine is relevant. It opens a huge can of worms, starting with an unleveled bed (very common) and no adhesive (somewhat needed on glass for PLA, very common) to electrical problems (like bad connection, somewhat uncommon). in my experience, the rough buildTak-clone surface is easier to start out with as a neophyte. Glass beds can get flatter bottoms though. Raft is not commonly needed for PLA.

Answer taken from OP's question

****Fixed it!****
Reset bed height to clear nozzle by 0.04 mm. Printed on raft.  I appreciate the answers.

@R.Ogburn - If you care to submit your own actual answer, I will delete this Wiki answer, thanks.


text:
Does PLA block wifi signals?
I printed a raspberry pi case from PLA. This case.
I fitted it to my raspberry pi and now the wifi keeps dropping out. When I take it out of the case there is no problem.
The filament I am using is Black, 3D Hero 1.75mm.
Has anyone experienced anything like this before, if so how did you work around it?
Is it common with PLA is there another material that wouldn't cause an issue?

What color, some colors may contain conductive pigment.

@r_ahlskog Black, 3D Hero, 1.75mm

Black would be a prime suspect, probably contains carbon. Being electrically conductive would make it attenuate the WiFi signal and likely be the cause of your problems, even more if it was grounded.

The issue could also be heat. Do yo have ventilation holes? Is there a fan?

@user77232 - There's a lot of ventilation holes in the pattern. I would doubt the Pi creates enough heat to cause issues, but you never know.

@user77232 There are vent holes in the pattern. There is no fan but the pi doesn't get get that hot.

I think @Pᴀᴜʟsᴛᴇʀ2 may be correct, that was my first thought as well. Check out this project from the Pi foundation, it has instructions for monitoring the boards temps using Python. You can then track the see if the dropouts coincide with temperature spikes.

Well, your experiment pretty clearly shows that at least the filament in question is at least attenuating the WiFi frequency in use.  Perhaps try switching bands (2 vs 5 GHz)?  Next trick - identify the location of the WiFi antenna in the R-pi and put a cutout in your case.

Try a little closer to the wifi source, may be you are too far away and the normal attenuation of an object affects your design. At home I have some interferences with an antenna of phone company, so I have to test on a shielded room.

Thanks for your suggestions guys. I will try to add a cutout for the WIFI antenna. Failing that, I will also try a different filament to see the results.

It would be interesting to see if the PLA is conductive. If you have a multimeter, measure the resistance between two points, say 1cm apart.

Typically the black pigments in polymers are mineral based. If you are having true WiFi issues then it sounds like your filiment is using black iron oxide also called magnetite for the black pigment. This is the same material they use in radar absorbing paints which would make sense as to why you are having radio related issues.

the other common black pigment is carbon.

It could be several problems

Shielding from the material
Heat
Mechanical load from the casing
A metal screw next to the antenna

To learn more about the problem, comparing different configurations is the only way to got (As you guessed, it might be shielding, so you could see how the same shape works when printed in white PLA).  Since comparing wifi signals is very prone to random changes, it is important to get better information than "random drops". Signal strength is a much better indicator.
A wifi signal test is shown here, comparing a bare PI with one in a aluminum case
https://www.youtube.com/watch?v=26OxCwEHoTk
Indeed the aluminum case reduces the signal strength, as it was to expect.
For a faster comparison you can use the command 'iwconfig'. It usually shows a signal strength (Tx-Power)
> iwconfig
wlp4s0    IEEE 802.11  ESSID:off/any
      Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm
      Retry short limit:7   RTS thr=2347 B   Fragment thr:off
      Power Management:off

A possible workaround might be to add an external antenna. The raspberry pi actually has solder points to add an antenna connector.
https://www.mictronics.de/2017/10/raspberry-pi-3-with-external-antenna/
However it might be simpler to produce several iterations of casings and compare the signal strength, depending on availability to SMD soldering.


text:
Can I use Araldite to stick PLA to metal frame?
I have a PLA base, that the MOSFETs are sitting on. I don't want to drill through the base of the printer, I was thinking of using Araldite to stick the PLA base to the metal frame. The PLA base will be stuck to the base of the 3D printer upside down.
Do you think this will work long term? I don't want the plastic falling off and the MOSFETs hitting the metal base.

Welcome to 3dPrinting.SE! Why not use superglue? It will hold to both surfaces without issue.

I tried it seems to stick ok. hope it lasts for a long time. since my printer is now working i will just print a plastic guard.

This is the reason I suggested superglue.

