text:
What do linear rail codes mean?
In looking at 3D printer motions systems, I've seen linear rails with codes like MGN15H and MGN9C. What do the letters and numbers mean?

MG stands for minature guideway.
N signifies narrow, whereas W means wide.
So, there is MGN and MGW. You may also see BMN which is equivalent to MGN
The numbers, i.e the 9 and 15, refer to the track width. The widths are: 5 mm; 7 mm; 9 mm; 12 mm, and; 15 mm.
The final letter, i.e. C and H, refer to the length of the block, where C is the shorter version, whereas H denotes the longer elongated block which can distribute the load better (as it contains more bearings). These two lengths of the block can be seen compared, in the image below, which shows (from left to right) track widths of 15, 12, 9 and 7 mm, respectively:

Source
Note that there is an error in the diagram for the 7 mm rails - the lengths of the blocks (22.5 and 30.8 mm) have been, obviously, reversed.
A detailed description of the product code is shown below:

Source: Hiwin
The other features of the rails may need to be considered, such as their profile (square or round) and the bearings (cantilever or saddle), amongst other things:

Your choice includes the profile of the rails, commonly square or round. It involves the kind of bearings, either cantilever or saddle slides, plus the stroke, load, speed, duty cycle, mounting area, and of course the mounting orientation, simply because the saddle could potentially move horizontally, vertically, along a wall mount, or even be inverted.

Source: What is a Linear Rail?


text:
Do unused PEI sheets degrade over time?
Will build surfaces coated in PEI lose their qualities, such as adhesiveness, if left unused but removed from packaging for long periods of time?

The PEI will be fine. It's widely used in industrial high impact, high heat and high repetitiveness parts because it doesn't degrade easily. Probably some in your car.

source: Stack Exchange

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

sort: votes


text:
PID fails too hot temperature with new hotend on Tevo Tornado
I am new to 3D printing. I had a big issue with the full hotend: thermocouple broke, the fan broke, plastic everywhere... (I don't really know why as hundreds of prints were good before)
Anyway, I decided to replace the full hotend (2 fans + thermocouple + cartridge). I have the issue of nozzle temp. rising to max value very fast (250 °C defined as max temp. to not exceed in my printer setup). PID autotune failed because of this.
I checked my printer, it is a 24 V supply (Tevo Tornado)! When I measure the resistance of the old cartridge, it is 40 Ohms and the new one is 4 Ohms. I would like to replace it but really don't know how to do with the 8-pin connector...
I don't know if the new hot end is for 12 V or for 24 V power supply but I thought it was not a problem anyway with my 24 V supply... I am completely lost here...
Could you help me with this issue?

See e.g. this question

A heater cartridge with a resistance of 4 Ohms (including the cables) is designed for use with a 12 Volt system. When installed on a 12 Volt system, it will have a power output of around 40 Watts. This will increase to 160 Watts if it is installed on a 24 Volt system.

This means I can burn my system, right ?
Is there any possibility to adapt this one ? I thought to use a 12 V on a 24 V was possible, but not the opposite.

@saphozzo Yes. That power level is dangerous. Use a 24V heater cartridge.

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


text:
Cheap nozzles bought from China
Questions like this are usually not allowed but since the price of a brass nozzle in Switzerland is 15.90 and the average price of a nozzle from Alibaba or AliExpress is less than 0.10, and nozzles are something you exchange frequently the issue becomes of such magnitude that we need to have a simple answer to the very straightforward question:
Do nozzles from China offer the same quality and results?

Related: https://3dprinting.stackexchange.com/q/9912/8884

I use cheap brass nozzles through the "A" place and they are almost certainly Chinese.
When installing a new nozzle I use a drill bit in a pin vise in the large counter-drilled hole on the top side, pressing pretty hard to assure there are no drill chips in there, either loose or still attached. I follow that with a nozzle cleaning pin of the appropriate size, then a good blast of Dust-Off or the equivalent from the "W" place.
I get reasonable nozzle life and performance.
In my case nozzle replacement is nearly always from blockage, almost never from wear so I've  never considered it worthwhile to use premium nozzles with better wear resistance.

Up until this year, I used the cheap nozzles - the original that came with my Ender 3, and both the ones that were supposedly by Creality and appeared identical to it, and similarly cheap ones off Amazon. I never had any problem with them that I attributed to nozzle quality, but I went through them fairly quickly since they were so cheap, just swapping one out if it got a lot of buildup that was hard to clean off rather than bothering to clean it well. I would say they are perfectly usable.
However, if you're already used to paying more for a nozzle, I would strongly recommend ditching plain nozzles and going with the Bondtech CHT. The performance and quality improvement from it is drastic. It gives more improvement to flow than going from a standard size block to a volcano size block (see Stefan's tests on CNC Kitchen), and a lot less backpressure, so you can get by with lower values for Pressure Advance/Linear Advance, which put less stress on the extruder and get more consistent extrusion. In terms of ratio of printing performance boost to price (not to mention ease of installation), it's probably the single best upgrade you can make to a printer. And while it's not a special durable material, it is coated, which makes it a little bit better than plain brass.

I'm using a 0.4mm nozzle, the Bondtech is only available in >0.6mm. Also I am using a direct drive extruder which forces me to use low speeds. The higher speed of the Bondtech would not be of much use. And I'm worried retraction will be as efficient as with a standard one. Steve only tested PLA, I print in many different materials.
I don't consider the original nozzles from ender 3 cheap. The print quality of those compared to 60 dollar ruby lined microswiss nozzles is identical. I mean cheap, cheap nozzles from china. You get a pack of 30 nozzles for under 2 dollars and free shipping.

@AzulShiva: The CHT originally was only 0.6 mm, but nowadays they have more sizes including 0.4. I'm using the 0.4. I used it with PLA, PETG, and TPU and it was an improvement for all of them, especially TPU where I now need just 0.2 pressure advance for the 95A I use and print it as over 8 mm³/s. I use the same retraction I used with other nozzles (1 mm but down to 0.75 mm seems ok if filament is really dry).

For other specialized nozzles like the ruby thing, the point is not print quality but being able to print abrasive materials without constantly swapping out nozzles.

Ruby alows printing polycarbonate or glass fiber filled material. For PLA brass is sufficient


text:
Ender 3D Pro extruder stepper motor shaft length
My stock extruder motor feed mechanism had started to shave the filament but not feed correctly. I order a REDREX Tech dual gear all-metal extruder to fix the problem. I ordered a hobby gear puller, removed the press-fit brass gear, and now have yet another problem. The shaft on the Ender 3D Pro is not long enough on the stepper motor to ensure the grub screw engages at the proper height with the idler gear. I'm anticipating having to shave a flat spot on the shaft (with a Dremel Tool) to ensure the grub screw does not hinder the 360-degree rotation of either of the two gears but now need to know how to order a motor with a shaft long enough to do this.
The literature that accompanied the REDREX Tech showed a 22 mm shaft height. I checked this with my digital micrometer and found I only have 13.5 mm of the shaft on this Creality-provided OEM stepper motor.  So how or where may I order a replacement stepper motor with the shaft longer by about 10-12 mm? Does the stepper motor 42-40 need to be a 42-50 where the second set of digits is the required extra 10 mm length of the shaft?

Hi, welcome to 3DPrinting.SE! Hardware recommendations or where to buy are out of scope for this site. What is in scope is the naming of the steppers in relation to the overall height.

How long did the stock extruder last?

Steppers are sized by the dedicated standards, for a NEMA 17 stepper (most frequently used in 3D printers) the width and depth are 42 mm. This is the 42 from the designated naming found by Creality steppers (42-40, 42-50, 42-60, etc.).
The second set of digits in the naming relates to the stepper body height (in the image below, this is the L dimension), not the overall height! The shaft has its own dimensions, usually these are about 22 mm, but Creality has ordered custom made steppers with shorter shafts with press fitted filament extruder gears (see Problems with stock gear with no screw on Ender 3 pro).

Does the stepper motor 42-40 need to be a 42-50 where the second set of digits is the required extra 10 mm length of the shaft?

No, the second set of digits doesn't relate to the overall height of the stepper.
Do note that the naming is short for the model number which is usually much longer, e.g. JK42HS40-1004AC-01F, you see the width/depth and length back in the model name. Note that generally speaking, larger length steppers create more torque, the longer the motor the higher the torque (exceptions apply when different gauge wiring in the stepper is used).

The following image gives an overview of the steppers used by Creality models. As can be seen, they do not always use the typical D-shaft steppers, but also steppers with round shafts, this makes it more difficult to attach pulleys with grub screw without creating a flat spot on the shaft. Note that double shafts means that there is a shaft on both sides of the stepper motor, this is convenient for attaching a knob for manual positioning.


text:
Advantages of buying a 3D printer versus using online services
I'm trying to figure out if it's worth buying a 3D printer or using an online printing service like e.g. this one in the long run. Anyone have any cost analysis?

3D printing services are never worth their money for ordinary parts (e.g., replacing a consumer 3D printer).
A quick quote from a small electronics box I've designed a few months back yields prices of 132€ per box. That's enough for a new printer already.

I'm with @towe -- my Ender 3 is too small for a unit I want to print, and I could buy a new Ender 3 for the price of about two prints.  Getting a bigger printer, of course, would cost more than that, but I wouldn't even consider service printing if I needed more than one or two of anything.

@ZeissIkon a larger printer costs usually... about 2 to 3 times of an Ender 3, the benchmark for cheap printers. But you can often split parts into multiple prints to mitigate scale

It depends
If it is worth to invest in a print made for you compared to getting a printer depends on the needs you have. Thee can be informed by the type of material you want to print and the requirements that has on you. Let me give you some examples when it is simply worth it to pay:

A metal printer costs in the thousands: upper five-digit for the most baseline and averaging in the low to mid-6-digit. Ordering a single or few printed pieces will be economical, and even ordering many parts will still be well below break-even, considering that the material sets you back by up to 600 \$ per kilo!
A nylon powder printer starts in the middle 4-digits but easily goes up to upper 5-digits and even middle 6 digits. Ordering for a small-scale production this way still will be economical.
Some specialty plastics need printers with very high-temperature chambers and hotends with extreme wear resistance. Such machinery can easily cost five digits, especially in large dimensions where it goes to six. Compared to purchasing price of the machine, ordering the part will be cheaper.

