Grounding the printer  

Re: Grounding the printer

Jody do not mess about with the way the printer is grounded it is just fine and their system is fairly complex it is just not obvious to the untrained eye.
The zap is from your personal static charge and can be in the thousands of volts range.... mist your carpets with fabric softener to reduce this build up in dry weather during the home heating season (unless you are lucky enough to live in an old building with real steam heat! that keeps the humidity up enough to reduce the buildup for things like carpets and rugs.)

When you get to your printer ground yourself to the power supply case to dissipate your charge... if the zap bothers you hold a coin (or other piece of metal a key or tool) in your fingers and touch the coin to the PS case.

Re: Grounding the printer

Jody do not mess about with the way the printer is grounded it is just fine

the printer (frame) isn't, though. running a chassis ground won't hurt a thing.

larger issue is that the LCD display is extremely sensitive to static. I've got a box full of dead ones (killed from static zaps) to prove it.

e: the frame itself is anodized so thats something to consider as well

Re: Grounding the printer

Jody do not mess about with the way the printer is grounded it is just fine and their system is fairly complex

You're right it's not obvious. In fact, there's no grounding at all. I read no continuity on my meter between the metal chassis of the PSU and ANY part of the frame of the printer. The only path for static electricity to follow out of the system is through the sensitive electronics.

Re: Grounding the printer

That is why when you approach the printer touch the cover of the Power supply before you touch other parts of the printer and zap the electronics. the LCD screen can also be zapped by backfeeding from the steppers even when the power is off if you rapidly move the bed forward and back for a while.

Why don't you ask the tech support why they do not run a ground wire from the earth ground in the power supply to the controller board? I would before I did something as drastic as that....

Re: Grounding the printer

Why don't you ask the tech support why they do not run a ground wire from the earth ground in the power supply to the controller board? I would before I did something as drastic as that....

Thanks, I will do that. As a ham radio operator, everything in my area is grounded for exactly the same reasons. We need a path to ground for static discharge that doesn't take it through the sensitive electronics. As built, the MK3 has no such path.

Re: Grounding the printer

Why don't you ask the tech support why they do not run a ground wire from the earth ground in the power supply to the controller board? I would before I did something as drastic as that....

Thanks, I will do that. As a ham radio operator, everything in my area is grounded for exactly the same reasons. We need a path to ground for static discharge that doesn't take it through the sensitive electronics. As built, the MK3 has no such path.

think about it this way...your laptop's power supply and electronics are separated, but is your laptop's chassis grounded? nope. anything sensitive is pretty well isolated and the board itself should be 100% isolated from the frame unless something was installed wrong. There should also be basically no continuity in the frame due to the anodizing, so remember to grind it off if you're going that route.

now to get back to studying for my license exam in a few weeks 🙂

Re: Grounding the printer

Folks-

Don't get the grounding mixed up. You ground for TWO purposes on your printer.

The first purpose is the SAFETY ground required because you have a device powered by line (mains) voltage - the 120 or 220 volts from the wall plug. This ground (or 'earthing', for some of you) provides a low-resistance path for electrical current if something fails. The idea is that there will be a low-resistance, i.e., high current path that will quickly trip circuit breakers.

Remember that old saying, "Electricity takes the path of least resistance"? It's a lie. Electricity takes ALL the paths, dividing current as it does so, in ratio to the resistance. The safety ground makes the lowest resistance, hopefully meaning that very little current flows through your carcass.

The second ground is a path for static electricity, the charge that builds between dissimilar objects. This is the electricity that shocks you when you walk across carpet and touch something. It won't hurt the human body, unless you count the damage you incur from bouncing off something unforgiving, in surprise.

It is, however, death to electronics. We who have to work around electronic circuit boards often wear grounding straps between ourselves and the wok surface to continuously discharge any possible static buildup before it can damage sensitive electronics.

You, walking up to your properly grounded printer, can carry a charge of several thousand volts which, under the wrong circumstances, can trun your printer into electronically dead junk. As previously posted, your best best is to touch the metal frame of the printer or the power supply to discharge yourself before you start pushing on the display or other parts of the printer.

Where'd I learn this?

The first part is because I've spent fifty years in industrial electrical power, 500,000 volts on down. I KNOW this stuff, including repairing circuit boards at the component level.

The second part is in my current capacity as an electrical 'subject matter expert' who had to devise procedures to protect against STATIC charges which ignited a pretty significant explosion and fire at one of my facilities. The electrical safety grounding was complete and in accordance with electrical codes and good engineering and installation practice - just like your printer. The people at the site did not recognize the importance of static grounding, also called 'bonding' to prevent static charges from building as fluids moved through non-conductive hoses between tanks. A little spark ignited a flammable atmosphere and WHOOM!

