text:
Anet A8 Hotbed Not Heating Correctly
For my Anet A8 I replaced the stock power supply 12V/20A with a eTopxizu 12V/30A, plus I added a fused 250V/10A power switch and mosfet.  The issue that I am having involves the hotbed, it has no issue heating up, but it doesn't heat up past 94 degrees Celsius when I try to print using ABS (not issues so far when printing with PLA).  When I originally installed the new power supply, I had the mosfet and the motherboard powered separately, but I tried powering them both with the same wire and the problem persisted.   I measured the voltage coming out of the power supply and it reads 12.44V, the voltage going into the mosfet reads 12.28V, coming out of the mosfet 10.58V, and the voltage reading on the hotbed is 10.25V.  If you need pictures of my wiring or anything let me know and I will update the post.

Hi kcthode, and welcome to Stack Exchange. When you say my previous question, to which question are you referring? You don't appear to have posted any questions prior to this one. Maybe I am missing something.

Does the answer helped you to get an answer on your question or helped you come to your own conclusions then please do vote and accept an answer. This helps us reduce the unanswered questions list. Found an other answer (then the already posted) yourself? Please add that answer (and accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

That is actually not uncommon to happen for the Anet heated beds, many users report this. Mine was able to reach about 100 ℃ out of the box (took a while to get there), but not beyond.
For the bed to reach higher temperatures you would need to make some adjustments. You should at least insulate the bottom of the heated bed with cotton or cork to reduce the heat dissipation by half. Note to speed up heating to e.g. 110 ℃, I often insulate the top of the plate with a removable piece of cotton or cork to remove it just before leveling and printing starts. Furthermore, replace the heated bed connector and solder the bed power wires directly to the pins at the back of the connector. That connector is NOT rated for the amount of current requested by the heat bed! E.g. due to the moving bed the connector jitters which leads to sparks; you see many pictures of burned or brown connectors on the internet. While you do that please consider replacing the wires to the heat bed also to some proper gauge silicone wire, AWG 14 should be good enough.

WARNING!
Last thing to mention of prime importance is that the stock firmware of the Anet printers has NO thermal runaway protection! I.e. if your hot end thermistor would fall out of the nozzle block, the firmware would detect the temperature drop and will keep sending current even if it does not measure a temperature rise. This leads to an overheated nozzle and is definitely considered to be a fire hazard!

Edit:
The answers to question How to increase bed temperature over 103 degrees are of great value to this question.


text:
What printer should I consider for printing microfluidic channels?
I am looking to purchase a 3D printer for the fabrication of microfluidics.
I am looking for a printer that can print channels with less than 200 µm cross-sections, preferably, can print optically transparent and biocompatible material, and costs less than $10,000.
Any ideas/recommendations? Could be any printer type (i.e. SLA, FDM, PolyJet).

I doubt that any extrusion system will handle dimensions that small.  Have you done any research to find what existing manufacturing houses use for microfluidic systems?

REcommendation questions such as this are not well served on the stack: there is no best answer. However, I would like to recomend you to look at systems that are not filament based. SLA/SLS/DLMS for example. On the other hand: even the generous budget of 10 grand might be too little for a SLS/DLMS machine. I know of no medical rated FDM material that got clearance for internal use at the moment.

I operate a fairly small SLM machine at work, and I'm aware that it cost somewhere in the neighborhood of 500k. A 200µm hole is difficult but doable with SLM / DLMS, and restricting to bio-compatible is not going to make things easier or cheaper. I'm less familiar with SLA, but it seems like a better bet. your main problem would be getting the beam offset dialed in to get accurate holes, and finding a resin that's going to suit your bio-compatible requirement.

"What Printer?" Let's look at your options:
FDM is the cheapest route into 3D printing, and may be cheap enough to buy just as a learning tool, as many of the concepts of 3D printing are fairly universal. It will not however likely have high enough dimensional accuracy for consistent 200 µm holes, and parts are not usually considered water tight (They may be most of the time, but pinholes are somewhat common).
BinderJet binder jet is the cheaper of the options for printing with powder, where basically glue is deposited onto layers of powder to solidify a part. I have personally used one to create a sand mould to cast metal into without having to create a positive with which to make the mould (ie lost wax casting). It can also be used to print ceramics or metals that are then fired in an oven into a more solid part. In general the dimensional accuracy is going to depend on not only the precision of the glue deposition, but the input powder as well. It may be possible, but I've never seen a water tight part come out of a binder jet.
SLM (SLS, DMLS, generally any metal printer with a laser (even sometimes an electron beam)) Can print quite high quality parts, but a 200 µm hole is pushing into the realm of difficult to achieve. Metal printers produce parts with a fairly rough surface (compared to a machined part), which is dependent on a lot of things, but primarily the input powder size distribution. Typical SLM printers use powder anywhere from 20 - 60 µm in diameter. With very small holes, you'll have to begin wondering about the likelihood that a hole will be sealed at some point by the random surface roughness exceeding the diameter of the hole. This also translates into a path with a lot of resistance, so pushing a fluid through it will require a lot of pressure. Again, I'm not in any sort of biological field, but I'm aware Titanium is pretty bio-compatible, and that is a *fairly commonly printed alloy (the current list of alloys that are pretty easy / standard to print isn't terribly long). Finally price: you can't afford it. I work with a relatively small (though somewhat high end) SLM tool at work, and I believe the final cost went up somewhere in the neighborhood of 500k.
SLA will likely be your best option. I don't have any experience with bio-compatibility (I'm a metallurgist), but there are many uv curing resin systems out there that are made for SLA printing. This is also likely the only type of system that can meet your dimensional requirements (water tight, small features, clear material, etc.) as well as your price target. Nothing can replace doing the research on your own, but this would be my choice. As for which SLA... (Note I'm fairly biased in this opinion) I'd look into Formlabs and possibly in particular their clear dental resin.
*PolyJet I don't know much about this one. It seems like a cross between SLA and FDM, but it seems likely to be out due to cost.

what about a subtractive process?

@tedder42 I mean... this is the 3d printing SE not the cam / cnc SE. I don't know what the application is, but drilling a 200µm hole with a twist drill is likely not feasible beyond a couple millimeters deep.

source: Stack Exchange

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

authors: นันท์นภัส เกตุประกอบ

sort: votes


text:
Why does MakerBot software shows holes in the wall of a 3d model?
I made a simple extrude on a sketch in Fusion 360:

But what MakerBot software shows me in the preview is

Can someone explain how to make it print a smooth wall? Mesh of the model also seems to be okay. Configuration is in the high preset.

Are you confusing infill patterns with holes?  Or display resolution (moire pattern) with actual surfaces?  What is your head speed setting,  layer thickness, etc?

What are your software settings? This could be anyting without proper information as we could not recreate this.

@CarlWitthoft I don't know how to call it. I am talking about leftmost part which is different from the pattern of the rest of the wall (face looking at the camera)

@Trish what properties do you need? I set default High preset

the most interesting would be: Version number of the software you use, Layer height. Wall thickness. Infill density. Infill pattern. What type of bed adhesion helper (is that a raft?). Material. Then a little Information about your model: if it is hollow or solid in design? It might help if you upload your STL so we can look if that is faulty for some reason, but if it is just a simple extrusion as said, that should not be the case unless the file is corrupt.

I guess you are referring to the corner of the part facing you in the first figure, and the sliced corner on the left in the second figure and not the white lines on the wall facing you. This latter effect is called Moiré or moiré pattern which is an optical illusion created by interference.
This appears to be a slicer error or a rendering error, the walls are not finished. Furthermore from your sparse question it is noteworthy to say that you have sliced the model on a raft.
Why not print the model, it will start a raft and when you come to the part it will clearly show whether it is a slicing or a rendering problem!
If it is a rendering problem, keep continuing printing, if not, stop the print and download a most recent version of any other free available slicer tool. The most commonly used free slicer tools are Ultimaker Cura and Slic3r. Setup a printer profile and select and modify material and slicing properties to create a new G-code file for you to print. You can now compare the rendering of used new tool to your current rendering and print the model to see if the part now prints well.

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


text:
Are parentheses allowed within a G-code comment?
I am wondering if this piece of G-code is valid:
G0 (Some comment (Its G0 command)) Y10 Z-5

I have tested this on my Chinese CNC machine and it strips out the comment and works flawlessly.
The machine processes this as G0Y10Z-5 which seems like the correct approach to me.
I have however never seen such comment in real CNC practise.
It would be nice if anyone is able to test it out on their CNC/3D Printer.
Many G-code simulators on the internet fail to process such a line in their parser so it makes me confused. I haven't found anything about it on RepRap Wiki or even Google.

BTW ... Welcome to 3D Printing! :o)

Why not just use  start-of-line " ; "  and avoid all risk?

For a nominal fee :-) ,  I'll write a regex that pulls all  "( * )"  out and replaces with a new line  " ; * "     Let the  sed vs awk flame wars begin.

You are right Carl. I was just caring for thirdparty code that I might need to handle someday. I personally use only ; comments. :-)

It looks like comments inside parentheses are not allowed in numerous parsers (ie. Marlin). This seems to be true for most of the 3D printers. Classical CNC milling machines use parentheses without problems.
It should work on Prusa printers as stated in their Wiki. Unfortunately there are no words about nesting of the comments.
I have however found a comment on cnczone.com forums regarding the nesting of comments within parentheses.

