3D Printer yet?

[mnementh]

Bearing in mind I'm very new to electronics, I wanted to double check I'm right.

I'm in the process of assembling most of this (to get rid of box on the side)  https://3duk.co.uk/index.php?topic=74.0 and he says to add an earth to the printer frame.

As the frame is coated hence is non conductive, I don't see the point (or am I missing something).

thanks

There is all sorts of exposed metal there; you can't count on the grounding of the PSU to do the job, and you really can't count on anodizing to act as an insulator for purposes of protection against potentials that can exceed 400V. For safety purposes, a "double-insulated" (chassis not grounded) piece of equipment needs to be completely encased in insulation capable of withstanding multiple KV.



People a lot smarter than you and me have spent the better part of a century figuring out all the ways a piece of equipment can electrocute you; that's why we have Insulation Testers like this, which can generate up to 15KV for testing to a safe "safety margin".

Also, adding a chassis ground greatly reduces common-mode noise that can play havoc with sensors; that big aluminum pyramid is a great EMI/RF antenna.

mnem
 

[Nominal Animal]

Sidetrack:  I've wondered if/how to connect chassis ground to 0V when using isolated AC-DC supplies incorporated in the device. My preference is to connect the chassis ground to supply ground, and keep it separate from circuit ground (since the AC-DC supplies here hobbyists like me can use are all isolated); here in the northern parts of EU, a CEE 7/4 plug connected to say a MeanWell AC-DC supply, with the supply chassis and printer chassis connected to ground, with the DC side isolated.  Better suggestions?  Reasons to do differently?

The fact that there may be safety caps connected between DC 0V and supply ground in the AC-DC supply (filter? suppression?) makes this too complicated for me to figure out.

[HobGoblyn]

Thanks, that makes sense.

I was previously thinking along the lines of worst case scenario the power supply is in an earthed metal case, if it did manage to touch frame, frame would Earth through power supply case. But I now realise mains cable could short to the frame.

Will put an Earth point somewhere to make things safe.

Only built my lab towards end of last year and beginning of this year, 3D printer has sidetracked my learning a little

I have a lot to learn but am enjoy myself

[Zucca]

Sidetrack:  I've wondered if/how to connect chassis ground to 0V when using isolated AC-DC supplies incorporated in the device. My preference is to connect the chassis ground to supply ground, and keep it separate from circuit ground (since the AC-DC supplies here hobbyists like me can use are all isolated); here in the northern parts of EU, a CEE 7/4 plug connected to say a MeanWell AC-DC supply, with the supply chassis and printer chassis connected to ground, with the DC side isolated.  Better suggestions?  Reasons to do differently?

The fact that there may be safety caps connected between DC 0V and supply ground in the AC-DC supply (filter? suppression?) makes this too complicated for me to figure out.

Well, regardless is the PSU is isolated or not. The real question is if the main cord with main voltage on it is connected to the device which has a metal frame.
https://en.wikipedia.org/wiki/Residual-current_device RCD is the key.

If the isolation happens outisde the metal case well you do not need ground it. It that case yes connect it to 0VDC for EMC stuff.

[Nominal Animal]

If the isolation happens outisde the metal case well you do not need ground it. It that case yes connect it to 0VDC for EMC stuff.

Yes, this is what I do with e.g. 5V USB microcontrollers in die-cast aluminium enclosures, as there is no separate "ground", only USB 5V and USB GND.  (That is, the USB GND is connected to the chassis at or very near the USB connector.  But I do wonder if I should put a big-ish resistor in between, to absorb the energy from static discharges from humans to the enclosure.)

This is a topic that might make a good Youtube video for someone like Dave or any of you EEs here.  Me no electrichicken, just a unclebumble.

Most current stepper board controller boards (all with integrated or plug-in stepper drivers) use a shared ground for motors and logic.  This is problematic, because if connecting via USB, you really need an USB isolator: the motor supply is separate from the computer power supply, and may not be at the same potential (or phase; consider electrical mains derived from two different legs of three phase power source).  Also, the motors do generate noise, which is not that easy to fully filter out from the logic side, because the logic stuff consumes a minuscule amount of current (50mA - 150mA at 5V) compared to the steppers.  The boards I've seen from RAMPS to SmoothieBoard just use several filter caps on the logic supply input and output pins and the MCU (and other external active IC) supply pins, use a shared motor and logic ground, and tell users to use the device "offline" (transferring files via memory cards or USB memory sticks), or have an Ethernet or WiFi connection for online use.

These 3D printers and mini-CNCs have such a board, a metal support frame, and a 12V or 24V AC-DC power supply (mainly for the steppers, but usually also used for the logic via a separate DC-DC converter).  If the AC supply has a separate ground connection (non-double-insulated supply), it should be connected to the frame; if it only has two AC wires, then the DC 0V should be connected to the frame – but should there be a power resistor or capacitor in series or in parallel to absorb static shocks, say someone coiling PLA in dry conditions with just the wrong gloves on, and accumulating a rather high static charge, and discharging it through the metal frame?