On the other hand, getting a printer gets cheaper once you:

use it sufficiently, for example, to iteratively modify a designed part or produce a medium variety of parts.
have the time and money to spare to learn and tweak your machine to do what you want.
the amount of parts you want to make would cost you more to have ordered than a new printer, or a substantial portion thereof. For an FDM machine, the first useful machines can be priced as low as 150 \$, while 300 \$ gets you a somewhat capable Ender 3 v2 - which has developed into some kind of standard unit for printers.

Also note, that some printing services have limits on what they will produce. Commonly they will not provide services to manufacture tools or items that might violate local law or make it trivially to do so, for example copying keys or even manufacturing Keyblanks.

One of the biggest reasons to buy a 3D printer vs using a printing service is one of the biggest advantages 3D printing has over other manufacturing methods: rapid prototyping. If you operate a 3D printer you own to make parts you're designing yourself, you can really iterate a design in realtime, immediately measuring results (tolerances/fit, strength, working of mechanisms, etc.) and be printing the next version to test it a few minutes after the first one finishes. If part of the result you need is something you can visually evaluate during the print, you can even be working on the next iteration while the previous one prints. Most of the parts I do are small enough, and my printer fast enough, that during design iteration both myself and the printer stay busy pretty much 100% of the time.
If you're sending designs off to a printing service, you lose out on this aspect of 3D printing. If you don't get things exactly right the first time, you either have to do all the fixup with non-automated tools, or you're out a lot of money and have to wait for another order cycle all over.
This might of course make sense and be okay if you're really good at checking your work before sending it off, or if you're mostly ordering prints of things someone else already designed and tested previously.

...or of the parts need to be hand-fitted and ground to finish anyway.

Just one experience from a few years ago. I needed a single, very small part to repair a game accessory. The repair clip stl file was available on Thingiverse. I went to a local commercial 3D printing service for a quote. The quoted price?  $75!
I ordered my 3D printer a week later.

While 75$ is a lot if the printer costs 150 to 300, if the printer to make it is 6-digit and a single kilo of material costs 300-600 USD, then you pay the 75.

Not criticizing the business but his price made my decision pretty easy.  Using his prices as a benchmark I've made tens of thousands of dollars worth of things for myself in the 3-1/2 years since. Some of them were actually useful.

I would think it depends on your future needs. If you will rarely need things printed then online is more convenient than buying a printer and doing the whole learning curve, storing materials etc,.
From what I have seen online, most people printing are not printing things they actually need.
If you want to produce things to sell, then you're better off doing it yourself.

It is probably cheaper for a business to order 3D prints than to pay an employee to get up to speed, unless that business is doing new designs regularly. This is especially true if the parts need to look professional, or need to use challenging materials (like anything other than PLA, PETG, maybe TPU).
If the business does buy a 3D printer, it can be economical to get a more prosumer model, than to pay an employee to futz with a consumer printer to coax good print quality out of it, or spend additional time modifying it- a 300 dollar printer can turn into a 1500 dollar printer with enough things going wrong or needing to be upgraded.
When evaluating the true price of an in house 3D printed part to a business, it’s important to include employee time interacting with the machine and post processing: file prep, slicing software work, prepping bed, loading filament, preheating bed, watching the first layer go down. Oh wait, it got messed up? Start again.  Once printing, time spent checking in on it, then time spent unloading filament, hand post processing (trimming a brim, removing goobers, zits, strings, drilling out precision holes). It is a hands on process, especially with consumer machines. Producing parts on the clock, I figure between 40 minutes (everything runs perfect) to two hours (Murphy’s law) of human interaction for a one-off part. Batches of more than one can be less, I had little clam shell enclosures done in batches of 6 come out to about 45 minutes of labor apiece to the company, ultimately (once 3D printer was dialed in).
Another factor of overhead is a 3D printer needs a space for it to live.
-Near ventilation if using noxious materials
-with enough table space to have a computer near it, and some hand tools, and a clear area to post process the parts
-away from employees bothered by the sound
-where it can be checked on easily
-where it doesn’t get cold in the winter, to the point where low ambient temperatures cause warping
Note, some of these space requirements can be sidestepped by printers with prosumer features: WiFi transfer of gcode to the machine (computer doesn’t need to be near printer), full insulated enclosures (cold ambient temperature resistance and less noise) with air filtration (may not need ventilation for fumes).
Business ownership of a 3D printer can be a waste if there isn’t someone on staff that is mechanically inclined and can use a CAD package. Without CAD skill prints are limited to what independent contractors design for the company (and who may themselves own their own 3D printer), or things that can be downloaded from the internet.
As an asset, it can be difficult to sell a 3D printer for anywhere near what it is worth, especially with aftermarket modifications. They are large and heavy and delicate so local sales are preferred over shipping, which severely restricts the market, especially outside urban areas.
Not a business? Time on your hands? Go for it.


text:
How to get dual Z, dual Y steppers and dual endstops working on Marlin?
I've been trying for days to get my BTT SKR2 board to work with both dual Y & Z-axis and independent end stops (2 per axis). The Y-axis does independent homing just fine no matter which way the gantry is aligned. On the Z-axis, however, two scenarios are present:

if my left Z-stepper homes first and triggers the left Z-endstop, it stops the right Z2-stepper and the right Z2-endstop is never triggered. This leaves the machine in a pause state while it waits for the Z2-stepper to trip the Z2-endstop which, of course, will never happen as Z2-stepper has stopped moving having been triggered by the Z-endstop.
If the right Z2-endstop is triggered by the Z2-stepper first, the z2-stepper will continue to spin until the left Z-stop trips. The strangest thing is that when I look at the state of the machine as output by the M119 code, each endstop shows exactly as they are supposed to. It is as though the left Z-endstop controls both Z-steppers and Z2-steppers, and the right Z2-endstop only resolves the 'pause' state when the left Z-endstop has already been triggered.

Please provide any insights you may have ...

Board: SKR2 RevB
Stepper Drivers: TMC5160
Build: MPCNC Lowrider with
dual Y and Z axis -- aspiring to independent homing abilities
Firmware: Marlin 2 Configuration version 02000903
Machine configuration:

Stepper motors X,Y,Z,Y2,Z2 using XM, YM, ZAM,ZBM, E0M
ports respectively
End Stops X,Y,Z,Y2,Z2 using PC1, PC3, PC0,
PA0,PC15 ports respectively

For reference, here are the salient settings in Marlin Version 02000903

Configuration.h
//============================== Endstop Settings ===========================
// @section homing
#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
#define USE_YMAX_PLUG
#define USE_ZMAX_PLUG

#define X_MIN_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // Set to false to invert the logic of the endstop.

Stepper Drivers
#define X_DRIVER_TYPE TMC5160
#define Y_DRIVER_TYPE TMC5160
#define Z_DRIVER_TYPE TMC5160
// #define X2_DRIVER_TYPE TMC5160 // 20220414 : JHH : remove
#define Y2_DRIVER_TYPE TMC5160
#define Z2_DRIVER_TYPE TMC5160

// @section extruder
// For direct drive extruder v9 set to false, for geared extruder set to false.
#define INVERT_E0_DIR false
#define INVERT_E1_DIR false
#define INVERT_E2_DIR false
#define INVERT_E3_DIR false
#define INVERT_E4_DIR false
#define INVERT_E5_DIR false
#define INVERT_E6_DIR false
#define INVERT_E7_DIR false

// @section homing
#define X_HOME_DIR -1
#define Y_HOME_DIR 1
#define Z_HOME_DIR -1

Configuration_Adv.h
/ #define X_DUAL_STEPPER_DRIVERS
#if ENABLED(X_DUAL_STEPPER_DRIVERS)
// #define INVERT_X2_VS_X_DIR // Enable if X2 direction signal is opposite to X
// #define X_DUAL_ENDSTOPS
#if ENABLED(X_DUAL_ENDSTOPS)
#define X2_USE_ENDSTOP _XMAX_
#define X2_ENDSTOP_ADJUSTMENT 0
#endif
#endif

#define Y_DUAL_STEPPER_DRIVERS
#if ENABLED(Y_DUAL_STEPPER_DRIVERS)
#define INVERT_Y2_VS_Y_DIR // Enable if Y2 direction signal is opposite to Y
#define Y_DUAL_ENDSTOPS
#if ENABLED(Y_DUAL_ENDSTOPS)
#define Y2_USE_ENDSTOP _YMIN_
#define Y2_ENDSTOP_ADJUSTMENT 0
#endif
#endif

//
// For Z set the number of stepper drivers
//
#define NUM_Z_STEPPER_DRIVERS 2 // (1-4) Z options change based on how many

#if NUM_Z_STEPPER_DRIVERS > 1
// Enable if Z motor direction signals are the opposite of Z1
//#define INVERT_Z2_VS_Z_DIR
//#define INVERT_Z3_VS_Z_DIR
//#define INVERT_Z4_VS_Z_DIR

#define Z_MULTI_ENDSTOPS
#if ENABLED(Z_MULTI_ENDSTOPS)
#define Z2_USE_ENDSTOP _ZMAX_
#define Z2_ENDSTOP_ADJUSTMENT 0
#if NUM_Z_STEPPER_DRIVERS >= 3
#define Z3_USE_ENDSTOP _YMAX_
#define Z3_ENDSTOP_ADJUSTMENT 0
#endif
#if NUM_Z_STEPPER_DRIVERS >= 4
#define Z4_USE_ENDSTOP _ZMAX_
#define Z4_ENDSTOP_ADJUSTMENT 0
#endif
#endif
#endif

pins_BTT_SKR_V2_0_Common.h
/
// Trinamic Stallguard pins
//
#define X_DIAG_PIN PC1 // X-STOP
#define Y_DIAG_PIN PC3 // Y-STOP
#define Z_DIAG_PIN PC0 // Z-STOP
// shifted EO diag to E1 etc..
#define E1_DIAG_PIN PA0 // Y2-STOP
#define E2_DIAG_PIN PC15 //Z2-Stop