Printable characters and white space inside parentheses is a comment. A left parenthesis always starts a comment. The comment ends at the first right parenthesis found thereafter.
Once a left parenthesis is placed on a line, a matching right parenthesis must appear before the end of the line.
Comments may not be nested; it is an error if a left parenthesis is found after the start of a comment and before the end of the comment.
Here is an example of a line containing a comment: G80 M5 (stop motion)

Source: cnczone.com

This is not universally valid G-code, and how it is handled depends on the implementation. You can use this style of comment on some machines, but not all.
The way parsing used to be implemented in Marlin (a very common 3D printer firmware), it would work fine unless the comment string included a X, Y, Z, E or F character. The parser simply looks for the first occurrence of X/Y/Z/E/F and then tries to parse the bit of text appearing after that character into a number. If the string cannot be parsed as a number, it defaults to 0 instead. For example,
 G0 (Some comment containing the character Y) Y10 Z-5

would be interpreted as G0 Y0 Z-5 and not as G0 Y10 Z-5, because ") " (the string appearing after the first occurrence of "Y") does not parse to any valid number. Your example happens to work fine because the comment string doesn't contain any special characters.
Marlin does support end-of-line comments, which should start with a semicolon and continue until the end of the line.
This is how it used to work in older Marlin versions. Newer Marlin versions have a more advanced parser, but it still would not play well with these parentheses-style comments. It is best to avoid them, as compatibility is not guaranteed.

This sounds even more weird to me. There are no comments about this behaviour for example in RepRap https://reprap.org/wiki/G-code#Comments

@JanVorisek I just noticed it is slightly different in newer versions of Marlin. Still, parentheses-style comments aren't supported.

You are right. Just checked few parsers including Marlin. I have came to conclusion that most of the 3D printer firmwares parse only semicolons as comments. Looks like parentheses are/were? prefered way in CNC Milling machines. I'll stick to the semicolon as I care about 3D printing mostly. Thanks for your time anyways :-)


text:
Where is the line between "inspiration" and copy and derivative?
Scenario:  I'm cruising Thingiverse, and I find the awesomest thing.  I NEED THIS IN MY LIFE.  I download it, print it, and for whatever reason, it doesn't work quite right.  OK, no big deal, I'll just download the source because the maker was so kind, modify it ever so slightly, and I will have the most awesomest thing evar!
Several hours later, I realized that I could have designed it from scratch in a software that is way more user friendly, deterministic, simpler, etc.
And then I do redesign it.  From scratch.  Maybe taking a measurement or two from the thing, or something related to the thing.  And I refine it, and it turns out better than the original was.
Did I make a new thing?  Did I only draw inspiration from the previous thing?  Did I make a derivative work?  Using Thingiverse's terminology, did I remix it?
I'm looking for some canonical guidelines to refer to for the US.  Thingiverse can be an example, but god answers should not be limited to Thingiverse, nor my specific example.
I ran into this issue while trying to print out a case for a Raspberry Pi Zero.  I'm not done redesigning it, but I've been wondering how I could share it on Thingiverse, and if any restrictions from the original model's licensing might affect me when I post my thing.

There are no "canonical guidelines" for this. Copyright law is incredibly complicated, with lots of gray areas. The description in your question is far too vague, and the answer could be anywhere between "yes, definitely copyright infringement" and, "no, totally in the clear".

So any random user has no hope of ever circumnavigating a possibly not at all copyright claim unless they talk to a lawyer?  Seems kind of extreme given that this issue is bound to come up when 3D CAD starts to become more mainstream.

The issue isn't any more bound to come up with 3D CAD being mainstream than it is bound to come up with pencil and paper being mainstream.

It would be good to make your question more specific. Right now it essentially requires a book to be written on copyright issues. You have to consider in what ways your redesigned "thing" is similar or takes inspiration from the original "thing".

It's interesting that you feel guilty enough to ask. :D    You'll need to make a personal ethical decision on whether sharing is more important than withholding as a rule for everybody.

nobody cares about copyright unless they are losing money from infringement. People post to thingiverse because they want to help others and perhaps build a portfolio, not make a fortune. If you feel you owe the original creator credit you should mention them regardless of if you must

So, then by the logic above, every Raspberry Pi case creator should mention the first one?  That doesn't sound right.

This is broad, and perhaps a sharper question can be asked.  It is related to some legal questions which come up with 3D printing because 3D printing makes it possible to make a "thing" that is closely based on another "thing", with no tooling cost.  It removes one of the barriers to copying or expanding or being inspired by another design.  IMO, this is an appropriate area of questioning.  @TomvanderZanden's points are correct that it is a very complex subject, and I doubt that the law is deeply established related to 3D printing.

I should start by saying that I am not a lawyer.  I have been both the complainant and defendant in patent cases, and have had the role of observing copyright compliance for a performing arts organization.  With that in mind, the following is my own opinion and information.

Ultimately, there is no simple answer to your question.  It would depend on the case law that applies to 3D printed objects, which is not very clear.  You are venturing into Copyright law, which is very different than Patent law.
For example, if someone had a patent on "A Raspberry PI case with a <describe a novel, special, functional feature>", and you made a case with that feature, you would be in infringement.  It wouldn't matter if the case looked like the original, or was completely different.  If it included that patented invention, you would be more likely to lose if challenged in court.  The one thing about patent court prosecutions is that it is really rare that anyone actually "wins".  The cost to put forward a case is very high, and usually someone runs out of money (sometimes even the "good guy") before a decision is reached.
Copyright is much harder and softer at the same time.  Copyright can relate to the design feel of an object -- such as rounded vs. square, or using a trash can vs recycle bin icon.  Prosecuting a copyright violation of this kind would require that the aggrieved rights holder demonstrate that the design was copied, or at least derived in an unpermitted way, from the original work.  This is often more a matter of opinion than law, which is why the lawyers matter, as well as the judge and potential jury.
Technically, you are not free to do whatever you wish in the privacy of your own home.  You are much less like to be detected and then prosecuted, and the penalties would be lower, but you are just as much in violation if you make one for your own use or sell them by the millions.
The best way to handle it, if you are prepared for possible adverse reaction from the original designer, is to ask them for permission.  You can say ask for clearance to use, such as by saying:

I loved your object <thing> on Thingiverse.  I plan to <put in your plans here -- make a few for me and my friends -- sell further varieties online -- whatever>.  Although I didn't copy your design, I would like to acknowledge that I saw your design before doing my own.  How shall I do that?

Your next steps will depend on how they respond.  Most likely, they will either give you free leave to do as you wish, or they will ask for something.
This happens a great deal in music, and expensive and acromonious problems have developed over who actually composed a particular guitar riff.  You can pick up the "Stairway to Heaven" case here.  If you are doing this commercially, it is better to negotiate ahead of time.  If you are putting your object back on Thingiverse for sharing, I'd just identify it as derivative an get on with life.

When you remix, either by modifying the existing CAD files (STL or sCAD or whatever), or by rebuilding essentially the same item from scratch, that is a remix and subject to whatever restrictions the original author put on his work.
So the critical issue so far as copyright is concerned is whether the output is a clear copy or remix.  No different from taking someone's novel and rewriting it using Notepad++ and LaTeX instead of the original Microsoft World.
Now, when remix or reuse is allowed by the originator, it is still incumbent upon you to provide proper attribution, just as you would provide footnotes and bibliography so as to avoid plagiarism in a research paper.
All that said, you are free to do whatever you wish in "the privacy of your own home" (IANAL and laws vary by location, but the chance that the copyright holder will track you down because you have a widget in your bedroom are nil). You can't publish or sell, of course w/o permission.

The first paragraph presumes that the work that the derivative is made from is protected under copyright to begin with, which might not be the case for the object given as example in the question ("raspberry pi case") and that the copyrightable aspects of the object are preserved by the remix. If the design is "purely functional" it does not qualify for copyright protection.

Why is the question of clear copy or remix "the critical issue"?

Regarding the last paragraph: under United States copyright law, merely preparing a derivative work is illegal, even if you don't sell or publish it.

@TomvanderZanden  and as I wrote , the chances of being caught, let alone prosecuted, are less than that of winning Powerball.

I did read that, but you also wrote "IANAL and laws vary by location", and that kind of implies you're making some kind of legal claim. Right now it reads as "It isn't illegal and even if it were, they couldn't catch you anyway".

authors: Андрей Лукьянов


text:
Anet A8 display on MKS Gen L board
So I have read this question, Connecting (Anet A8) 2004 display to MKS GEN L.
That looked so easy, so I rewired the connectors and switched the VCC and GND pins. In the Marlin firmware I disabled the MKS GEN L display and enabled the ZONESTAR_LCD and ULTRA_LCD.
Yet when I run the printer, I only get the fully white rectangles. Is there anything else I have to do?
I have a compilation warnings now, because the ZONESTAR_LCD redefines some of the pins that ULTRA_LCD sets, but I guess that is ok. Could it be caused by still including the U8glib library? Do I have to also remove some constant regarding this?

Hi and welcome to 3D printing.SE! SE websites are driven by questions and answers, your question is more a forum style comment to another question where you ask for help to start a discussion. This is not where the comment section should be used for. Please read the help section, accessible through the button with the question mark at the top right menu.

Hi Zdeněk and welcome to 3D printing :-)  I'm sorry that you can't leave comments yet.  Please don't let that put you off though and feel free to ask an original question, or post an answer to someone else's question. Hang around the site, try to earn some reputation and at a reputation of 50 you will be able to leave comments. Good luck in the future. Oh, and don't forget to take the tour.

Ok guys I got it! It really was just what is the answer in the other question (Connecting (Anet A8) 2004 display to MKS GEN L)!
My problem was: I used jumper cables and some duct tape to hold them together ... and the only issue was, that I didn't insert it enough. I got mad today and just pushed them really hard more into the AUX2 connector and it suddenly works!

Yeah, it's always a good idea to push the connector home firmly and fully. :-) I'm glad that you solved your problem.


text:
Where is a reputable place to download Ultimaker Cura?
I noticed that my version of Ultimaker Cura was out of date, so I tried to go to their website and download a new version.  For whatever reason, I could not get the download link to work properly in Firefox with a slew of security extensions.
Where are reputable mirrors for Cura?
Download.Cnet.com and Sourceforge came up as sources, but years ago they both went to the darkside (SourceForge: HowToGeek, thecomputerpeeps).  I don't see anything else that looks even remotely reputable in the search results.
I did some analysis, and it appears that the drop down and form don't work correctly if you select "I don't want to share any personal information", leading me to think this is web page bug.