@Pᴀᴜʟsᴛᴇʀ2 I guess that the base of the MOSFETs are not flat (component pins); Araldite is an epoxy which has better filling properties.

@0scar Araldite can be epoxy or PU or Cyanoacrylic

@Trish Thanks! I only know it as epoxy, which appears the best adhesive for this application.

Araldite is a brand that refers to a range of structural epoxy, acrylic and polyurethane adhesives. Among the vast number of products marketed under the name are also "metal repair" paste and what seems to be silicone based glues. Depending on what Araldite you have on hand, all of these types can be useful for PLA and any other 3D-printing material, as I had elaborated here. I suggest grabbing either an epoxy or PU variant or some kind of silicone for this use. You should make sure several things though if you go with epoxy or PU:

make a small sample print and clamp down one side, then put a small weight on the other side. Apply the glue in the center of it. If it sags considerably during the bonding, the heat of the glue curing is warm enough to soften the print. If this happens, you should take precautions to prevent it from deforming during the bonding, e.g. not apply too much pressure onto the bond.
The MOSFET can get rather hot. Make sure that the clamp holding the MOSFET still holds the item as it gets hot, as PLA starts to get malleable enough to deform under stress at 50 °C and usually fails quickly at about 100 °C.

Silicone-based glues depend on an area to force ratio to stick but offer a flexible bond that is somewhat thermal resistant and very gap filling.


text:
4pin fan on RAMPS board - direct?
The question is simple - I have a RAMPS 1.4 running Marlin 1.1.9 with the three MOSFETs being used (end, fan, bed), but I'd like to have a couple other Marlin-controlled fans. One of them would be a 4-pin, 6000RPM cooler I got from a dead graphics card. Seeing how it runs perfectly at 12V 350 mA if I keep the control pin disconnected (and ignore the sense pin too, of course), Could I connect 12V and GND directly to the PSU (or RAMPS 12V header) and the CONTROL pin to one of the pwm servo control pins like D11? Or do I need a resistor?
I could add some info about the fan if needed, but it's a FirstD 4-pin, 12V 0.35A fan that can run up to 6000 RPM.

On a side note:
I use a L298N dual H bridge motor driver to drive up to four fans on one PCB using normal 5V PWM pins.
That might be an option if you're missing fan mosfet ports but don't have 4-pin fans available for all your needs.

@TobiasWeiß that is a nice solution, but I think I'd go with simple transistor driving if I need to use more than this one fan - i'll test thoroughly, but i don't think there'll be more than 1W of dissipation on them even at rather high PWM speeds.

Yes, this should work.
According to this 4-pin fan specification, such fans use a 5V PWM signal.
You would have to make sure the PWM frequency on the pin you use satisfies that 21-28 kHz range specified in the document.
According to 3.3 and 3.4 in the document, you may not be able to turn the fan off completely when using the PWM input signal.

Indeed works perfectly. The fan idles at  very low RPM, inaudible, and ramps up as soon as a motor is activated (i have it set as a fan for my drivers, since I'll receive my TMC2130's soon). Using these 4-pin fans seems like a good alternative to making a separate fan driver, if you can salvage them from an old PC CPU cooler or something of the sort

which pin did you use?


text:
School grant proposal
I've been asked to come up with a grant proposal for a new 3D printer. My question is:

What supporting components and training would be most beneficial to support educational use in a K-8 school? In other words what things am I missing in my list below?

Specific suggestions for things on my list that I may not have thought of are welcome too. A specific tool, etc.
The suggestion was to include a base proposal with stretch goals that include everything needed.
My current ideas are:

3D Printer - option of a Prusa Mk3 or a Railcore 300ZLT. Possibly add another Prusa Mk3 kit as a stretch goal for students to assemble.
Replacement and optional parts such as a hardened nozzle.
Training and professional development
Filament - a variety of kinds such as PLA, ABS, flexible, conductive, etc.
Dry box or supplies to make one.
HEPA filter.
Enclosure - heated and/or soundproofed.
Maintenance tools or supplies. Lubricant, etc.

What are the students expected to do with the printer?
An Ender 3 / TronXY XY-2 with PLA should be sufficient for generic middle school projects.

@TobiasWeiß Some of the advanced students are pretty impressive and could learn to do pretty much any of the steps in the 3d printing process from modeling to managing the printer including building and maintenance. We have a pla printer, and there are some projects the students would like to do to take advantage of the properties of other filaments such as strength flexibility etc.

Also I wonder why the downvote. A comment may have been better. I’ve done substantial research and I’ve read the help center posts about what to ask and what not to ask. The question is answerable with specific answers. Oh well, you can’t please everyone.