//
// Limit Switches
//
#ifdef X_STALL_SENSITIVITY
#define X_STOP_PIN X_DIAG_PIN
#if X_HOME_TO_MIN
#define X_MAX_PIN PC2 // E0DET
#else
#define X_MIN_PIN PC1 // E0DET
#endif
#elif ENABLED(X_DUAL_ENDSTOPS)
#ifndef X_MIN_PIN
#define X_MIN_PIN PC1 // X-STOP
#endif
#ifndef X_MAX_PIN
#define X_MAX_PIN PC2 // E0DET
#endif
#else
#define X_STOP_PIN PC1 // X-STOP
#endif

#ifdef Y_STALL_SENSITIVITY
#define Y_STOP_PIN Y_DIAG_PIN
#if Y_HOME_TO_MIN
#define Y_MAX_PIN PA0 // E1DET
#else
#define Y_MIN_PIN PA0 // E1DET
#endif
#elif ENABLED(Y_DUAL_ENDSTOPS)
#ifndef Y_MIN_PIN
#define Y_MIN_PIN PC3 // Y-STOP
#endif
#ifndef Y_MAX_PIN
#define Y_MAX_PIN PA0 // E1DET
#endif
#else
#define Y_STOP_PIN PC3 // Y-STOP
#endif

#ifdef Z_STALL_SENSITIVITY
#define Z_STOP_PIN Z_DIAG_PIN
#if Z_HOME_TO_MIN
#define Z_MAX_PIN PC15 // PWRDET
#else
#define Z_MIN_PIN PC15 // PWRDET
#endif
#elif ENABLED(Z_MULTI_ENDSTOPS)
#ifndef Z_MIN_PIN
#define Z_MIN_PIN PC0 // Z-STOP
#endif
#ifndef Z_MAX_PIN
#define Z_MAX_PIN PC15 // PWRDET
#endif
#else
#ifndef Z_STOP_PIN
#define Z_STOP_PIN PC0 // Z-STOP
#endif
#endif


text:
Large format heated bed
I'm building a larger format printer with a heated bed. The bed size will be 1080 x 1080 mm. It will be mounted on a 40 x 40 mm aluminum T-slot frame. I was thinking of using an Aluminium Precision Tooling Plate something like 5083. I'm not sure what thickness I should go for. I was thinking 10 mm but maybe I should go up to 12 mm to avoid warping at higher temps? I've seen some manufacturers go up to 16 mm but isn't that overkill perhaps? Does it seem like it's a balance between heating times and warping?

Warping is caused by a heat differential within the aluminium. Not really dependent on it's thickness. If it's heated uniformly it will expand uniformly. So I assume manufacturers are suiting their aluminium plates to their heating systems.

Ok i see. Thats good to know then. We were intending to use (9) separate heaters to heat only the area of the bed that would be used for each print assuming different print sizing's. So now im wondering if thats such a good idea?

I don't know, logically it seems a risky idea. What if you had you aluminium in 9 sections? I'm assuming you're going to put a sheet of glass or something down to actually print on.

Hi, thanks so much for taking the time to answer. We are a Hackerspace and its a group project, but nobody is proficient on larger heatbeds. The idea to have aluminium in smaller sections is interesting. Im not sure where to source the borocillicate glass 1m x 1m.?The biggest i can find is 500. We are in Australia.

Sorry I have no idea, I'm in Samoa, the biggest we have here is nil by nil... hehe... I'm using a piece of louvre I cut to size. Also I have no experience with large beds. My aluminium knowledge is just general engineering knowledge. Sounds like a really interesting project. Hope it all works out.

Hi Kilisi, ah i see haha.....yes well thats a small size. I think now maybe the reason for the larger thickness (16mm) is to lessen any warpage effect from heating in different areas...ie the center only for smaller prints. We can cover the aluminium with stick on 0.2mm PEI sheets and join them carefully. We,ve managed to build the printer ok and use Duet to run it. The bed is stationary. So far so good. Thanks for the input.

Take care in Samoa.

I think you'd need a Duet and the other components for monitoring and controlling a multizone heated build plate.

Hi user77232, yes thank you, im using Duet. The printer works very well with it and its an excellent program. I think now that we will just use a single zone heater and heat the bed uniformally. Thanks for your input. Im still a little unsure about the bed makeup. I think we will use 12mm aluminium plate and a 2.5kW heater. I have no idea how long it will take to heat up. Will use PEI stick on sheets i guess.

You can print directly onto aluminium, did that for many years, I do/did use 3DLAC for adhesion.


text:
What happens if you try to print with UV resin that's well past it's use by date?
I've got a bottle of UV resin that got left at the back of  draw and forgotten about. It's probably 6 months out of its advertized use by date.
What is likely to happen if I try to print with it?
It's Elegoo standard Black.

Quick answer without research: it may start to self-cure, causing viscosity changes and clumping.  If it is hygroscopic, it may also absorb humidity which can cause it to fail to cure, but a well sealed container should prevent that.  It may be possible to use by filtering for particulates and diluting with fresh resin, but print quality could suffer.

Try it and find out? Don't use it for anything critical. Expect to have to reprint, be happy if you don't have to.


text:
Printing in Material That Is Safe to Drink From/Dishwasher/Microwave Safe
I'm looking to get printed a design for a coffee mug, which needs to be dishwasher safe, microwavable safe, and safe to drink out of. What kind of filament or equipment would give these properties? If not, is there a company that offers such services?

about 9 years ago there was one doing their own 3d printed ceramic+glaze mugs but they did not accept custom one-off designs and I do not believe they achieved dishwasher safe - glaze and fire process after 3D print did not cover everything.  All other info I have might be obtained by searching the nets.

I’m voting to close this question because recommendation questions are not allowed on the stack.

PETG meets the requirements for dishwasher safe and safe to drink out of, but if you're not careful in the microwave I think you'd get it hot enough to damage it. (FWIW I have PETG cold beverage cups that have been through many tens of dishwasher cycles with no problem.) Kilisi's answer is probably what you really want.

@Trish: The actual question part of the question body, "Does anyone have any experience of using a filament/equipment that would do this?", is on-topic, and I think the question is okay to answer regarding what technologies would be appropriate and how to look for a service offering them, without recommendations of a particular service to use. "There don't seem to be any services doing this at present" also seems like a reasonable thing to put in an answer, if that's the case.

@R..GitHubSTOPHELPINGICE only if rewritten that way

OK, I've made an edit that I feel is still faithful to OP's intent while focusing on what's in-scope and removing the apparent shopping question part.

@R..GitHubSTOPHELPINGICE The "suggest a service" part is the disallowable part: it asks for a recommendation. But "What type of filament or equipment" would work.

@Trish: Was "are there services of this sort?" inappropriate even?

Yes, that part is readable as "recommend me a service"

IMHO, this question was fine at edit #2, there was no (direct) request for a recommendation, merely an inquiry as to whether anyone had experience. The subsequent edits appear to have put words into the OP's mouth, which is not really correct nor fair. The OP's latest edit #5 has now (re-)introduced the recommendation request (which isn't strictly allowed). I believe that the question should be rolled back to edit #2 and then left as it is.

@Greenonline I’m unable to find a single company that does this; it’s not like I’m asking for a recommendation as to what works well and what doesn’t. The closest thing I am able to find about this is to purchase a WASP clay extruder but I still need a kiln and have to look up the specifics of that. I’m looking for comments like use PETG, upload your STL file here and use this filament, and stuff like that. I would appreciate it if new comments were only about this subject. I think it would be beneficial to even delete the comments that are not about this subject above

You need to find a company like this.

Or you could 3D print clay yourself, there are clay 3D printers online.

Do you have any ideas of what company might do this? I have been searching but cannot find anything out there

Depends on your budget

Something that a high school student could afford if they really wanted it

That means nothing to me. Not even sure what highschool is, but when I was in school I could afford a coffee mug from a $2 shop once in a while I guess.

"High School" US term for grades 9-12 for students (roughly) aged 14-18. 12th grade ("Senior" or "High School Senior") is the last year of federally mandated education. After successfully completing all 12 years, people move on to secondary education ("college"), the military, or civilian work force.

The problem is quantifying "what a highschool student could afford" - is that 5$ or 50$ or 500 $? All of those are reasonable for different high schools in different areas....

Is there something that does this for around those prices?

What prices? For 500 I can hire a master potter to make a all series unique mugs, for 50 I can order some customized mugs on a basic model from a print shop. For 5 I can get one or two mugs from IKEA.


text:
Pros/Cons of 3D printed part cooling mods
In my previous research for mods for my Ender 3v2, I came across the topic of part cooling mods. The two most common are the Petsfang and Hero Me sets.

What are the pros and cons of third-party/DIY part cooling mods?

What benefit does having a third-party/DIY part cooling mod provide?

What makes you think your printer has a cooling problem? Fixing things that aren't broke seems to be a staple of DIY 3d printing mods

@Kilisi I never intimated that I had a cooling problem. In my research about mods, I came across part cooling mods and thought about asking here to get better informed. Additionally, mods can be done to improve performance depending on how you look at things.

a small box fan to the side of the printer hits the top layer constantly, unlike a fan attached to the nozzle, which only cools during the brief period that the head is hovering above.

Cooling duct design is not well understood by either the 3D printer OEMs (exceptions may apply) nor by the aftermarket cooling options or most of the  homebrew designs.
The problem is the lack of the understanding in aerodynamic design. Note that the fans that we use to produce the cooling flows are pushing flow, they do not create a large pressure difference. So with not too much pressure difference you should avoid long ducts and sharp bends in the flow path, narrowing of duct annuli or (you should) narrowing the duct annuli when air is bled out.
Looking at many of the options available, it is clear that many of these design rules are not taken into account.

+1. Add to that that even normal 3D printing design rules are hardly ever followed - being support-free with no overhangs and reasonable chamfers, making holes properly printable with angled roofs, easy fastener placement etc.