If one of your security extensions is blocking you from downloading software from the publisher's own site then either disable the extension (maybe temporarily) or look for alternative software -- you are always less secure downloading from unauthorized 3rd party mirrors because a good mirror site will have a copy of the original (including anything bad that might be in it) and a bad mirror can add malware of it's own - a mirror will never remove bad staff from the original but can add new bad stuff -- don't make yourself less secure just to please security software

I believe, it is the security extensions borking up. Disable them for the ultimaker site.

Reaction on the edit: I always choose that option, but I do get the DL link after that.

The answer to your question is: "From the application developer itself!".
Below is the explanation how you can (directly) download Ultimaker Cura from the most reputable source: Ultimaker.com

Regular download
When clicking the link to download of the Cura application download button from the Ultimaker website you are presented with a pop-up GUI that asks you if you want to share where you are using the program for. When you select the required field and press download, the download starts. If this doesn't work, a direct download approach can be used.
Direct download
If the regular download method fails, or you do not get the pop-up GUI, you can use the direct link for Ultimaker Cura from the developer's website:
https://download.ultimaker.com/cura/Ultimaker_Cura-4.1.0-win64.exe
This link can be found at the download directory at the website:
https://download.ultimaker.com/current/
This web directory overview also shows all previous releases and installers for other platforms.
As of version 3.6.0, the download does not appear to be in the list, this link will show an overview: https://ultimaker.com/en/products/ultimaker-cura-software/list
Do note that the latter link will show the pop-up.
As of version 4.1, the web directory overview link will serve a 404.
Github
The Ultimaker Cura Project has a Github, where they offer the current and previous editions under:
https://github.com/Ultimaker/Cura/tags

Cura is a software tool developed by Ultimaker for 3D printers. There is a downloadable page for this tool: https://ultimaker.com/en/products/ultimaker-cura-software/list. There is no restriction to download it.
I'm using Firefox on all my PC's and it can be downloaded with no problems, even if I'm using Windows XP, the main PC works at full speed with 3D models.

This shows the list, but is not a direct download link to the file, there is a GUI interface between that page and the actual download, this is probably why the OP is not able to download the file


text:
Z-Axis doesn't work only during printing
Problem:  Z-Axis doesn't work during a print.  It attempts to work, maybe climbs on the Z-Axis, but screws back down.  It whines, too.  But, Z-Axis DOES work while not printing.  It doesn't matter if the bed and nozzle heating or not, if it's not printing, it works as it should.  I don't know what else I can do to troubleshoot this problem.
I have:

Changed the Ramps 1.4 board twice
Swapped drivers around, bought new drivers
Swapped X-Axis and Z-Axis motor connections
Cleaned threaded rod.
Leveled two Z-Axis threaded rod riders to near atomic perfection.
Changed firmware to each of the 3 latest updates
Remounted motor so both face same cardinal direction
Cursed
Changed jumper configurations from 16th microstepper to 8th for more power.  No dice.  Fried two drivers that way.
Dialed and redial and tridialed and quaddialed the driver pots
Recalled the Z-motors work while not printing so it isn't the driver pots
Cursed again
Scoured the web for similar issues
Looked for G-code that might limit Z-Axis elevation
Died a little.  Just a little

Hardware:

RepRap Guru DIY Prusa i3 V2 3D Printer Kit
Ramps 1.4
A4988 Driver
Firmware:

Marin 1.1.8,

1.1.7 (screen didn't function),
1.1.6 (screen didn't function),

RepRapGuru_Marlin_v4,
RepRapGuru_Marlin_v2

Additional information:

My power supply is the original 12 V 360 W supply with the kit.

The 5 amp power in is 12.02 V, the 11 amp power port is 11.96 V and 12.18 V depending on which heater is on.
The bed measures 11.50 V and the hotend is 3.4 V

While heating the bed and hotend I am using the LCD screen and rotary encoder to move my axes. It works as expected until printing. I have upgraded to an aluminum 12/24 V hotbed from the original PCB.
Currently getting Repetier. Will update.
The z-axis leadscrew is M5-0.8 mm

Sounds like a lack of current, or Z-axis steppers not producing enough torque or X-gantry too heavy

What about your power supply? Is it producing enough to power the printer when it is powering the heated bed and the hot-end? Did you measure the voltage (drop)? You say it's working fine upto the point that you start to print, the difference IMHO is heating the nozzle and bed, which together take about 75 % of the power of the printer.

Please explain exactly what you are doing to drive the Z-axis when "not printing" .

Please measure for us the following voltages: Board supply from the power supply; the motor's power supply (run a G1 Z100000 F1000 via Repetier).

Just thought of something else. What is the lead and/or pitch of the leadscrews/threaded rods? If the pitch is too high then that could cause the stepper to bork, see this answer: A more aggressive leadscrew will require more torque to drive.

Great questions so far.  Oscar and Carl Witthoft, my power supply is the original 12 volt 360 watt supply with the kit.  The 5 amp power in is 12.02v, the 11 amp power port is 11.96 and 12.18 depending on which heater is on.  The bed measures 11.50v and the hotend is 3.4v
Carl Witthoft, while heating the bed and hotend I am using the LCD screen and rotory encoder to move my axises.  It works as expected until printing.  I have upgraded to an aluminum 12/24v hotbed from the original pcb.
Trish, Currently getting repretier.  Will update.
Greenonline, the z-axis leadscrew is m5-.8.

Thanks for the informative update! Hi and welcome to Stack Exchange 3D Printing btw... :-)

Oh, yeah. I have added the information from your comment to the question. Comments are rather ephemeral in nature and are only used for asking clarifications. They usually end up getting deleted.Any additional info should be edited into the question, so then it is all in one block and the comments need not be scoured in order to get the complete picture. Cheers.

I would check the gcode you're generating to make sure it's not full of "bad" z-commands.
Further, I'd take any gcode file you have and manually edit it, leaving in all the initializations, heatings, zeroing, etc.,  and then delete everything except some z-motion commands.  Run that as a test case to see what happens.
I  think it's extremely unlikely that the gantry has enough mass to force the z-screws to counter-rotate (lowering the gantry), and you'd see that with power off in any case.
edit
As Greenonline discovered, a bad choice of lead screw might cause the behavior you're seeing.  It would be a bit scary if a stock kit such as the one you bought provided high-pitch Z-screws.  Better check that out!

Also check the gcode for how FAST you are attempting to raise the Z. The motor may stall if trying to move too fast.

If the lead of the leadscrews is too large (8 mm) then that could cause unscrewing, maybe? See this comment of Tom's: with an 8mm leadscrew, the weight of the printbed or carriage can overcome the (idle) torque of the stepper, causing the bed or carriage to drop like a rock when the stepper is disabled. This can be rather annoying.

Carl Witthoft, I think you are on to something with rogue commands limiting the Z-Axis. Thank you for pressing me to try a new program. Now I need to learn it... So, it works now. The only difference is that I am printing from Repitier using Cora instead of using Slicer to make g-code for an SD card. While, I am happy with the results, I am dissapointed that I still don't KNOW the source of the issue. There must be some command from stock Slicer causing issues.

The threaded rod is a 5mm diameter with a thread pitch of .8mm

If you can post sample gcode files from each source (Slic3r and Cura) , from the same STL file, perhaps we can identify what's messing things up.  Quite possibly the internal "configuration data"  in Cura's software is a better match for your printer than the same internals from Slic3r .

Carl Witthoft, I think you are on to something with rogue commands limiting the Z-Axis.  Thank you for pressing me to try a new program.  Now I need to learn it...
So, it works now.  The only difference is that I am printing from Repitier using Cora instead of using Slicer to make g-code for an SD card.  While, I am happy with the results, I am dissapointed that I still don't KNOW the source of the issue.  There must be some command from stock Slicer causing issues.

If you can post sample gcode files from each source (Slic3r and Cura) , from the same STL file, perhaps we can identify what's messing things up.  Quite possibly the internal "configuration data"  in Cura's software is a better match for your printer than the same internals from Slic3r .

I'm not entirely sure if this is an answer or should be a comment to @CarlWitthoft 's answer. As you don't have 50 rep points yet, you can't post a comment. I'll leave this as it is for the moment, so that you can provide Carl with more information, and have a bit of a back-and-forth to solve your issue. However, any new information should go into your original question... or a new question (referring back to this one) if your original issue has been solved. Then, at a later point, once the dust has settled, I'll convert this answer and carls comment to comments under carl's answer.

I'm converting this answer to a comment. Even though you have less than 50 rep points you can comment on Carl's answer, as it is an answer to your question. See the "special Note" on the first answer here: https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead

Actually, after re-reading this answer, it could actually be an answer, if (as Carl suggests) you edit this answer and add/post the G-code that didn't work and then the G-code that did work, that way the "incorrect commands" could be identified, and then you will hopefully discover the source of the issue. Doing that might help other people with the same or similar issue. If you do this and then flag your changes, using the flag link under your answer, then I can undelete your answer. I hope that you understand :-)

I've undeleted this, because I couldn't work out if it was an answer or not and, as it has been playing on my mind for a few months, I decided to err on the side of caution. I sincerely apologise for any confusion :-)

From your comment

the z-axis leadscrew is m5-.8

I presume that your lead is 8 mm? You don't state whether it is a threaded rod or a leadscrew, so I will presume that it is a leadscrew.
If so, then I would suggest that you choose a different leadscrew, one with a lesser lead, say 2 mm or 4 mm. This is because, for a 8 mm lead, the stepper motor has to lift the X-axis gantry by 8 mm upon one rotation, which requires four times the amount of work that would be required to lift the X-axis gantry by just 2 mm if a rod with a 2 mm lead is used.
So you need to either:

Change/upgrade your stepper motors to ons with more torque, or;
Change the rods, for some with a smaller lead.