Sounds reasonable. Is the printers "certification" important in that regard? It might be more interesting to have them build and improve a CoreXY style printer mostly on their own, using something like an X5S as a starting point.

@T.M, The exchange is about finite answers, not product reviews or opinions. It's also way to broad, because you didn't specify a price range. Just by something from Stratasys.

@user77232 The question isn’t product recommendations or even about the printer at all. It’s asking what other items besides a printer do I need to include. The budget is flexible because it’s for a grant proposal. The amount will depend on what I need and that’s what I’m asking.

@TobiasWeiß Building completely from scratch might not be reasonable but building from a Prusa or Railcore kit for example may be.

@T.M, A better place for that kind of question would be Quora.

The question changed after I answered, so I'll answer the new question.
My answers are based on seeing the results of 3D printing deployed in a nearby school system, and my own experience as a FIRST Robotics mentor in my son's school system.
Current question's answer

K-8
You are ambitious.  At the K level, I can see a group project to change a design (such as bracelets), and print the result.  This would be done by an adult operating the design software and managing the printer.
At some point, maybe G4-G5, the students would be in more control, with assistance at hand to help jump past barriers that appear (software bugs, clogged nozzles, ...).  By G8 the students should be able to handle the whole workflow if they have come up through the program.
It would be great if there were a version of Logo for 3D printing.  Maybe there is.
CAD
You will need some form of CAD software to make 3D printing useful.  Depending on the students, and assuming a small budget, you could look at OpenSCAD (or SolidPython) and OnShape.
OpenSCAD uses a simple language to specify and transform geometric shapes and to perform union, intersection, and subtraction functions.  SolidPython is built atop OpenSCAD works with Python IDEs.  With the Python language, loops and conditionals are more natural.  OpenSCAD is pretty simple, but some people prefer Python.  Designs are not "drawn", but are programmed.
OnShape is a cloud-based, traditional 3D design and modeling tool.  Free user licenses are available with the caveat that all designs are publicly accessible and copiable, but others may not change your copy. It will be familiar to users of AutoDesk and SolidWorks systems, although the dialect will be strange.
Both produce STL files for 3D printing the designs.
What is the purpose of 3D printing at the school?
Other training really depends on how 3D printing is integrated into the core curriculum.  If 3D printing is part of a class in the static analysis of structures, then the class would be providing the training about strength.
IMO, the best training is accomplished by giving students access to the equipment with a mentor available to answer questions.  Each student comes to 3D modeling and printing with their own curiosity and motivation, and those are best served by smoothing their chosen path with information and advise.
What can go wrong?
The worst outcome is where money is raised, equipment is purchased, and no one is available to make it work.  Or, it works great until the inevitable problem arises, and no one can resolve it.  I've seen this happen in a large, well-funded school system.  The students get frustrated, and the program loses credibility.  The well-off students buy their own equipment and carry on, while those who can't dismiss 3D printing.  3D printing becomes another failed adventure.
Typical Problems
Working in any school system is complicated.  CORI checks are required.  Special certifications and permissions are needed to work on school property.  Insurance and liability are raised as problems which block progress.  Often nothing is possible without a teacher-on-staff taking personal responsibility and directly supervising activities.
Scheduling prints which take over a few hours may be impossible.
Most problems can be overcome with strong support from teachers and administration.
Training Required
The most important persons to be trained are the teachers and/or mentors.  They will train the students, and the students will train themselves and each other.
The teachers/mentors should be familiar with the general operation of the CAD software, know how to operate the 3D printing devices, and be able to resolve all common problems.  Keeping the equipment available is important.  Going down for a month is a long time in a school semester.
If 3D printing is integrated into a specific part of the curriculum, the teacher of that curriculum will provide the subject matter training that is being demonstrated through printing.  The physics teacher, the math teacher, or the art teacher will use the 3D printing to teach their domain.
Supporting Components
Look to the chemistry department for a fume hood to use for ventilation and a fire-proof enclosure.
Consult with the responsible authorities in the school to determine if special ventilation is required for occasional classroom use.  Whatever they say, it may not be enough because of parents' fear of plastics.
Have spare parts on hand to quickly bring a printer back online.  The ideal spare part is an extra printer -- plus other parts to restore the broken one when it fails.  Consider the latency in the supply chain for replacement parts.
Have a purchasing flow authorized that allows spare parts and operating supplies to be purchased quickly.  In some school systems, it can take months to purchase materials because such purchases are handled on a semester-by-semester basis.  That won't work when you really need a spool of a special color by yesterday.  If necessary, look to PTA-like organizations because they may be able to operate more quickly.
Consider using PLA in the classrooms.  There is friendly web content about PLA being sustainable, "natural", and biodegradable, rather than the ABS stigma of being petrochemical.
If the upper grades have a community service requirement, allow the 3D savvy students to volunteer as 3D printing mentors to the younger grades.