@towe you mean like this primer I wrote?

@0scar So it seems as if you are saying that the part cooling mods that are out there are not useful almost detrimental to 3D printing. Am I correct?

@agarza I am saying that there are cooling mods/designs out there that don't adhere to proper aerodynamic design. If that is detrimental to the print quality is another question answered below. What I do know is that the fan nozzle on the Anet A8 was narrowing so much that virtually no air bled out. Similar to most of the ring around the nozzle style cooling ducts, for every hole the main channel should be narrowed else the air will slow down making it way less effective. Most of the ducts have a constant area cross section even when air is bled.

@0scar Very true. I was looking at the Petsfang and Hero Me. David Crosslink recently had an interview on YouTube with the designer of the Hero Me. I'm not well versed in aerodynamics but it sounded like he designed the Hero Me to provide better airflow around the nozzle.

@agarza The answer was meant to be generic and doesn't specifically address the cooling options that are mentioned. For the Hero Me or at least some of the available options seem okay, short distance from fan to exit, but they still have a steep convergent nozzle. The petsfang has long ducting and 90° bends. Print them, try them modify them !

Part cooling is essential to print at any decent vertical speed (layers per second), which is critical if you do rapid prototyping of small parts or vase mode prints. This is because you can't (repeatedly) print on top of material that hasn't yet cooled enough to be rigid; if you do, after a few layers, you'll find nothing is in the right place and it's all a bunch of goo getting dragged around by the nozzle. In fact, if the part is small enough you might not be able to print it at all. That's because, while slicers have features to slow down to guarantee a minimum layer time for cooling purposes, if the hot nozzle sticks around in the vicinity of a tiny part the whole time, just the heat from the nozzle will keep it from properly solidifying.
The Ender 3 (and as far as I know, the v2 as well, along with just about every other Creality printer) has pitiful stock cooling. It's off-center from the nozzle, and aimed more at the nozzle itself rather than the part below it, so that it saps heat out of the hotend (making the heater work harder and reducing your max achievable flow) at the same time it's (barely) cooling the print. So upgrading it is desirable. But, as you've guessed, there are cons too.

Some, especially those utilizing the stock 4010 fan, reduce airflow by constricting the airway too much. The 4010 does not really have the power to compress the air much, so if the airway cross-sectional area decreases along the way, that will reduce flow. Does the increase in focus/delivery to the right place make up for the lost flow? Maybe.

Some focus the air too narrowly while increasing its pressure, delivering high-pressure air to a still molten point on the print. This can actually cause the extruded material to bend in the direction the air is pressing it before it cools enough to solidify, giving an inaccurate print.

Large fans and ducts add mass to the toolhead, which can increase ringing, especially if they're not sufficiently rigid.

Many of the cooling mods mount awkwardly to the toolhead in ways that interfere with the motion of the carriage, reducing total build volume.

If the cooling mod blows on/over the heater block, it can reduce melting performance and pour heat onto the part you're trying to cool. Most try to avoid doing this, but you may find you want additional insulation around the block if you use more powerful part cooling.

Some people will also tell you that "too much cooling" will harm your print quality, hurting layer adhesion, making the print warp, etc. I use a rather extreme cooling system and have not encountered such problems that can't be remedied with a slight increase to the nozzle temperature, yielding better overall quality and equal strength to what I would have gotten with lower fan. But I print just PLA, PETG, and TPU, so it's likely that this could be an issue with other materials like ABS or nylon. If so you can always reduce the fan speed.

I've added an answer to focus on aerodynamic design as you touch under 1.. Great answer and good insight in that the poor designs restricting airflow may cause an "inadverse" effect of good prints! :-)

In the context of a heated build chamber, part cooling is not necessary

@user77232: Depending on what materials and what print speed, it may be needed.

The best 3D printed cooling solution actually is not used generally - and it can be rather loud. I am talking pretty much the very same setup one uses in a CNC-mill to spray or mist cooling liquid on the item. That's either flood cooling (with a full jet) or mist cooling (with a mist). Just, in this case, using air hoses and a compressor or air pump, it's best called "airblast".
In such a setup, all the ducts are extruded tubings, the nozzles are metal and the only 3D printed part is a holder for these parts. But how is this loud? It's often loud because this setup needs a compressor to run and push air through the air hoses. And compressors can be rather loud.

(The "spray cooling" is called mist cooling, which contrasts flood cooling in terms of CNC Milling) <- that's just for your general knowledge Trish.

@user77232 Yes, one could use a dry Mist Cooling system, but I actually meant either setup: their setup is close enough to one another to convey the idea. Some people have turned aquarium pumps into coolers, though the effectively is questionable.

At least several people doing high performance printing are using CPAP systems for this rather than a full-fledged compressor.


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FlashPrint Slicer: Second layer overlapping with first layer
When printing using FlashPrinter v4 or v5, the second layer of the model is not with respects to the first layer's thickness nor height. This can result in the second layer being below the first, the second layer being 100 % overlapping with the first, or the second layer can be marginally higher than the first. The example below will show the second layer overlapping 100 % with the first layer.
The goal is to not have the printer head scrape through the first later or applying unintentional smoothing/melting.

These are my layer settings. Relevant raft settings are:
Space to Model (Z) = 0.30 mm, and
Top Layers - Layer Height = 0.30 mm


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Wifi goes down in Octoprint after 5-10 minutes with reboot required to reconnect
I recently installed Octopi on my Raspberry Pi 4 and noticed some unusual behavior in that I lose the Wifi connection every 5-10 minutes immediately after boot. Once disconnected, I cannot re-establish the connection because my network's SSID doesn't even appear in the network list anymore. The only way I can re-establish the connection is to reboot the device.
With that said, I did find a troubleshooting discussion of similar problems at octoprint.org: OctoPi losing network connection mid-print.
Following the various advice, I must have tried about 12 different things, but none of them have fixed my issue. At first, I thought that wifi power-save mode was the most likely culprit. iw wlan0 get power_save indicated that power-save mode was turned on, but then I turned it off with iw wlan0 set power_save off and the wifi still disconnects.
Going a step further, I set up a script to run the iw command right after boot so that the change is made permanent, but that didn't work either.
Other troubleshooting attempts I tried:

Verified there is adequate power
Configured with settings for hidden
SSID (even though mine is not hidden)
Set up a reconnection script
that doesn't work because it can't find the network
Properly set up
regional settings

I am at my wit's end.
As for my setup, I have an 8 GB Raspberry Pi 4 and am using an image of OctoPi 0.18.0 with OctoPrint 1.7.3. This I downloaded and imaged onto a 128 GB micro-SD card using the Raspberry Pi Imager. My wifi network is 2.5 GHz secured with WPA2 with a visible SSID and is definitely within close range. One way that I know that it is not a hardware issue is because I have another image with the Raspberry Pi OS 64-bit version and wifi works just fine when I run that.
As for Octopi, one atypical difference is that I am running it with a desktop. It may be that, for whatever reason, perhaps that particular distribution of RPi OS has a major bug in it? If so, then maybe I do have a solution, but I don't want to run without a desktop because I have a nice setup on my 3D printer that includes a touch screen. Given that is the case, could I maybe use the 64-bit Raspberry Pi OS and just load OctoPrint onto it with sudo apt-get [package-name] or something like that?
Any additional troubleshooting advice is much appreciated, but I suspect that not much else will work. I am not a greenhorn when it comes to linux-bases systems, but this is my first time trying out an image using Octopi.

It's probably something awful with whatever desktop-environment-integrated network manager you installed. These days a number of them (particularly whatever Android and ChromeOS are using, but I wouldn't surprise me if it's some of the same underlying software logic) are outright malicious about aggressively disconnecting and shadow-blocking networks they've decided are "low quality".

@R..GitHubSTOPHELPINGICE Yikes! I have a 1GB fiber connection and regularly get speeds in excess of 250 mbps over my wifi connection so I would not have guessed it could be a network manager doing such things. Any command that I could run to check and see?

I'd love to know so I could get Google devices to stop doing it... It doesn't seem to be a matter of bandwidth, but of how often the radio signal experiences disruption, and also something to do with WPA rekeying intervals. It's been over a year since I dug into it and didn't get anywhere solving the problem.

I think I have a solution for this. Please follow the steps mentioned in this Github page of mine for the Wifi connectivity issue. I rarely have any issues with the wifi signal dropping randomly.

Wi-Fi connectivity issue

Ensure that you have set up a static IP address for your Raspberry Pi.

Ensure that the command sudo ifconfig wlan0 up and sudo ifconfig wlan0 down works without the user password requirement.

To run the aforementioned commands without a password, do the following steps:
sudo nano /etc/sudoers.d/010_pi-nopasswd

Add the following line to the file
pi ALL=(ALL) NOPASSWD: /sbin/ifconfig wlan0 up, /sbin/ifconfig wlan0 down

Here pi indicates the username of the Raspberry; update it as per your name.

Try running the commands sudo ifconfig wlan0 up and sudo ifconfig wlan0 down, it shouldn't ask for a password.

Beware before running the previous command ensure that you have not recently typed the password for any other sudo command or else try this in a new terminal.

To know more about this search the command sudo visudo

check_wifi.sh - script to check if Raspberry Pi is still connected to the wifi or not. If not then it restarts the wlan0.
#!/bin/sh
# keep wifi alive
if ping -c3 192.168.0.1 #router ip address
then
    echo "......"
    echo "No network connection, restarting wlan0"

    sudo ifconfig wlan0 down
    sleep 30
    sudo ifconfig wlan0 up

else
    echo "Wifi working normally."
fi

Add a cron job to check the WiFi connectivity every 5 minutes - sudo crontab -e
# cron job for checking the wifi connection every 5 minutes
*/5 * * * * /home/pi/Octopi_Setting/check_wifi.sh > /dev/null 2>&1

Additional resources:

How to list, display and view all cron jobs in Linux
How To Add Jobs To cron Under Linux or UNIX
Editing sudoers to allow ifconfig only on certain interfaces
Add test user to the sudoers file, to run ifconfig

I have made some formatting changes to be more in line with the site's guidelines. Please review your answer to make sure I didn't mess anything up.