Depending where you are in the world, one option may be cheaper than the other.
If you are going to upgrade your rods, then change from a threaded rod (if you are using one), to a leadscrew, as they are much better quality, have less friction, more precision and less wobble. However, you may also have to change your [rotary] fittings, i.e. the nut that goes around the rod - although you would have to do that anyway if you change your threaded rod for one with a lesser lead. Also, many threaded rods, and leadscrews, come with the rotary fittings included.
Also, you state that your threaded rod/leadscrew is M5. Again, if you are going to have to change it, it might also be worth changing from M5 to M8, see Lead screws - M8 instead of M5?

For a more in depth explanation, see this answer to the question, Would using a leadscrew with 1 or 2 mm lead, en lieu of 8 mm, result in a better printer? Here are some highlights:

A more aggressive leadscrew will require more torque to drive. We have one kit printer we bought a couple years ago that has an overly aggressive multi-start leadscrew for the z-axis. The small motors included in the kit do not have the torque required to reliably start upward movement of the carriage, leaving it sitting there skipping steps until the carriage is given a little upward nudge to get it going (no, it's not a lubrication issue or a driver that needs turning up).

and

(As Tom points out) An 8 mm lead can result in the weight of the X-axis gantry (especially in a P3Steel) overcoming the idle torque of the stepper. As a result of this, the X-axis gantry can end up sliding down the leadscrew, in particular at power down

Note that there is a difference between pitch and lead:

Pitch is the distance between adjacent grooves on the rod, whereas;
Lead is the distance travelled along the rod upon one rotation

The difference depends upon the number of leads, or starts that your threaded rod has.
From What is the difference between screw pitch and lead?

Learned something new!  Thank you Greenonline!  So, I have threaded rod that is m5 .8.  It is 5mm wide with with a pitch of .8.  The kit is from reprapguru.com.  I have had so many issues with it, missing parts, terrible documentation, certain prusa firmware not functioning  at all (1.1.6, 1.1.7).  I do not recommend it.  Original firmware broke my  endstops off.  Since this is my only printer, I assumed the aggressive nature  of the machine was typical.  I now have some office rearrangement to allow the printer to remained connected to the computer.

Just to clarify, is that a pitch of 0.8 mm, or 8 mm? 0.8 mm sounds about right, but it is the number of starts that is important really... How many starts does the rod have? 1, 2 or 4?  Regardless, it is a shame that your printer seems a bit of a 'mare. However, I'm sure once you get used to it, it will be fine :-) Glad you sorted your problem anyway. :-)

Yes, its a pitch of .8mm.  What is the number of starts?  How does this affect Z movement?  The supremely unfortunate part is that it used to work.  I've had the printer for a few months, it was out of commission for a month or so while I was replacing parts and diagnosing syptoms.  It was never easy, but it worked well enough to keep.  The issue may be from a Z-axis speed increase by accident, but reflashing and deleting and installing new slicer didn't fix the issue (which would make sense if the custom files were stored elsewhere).

After reading up on lead screws, I will upgrade eventually.  Until then, the machine works with cora.  Thank you for your help and knowledge.

@RMF - The number of starts, or leads, is the number of individual threads. Referring to the pic in my answer, look at the end of your rod... how many entry points are there on the bottom? It could be just one, or maybe two, or possibly four. That number is the important number of starts.  You then multiply the pitch (in mm) by the number of starts to get the all important lead (in mm). Does that make sense?

It is this lead that affects the Z-movement, as it is the distance that the gantry will  move upon one rotation of the stepper motor. The smaller that distance, the more precise the printer (in theory), w.r.t the layer thickness, although there is a limit (depending on the thickness of your filament).

But, again,  the OP is using the lead screws that came with the stock printer kit.  If there were something drastically wrong (pitch, lead, whatever), you'd think hundreds of buyers would be reporting this problem.

@CarlWitthoft - good point

I had the same issue with an Ender 3.
The threaded rod was not lubricated enough. Adding some lithium grease, applying it evenly, and moving the Z-axis from top to bottom multiple times fixed the issue.
I had to recalibrate the Z-offset after that.


text:
Nozzle heats up past the setpoint and increases
I made a few successful prints since I got my CR-10 two weeks ago and I didn't run into any major trouble. The printer is new.
Today I set it to "preheat" mode while I was preparing the SD card with the settings being 210°C for the nozzle and 60°C for the bed. When I wanted to start the print I noticed that the temperature showed as "actual temperature" on the printer's screen showed 233°C and it was going up steadily while the "requested" temperature was still 210°C.
Thiking it might be a mis-manipulation on my part I powered it down for a few minutes (I got scared by the high-temp) and then powered it back on. I then immediately requested the print to start. The CR-10 heated up to the proper value, started printing and kept heating the nozzle. I stopped it at 217°C.
I looked for an answer on the internet but all I could find is people having trouble with the nozzle not heating at all ...

Hi and welcome to 3D Printing.SE! How did you measure the "actual" temperature? E.g. using an external thermometer, thermistor, thermocouple or a pyrometer, or read from the display? Maybe you could add that to the question.

Thank you for your advice. I updated my question. The "real" temperature is measured by the printer itself and is displayed on the printer's screen.

Does this happen at lower temps, e.g. 195 (which is sufficient for most PLA filaments)?

If you know them, post the firmware version and control board type/version, etc.

Have you found & fixed the problem? If any of the answers helped you to get an answer to your question or come to your own conclusions then please do vote & accept an answer (using the tick button next to it). This helps us reduce the unanswered questions list & stops the question from being bumped once in a while. If you found another answer (than those already posted), please add that answer (& accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

@0scar I'm still in the process of fixing it. I did some more analyse work on the printer and it seems to come down to the motherboard, hardware or software I don't know yet. I'm very busy lately that's why I couldn't get my nose back into this earlier. I'll surely let you guys know when I fixed it. (I'm a StackOverflow user, I'll accept the right answer if there is one :-) )

Thanks for the feedback! You can also join us in [chat] if you require help and feedback. Personally I'm curious what the cause of this problem is, this is really an odd one!

This is not an easy one to solve, the firmware of the printer should be keeping the printer at a certain temperature depending on the temperature setting and the current value. If the firmware is not able to keep the temperature at the requested level, but goes beyond that level, that could be considered "strange". As it measures the temperature (and reports it on your display) it must know that it is over the limit and thus should not power the hotend.
In this process there are a few possible candidates for you to look at:

Check for a faulty MOSFET (sort of an electronic switch) on your controller board (is it leaking current to the hotend?).
Check and or update the current settings for the PID values (settings for the control loop of the hotend). The PID values control the overshoot of the temperature. E.g. is this is very large overshoot? When incorrectly configured the temperature can get higher, but normally should never increase to infinity, are you sure it keeps rising? The determination of the new values is called PID tuning. Important commands (that need to be send over a USB connected printer with a 3D printer terminal application like Repetier Host, OctoPrint or Pronterface):

The M503 G-code command shows the current settings (somewhere in the heap of all settings).
The M303 G-code command can determine the values.

Reflash the firmware
Replace the printer controller board

You could replace the thermistor and the heater cartridge (just to be sure, most definitely not the problem, but they are really cheap to replace). The thermistor works as it reports the temperature, and the heater element doesn't get powered by itself.
As suggested below the most likely candidate for your problem is the MOSFET. These are pretty easy to replace (depending on your board) or replaceable by an external MOSFET module (if you happen to have one lying around).

I would suggest checking the MOSFET first, as this is the most likely explanation in my opinion. Measure the voltage on the gate. If it changes when the temperature setpoint is exceeded, but the heating does not stop, then the MOSFET is fried. Another good thing to check would be whether it starts heating without any input. I don't think replacing the thermistor or heater cartridge is a good recommendation (a broken heater cartridge certainly wouldn't heat up the hotend without power being applied to it).

As far as I know, the MOSFET is only related to the heating bed. I couldn't find any schematics nor any obvious pointer to where the nozzle's power command components where. With a friend of mines we tested (multimeter) a few components such as the thermistor and the heating resistor just "to be sure" (we didn't really know where to go). Everything is ok.
We flashed the firmware and installed Marlin (latest version). Nothing changed.
So I'm going to order a new board. I don't have enough knowledged of the board to try and fix it and can't find any schematics for it online. I'll let you knopw

@Wndrr Both the connectors for the heated bed and the hot end have a MOSFET attached; this is because the micro-controller cannot handle high currents, instead the low current connection to the micro-controller schedules the high current loop (like a gain) to the hot end cartridge. If there is a failure in the MOSFET, current may leak continuously. So did you measure the voltage over the cartridge during overshoot?

I've repaired the printer a while back, but I forgot to update this thread. I tried everything but ultimately changing the motherboard was what solved the problem. I suspect I might have burnt something by heating both the bed and nozzle at the same time from a cold start. That's my best guess at why the MB failed.
Thanks for your help !

@MathieuVIALES Many thanks and nice to come back after a while and report that you fixed the problem by replacing the board! The MOSFETor the pin/port scheduling the MOSFET are definitely suspects on your old board and certainly could have been damaged. Have fun printing!

A similar condition occurred in my 3D printer. I solved the same. I checked all my connection and I came to know that I connected the thermistor of the extruder in the wrong port. So just check the connection of your thermistor.