(Those who have a whiteboard in their office: I recommend you put a big carbon resistor, say 1M, between the aluminium pen tray and a nearby grounding point.  No more annoying zings from static discharge.  Should one put a capacitor in parallel to the resistor also? Why?)

So, there is a point on A) how to design better (or a simple example of using external bigger drivers (up to several amps peak per phase) with optoisolators); B) how to safely connect an "offline" printer with shared motor-logic supply to a PC via serial or USB-serial using an USB isolator (the el-cheapo Chinese clones of ADuM3160 appnote, that work with low and full speed USB 2.0 (1Mbit/s and 12Mbit/s respectively), have worked perfectly for me thus far); and C) how us hobbyists building our own printer enclosures and tinkering with our printers etc. should deal with grounding and static shock dissipation sensibly.

[Brumby]

I was previously thinking along the lines of worst case scenario .......

Good approach.  Understand, though, that Murphy is a creative bastard.

[mnementh]

No, she's a bitch. And she has puppies. 

mnem
Maxim #9. Capacitors are Murphy's footsoldiers.

[KaneTW]

What flatness requirement is adequate for a 3D printer? My rental Raise3D plus is a goddamn pain to get level. I finally got it so that the calibration prints all come out MOSTLY nice, but it's still a bit unlevel. Pretty tired of messing with it though and I just want to order a really flat replacement plate.

I'm thinking a 50um spec, ideally less. The difference between level and unlevel is small enough that I can't feel it with a 80um feeler gauge over a 100um one, and have to go by print quality instead

[mnementh]

Depends on the machine. For non-auto-leveling, my experience shows me that relatively, 1/3 to 1/2 of layer height is all it takes to turn near-perfection into a fustercluck. As most modern machines print at 0.10-0.15mm in fine mode and 0.20mm as medium-res or draft mode, then that means a few thou is all it really takes to fuxxor you over big time. 1/2 of 0.20mm is 0.1mm or 3.9 thousandths of an inch.

Not sure how well auto-leveling machines manage to resolve this; that's one of the reasons I was interested in the CR-6SE.

mnem
 

[CatalinaWOW]

Coming at it from another direction, I find that I am adjusting my bed leveling screws +/- about 20 degrees to get overall good results.  The screws have a 0.7 mm pitch so that works out to about +/- 40 micrometers.   There is a bit of subjectivity on what "good results" means, and also on the amount of rotation on the bed leveling screws, but it is fairly consistent with KaneTWs observation.  I am sure that is ball park close to a good tolerance.

[MarkF]

After seeing this video, I just updated my Marlin firmware (to version 1.1.9.1) to enable Mesh Bed Leveling.
It allows you to manually set 9 mesh points to further fine tune your level after you get you bed close with the leveling knobs. 
The fine tuning is done through the display and it is saved in EEPROM.

This does not need any extra hardware and may help with warped beds.



I haven't had a chance to run through the procedure yet.  Just got it installed.

I'm using version 1.1.9.1 because I have a CR-10 Mini with the original Melzi board. 
It doesn't have enough program memory to run version 2.0.

[HobGoblyn]

If you download the source code you can increase the no of mesh points.

[Monkeh]

I'm using version 1.1.9.1 because I have a CR-10 Mini with the original Melzi board. 
It doesn't have enough program memory to run version 2.0.

That's odd, because I've built Marlin 2.x for those controllers a few dozen times..

[xrunner]

In that video he really doesn't clearly state what you have to do when it's finished with all the points. He says -

"When you are finished the printer will beep to tell you it has saved the mesh"

No, it hasn't saved the mesh, it just finished all the points. You must scroll down a few lines and press "Save". He should have clearly shown that step.

This has burned me several times because I know I have to save it but the menu doesn't show "Save" unless you scroll down, and if I'm in a hurry I've forgotten to do it.

[mnementh]

CR-6SE Update number FUCK YOU mnem:

Here is the link: https://www.creality.com/blog-detail/creality-cr-6-se-3d-printer-shipment-update-20

🚀So far, 4090 Units Creality CR-6 SE 3D Printer With Add-ons Have Been Shipped!

⭐Besides, there are two batches left that have not been delivered yet. If everything runs smoothly, We expect to ship all the shipments within the 25th of September.

If your tracking number has not been updated for a long time, please don’t worry, it is currently onboard or customs clearance, and will be delivered to you immediately after the goods arrive at the port and received by UPS/FedEx Courier express company. (It will take about 50 days for it to be delivered to you)

Meanwhile... people have been able to buy retail for weeks now, and already have them in hand (because they actually got the Express Shipping they paid for) and are bitching about shit falling off and catching fire. 

Oh, and still no idea whatsoever when our add-ons will ship, much less be delivered. 

mnem
They're coming... they're coming... Yeah, so's Christmas.

[Ed.Kloonk]

Please find my Librem 5 thread.

 

[RoGeorge]

Seen this on Hackaday this morning, and thought might be of interest here:
https://hackaday.com/2020/09/23/reforming-3d-prints-with-salt-and-heat/

[SilverSolder]

That is actually really clever, he is basically casting the component...  using the 3D print both as the pattern and the material to be cast!   