I added in a disclosure; going forward, please remember to always mention when you are linking to a resource of your own as per the promotion policy.


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How to tune Longer LK5 Pro for smoother prints?
I need to print parts that fit together very well on the Longer LK5 Pro. However, after printing a Benchy, I noticed that whatever I print has a lot of imperfections. Is there any way I can fix this? All I know about the printing conditions was that I was printing at 230 °C nozzle temperature with 60 °C bed temperature. I was using PLA+. I was also printing the Benchy file that comes with the Longer LK5 printer. I tried tightening the Y-axis belt, that moves the bed, and the wheels on the bottom of the bed.
Here are pictures of my Benchy:

Looking up your printer, one thing I noticed is that it has power loss recovery. This feature writes to the SD card at the start of each new layer, stalling the print for at least a significant fraction of a second with the filament unretracted, which will make a nasty blob wherever the toolhead happens to be positioned. Absolutely turn this off. It's impossible to get quality prints with that feature on. If there's no menu option to turn it off, you'll have to rebuild the firmware or get alternate firmware from someone else.
It looks like you have moderate overextrusion. If the esteps were tuned, you probably adjusted them too much in the direction to increase extrusion and should reset to the factory setting and calibrate again, erring on the side of less extrusion rather than more.
There are a number of places (especially on the cabin) where some walls are inset relative to where the wall was supposed to be, and where it's present in other layers. This is almost surely a result of losing material to oozing in the interior of the model, as a result of "combing". See this answer for details.
On the hull (especially the bow), it looks like you might be experiencing the consequences of numerical precision bugs in Cura, which result in erroneous tiny segments that break up smooth traversal of curves, leaving blobs where the toolhead stutters. Watch during printing and see if the nozzle is stuttering (suddenly slowing down then speeding up again) along these curves. If so, make sure the Maximum Resolution and Maximum Deviation settings are 0.5 and 0.025 respectively. These are the modern Cura defaults that avoid the problem, but some profiles (and some older versions of Cura) have values that trigger the bugs.

Power loss recovery can be worked around, for example by having a move out of the print whenever swapping layers or saving. Not the fastest way, but possible.

@Trish: Well that's also necessarily going to waste a lot of material and make it hard to keep the nozzle primed properly. As I understand it, you need to make an actual "print move" (motion & extruding together) in the new layer to trigger the save. And the save is also not synchronous with respect to the gcode; it starts when the first print move of the new layer is processed, but Marlin's interrupt handler keeps running the planned moves during it, so it's unpredictable where the planner buffer might become exhausted during the save unless you use long dwells.

230 is very hot for PLA+ and the pictures look like it's printing too hot for a start. It's hard to tell if there are other issues until that basic one has been cleared up. Where did you get the instructions for 230 degrees?
I suggest printing at 200 degrees or perhaps 210 degrees and then moving forwards from those results.

The recommended temperature was 230 degrees

This is the specfic filament Polymaker Matte PLA Filament 1.75mm Wood Brown

Have you tried printing it cooler?

I looked it up, people using it say 200 degrees on Amazon and most of them are very unhappy with the filament https://www.amazon.com/Polymaker-Filament-1-75mm-Peanut-Carton/dp/B094FDSQHC?th=1

Besides the high temperature, also check for over extrusion.

230 is on the hot end of PLA temperatures, but should not cause this kind of issue unless the layer times are very short, which is not going to be the case with a Benchy unless you're going for #speedboatrace speeds. And at those speeds, you need 230+ to get the flow - and of course appropriate cooling.

Just got an LK5 and printed the included Benchy gcode. It looks pretty similar to the benchy in the pics with some of the blobs in the same location. Then I downloaded the benchy from Thingiverse and sliced it with the Longer 1.3 Slicer. Pretty good results from doing that but it took longer to print.

Welcome to 3D Printing! This is really a comment, not an answer. With a bit more rep, you will be able to post comments.


text:
Can I power an external stepper driver without motor connected?
I have not used external stepper drivers yet, but I am using them in a new build.  I have an optional stepper driver that will be connected to a stepper motor for a rotary attachment.  Can I leave the stepper driver connected to the power supply, but disconnect the optional stepper motor when not in use?  Will powering the external stepper driver without a motor attached fry the driver?

Why not use a switch and sidestep the whole issue?

@Kilisi Mainly laziness.  I didn't think about the possiblity of it being an issue until I started hooking up the motors.  So I would have to take apart my electronics enclosure, drill another hole and add another switch.  I think at this point I will just unplug the power connector to that driver when I'm not using it.  I'm still curious if the external drivers can handle being powered without a motor connected.

I would think it's a risk not worth taking https://electronics.stackexchange.com/questions/345003/why-does-disconnecting-a-stepper-motor-while-powered-on-damage-the-driver

It won't hurt anything to power a stepper driver without a motor attached. They are just totems/hbridges that don't rely on load for stability or bias.


text:
The weirdest DIY 3D metal printing
I have a very eccentric, weird, unusual and strange idea. I need some advice and serious professional help.
I'm interested in 3D printing in PLA a hollow complex structure with 0.2 thickness walls (Yes! That thin!). Fill it with very fine copper powder with a little borax powder thoroughly mixed. Use superglue to join halves or other shell pieces together, making sure the powder is very well compacted. Then in a separate container I want to make some thin plaster of Paris (calcium sulfate with a lot of water). Mix in it, some of my trimmed hair (about 5mm in length). No joke. Seriously. Please, I'm begging you with all my heart, hear me out! There's a very good useful reason for doing it. I then place the object (3D printed flimsy crappy shell filled with copper powder) in a DIY drywall box and pour in the plaster over the 3D printed shell object until the box is filled and object completely covered. Leave it to dry and completely solidify for a day. Then I bake the entire thing in a furnace making sure I'm over the copper melting temperature and voila! 3D printing in copper very complex intricate models with ease. Can it be that easy? Or am I deluding myself?
The hair purpose, after it will burn inside the plaster while in the furnace, is to create very thin tubules or air holes for water and gases to escape and to prevent cracking of the plaster under intense heat. I don't want to use hay because the straws are too thick. I have to use very thin organic straws. I just can't think of anything more accessible than my hair. Do you know of something even thinner and more accessible than human hair? Please let me know. I know it sounds and looks very odd, weird and strange. I'm opened to alternatives or other suggestions, otherwise I wouldn't be here making a fool of myself with such an insane ridiculous idea.
I was thinking to add some form of additional volume above the object, which is connected to the model by some thin hollow tube. All this volume (like an empty cube (shell) ) will also be filled with very fine copper powder providing additional melted copper to the model, in the case if the powder was not very well compacted inside the shell model.
Could this absurd ridiculous insane crazy idea work? I have never heard of anything like this. This is so bizarre and strange. It seems to be some form of odd mix of multiple techniques. But besides all this, will it work in the end? Will the plaster hold while some of it(depends on the model) will be inside molten copper? Or do I have to mix in the plaster, not just hair, but also some individual singular fine strands of steel wool?
I don't know who and where to ask such a thing. Am I in the right place? I don't know what this idea is, I don't know how to name it, I don't know how to ask or formulate this idea, I don't know how to google it or search it. I don't know anything. I really need some guidance, help and advice.

While yes this is very different, my initial thinking is that it may not work. Not being thoroughly experienced in this, I would imagine that the PLA would melt and lose its shape before the copper inside would fuse together. Maybe someone else could elaborate if I am correct.

Of course it will melt. I'm counting on it. It is supposed to melt. I feel sad for not being properly understood. The sole purpose of the 3D print is to create the required cavity inside the solidified plaster. After it will melt it will probably leave only some carbon residue at the very bottom of the mold, or it will completely evaporate. I'm not sure. I don't know. That's why I'm here. To understand what I'm about to do, better.

I guess I didn't explain fully. The PLA will melt before the copper fuses together. PLA has a melting point of ~200C while copper is ~1000C. So the PLA will melt (and probably burn off) before the temperature gets hot enough to melt/fuse the copper.

Yes. I know. I'm using the PLA JUST to make a mold (cavity inside the plaster in the box). Then when it's placed in the furnace, the hair, the PLA print, all organics will slowly burn away as I approach 1000C to melt the copper powder. It's designed to work this way. I'm not sure, what you see in the process as a problem. The PLA will have to melt. It has to melt. It will not probably burn. It will definitely burn. It is designed to burn and leave nothing behind(that's why 0.2mm walls). The only remaining thing in the furnace climbing above 500C will be copper powder inside a cavity in a box.

Hmmm... I think I'm beginning to see what your process is (coffee hasn't fully kicked in yet).

Can you at least tell me what this madness is? English is not my native language so I can't even begin a google search. I don't know what to search for. What is this that I'm describing?
It's not  because I'm not extracting any ores.
It's not any form of  because it doesn't involve any liquid material being poured anywhere.
It's not  because I'm not pouring nor forcing any metal into a mold.

Perhaps it's a little bit related with  but I want to actually melt the powder, not just bind it without liquefaction.
It's not  because i'm not injecting anything into anything. My powder is already there. I'm just melting it.
I have no idea what to google. What on earth is this mad idea in my head which I'm describing? Just give me one single word to search for, besides the self-criticism I've expressed so far.

Putting the PLA and powdered metal together into the cavity made by the plaster isn't going to work.  What's going to happen, at best, is that the PLA will float to the top and get burned off and/or escape, and the copper powder will compact down and leave more than half your mold empty.  At worst, the PLA won't burn off evenly and will leave defects in the metal.  If you have a large sacrificial cavity at the top and fill that with copper powder, it might work.

I don't see why it wouldn't work. It doesn't seem to be the optimal way but I haven't tried it.
Only thing that might be an issue is that PLA doesn't burn away clean (not for me anyway) which can leave defects in the product. But there are filaments specifically made for casting which apparently burn away with no residue.
This is assuming you can actually successfully print a complex object with walls that thin.

Care to explain the downvote?