Actually my 3D printer circuit board frequently failed because of over current. I then added a multimeter in series with my power supply and the load, also a voltmeter across the voltage regulator. I then corrected every motor driver DRV8825 to a reference voltage of 0.6 V so that the maximum current supplied to each of the motor will be less than 1 A. All these made my circuit checked ok. Then I uploaded the G-code, but I couldn't print because my extruder gets heated about 280 °C and got reset and suddenly shut down the extruder supply. This continues to happen.
Then I reinstalled the Marlin firmware and I also changed the port of my thermistor. Now my 3D printer is ok and prints nicely. I also faced another problem while I gave the print command - it showed that the extruder and bed had started heating but it actually was not heating. So I reinstalled the firmware again and this fixed it. Now my 3D printer works OK. You just try for these steps:

Check the connection.
Reinstall the firmware.
Try manually preheat the extruder, and just see whether it heats to infinity.

These are my working experience please try for these, I think it will help you. Just don't leave it you will get the solution. Keep on trying.


text:
Z-axis comes down and presses the bed while printing
I am using a Prusa i3 with Marlin Firmware.
All the components of my 3D printer working fine. I have a problem with my Z-axis, it comes down and get pressed by the bed. I have tried adjusting the endstop switch and calibrated the Z-axis still Z-axis comes down while printing.
edit: - additional information -
While printing the first layer is printing okay, but while filling the inner layer and continue with the next layers the nozzle actually drags and pressed the print.
Can anyone explain why this happens?

Hi Midhun and welcome to SE.3DPrinting! This a little too less information to work with. E.g. does the nozzle hit only a part of the bed, like a corner, or is it digging into the whole bed?

the Prusa i3 is a large family of printers - is it a Mk1, 2 or 3 or a knockoff?

Thankyou for your reply,actually while printing the first layer is printing ok, but while filling the inner layer and continue with the next layers the nozzle actually drags and pressed  the print. Thi s makes the print more worse.Can you please suggest me any solution

In order to get the attention of people you should add the @ followed by the username. This will send a notification to that user. I just now found your update. This extra information should preferably be inserted into your question, comments are used for information requests.

When the head/nozzle assembly runs into the bed, you need to watch out for:

Check for Endstop problems:

Is the switch properly wired up?
Is the switch working?
Is the switch mounted firmly to the frame and correctly adjusted?

Level the bed as level as possible; what is meant here is that the bed needs to be parallel to the X-axis, not bubble level. This ensures that the nozzle is exactly at the same distance away at every point on the build platform. You achieve this by setting the Z endstop as such that the nozzle is close to build platform with platform screws screwed in for some distance. When the endstop is firmly attached, home the printer through the menu of the printer, try adjusting the screws such that the level is everywhere the same (in between changing the location of the nozzle carriage to set the level, home the machine once in a while). Use a piece of paper for the correct distance; a slight resistance felt when dragging the paper is sufficient. Please note that it makes a difference when you level the bed cold or hot, hot is preferred.
Slicer settings; Be sure that your slicer doesn't introduce a Z offset.

EDIT:
With respect to the additional information, you really need to check the level of the bed, level with a hot bed and a hot nozzle (e.g. PLA temperatures of respectively 60 °C/190 °C). Furthermore, be sure that you get enough adhesion. Use (sanded and cleaned) tape, hairspray, glue stick or whatever trick you can find to get the filament to stick well enough that it won't be picked up by the nozzle and dragged around. For me personally printing directly on the aluminium bed with 3DLAC (sort of super strong hairspray) or on glass works best, I'm not a fan of tape.


text:
Positioning Extruders after Tool change : Marlin 1.1.6
I'm currently working on a project which uses two extruders. One for making an impression in a powder and other one to dispose a liquid in to the impression made by the first extruder.
I'm currently manually writing gcode for the purpose, and have some doubts about gcodes and setting up a second extruder. I've once configured a dual extruder system, but it uses old marlin and current one has a variety of dual extruder system, so confused about which one to choose.
Firmware : Marlin 1.1.6

Machine : custom made

Board :  Ramps 1.4

configuration file : Configuarion
Dual extruder setup: two nozzles with separate stepper motor for each nozzle. For the sake of simplicity let's say something like this
Which category does this one go?? By reading marlin documentation it doesn't belong to any special category (???)
I only changed following in FW,
#define EXTRUDERS 2

#define TEMP_SENSOR_0 5
#define TEMP_SENSOR_1 5

I tested by sending T0 and T1 to select extruders and extruding them
Do I have to change anything else??
This is the test gcode:
G28       ;home

T0        ;select extruder 1
G0 X20    ;move to X 20
G92 E0    ;set current position of extruder as 0
G1 E10    ;extrude 10 mm
G92 E0    ;set current position of extruder as 0
G1 E-10   ;retract 10 mm

T1        ;select extruder 2
G92 E0    ;set current position of extruder as 0
G1 E5     ;extrude 5 mm
G4 P500   ;give a delay of 500 ms before next move

T0
G0 X 30
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X 40
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X 50
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X 60
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X70
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X70
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

T0
G0 X80
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G92 E0
G1 E5
G4 P500

What it does is:

After homing, move to given position
Activate extruder 1 and extrude some(make impression)
then activating extruder 2 and extrude
move to next position and repeate

What I actually want is:

After homing, move to given position
Activate extruder 1 and extrude some (make impression)
then activating extruder 2
move extruder 2 to the position where extruder 1 extruded material
Extrude material (by extruder 2)
Move to next position and repeat

one way to achieve this is add an additional code after enabling extruder 2
eg:
T0
G0 X 20
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G0 X15   ; if X offset of E2 from E1 is 5mm, assuming no Y offset
G92 E0
G1 E5
G4 P500

T0
G0 X 30
G92 E0
G1 E10
G92 E0
G1 E-10

T1
G0 X25
G92 E0
G1 E5
G4 P500

In plastic extrusion this is normally done by setting offset in Slic3r.
Is there any other way to do this, position E22 to the position of E1.
Is there any specific G/Mcode for it??
There's a provision to set offset in Marlin. But this is what it says in marlin documentation
"Z hotend offset only available with DUAL_X_CARRIAGE or SWITCHING_NOZZLE."
Does it work with normal dual extruders.?(Does mine come under any two system mentioned above?)

Interesting project your are working on.

Does it work with normal dual extruders.?(Does mine come under any two
  system mentioned above?)

The hotend/extruder you mentioned above is a E3D Chimera like system. And it is not suited for your application because you cannot lower/lift the hotends independently from each other.
examples of these configurations

DUAL_X_CARRIAGE:

look at BCN3D sigmax dual extruder

SWITCHING_NOZZLE:

look at ultimaker 3 mechanism for lowering/switching the active hotend.

The above systems aren't well documentend and will be hard to make.
I advice you to look into an interesting blog post from E3D about a tool changer. It is opensource, well documented so you're be able to create one yourself with tool heads for your application. A spade to create patterns in the powder. And a liquid tool to fill the patterns.

The extruder from robotdigg is there for the purpose of showing that I'm using two motor two nozzle system not one motor two nozzle one. I use a linear actuator like one from openbuilds as extruder 1 to make punctuation mark and and a Auger based pneumatic system to dispense liquid. Dispenser system is fixed but the linear actuator can move up and down


text:
Which outdoor filaments for unheated beds?
I am searching for 3D printing filaments, that are suitable for outdoor purposes, but printable on unheated beds.
I will mostly use it for sensor node enclosures (should withstand temperature up to 50°C/120°F) and car accessories (70°C/160°F).
If it requires annealing, it should have low shrinkage, since I will be printing parts that will fit into each other.

Considering your temperature requirements PETG could be used on unheated beds.
High operational temperatures for your products requires filaments with a high glass transition temperature (the point where the plastic becomes soft). A filament with a high glass transition temperature causes filament to shrink considerably when the bed is not heated (as when the bed it heated, the plastic is soft and withstands the shrinkage stresses better). Basically, your requirements are in contradiction. You should be using a heated bed and ABS, or a high temperature resistant filament like a co-polyester.
Example of filament comparison

If a heated bed is no option, PETG is you most likely candidate for printing as many filament manufacturing brands say that a heated bed is optional. My personal experience is that PETG very much likes a heated bed, getting it to stick at lower temperatures is more difficult.

note to the point of PLA and Ability to print transparent parts: Yes it is possible, i have 2 transparent PLA filaments by my own.

@Horitsu To print really transparent, see this

PETG is good for your project.
You can also print transparent ABS on unheated bed with ABS juice.I tried transparent ABS in outside environment and it work fine.I live in India where outdoor temperature reach to 45C in summer.It is easy to print small parts.ABS juice may or may not work with large parts depending on your ambient room temperature.Ambient room temp should be above 30C for ABS on unheated bed.I suggest you to use a enclosure for printer if you are in cold area.


text:
Is hot glue suitable for FDM printing?
Is hot glue suitable for FDM printing, or some process similar to it?
I think it has all of the required properties, and could produce a flexible transluscent print.  It's cheap, hotends are cheap, and the technology has been around for a while.
I couldn't find any examples or anyone talking about such a material for use, on here or the general Internet.  I wonder if there are tradeoffs or challenges that make it not worth pursuing.

Because here are only answers with the mindeset of "don't do it, because it don't sounds it could work, but nobody know it for sure.": If you are interested in this, then try to do it. Even a failture and researching the reasons why it cannot work with evidence is something good.

i've seen these on youtube. the prints aren't great, but they resemble the model...

Have any of these answers answered your question?

You could mount a hot glue gun to a 3D positioning frame, but you would immediately notice the following:

Hot glue sticks are fat, so you lose a lot of precision for each feed/retract increment. I.e., it's a lot harder to get precise feeds with a fat stick because the stick size is so much larger than the nozzle.
Hot glue sticks are short, so you would to create a filament to spool the stuff or come up with a glue stick feeder.
Hot glue melts at 120 °C and common plastics such as nylon melt at much higher temperatures. So hot glue would make an AWFUL structural part like a stepper mount. Even PLA barely deals with stepper temperatures. Note that temperature tolerance is irrelevant for costume parts.
Hot glue is soft, which makes it a great glue, but not very stiff for, say, making parts for a 3D printer. However, the parts might be fine for  use only in costumes, etc.