Previous answer
If your question is about what equipment to buy, it would be off topic as being a question of opinion and recommending specific vendor's equipment.  I am answering the question about determining what should be in a proposal.
Like any consideration of acquiring a 3d printing capability, there is some data that must be known before you can determine such a list of equipment.
First, what will the capability be used for?  In a school context, it could be used as part of a curriculum, probably not on the topic of 3d printing, but perhaps something else. Or, it could be part of a school machine shop or hobby shop.  It could be used by a robotics club, a rocket club, or a theater club.  Based on how it will be used at the school, you can determine the next data.
Second, what will be capability be used to print?  Based on that, you can judge which devices meet the need.
Third, based on the "what", and a sense of "how much", you can judge the type and quantity of supplies you will need.  Supplies for the first two or three years should be included in the proposal.
Fourth, estimate the amount of special staff time that should be needed, find a sponsor within the school who will commit to that time, and estimate the funds required to compensate them.
Finally, roll up a sales document, ideally based on a rubric from the granting agency, which included the benefits, allignment with the grant guidelines, and the costs.  Validate the proposal, especially the cost and the staff requirements, with whoever invited you to submit a proposal.
... and remember to actually submit the proposal by the deadline.
Bringing 3d printing into school is a great addition to other educational and engineering tools.  With the right support from the existing school staff and a clear vision of how it will fit into the school activities and existing culture, 3d printing succeed in a school setting.

Your question doesn't have a lot of detail on how you use your existing printer (and I had to dig into the comments even to find out that you already have one: the question sounds like the grant would be for your first printer), so this is necessarily going to be generic suggestions, not all of which will apply to you.
CAD software and training
Getting the kids to download something from Thingiverse and print it out is great for the younger ones, but to really enable them to think as engineers, they need the tools to design their own things. Giving them access to real CAD tools, and the teaching support to use them, is hugely preferable. Fusion 360 is common in education (and with hobbyists) as the bargain option, but if they really want to see what's used in industry, Solidworks, Creo, or NX could be a worthwhile investment. You need to account not just for the software licence itself, but for training up your existing staff and/or hiring in some new skills. Even if you have volunteers from a local engineering company, there'll be the cost of background checks (DBS in the UK) or whatever process you need for volunteers.
Exotic filaments
I'd say it's better to establish a budget for filaments and then spend it over the course of the year, instead of buying some interesting filaments up-front. Odds are, one of your students will come up with a project that wants a particular type of filament, but you won't know which until they do. Having a budget keeps your options open, while buying exotic filaments up-front creates a big risk you'll just never find a use for the particular ones you chose.
Self-assembly printers
Unless you're planning to buy a new printer every year, assembling the printer is only going to be an activity for one cohort of students. Having your printer club put together the new printer can be a great add-on (and look good on your proposal), but only go for it if you need the printer anyway.
That said, since you already have a printer, you might consider one of the RepRap-based plans where you can print most of the parts. You might find that the bag of bits needed to make a RepRap is cheap enough that you actually can have the kids build one from scratch every year.
Noise and smell abatement
3D printers can be quite noisy and contribute to indoor air pollution. If you don't have a dedicated space for them, this may lead to having to agree to restrictions later on: e.g. no printing during class time, no printing while room is occupied, print room has to have the window open (so can't be used on rainy days). Depending on how budgets are in your school, maybe you can spend all your money now, and later on get an extra allocation from an H&S budget to fix any problems (e.g. by adding ventilation). But it might be easier to be honest up-front and include anything you'll need to make your printers good neighbours now.
Hardware for printed parts
Some kinds of projects benefit from hardware that you can't print. For example, my old school ran a project where each student designed and built a clock, using an off-the-shelf clock mechanism and whatever material was lying around in the lab: sheet acrylic in various colours, plyboard, and softwoods. If you have any similar projects in mind - RC cars, kitchen timers - it might be worth thinking about specialised components now. Pin badge backers are always popular. Even if you aren't, a handful of threaded inserts, bolts and screws, hinges, rods, sandpaper, and primer will hugely increase the range of functional parts you can create.