I think this is just an overcomplicated lost-PLA (investment) casting.
What you're asking for is to create an object, create a mold around it, and then burn out the object and replace it with metal.  Traditionally this is done with wax, and called lost-wax casting, but the same can be done with anything that melts/burns away, including PLA.
Rather than worrying about burning hairs and pressure and compaction of metal powder, print a model, and use the correct kind of plaster (a search for "investment casting plaster" will get you going down the right path) to make your mold.  Heat the metal powder in a crucible, instead of the mold itself, and pour it through the expansion/extra material tube you were talking about.

Comments are not for extended discussion; this conversation has been moved to chat.


text:
Are there any nozzles shorter than volcano but longer than MK8?
I have a semi-diy hotend setup on my MOOZ-2 (an obscure chinese printer). It requires that the total nozzle length (including threading) is longer than 15 mm. So far, I've been using Volcano nozzles because they're the only ones I can find that meet this requirement. However I believe this negatively impacts performance because they stick out way beyond the heater block (see picture below). Unfortunately, the next size I can find are MK8 or V6 nozzles which are 13 mm - too short! Are there any nozzle sizes in between that I could use?

Have you considered using a different hotend instead, so its easier to get new nozzles?

I wish I could. My printer is only semi-diy, and I can only control the length.

Add an image of the hotend when fastened to the printer. It is quite hard to imagine that you cannot lower the heat break/heater block/nozzle. How DIY is the printer/hotend? What changed to the original printer setup?

@Oscar, it's very hard to capture in camera what's going on, but there's a plate installed below the heater block for safety that has a hole for the nozzle. Due to the air gap between it and the heat block, the nozzle must be at least 15mm long to stick out. I cannot move the motor, as the entire extruder setup is mounted inside an aluminum enclosure that I did not make. Nor can I put in a longer heatbreak, as it is the only titanium heatbreak that's M6 threaded (on both ends) that I can find. Most of the components were custom designed for the printer. The only stuff I did is in the picture.

@Rafael: Aside from being hard to find nozzles for, that sounds like an excellent design. The plate not only provides safety but should greatly aid in cooling (blocking radiant and convective heating from the block onto the part) and avoiding heat loss (same factors) from the block that would reduce flow/efficiency.

@R..GitHubSTOPHELPINGICE, the plate actually contains a thin aluminum channel that blows air from a cooling fan (mounted on the side of the enclosure) directly onto the part.

Yes there are, the vendor of the printer sells 17 mm length spare nozzles for reasonable prices.

Those are actually the original nozzles, but it's 37 bucks for five with shipping, and I don't want to pay that.

@Rafael Yes they are, but they are available! Prices are very reasonable, I have nozzles that cost over 100 Euro each and e.g. Ultimaker UM 2+ 5 "nozzle pack" is 80 Euro without shipping and e.g. Bondtech CHT 20 Euro without shipping, et. If you want to buy cheap nozzles but you don't have a lathe, an M6 nut and a hacksaw will be enough to trim a Volcano nozzle (saw next to the nut). Make sure to file the threads and deburr the inner hole. With some elbow grease this should be very doable.

@Rafael If you see the prices they call for a single Ruby nozzle... 7-ish per nozzle is peanuts then.

Could you get an extender made? That would give a larger metal body to hold and conduct heat to the nozzzle tip better, and would allow you to use standard nozzles. What I'm thinking is a cylinder of around 9-12 mm diameter, with one end machined then tapped to be M6 external thread, and the other tapped as M6 internal thread, with a 2 mm hole through the center. If you know someone who has or has access to a lathe and taps, they should be able to do it for you.

It's a good idea. Unfortunately I don't have access to a lathe but perhaps there's some service that will do it.

bling hole threading is a PITA if you can't have a gutter at the end... unless you trick the construction and make a 2-parter...


text:
Is there any way to salvage PLA filament with inconsistent diameter?
I have a spool of PLA filament where the diameter is visibly inconsistent. So it will only print a meter or two and then start slipping instead of being fed into the nozzle. Is this still useful for anything or can it be salvaged somehow?
I can't return it, the shipping costs more than the spool.

Try to get the seller to refund it without return. Any reputable one should do so. If they don't, leave bad reviews (either on the marketplace they sell on, or in relevant forums).

Do a CC chargeback for that roll of filament. You're not supposed to cover shipping in such a case.
As for practical use, I'd melt it down to make PLA plates from in an oven.

In principle you can re-extrude it with a somewhat simpler machine/setup than making filament from scratch, but controlling the diameter is the hard part of making filament - as you can see from how the manufacturer of yours botched it.
I would first try insisting on a refund without returning the item unless they pay return shipping, and that they cover the original shipping cost. The product they delivered is not usable for the purpose it was advertised for.
As for salvaging it - if that's what you really want to do, or if you end up stuck with it - as long as it's not too wide to fit through the filament path to the nozzle, an extruder that's spring loaded can probably manage to push it reliably. You will of course have pulsating under- and over-extrusion which will make it largely unusable for serious parts that need to be dimensionally accurate, strong, or visually appealing, but there are lots of things without these requirements it might be useful for. If your printer isn't capable of handling it, you could perhaps sell or trade it to someone whose printer can handle it.
Getting more on the wild end of things, there are filament diameter sensors that can be integrated with your printer and firmware (I'm pretty sure Klipper supports this; not sure about Marlin and others) to measure the diameter and compensate extruder motor steps to keep the extruded volume per requested E-axis length constant. This would in theory make it possible to use the bad filament for serious prints.

I can't think of anything that doesn't need to be functional or visualing appealing. What on earth do you print? But in any case the deviation is not a small one, it won't print

Stencils, jigs for guiding a router, test pieces that are for calibrating a part of the printer where extrusion width accuracy doesn't matter (like input shaper), ... are a few examples of things that could be printed with low-quality filament.

Personally I store all my filament waste in tubs for the day a recycling/reuse solution offers itself.  You can "compact" waste prints using hot air which also sticks the whispy pieces together.   Someone will eventually come out with a "re-extruder" that simply cooks old filament and then produces a consistent 1.75mm or 3mm output.  Cost is the limiting factor here, both in up-front equipment and ongoing electricity cost.
Plain unused filament is specified as a pin for a hinge in some designs.  However that doesn't use very much.
It can also be used as string, but tends to break at the knot if tied tightly.
Filament could be platted into a rope, but that's going to be more decorative than useful.
Last thought, I've not tried it but filament has a low melting temperature compared to metals.  You may be able to "cast" a 3D shape in a metal mold an a hot oven or with a gas torch or perhaps even in a fire. Fumes could be an issue, and you'd have to somehow stop the plastic from igniting.
I doubt it would be possible to cast a thin round cylinder; the top would be flat at best.

I happened to come across a "spring mandrel" at https://www.thingiverse.com/thing:92266  One could soften the poor filament and then wind it around a structure like that, and when cooled you have a low-pressure coil spring of a length and diameter you chose.  Probably not that strong or robust, but worth a try if you need springs for other prints.


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Prints on bed are missing parts
I'm new to 3D printing, I have printed the cat that comes on the SD card on my Ender 3 and it's amazing the level of detail. After that, I tried to print another figure and I don't know what I'm doing wrong. I don't even know what to search for troubleshooting images because none of those seems similar to my problem.
I used Ultimaker Cura to generate the G-code, it's the same filament, good (I think) bed leveling with 50 °C and nozzle at 200 °C. Is something wrong with the printer? Or is it the configuration of my G-code and what parameters do I need to check?
The next images are:

my first cat (nice print)
what I want to print
what I actually print

What is the filament diameter you sliced the object with?

@0scar: That was my first thought too - the classic Ultimaker 2.85 mm bug. But the base looks okay-ish. So I wonder if there isn't heat creep or failure to unretract from using really bad retraction settings.

@sadak: Perhaps you could post the sliced gcode somewhere (with a link to it) for us to look at and see if it's wrong in any obvious ways.

@R..GitHubSTOPHELPINGICE That was my second guess based on the answer of the 2.85 mm.

There are two big areas of difference between the successful sample print and the model you're failing to print: geometry and how it's sliced.
First, geometry. The sample print looks detailed, but if you actually think about it, each cross section until you get to the ears at the very top is just a single, mostly smooth loop, whose shape differs very subtly from one layer to the next. (And indeed, when you get to the ears, it doesn't look good anymore - there's bad stringing from missing or wrong retraction.) This is the easiest type of object to 3D print, and there's a reason they chose it as the sample - it's hard to get wrong, and it looks nice.
The tabletop mini style figure, on the other hand, has a lot of (very small!) disconnected components in each cross section once you get past the base. Printing these accurately (or even successfully at all) requires your printer to be able to stop the extrusion, move the print head to a different location, and resume extrusion there, without losing material to oozing on the way or skipping/jamming when it restarts. This is perfectly doable to an Ender 3, but it requires good instructions from the slicer.
That's where we get to the next part of what's different: slicing. The sample print was sliced for you with Creality's preferred options to show off the printer's capabilities (and they didn't do a very good job at that - see the stringing at the top, which a properly sliced print on an Ender 3 should not have). Yours you sliced yourself, with whatever profile came with Cura. Even if the stock slicing profile they provide is fairly good, this is a really difficult print (see geometry above) and will require a good bit of work to figure out how to print it successfully. It probably needs some supports, and needs retraction tuned well, and probably needs combing limited.
I could go into details for how to go about finding the right options for this print, but I think you really need to start with something much simpler. I know I did the same kind of thing (looking for fancy models and trying them) when I first got my Ender 3, but it ended up being frustrating and took a lot longer to figure out what I was doing wrong than it would have if I started out with things like boring cylinders or calibration cubes. Start really simple. That way you can get to know how the slicer works, what options are available and how they affect what the printer does, and most importantly do an overall sanity check that it's slicing right for your printer. (Cura used to have a bug where it always wanted to reset to the wrong filament diameter, 2.85 rather than 1.75, which gave extremely underextruded prints, and parts of your failure look like that may be what happened, but I doubt it is since I think that behavior was fixed a couple years ago.)
In slicing and printing some simple test pieces, you'll probably find you have questions about what's not going the way you expect. Ask those. Then, once you get the problems worked out, start trying more elaborate prints, and ask more questions when you run into problems with them. After getting past very basic checks, a good next stage would be "nontrivial objects that don't need supports".