But, if you then used your 3D glue printer to dispense glue for gluing stuff together, well...that might be valuable. :D

to 1) there are many geared extruder setups out there. to 2) there are also longer sticks avaiable and glueing together is also an option. to3&4) if the goal is a flexible translucent part, than i think more of costume parts than mechanical parts. (btw. in costume making hot glue is a often used thing)

@Horitsu thanks for comment. Edited answer to support cosplay.

Yes, we have Hyrel users who print with Hot Melt Adhesive 3796 from 3M (essentially a high performance hot glue) with our Krakatoa series print heads.

These heads don't print with filament; the user fills a metal reservoir with paste, gel, or even powder or granules, loads the reservoir onto the head, loads the head onto the printer, applies heat if necessary (some models up to 250C), and then prints the gcode with positive displacement. The KR2 is like the KRA above, but it is made specifically for higher temperature, higher viscosity materials, with tighter tolerances and multiple gaskets.
I have used this model head to print materials including hot glue, polycaprolactone, porcelain, vasoline, toothpaste, plasticine, and metal clays.
Watch Hyrel3D KR2 and TAM Overview for an overview of this head.
Note: I sell this equipment, and have used it since 2012.

I think it would significantly improve this answer if you describe that the KR2 is a heated precision syringe which is specifically designed to extrude gel rather than rigid filament - and this addresses the first two issues mentioned in one of the other answers (feed precision when using a large cross-section stock, and printable volume per machine load). Presumably the 'hot end' temperature range is also more suited to lower melting points.

I didn't want to turn this into an advertisement, but I'll elaborate some. Thanks.

I read 'toothpaste' and thought 'lol, I mis-read that as toothpaste...'

You wouldn't believe the materials we've tested with...

If the user, TheSmasherOr (who suggested the edit) posts their own answer, then this wiki answer can be deleted

From this (rejected) suggested edit:
There have been some new and interesting discoveries by Stefan Hermann on this subject; it seems that Hot Melt EVA Plastic can indeed be turned into a sort of Filament and used inside a 3d printer. This filament has to be oiled after melting as to not stick to itself and everything it touches.
After all of the conditions are met though it can be perfectly good to use in FDM 3D printers to make what you would normally make using one. although it is quite difficult to bridge and make overhangs due to the goopy nature of EVA.
More on this topic can be found in this ~19 minute video by Stefan Hermann of the CNC Kitchen YouTube channel:

I think not. Unless you intend to make a very special printer that feeds on glue stick, you must make filament from it. Should be doable.
But my experience with cold hot glue, is that it is not very durable. It's a bit elastic but nothing like elastic filament. It breaks instead. So when you have your filament, I think you will have a bit of trouble handling it, feeding it into the printer etc. If you, for instance, clog the nozzle the slightest, the extruder will tear the filament to shreds very quickly.

authors: คนขับรถแท็กซี่ ก้อมีห้วใจ


text:
Extruder Clicking without Extrusion Problems
I own a DIY Hypercube Evolution equipped with Tevo Titan extruder, Clone Chimera hotend and Capricorn's High-temp PTFE tube. I use RAMPS with Mega and A4988's.
During prints, my extruder motor randomly clicks. I touched the filament and during the clicks I'ven't felt any problems with extrusion. I looked at the motor shaft to control if it clicks at special angles or randomly, but it clicks randomly. My prints do look very good: clear and shiny.
Do you have any suggestions? (the sound really gives me headache)

Hi Mehmet and welcome to Stack Exchange 3D Printing!

It's hard to tell what kind of e3D hotend was used

What kind of e3D Hotend is used?

Even though you may have acceptable extrusion, any clicking from that area of your printer is likely to be a missed step on the extruder motor. This may be insignificant with respect to print quality, but as you suggest, it is an irritation.
If you are confident that your nozzle is clean of debris (which is likely), you could consider to raise the nozzle temperature a few degrees. If the nozzle is not applying enough heat to the filament, it may resist being forced through and a click representing a delay, allows that much more heat to be applied.
You should not have to increase by much, certainly no more than five degrees.  It's also possible that you can slow the feed rate a bit to accomplish a similar result.

Increased the hotend temp 5 C, but it just clicks:( Will try re soldering the extension cable of my extruder soon

If an extra few degrees of heating the hot end does not work, you could try to increase the amount of Ampere through the steppers. Increasing the current will increase the torque of the stepper.
The question is what your current  Vref of your extruder stepper driver is. To get a maximum current of 1 Ampere you require a Vref of 0.4 V if you have genuine Polulu A4988 stepper drivers with a 0.05 Ω (Rs). Chinese drivers often have a different sensing resistor (Rs = 0.1 Ω). With formula:
Vref = I_TripMax * 8 * Rs
You can then calculate the Vref to be 1 * 8 * 0.1 = 0.8 V.

My Vref is 0.8V now. But ı found out there is a lot of dust on my extruders gear, i cleaned them and ill try it that way first. Thanks for the answer btw

If you find a solution for the problem, and it is different than the already posted answers, please post this in an answer. This will help other that may stumble onto your topic while searching for their similar problems. You will be able to accept your answer after 48 hours! If cleaning does not help, please update your question to include that you had a lot of debris in the extruder gear housing and cleaning did not help.

I will of course share the solution if ill be able to find it :)

One thing or another limits (controls) the flow form the nozzle.  in ideal operating conditions, the molten/softened plastic is kept in a small pool in the nozzle, without high pressure, and responsive to pressure by flowing from the nozzle.  The plastic must be viscous and self-adhering enough that gravity and residual pressure on the melt will not be sufficient to draw the plastic out.
If the plastic is too stiff, such as through not being at a high enough temperature, as the filament is fed by the extruder the pressure will increase until the pressure is high enough to force plastic from the nozzzle.  The plastic that is being fed by the extruder elastically compresses to generate the pressure.  Hooke's law in action.  This causes a delay at the beginning of extrusion, and a continuation of extrusion at the end.  The elastic "wind up" of the filament gives us the delay.  A printer in this mode will appear to work pretty well.  It may require higher "retraction" lengths to unload the pressure.
If this is the operating mode, the filament outflow rate may be less than the rate at which filament is passing through the extruder.  Pressure continuallly increases until the extruder motor has insufficient torque, at which point it skips.  The pressure is not reduced very much by the skip, and plastic continues to flow, lowering the pressure until the extruder can again advance the filament.
It might be worth increasing the temperature.


text:
Split/edit part in FreeCAD?
I'm trying to modify some parts on this thing. I'm kind of new to dealing with the modeling aspects of this.
I am attempting to widen the part essentially 3mm. This would involve modifying the chain segments, and the anchor points.
I have already attempted this with 3D Builder and the result was less than stellar. I split the part, cloned off about 3mm of the middle of the X-Chain (including the top & bottom bits). The intent was to break the part, translate one of the halves off 3mm, add back the 3mm into the gap.
When I put all the parts back together and merged them in 3D Builder, the resultant model, while visually on screen appeared to be one piece, the slicing proved otherwise.
Is there a way that I can do the above in FreeCAD? I'm learning this so tutorial links would be more than sufficient. But if there is someone who can explain this process to me in FreeCAD that would also be appreciated.

I found that the answer provided by @Marco was helpful but not the correct answer I was looking for.
Here is the general approach I used (Based on this).

Create new document
Import STL file
Switch to Part workbench
Select imported mesh
Part -> Create Shape from Mesh (use default tolerance)
Delete imported mesh
Select shape
Part -> Refine Shape
Delete "unrefined" shape
Select refined shape
Part -> Convert to Solid
Follow instructions in link provided.

Below is the list of instructions from #12

Have shape loaded
Switch to a plane that you would like to cut parallel to. e.g. XZ
Switch to Draft workbench
Draw rectangle around item to cut
Upgrade using '^' up arrow (blue) in toobar
Adjust the Placement Angle/Position via the "Data" in the property editor lower left side.
Switch to the "Arch" workbench
Double click the solid to cut in the 3d view
Ctrl+click the plane you will cut with
Select "cut-plane" and choose which side to capture

You will have to play around with the pattern in 12. The idea is to use the same Face created through 12 to cut the part at the same point twice. To create two halves. Take note of the position of the Face created in 12.
In my case, I was attempting to stretch the part along the Y axis, so I was able to cut the part with an XZ plane (created in 12) and offset with a distance in the Y plane.
After performing this "split" I created a cross-section of the at the point of the cut and extruded the cross section 3mm.
Afterward, I was able to use the Edit -> Alignment tool to attach all three parts back together.
Once attached, I selected all three and performed a "union" operation to make them all whole again, then executed the Part -> Refine shape.
End result was that I could make the chain links 3mm wider than the original.
I'm still working on tweaking out the other components that constitute this feature but still this is an interesting exercise.

Maybe you can get the essentials from the link and post them also. If the link dies, splitting the part is then not addressed in the answer.

@0scar - I will detail that a little later today thanks for the request

@0scar - sorry for the huge delay - I paraphrased the steps on that site

When you want to change an STL file in FreeCAD then this is how I do it. I open the STL file in FreeCAD and select the option in the Part/Component sub-menu: Make a form from mesh (hope that I translated it well. I use the Dutch version). It can take quite some time but when it is finished you have an editable object. Just remove the STL object and do what you want.
When you finished then you can perform all actions like if you created it from scratch with FreeCAD.
I am a beginner in 3D design so there might be 'smarter' solutions. When I want 1 special part then I create as many cubes as needed and perform a MINUS action on the solid and a cube. After a while I end up with only the part I need.

Amazing, I never knew FreeCAD could do this, thank you. A video explaining this is at https://www.youtube.com/watch?v=fL6t_lOnyQ0

This describes how to make a solid from a shell object (STL), please also address the question and explain how you split that solid using a plane.