So you might be able to use other casting techniques, like using fine sand (instead of salt),  perhaps even high temperature silicone would work...

[mnementh]

Please find my Librem 5 thread.

 

Yeah; this is not really comparable; these are people who are an unknown quantity producing something that hasn't been before. The reason so many people got sucked into the CR6-SE KS is because it was CReality - an established brand in the business of what they're promoting on the KS, and that has up til now for the most part kept their promises to customers.

That is completely different from this scenario, where they clearly deliberately used of the "free-for-all" nature of KS to take advantage of 3DP enthusiasts to essentially bankroll their next product without the pesky interest and/or partnership of commercial investors. This was all based on them promising to provide a level of service they have been providing for over a decade, and then reneging on those promises because KS says they can.

Now if your phone was being KSed by like Nokia... then I might consider it comparable. But there's a huge difference between making an honest attempt to keep your promises and running out of money like that phone, and being a well-known brand and advertising your product like it was any other of your well-known products only on KS, then using the fact it's KS as an excuse to charge for Express Shipping but shipping via slow-boat, then taking all the money and bankrolling production for retail BEFORE YOUR KS CUSTOMERS even have half their product on the way.

They simply do not think the same way as Westerners.

mnem
 

[Zucca]

Now the bad news....
 
Murphy got me again, I pulled away the Laptop with too much joy, the connected USB Cable ripped of the micro USB port on the Ender.
 
will fix it, just a PITA! Stupid me.

Fixing it, of course all the PCB pads are on the stripped connector... 
Found pin 5-6 on the CH340G which are D+ and D- of the USB.
Ender 5 silent board is easy to rev eng.

Do I need to wireup the 5V+ Bus from the USB cable to the Ender board? I am reading about people taping the 5V pin on the USB connector to avoid the Display to stay on when the rasberry pi in connected.
So I feel I can live without the 5V connected to the board.

What do you think?
I feel I can live without 5V from USB

[Mr. Scram]

Yeah; this is not really comparable; these are people who are an unknown quantity producing something that hasn't been before. The reason so many people got sucked into the CR6-SE KS is because it was CReality - an established brand in the business of what they're promoting on the KS, and that has up til now for the most part kept their promises to customers.

That is completely different from this scenario, where they clearly deliberately used of the "free-for-all" nature of KS to take advantage of 3DP enthusiasts to essentially bankroll their next product without the pesky interest and/or partnership of commercial investors. This was all based on them promising to provide a level of service they have been providing for over a decade, and then reneging on those promises because KS says they can.

Now if your phone was being KSed by like Nokia... then I might consider it comparable. But there's a huge difference between making an honest attempt to keep your promises and running out of money like that phone, and being a well-known brand and advertising your product like it was any other of your well-known products only on KS, then using the fact it's KS as an excuse to charge for Express Shipping but shipping via slow-boat, then taking all the money and bankrolling production for retail BEFORE YOUR KS CUSTOMERS even have half their product on the way.

They simply do not think the same way as Westerners.

mnem
 

Well, that was predictable. A company that has your money and knows you're not going anywhere isn't going to trip over their own feet to fulfil your order if they can take someone else's money at full price. Don't expect business to engage in ethics if it isn't profitable, Western or not.

[mnementh]

It's unlikely to cause harm to leave the 5V line disconnected. I'd try it and see; if you can still communicate with it as needed, then don't bother with the 5V. Obviously do make sure the GND is reconnected tho. 

mnem
 

[xrunner]

Do I need to wireup the 5V+ Bus from the USB cable to the Ender board? I am reading about people taping the 5V pin on the USB connector to avoid the Display to stay on when the rasberry pi in connected.
So I feel I can live without the 5V connected to the board.

Correct do not re-wire the 5V. I made myself a special USB cable with the 5V line cut to connect to my Pi running Octoprint.

[MarkF]

You may want to go ahead an connect the +5V if for some reason in the future you have the board out and want to burn new firmware.

As far as the Rasberry Pi, I don't care either for the Pi powering the printer when using OctoPrint.
I see the the same thing with the Pi powering my Creality CR-10.
I was considering building an adapter or a USB cable to block the 5V from the Pi.
Then you have a choice when doing any maintenance in the future.

[mnementh]

You may want to go ahead an connect the +5V if for some reason in the future you have the board out and want to burn new firmware.

As far as the Rasberry Pi, I don't care either for the Pi powering the printer when using OctoPrint.
I see the the same thing with the Pi powering my Creality CR-10.
I was considering building an adapter or a USB cable to block the 5V from the Pi.
Then you have a choice when doing any maintenance in the future.

Yeah; a good point, but it's the same work whether you do it now or later. If you already have the board out might be worth modding in a bit of 0.100" header with a jumper to be able to isolate/connect the +5V easily. A bit of header with some wires soldered on, a blob of epoxy on an unpopulated corner of the PCB, and Bob's yer auntie. 

But I wouldn't go pulling the board out to do this if you've already installed it; that's doing twice the work just in case you need it someday. 

mnem
"Sufficient unto the day is the evil thereof." ~grandmomma