The Cura Ender 3 profile will not give you that print. It's a very safe profile. And that print was failing from the start long before it had any complexity to speak of.
So it's the printer or the filament. Hard to tell which without more detail. It looks like it was failing from the first layer. So do some research on what a first layer should look like and troubleshoot from there.
Also doublecheck you are using the right Cura profile for your filament type and machine.
I have to say, the cat print doesn't look very good either.

That print is not possible on an FDM 3D printer. Period. Only a resin printer can pull off something as complicated as that. Perhaps a dual extruder with water-soluble support material will be able to pull it off, but even then you will have to scale the model up at least 2x, as the details are simply too small.
I'm a 3D printing veteran and I wouldn't even attempt something like that on an Ender 3. It's just not possible.
As for the first print, your retraction speed is too low. If that doesn't help remove the stringing, increase your retraction amount too.


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3D Builder: position shifted after auto repair
I build and export my model using ZBrush and as STL files.
To fix the mesh for 3D print, I try to use 3D Builder which can automatically repair my parts.
As it saves as a single file, if I import all parts at once,
I import the files one by one, repair them, then save them as a new file.
After all the parts were repaired, I import all parts to see the result
but find some repaired parts' positions shifted.
How should I handle these issues?

Why not just move them back where you want them?

@Kilisi because I break into parts using boolean inside zbrush, if i move by myself, there will definitely have some tiny overlapping

STL models as exported by software often include their origin in the origin of the design software. However, when using software to fix modeling errors, those origins are not always retained and thus when importing them into a different software their center of mass is taken as the new point of reference.
Slicers are notorious in that they ignore the included origin. Even if models contain an origin that would, when imported into 3D design environments result in the items lining up correctly, the slicing software will simply not care and take a lowest point in the projected center of the object as the coordinate for the item, as this is what is relevant for positioning in the software.
To mitigate that problem, it is best to export models that need to be joined after processing a boolean union on them.

I came across this thread as I was facing the exact same issue. I am also using 3D Builder to repair my STLs before 3D printing them.
The previous answers were however not sufficient (for me) so I went on a trial-and-error spree to determine what was happening, I think I found the answer! (hope that you can still use it!)
An STL file has certain characteristics regarding its location (origin point): X, Y, Z and rotational for the same axes. When you import one or multiple STL files in the 3D builder, it keeps all of these origin points except for the z axis, it automatically places the model/models on the bed so that the lowest point in your (combined) model has a point of Z = 0.
To ensure that all your parts have the same "origin point" you should import the model all at once and then remove all parts except for one. Then, auto-repair it and save it under a certain name.
For example: You have a combined file consisting of three parts.

Import parts 1-3 → remove parts 2 and 3 → repair remaining part 1 → save as part 1
Import parts 1-3 → remove parts 1 and 3 → repair remaining part 2 → save as part 2
Import parts 1-3 → remove parts 1 and 2 → repair remaining part 3 → save as part 3

You now have a repaired model for all parts and their origin points should all be the same!

It has moved the object to the ground as close as it could. This is generally best for 3D printing separate objects.
If you need them together, you can reposition them, or combine them.
Alternatively, change the 'Collision' and 'Intersect' settings until you get what you want.

Thanks, so I guess even the position was shifted, it will not affect the printing result.


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Creality slicer filling in holes that aren't supposed to
I'm pretty new to 3D printing and I made my own file in Blender. I exported it to Creality slicer, printed it, and it was filling the holes that aren't supposed to be filled.
It's supposed to look like this:

but ends up looking like this:

I looked around and saw that it might be broken or something so if anyone knows how to fix that Heres my stl file:
https://drive.google.com/file/d/1auVJb8xFT_33rf3gDXCzf5Hz6K9TvfSv/view?usp=sharing

I don't use that slicer, but there are issues with the STL file, when I fixed them and sliced it looked ok.
So I suggest to fix your STL first. Lots of programs including blender have tools to help with that. Or you could use a free online stl repair.


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Is it possible to make flat parts less flexible by adding geometry to one side?
I have a resin printer, and when I print medium to large flat surfaces they tend to warp a little after a few days. I was wondering if it's possible to reduce this by adding lines/circles or other geometry to one side (e.g. when only one side will be visible).
I vaguely remember seeing somewhere that they (used to?) mill a specific pattern into the metal back of MS Surface Pro devices to reduce flexibility. Although I'm unable to find anything about that now.
Does anyone know more about this?

You are looking for something called "stiffeners", these are use abundantly in aircraft structures. E.g. in wing and fuselage sections.

As the answer below suggests, one can add stiffeners to a design to provide what you seek. Rather than remove material as noted in your question, you'd want to add material in a design complimentary to your objective. Are you using 3D modeling software? If yes, what program? Some are easier than others to achieve this result.

@fred_dot_u I'm on the free version of Fusion 360, would be cool if it had a feature to do this automatically but I fear that even if it does, it won't be in the free version. So... I guess I have to make something up in a sketch and add it manually, right?

Asking for a semi-automatic method to create reinforcements pushes the requirements into more of an analysis type of CAD program. It certainly should be easy enough to sketch in a new part. I'm no F360 wizard and I might be able to create an offset plane and sketch in and extrude a few fins here and there.

Yes. You'll find this all over the place in injection molded parts even even formed metal like disposable buffet serving containers (although there it's visible on both sides), and the same idea works for resin (or FDM) printing. I'm not actually well-informed on the detailed theory of how you make good geometry to do this, but in practice pretty much anything works.

At it's most basic you just put a rib along where you want it reinforced, the shape of the rib makes a difference as well, usually wider at the base depending what you want to do.


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Best filament to print the housing for a laptop?
I have an old notebook computer that works just fine, but the outside of the lid is badly damaged and needs to be replaced. The screen and wiring are fine, so I only need to replace the housing that is exposed to the outside world.
What is the best filament for an impact-resistant printed housing? Should I consider other options that may prevent damage to the internal components? Are there any alternatives with cosmetic benefits?
Edit:
Since I was asked, presume I may be willing to buy a new part to upgrade or accommodate a new filament type.

Are you asking about material type ie. PLA, PETG, PC... or specific brand of filament? Tell me some more about your setup. What materials are you capable of printing with your hot-end/printer?

I tagged the question with "filament-choice" because I believed that signaled material type rather than brand name. Are different brands within the same filament type so significantly different that I should beware?

@whensquaredequalsanegative: For some materials, the material name is more a broad class of polymers rather than one specific one, so things can vary by brand. But I think you're right to just be asking about material types and I'm not sure why that wasn't clear to John - it was clear to me.

For casings I use a combination of TPU and PETG or PLA. PETG shell gives it rigidity and TPU gives it a bit of impact protection. So corners and inside layers of TPU within a hard PETG or PLA shell (shell has no corners).
I haven't had a problem with either but obviously PLA won't withstand heat very well, so it depends on environment.
For a laptop case you'd maybe want to do it the other way around with the outside shell of TPU and inside layers of PETG for rigidity.

If you just cared about impact resistance of the housing itself, the clear choice would be TPU, which would be basically indestructible. However, the housing is there to protect what's inside - not only from impact, but from stresses (e.g. bending) that could break it. This means you need a material that both provides rigidity and avoids breaking easily itself.
If you were doing an old (90s or earlier) style laptop case that's a tank, I'd actually say yeah, go with TPU 95A or higher (98A or so if you could get it) and add some reinforcement ribs/stiffeners. This stuff can be quite rigid at 100% infill, and it will hold up fine to heat, abrasion, even most chemicals. But if this is a modern slim style case, a small amount of material needs to provide a lot of rigidity and that's not going to work.
PLA actually fares really well here in some ways - it's one of the most rigid printable materials, and very easy to get good bonding. If you check for example CNC Kitchen's strength tests, you'll find plain PLA usually coming out on top of most comparisons. However, PLA doesn't handle heat well, which might rule it out.
ASA, ABS, or PC is probably your best bet, but I don't have any experience with them so I'll leave the part about them as something for another answerer to write.

I wouldn't trust PLA: it's strong but brittle, which makes for low impact resistance.

@Mark: That's what people say, but if you actually go and do the tests (or look at data from someone who does), it seems it's better than most of the alternatives. Somewhat related: I have tiny PLA gears operating in places where the PETG ones I tried first kept breaking.

Strength is not the same thing as impact resistance.  People frequently conflate the two, but the difference is why we armor things with steel, not glass.

@Mark: Can you find test results where PLA fared worse either way? I know Stefan tested both and I believe the PLA did surprisingly well, but I may be misremembering.

ASA, ABS and PC are probably stronger and more resilient, but they also out gas toxic gasses when printing, so you'd need to vent that safely.


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Severe blobbing prevents printing. What settings can I change to fix this?
Bought a new printer. When this problem has happened anywhere from the third to the twentieth layer up. An excess of filament suddenly exits the nozzle, often pulling the print from the bed when the nozzle moves away. The only advice I've found so far is that the nozzle or hotend may have damage, but I didn't find any when removing them to examine them. I've tried a few different ranges of settings. Guidance would be appreciated.
I'm using a Creality Ender 3 with out-of-the-box equipment and slicing with the most recent Creality Print version. Settings are default (bed: 70 °C and hot end: 200 °C).

Here's what I get if I set everything to default, switch filament spool, and use a .gcode file that was sent in-box from the manufacturer. There was not really ever anything printed, since the blob was stuck to the nozzle and was dragged around in three dimensions until I stopped the printer.

Are you using any kind of adhesion for the surface of the bed? How did you tram ("level") your bed?

I've tried both a glue stick and an adhesive tape. I adjusted the distance and retraction a bit away from the bed to see if the tape needed room. The tallest portion of a print I've had was about an inch an a quarter, which ended with a baseball-sized cloud of cotton candy filament next to the incomplete print.