I'm going to up vote this but it is not 100% the answer. I'm answering my own question on this.

I found Dave G's answer to be helpful, however I could only use additive features (e.g. Pad) on the created object, and could not make subtractive features into the object (e.g. Pocket).
Here's what worked for me using FreeCAD 0.19 (Instructions from this site):

Create new document
Import STL (File --> Import)
Part workbench --> Create shape from mesh
Part workbench --> Shape builder...
Create shape, select "Solid from shell". Make sure "Refine shape" box is checked. Press "Create" button. (You may need to switch to the "Model" tab in the Combo View and select your shape object.)
Change to the PartDesign workbench. Select the newly-created "Solid" in the Combo/Tree View, then select PartDesign --> "Create body"
A new Body will be created with your Solid as a BaseFeature that can work with Pad and Pocket features.


text:
Prints to one side
I use Cura for creating the G-code files for my (2 1/2 year old) Prusa i3.
I have to put the prints in the corner furthest from the X-Y-Z origin symbol as the machine prints in the middle of the bed. How do I remove this offset?

I am pretty sure it is something in the cura config. Can you check that out by testing with another slicer, for instance slic3r?

Hi Phil and welcome to SE.3DPrinting! If you would please add an image of your printer settings, that would be a great help for others to find the problem. I'm also pretty sure it is in the settings.

this happened with my cr10 because i had the bed size set incorrectly.

Not being able to see your settings, or your G-code, it is difficult to say. If it is slicer settings related, a common mistake is that the "origin at center" option is active. You should remove the tick mark at "origin at center" in the printer settings of the printer profile you use in Ultimaker Cura. Your origin is not in the center, it is left-front.
Another possibility is that the offset of your printer origin is way off. To check that you should connect the printer over USB and use programs as Repetier host, Pronterface, etc. to instruct the printer to go to (0,0,0) and see where the head ends up. You can also do this by printing a G-code file with homing code (G28) and a movement instruction (G1 X0 Y0 Z1 F1500). If the head moves to the left front, you know the printer is correctly setup, and you should look at the slicer.
E.g. when M503 is send in a terminal to the printer over USB, amongst the output you can find:
...
Recv: echo:Home offset (mm)
Recv: echo:  M206 X0.00 Y2.00 Z0.00
...

When the X and Y values are high, this can also cause the printer to have a large offset.

I've checked the Origin at Centre and it isn't ticked. Also downloaded Slic3r and tried that but with the same result. I'm inclined to think the problem is with the machine settings

@Phil please add a link to the G-code or post the first 20 lines or so. Post is updated to your comments.

I think I've broken it all together now. I updated the firmware through Cura. All the English changed to Chinese and now the display is just blank. I had a look at reinstalling the drivers but everything was in Chinese and I seem to remember that some built in software changed the default language on my computer to Chinese when I first had the printer.

Do you have a genuine Prusa i3? Those are pretty easy to flash new firmware on.

It's not a genuine Prusa, it's a Chinese clone on got cheat on Black Friday weekend nearly 3 years ago. It looks like a total fire hazard with all my home repairs but the only real problems have been the connections on the heated bed breaking and mismatched wiring when I've had to replace the extruder a f few times. I am currently awaiting delivery of another Chinese machine.

@Phil If you post the brand and type and post that in the question, people will be able to help you with the re-flash (although a new question may be better, when that is fixed, this one can be fixed after that).


text:
Build plate cools during print
I am using a Flashforge Creator Dual Extrusion 3D Printer with RepG (ReplicatorG), and tonight a print completely detached from the build plate.
I reset everything and watched it closely.   It is a simple abs print at 230/110 degrees.
A few seconds after start of print, I noticed that the print bed temp had dropped to 109... and kept dropping.
This is new behavior.  I haven't started to troubleshoot yet.  I am looking for suggestions on how to troubleshoot the issue.
Edit 1:
Tonight RepG would not connect to the printer.  I reseated the USB cord
  and now it does.
The test print is ABS at 230/110 from this open scad.
difference()
{
    cylinder(d = 10, h = 2);
    cylinder(d = 9,  h = 2);
}

Pᴀᴜʟsᴛᴇʀ2/Oscar
  Once the print starts the print bed begins cooling.  It is cooling before
  any filament is laid down.
Edit 2:
Examination of the gcode shows the root cause.  It does contain
M104 S230 T1 (set extruder temperature)

It does not contain a
M109 S110 (set build plate temperature)

When I manually add the M109 to the gcode file, the model prints normally, and the build plate temperature holds for the duration of the print.
The drop in temperature last week is due to the fact that I tend to preheat the printer before actually starting the print.  Since there was no M109 the bed plate cooled to ambient temperature.
There isn't a hardware issue here.   Most likely it is a Rep G configuration error of some sort.
Edit 3:
I resolved the issue by a fresh install of the latest Rep G.  I rebuilt the profiles from scratch with G Code to set the correct bed temp.  Thank you for your suggestions.

Is the bed losing connection for the heating element once the bed starts moving?

Is this happening while depositing the first layer, or after the first layer?

Please edit your question to include the requested information asked for in the comments! Thanks!

I will be investigating it this weekend.  There will be an edit after that.

Please add a link to the G-code file so that we can download and look at it more closely.

Check your slicer settings.   Some slicers allow the temperature to change at a specified layer.   You may have programmed the slic3r to turn off the bed after the first (or maybe zeroth) layer.
You call also examine the G-code for M140, M144, and M190 commands.
Of course,  the usual intermittent electric connections,  power supply failures,  etc. should be checked,  but don't overlook the possibility that it is working exactly as you are asking it to work.

@EvilTeach That came to my mind also, hence the question for more information, we'll see after the update.

Your bed is obviously capable of heating up, so I would double check your cable for any kinks, cuts, blow-outs, or general connection issues both where your machine rests during warm-up and Z0 where your machine begins printing.
Most likely there is a poor connector or kinked/cut wire for the build plate.
If that doesn't appear to be the issue, I might also suggest checking your power supply. I've heard of other similar machines' power supplies not being quite strong enough to support two extruders AND a heated bed.

Preheating the bed is a commonly used approach to shorten the time to print. I'll explain; it actually does not shorten the physical print time itself, but before you start a print there is always stuff to do like inserting the SD-card or loading the model in the print server, while you do that, the bed will be heating, so time gained.
When you load a model it apparently resets the temperatures, so preheating will only have an effect when you also actually set the bed temperature in the G-code file. This means that either your G-code file has some codes that influence the temperature, the connector is loose or loading a print over the program you use must reset the bed temperature, there aren't any other options.
To comment on your G-code, M109 is used to set the extruder temperature and wait till it is reached, M190 is used to set the bed temperature and wait till it is reached. Usually M190 is used to set the bed temperature before the first layer is being printed; the printer waits until the temperature is reached before the printer continues to the next command (usually the heating of the hotend). If you have selected a different temperature for the rest of the print you will find the M140 G-code command prior to printing the second layer.
I have tested on my Prusa i3 clone running a Marlin fork to print a model with all references to M190 and M140 removed. I pre-heated to 70 °C (for PETG) and loaded the model in OctoPrint print server and commenced the print. The printer retained the bed value and did not drop.
Basically, it is needed to take a closer look at your G-code file. The answer must be in there. If there is nothing to find in the G-code file and electronic connections are fine, the answer must be found in ReplicatorG, this might send reset signals prior to sending the print, but that sounds really strange.


text:
Replicator+ Experimental Extruder Filament Slipping Error
I'm experimenting with MakerBot's new "Experimental Extruder" which essentially opens their software (MakerBot Print) to change traditionally "behind-the-scenes" settings like retract rate/distance, nozzle diameter, etc.
I am currently attempting to print with the following conditions:

0.8mm nozzle (brass)
0.6mm layer height
2 shells
5% infill
212 °C-215 °C extruder temperature
The part is pretty much all an outer shell (see image)

I know that the results of testing the Experimental Extruder with a larger nozzle often required a lower extrusion temperature and the retract rate/distance to be increased. While testing the Experimental Extruder, personally, I found success increasing the retract distance to 0.850mm.
I know that this issue can be resolved by adjusting the extruder profile, but I'm continually running into issues with self-resolving "Filament Slip" errors which inevitably result in "Filament Jam" errors. So, I'm obviously not making adjustments to the correct settings.
Here's the PrintMode file for reference:
{
    "version": "0.1.0",
    "name": "TBM0115 Draft 0.8mm Nozzle 0.6mm LH",
    "settings": {
        "brimsModelOffset": 0.02,
        "doBrims": true,
        "doRaft": false,
        "extruderProfiles>0>defaultTemperature": 215,
        "extruderProfiles>0>extrusionProfiles>bridges>feedrate": 50,
        "extruderProfiles>0>extrusionProfiles>floorSurfaceFills>fanSpeed": 0.2,
        "extruderProfiles>0>extrusionProfiles>floorSurfaceFills>feedrate": 50,
        "extruderProfiles>0>extrusionProfiles>roofSurfaceFills>feedrate": 60,
        "extruderProfiles>0>extrusionVolumeMultiplier": 1,
        "extruderProfiles>0>nozzleDiameter": 0.8,
        "floorThickness": 1.2,
        "layerHeight": 0.6,
        "maxSparseFillThickness": 0.4,
        "modelFillProfiles>sparse>density": 0.05,
        "modelFillProfiles>sparse>pattern": "linear",
        "extruderProfiles>0>retractDistance": 0.9,
        "extruderProfiles>0>restartExtraDistance": 0.15,
        "doFixedShellStart": false,
        "extruderProfiles>0>extrusionProfiles>outlines>feedrate": 30,
        "numberOfBrims": 3,
        "numberOfInternalBrims": 3
    }
}

results of testing the Experimental Extruder with a larger nozzle often required a lower extrusion temperature is in contradiction with expectations, e.g. a nozzle/layer height combo of respectively 0.4/0.3 lays down 4 mm³ per 100 mm, a 0.8/0.6 combo delivers about 30 mm³ for that same distance!; this is a lot of heat that is dissipated and needs to be replenished. As the filament heating up time is shortened by the increased feed rate you should increase the temperature to get the filament center to heatup also. In fact your problems could be related to not heating up the filament too fast.

As the comment section doesn't allow to use too many characters, I've converted the comment into a proper answer.
In the question is stated that:

... results of testing the Experimental Extruder with a larger nozzle
  often required a lower extrusion temperature...

This is in contradiction with expectations. When the filament feed rate or volume increases, generally a higher temperature is required to heat up the filament because the resident time of the filament in the heatbreak and nozzle decreases.
As the filament heat up time is shortened by the increased feed rate you should either:

increase the temperature to get the filament center to also heat up. In fact, all your problems could be related to not heating up the filament too fast (filament jam or slip). When the center of the filament is not soft enough, it will be harder to push through the nozzle, hence the slip and the clogging, or
decrease the print speed, decreasing the print speed will increase the filament resident time.

As an example, a nozzle/layer height combo of respectively 0.4/0.3 lays down 4 mm³ per 100 mm, a 0.8/0.6 combo delivers about 30 mm³ for that same distance! This is a lot of heat that is dissipated and needs to be replenished. A reduction of print speed by a factor of 7.5 (30/4) will also address the increase in heat up time.

Thanks for the breakdown! I'll try that approach and see if there's any improvement before I accept this.


text:
Layer 1 won't adhere anymore
I have a new Tevo Tornado, which I have completed two good prints with, a 20x20 test cube from the supplied SD and the spool holder also from the SD. I say this to note that the printer was capable of producing a good print.
Print 3 was a design I created in Fusion and it printed badly, very disappointing holes missing. Stringing gaps between material just rubbish. I downloaded a simple print from Thingiverse just to see if it was my poor design skills or the printer and that came out just as poorly: lots of strings between details. Both of these were sliced in Cura. As that doesn't have a tornado driver, I downloaded one from the support group and the prints have not even started properly, see pictures for example.
I might be going down rabbit holes here but this is what I have found and tried:

1 relieved bed - done to ridiculous degree of accuracy, cold gross levelling then bed and nozzle at PLA working temp using feeler gauges. I have done 0.1 mm, 0.15 mm, 0.2 mm

Now I have added to the suspicion the z axis coupler see images below:

YouTube videos, that I have seen, show couplers that are not a spring - any thoughts? I would certainly appreciate the time anyone has to impart their knowledge.
EDIT 1: (Additional information posted as comment, now moved to question)
The print bed is brand new from Tevo the unit has only done a few prints most aborted, and I also thought perhaps a residue from the feeler gauges had contaminated the bed, but I have cleaned it with alcohol wipes and also tried putting prints on to unused parts of the bed. You are right the g-code from the test print was from an unknown slicer, no doubt tuned by the manufacturer the part I designed in Fusion was sliced by cura. I have since tried the original test piece and it fouls the extruder nozzle almost straight away.
The main differences and there are not many between the set up parts, are that the Cura code does a G92 E0 G1 F1500 E-3.5 before starting layer 0 (both set z0,3). The test piece just does a G92 E0 G1 F7200 the feed rates are different the cura print sets M204 S500 and the test sample sets no acceleration. I assume there is a default in the Marlin firmware.. there is no doubt some globs of PLA stick like in dots between the strings, but the extrusion between direction changes do not kind of like join the dots where dots stick and joins don't.
I am going to change the coupler because, well, I don't know what else to do. Replacing it with a better one can't help. Other things I have thought about - PLA temps - I have gone up the whole range according to the manufacturers bandwidth in 5 degree increments no difference I have also done some bed changes but neither hotter nor colder (it's 30°C and humid at the moment, so maybe a materials property issue, but then again no difference in conditions between a successful first test and all the messes). I am storing the PLA in a gel bead box to reduce humidity. still basically stumped!
EDIT 2: (Additional information posted as comment, now moved to question)
Thanks for your observation, it's a new bed and I clean down with alcohol wipes ( isopropyl) I don't think I have ever put a finger on the bed - very aware of that. While I don't know what I am talking about on the one hand I am semi convinced it is not the bed, anyway I am going to get a glass bed in part to deal with the protruding screw head issue.

The images that you refer to showing your print are missing, and two of the images (1st and 3rd) showing the coupling are the same. Please add the images of the print (using the add image button in the editor).

Maybe related https://3dprinting.stackexchange.com/questions/4755 but the question is incomplete without a photo of the problem

Hi ventis! We are aware that you cannot comment on either your question or answers generated by the community, but you cannot use someones answer to add your information, instead you should use that information to make an even better question so that people can change their answer and others can add new answers, all to help you fix the problem. By doing this we record your problem and the solution for eternity, that is what sets SE sites from regular forums. I copied your reply into your question, I'll leave it up to you to redefine and restructure the question.

Ventis, as 0scar says, please add comments to the answers provided (or, better still, update and refine your question), instead of editing the answers and adding a comment there. It is way too confusing. Even though you have less than 50 reputation points you are still able to comment on your own question and other answers to your question. See Why do I need 50 reputation to comment? What can I do instead?

There is still no photo of the actual failure. This question is very hard to answer as it stands.

Update and close
I have changed the coupler on the z axis and levelled the bed put a print on to test, skirt and first layer look good so I think we can call this one closed and thank you very much for your comments.

so over the weekend I have run a couple of prints, one very successful the other a complete fail, I would however judge the layer 1 adhesion issue to be largely solved by the replacement of the coupler, which was slightly fiddly. What I did notice was in purchasing a new coupler the design used by Tevo has to sets of perpendicular grub screws one for the lead screw and on to locate in the stepper motor shaft. The stepper motor only has in flat face so picking up on this is important and the factory had not - sloppy ! Secondly the lead screw has no faces so I dremeled two peep faces
Once the lead screw was dressed the locking down of the coupler was simple and secure. Took about 30 minutes to fix after days of misguided bed levelling and slicer tweaking.
Old and new coupler new one bought as a pair from amazon £6 could have for them cheaper but I wanted next day not to wait.

Hi ventis, great that you solved your problem. Could you please update the answer, the current answer you have is rather terse. Please expand which couplers you used an preferably add a picture. We cannot close questions, SE sites operate different than normal forums. We store questions and complete answers so that other people may benefit from them. I encourage you to expand the answer, you can accept it after 48 hours (there is a tick mark near the counter on the left) and people will then vote for the complete answer. Thanks!

OK hello, so iver the weekend I have run a couple of prints, one very successful the other a complete fail, I would however judge the layer 1 adhesion issue to be largely solved by the replacement of the coupler, which was slightly fiddly. What I did notice was in purchasing a new coupler the design used by Tevo has to sets of perpendicular grub screws one for the lead screw and on to locat in the stepper motor shaft. The stepper motor only has in flat face so picking up on this is important and the factory had not - sloppy ! Secondly the lead screw has no faces so I dremeled two peep faces

Once the lead screw was dressed the locking down of the coupler was simple and secure. Took about 30 minutes to fix after days of misguided bed levelling and sliicer tweaking.

Such information should be inserted into the answer to conserve for the future! Also the answer is very terse. This is not a forum where you have to comment on other people, instead you update your answer. Please read the help section, accessible through the button with the question mark at the top right menu. Please take the tour and also have a look at the questions and answer to understand how SE works.

Hi again Ventis, thanks for the updates. :-) You are able to edit your posts using the edit link just below the post.

The "springs" connected to the stepper motors aren't a problem.  They are special shaft couplers which allow some relief if the motor mounts are not strictly perpendicular to the lead screws.  They are very rotationally stiff and allow just a little bit of misalignment between the shafts.
The first two prints were from the SD card.  You didn't talk about slicing from an STL file, so it is possible that they were pre-sliced for this machine.  Every G-code file has introductory code that initializes some aspects of the operation.  Check the "preamble" code at the front of the files you have sliced.  Are there commands that look different?  Is the Z parameter for the first layer different from the pre-sliced files?  Are there G-codes missing from the files you sliced?
If you are trying to understand what the G-codes do, this resource may be helpful.  Some possible commands could be commands to limit acceleration, jerk, speed, or introduce offsets.  Also check that the temperatures are being set correctly in the G-code you generated.
If you had sliced the files on the SD card, then double check that the parameters were the same.  Try re-slicing the object and comparing the G-code that is generated.

Slicing can only have limited impact on layer 1, but these are all good things to check.

Based only on your title, and not on the content of the question, I would guess that maybe your print bed is not clean any more, and this is causing bad adhesion.
There are lots of bed surface material options - I guess you have some specially engineered high stick surface on this printer so you should check the manufacturer's specific direction regarding the print material since there is a risk (eg with PETG) of excessive bond strength requiring the use of a release agent in some cases.
I use kapton tape on my bed, and always wipe over with acetone or isopropyl alcohol before printing. Soap/water might also be effective - the problem which you're maybe facing is the oils deposited from touching the bed with fingers.

What it may useful to improve your prints, are the following elements, according to my personal experience with the Tevo Tornado:
1) level the bed when it's warm.
2) print a cylinder that should measure 100 mm, afterwards measure it with a caliper: regulate the steps per mm according to the difference (many guides for calibration are available, for example: https://youtu.be/Wk3qYOB4E9I)
3) print this object to be installed on the z axis and regulated with an M5 screw and nut: https://www.thingiverse.com/thing:2827664
4) Print a test for temperatures, like this: https://www.thingiverse.com/thing:2131069
I hope it helps. Happy printing.

authors: احمد فاضل فداغه