I followed the instructions that came in the box on how to level the bed.

More information would be useful, to narrow the possible causes, but consider to perform an extrusion step check. This involves marking the filament at the most convenient location. This would be at the top of the extruder on a direct drive system, at the removed bowden tube for a non-direct drive system or at the entrance to the bowden tube on the same time of system. Mark also a specific distance, often 10 mm or 100 mm and then command an extrusion of that distance.
Perform this with the extruder positioned a suitable distance from the bed, to avoid collection around the nozzle.
Compare the amount moved by the extruder with the marks created. This will determine if you have extruder step mismatch.
This requires a means to communicate with the printer, either via manually created g-code on the card or via appropriate software while connected to the printer via USB.

If I don't concentrate on the blob, but on the rest of the print of first posted image, it can be concluded that the initial distance of the nozzle to the bed is  too large. This causes adhesion problems and buildup of material like a blob.
Dial in the correct nozzle to bed distance using a piece of paper and depending on the bed surface an adhesion product.

That's not excessive Filament, it is "blobbing".
Blobbing happens in several cases, but the most common are:

The printed filament is deposited too hot on other hot filament, resulting in the filament to get dragged behind and create a bead of molten plastic that hardens out as a long blob.

A typical reason for this would be to print a thin cylinder of a vers small diameter without forcing a break in between the layers. The best example I have for you is a 6mm outer diameter hollow cylinder with exactly 2 perimeters (one inner, one outer). If this is printed continuously, this item can be brought reliably to blob.
If the printhead crosses over already printed but not adhering filament on the bed, it can pick up that filament, gathering a blob at the nozzle by accumulation. That is most likely what happened on the photo.

The model might be defective creating areas that induce blobbing.
A bad slicer solution and settings can induce in blobbing.

I strongly suggest to use either PrusasSlicer (a Slic3r derivate) or Ultimaker Cura, from which Creality Print diverges. Note, 70 °C bed temperature for PLA is excessive -> 50 °C are more than enough usually.


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Bed leveling suggestions given this mesh generated by BLTouch
The printer is a Creality CR-10 S5.
Marlin 2.0.7.2

Here is the highest point.

Deepest valley

Further the leveling screws on the right X0,0 and X=0, Y=467 are barely at the very bottom of the screw.  The ones on the left side are cranked super tight nearly at the maximum tightness. The BLTouch is doing a 10x10 grid so the resolution is pretty high.
Any suggestions as to how to get it flatter?  Does anyone else have this issue and resolve it?
I can print with a raft.  Any way to confirm if my bed is actually this bad or sensor glitch.  I obviously can't see at sub-millimeter levels with my eyes.
Could this be an issue with the Z-axis?
So here are the wheel pictures:

So, I changed the wheels, and re-leveled.  I got this:

Except for about 1 cm of the corner opposite the red side it is level enough to print on.

Photo of the x-axis and wheels please. Could be a flat wheel

@Trish I added pictures of the wheels.

The wheels look as if they need to be replaced...

@0scar which is why I asked for photos of them :)

I doubt the corner is 1 cm off-set, this is probably in mm, so it is 0.6 mm! Getting new wheels clearly worked, you should accept the answer of @Trish and delete the last addition to the question and create a new question referring back to this one. In that new question we can elp you further solving this.

Understanding the pattern
Indeed, it looks like the error is induced by the X-Axis, as the pattern is very uniform over the Y-axis. The most likely reason for such an error is either damage to the rail, or damage to the motion system using the rail.
Damage to the rail would either be a deformed or a deep spot in it.
However, in your case, it is quite easily the wheels being worn down on the leading and lower roller while the trailing one does show to be not pressed against the rail properly. As a result, the print head can possibly might either tilt a little or the contact surfaces of the wheel might no longer run perfectly concentric with the wheel's hub itself and the printhead. In both cases, the head does a little wave dance around the ideal Z-position.
I would try to tighten the rollers, and in either case swap them out for spares.
After re-fitting
The new mesh leveling tells me that the back right corner needs to go down quite some (about a millimeter) and the whole left can go up a little. The front right looks about right, maybe a little on the low end, but not too much. A BL-touch printer still needs leveling in itself.

@Trish Changing the wheels seem to even out the center.


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GT2 belts lengthened?
Can the GT2 belts lengthen themselves if they are tentioned too much?
I had them tensioned quite a bit until I saw the video from "Lost in Tech". I then decided to reduce the tension, but the dimensional precision was all over the place. So my guess is, that the belts are too long now?

Possibly, but I think overtensioning will damage your motor bearings first. Can you elaborate on how you determined that "dimensional precision was all over the place"? I would expect stretching to yield a uniform % error across different object sizes, possibly with a mess at a point where the part of the belt that rested on the pulley for long periods without use stretched less. If the errors are more random, it seems likely something else is wrong with your printer. You should probably also tell what printer this is on.

First of all there are two methods to achieve the belt be tensioned.
First method is when both ends of the belt hard attached. In this case if there is a fluctuation in the mechanical system then it will be absorbed by the belt itself. And in this case with big tension it will result in stretching over time with tension disappearing.
The second method is to use spring at one end. The spring will absorb all the fluctuations with little or no effect on the belt.
But I had really bad problems with GT2 PU belts (including steel reinforced), under big tension they degrade suddenly with big change in the geometry at some position. When removed they look twisted. Looks like some reinforcing wires slipped inside the PU body of the belt.
Once switched to rubber GT2 belts (fibreglass reinforced) I never had problems connected to the belts. I can tell that rubber GT2 belts have no noticeable change in the geometry over many years of constant use under high tension with the spring.

As I've seen in todays video from Makers Muse, he also says that these belts can lengthen over time:

 (Link with time code)


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Ender 3 v2 X-axis home fails
I have a problem. I upgraded my Ender 3 v2 for direct drive and added CR Touch. Updated software to bugfix-JyersUI v2.0.1. Now if I turn on my printer first homing X-axis moves to the left clicks one time (usually clicks 2 times) to endstop and that's it. Every after homing X-axis moves right. Changed endstop with a different endstop; same problem. Changed firmware with less possibility firmware and homing is successful.

This sounds like two different problems: X-axis homing problem and an LCD display problem. If this is correct, please [edit] your question to one then create a second "question" to address the second problem. I have used JyerUI so I can offer help but this sounds like 2 different problems.

Lcd display problem does not bother me. Homing issue is the main problem. If u can help me with homing problem that will be great.

My problem was with the Z-axis so I don't know if this will actually help (that's why I'm writing as a comment). Check your wiring from the CR Touch to the mainboard. I had a misconnection on my printer and was causing the Z-axis not to lower to the buildplate.


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Effects of bad power supply on temperature/flow?
I've been trying to trace down a mysterious reduction in the flow I can achieve. Since recording this flow test video where I successfully achieved a nominal 30 mm³/s (almost surely with underextrusion, but with no skipping or warping), something happened whereby I'm no longer able to reproduce it.
Shortly after that was recorded, I discovered a burnt-out XT60 connector between the power supply and printer, and replaced it. That made a lot of voltage sag issues (fans slowing down when heaters turned on, etc.) go away, and I'm wondering how it might affect temperature measurement and indirectly flow.
Could the thermistor voltage have been affected by undervoltage/limited current availability from the power supply, and if so, how would that manifest? Hotend (including thermistor) is stock Ender 3. The controller board is SKR E3 Mini V2. Naively, I would expect that if there was actually reduced voltage on the (3.3V?) line feeding into the thermistor, that would appear as higher resistance, and thus lower temperature, driving the controller to heat it well above the requeste temperature, but I'm not sure if that plausibly could have happened.

Heck of a flow test, is that video sped up?

@Kilisi: No, it's realtime.

Very impressive :-)

@Kilisi: Yeah, now if only I could still reproduce it. Thus this question.

@Kilisi: Yeah, if only I could still reproduce it. Thus this question.

thermistors likely use 3.3v or 5v signaling. It would take a lot of sag for those rails to drop below set voltage if fed 12v or 24v; all they need is a volt or two above output. As far as the effect of a sag on the 3.3/5v line, it's impossible to say universally because the thermistor could be on either side of the voltage divider, so it could be too high or too low, or it could use a current source unaffected until the rail dropped to <1v. It could even be a thermocouple instead, so the effect would be how the gain amp responds to sag or the MCU glitches. In short (haha), we can't say...

@dandavis: I've specified a particular board and thermistor, so it's not impossible to say.

well i didn't catch the model somehow, my bad. I found a schematic and it's on the gnd side of the divider. So that's half the equation solved. But i was not able to find a part number for the actual thermistor. If you could find out if it's NTC or PTC you'll have your answer.

@dandavis: It's EPCOS 100K B57560G104F or equivalent.

that's an NTC, so it would appear as warmer. That said, I highly doubt your 3.3v "rail" sags, and if it does, the whole controller would freeze up and nothing would operate.

OK, so it sounds like there are multiple reasons this isn't possibly the issue. Would you like to write the comments up as an answer so I can accept it?

As worked out by dandavis in the comments, this is not plausible:

thermistors likely use 3.3v or 5v signaling. It would take a lot of sag for those rails to drop below set voltage if fed 12v or 24v; all they need is a volt or two above output. As far as the effect of a sag on the 3.3/5v line, it's impossible to say universally because the thermistor could be on either side of the voltage divider, so it could be too high or too low, or it could use a current source unaffected until the rail dropped to <1v. It could even be a thermocouple instead, so the effect would be how the gain amp responds to sag or the MCU glitches...
I found a schematic and it's on the gnd side of the divider. So that's half the equation solved...
[The EPCOS 100K B57560G104F] is an NTC, so it would appear as warmer. That said, I highly doubt your 3.3v "rail" sags, and if it does, the whole controller would freeze up and nothing would operate

It turns out the PTFE in the heatbreak was badly burnt out, and friction from this may account for at least a large part of the loss of flow (I've been able to get back some but not all). But I still have not fully explained or solved the problem. In any case, the power supply issue does not seem relevant, answering this question as stated.