Re: Grounding the printer

You, walking up to your properly grounded printer, can carry a charge of several thousand volts which, under the wrong circumstances, can trun your printer into electronically dead junk. As previously posted, your best best is to touch the metal frame of the printer or the power supply to discharge yourself before you start pushing on the display or other parts of the printer.

Yep, that's what I want to avoid. The only circuit path I see for that voltage right now is through the build plate into the wires that connect that carriage to the electronics on the printer. Adding a ground strap from the carriage to the metal cage of the PSU should shunt that off to ground, yes?

Re: Grounding the printer

The second part is in my current capacity as an electrical 'subject matter expert' who had to devise procedures to protect against STATIC charges which ignited a pretty significant explosion and fire at one of my facilities. The electrical safety grounding was complete and in accordance with electrical codes and good engineering and installation practice - just like your printer. The people at the site did not recognize the importance of static grounding, also called 'bonding' to prevent static charges from building as fluids moved through non-conductive hoses between tanks. A little spark ignited a flammable atmosphere and WHOOM!

I recall visiting a place that made fireworks, the big sort used in professional displays. the whole complex was made up of several dozen concrete block buildings that were each quite small with very flimsy roofs. as visitors we were shown a dummy "training" version of these huts and as you entered you had to touch a copper plate just inside the door... and they too had bonding straps that they put on attached to each bench work location... no more than 2 workers to a hut... lots and lots of other safety rules such as all work stops and huts cleared if lightning was within 25 miles of the place... one item they mentioned was pouring the fine powdered piro items from large barrels into smaller containers and that the act of pouring it could generate a static charge I expect that knowledge was was hard won in the early days of black powder manufacturer in the pre industrial age. About 50 miles from where i grew up was the town of Hazzardville, CT where powder was made before the civil war and given the incidents that happened there it seems an apt name for the place.

as a teenager (more than 50 years ago) i experimented with trying to ignite black powder with static electricity. and i failed with ordinary FF size powder grains it was only when I had ground it down into a Talcum powder like dust that I made it ignite.

Re: Grounding the printer

I bought a lo0ad of integrated circuits for a project.

they were individually packed in antistatic plastic housings and individually thouse housings were packed in antistatic plastic bags

I started off, openning the bags to put the chips in the carriers, into a component tray, throwing the bags into the waste bin...

After a while, the bags started floating out of the bin, because of antistatic build up...

Not what was expected...

At our Labs in Martlesham someone found that if you mounted a bulk antistatic chip tube, at an angle, and slid integrated circuits into the top end, the chips would slide through the antistatic tube into a container, building up a significant charge in the process. the operator was static bonded to earth and the chip tray was bonded to earth the total static generating effect was between the chips and the bulk carrier...

Static is scary stuff...

Interestingly I have a Ham radio license, and I am also very careful when loading Smokeless powder into my rifle cartridges too... there seem to be a number of similar interests crop up in this community.

regards Joan

Re: Grounding the printer

The only circuit path I see for that voltage right now is through the build plate into the wires that connect that carriage to the electronics on the printer. Adding a ground strap from the carriage to the metal cage of the PSU should shunt that off to ground, yes?

I think we need to take a step back here. You can't ground the "build plate", and you can't ground the carriage.

From a datacenter perspective it makes perfect sense to grind down the frame and attach a ground, but keep in mind theres not necessarily continuity between each leg, so heavy gauge wire from each leg and each end plate to a bus bar and then to a dedicated plug, not piggybacked onto the power supply.

I am also very careful when loading Smokeless powder into my rifle cartridges too...

funny I just watched something about 16-17 century naval guns, and the gun crews would all have special uniforms with no metal, no buttons, and special non metal tools, etc. from what I understand fireworks makers have similar rules...

Re: Grounding the printer

In the 16th and 17th century they didn't have man made fabric to worry about... 🙂

Re: Grounding the printer

In the 16th and 17th century they didn't have man made fabric to worry about... 🙂

found it! how about a naval gun charged with 450 pounds of blackpowder? :p

RE: Grounding the printer

I'm also having issues with static discharge on the I3 MK3S. Sometimes when I touch the frame or the bed, the LCD will go blank for a few seconds.  Sometimes the printer resets entirely.  I'm having a really hard time believing that this is correct and safe for the electronics.  I have other printers, and none of them so much as blink when I discharge on their frame.

I have the MMU2S I put together myself, but the main unit was purchased pre-assembled - if that helps clarify anything. 

Please reassure me that I'm not going to wreck my printer one of these days by merely touching it.

Scott

RE: Grounding the printer

Place an ESD surface sheet under the printer, and touch it before touching the printer.  They can be purchased for under $50. 

The printer has too many discrete places to ground and the task of grounding everything properly is problematic.  Plus, most of the effect is the ESD current creates a magnetic field that propagates and disrupts the electronics (it's probably not a conducted impulse doing the damage).

Also, if you want to minimize issues until you get the ESD sheet, touch the power supply case first (easier said than done, especially if you have the black PS).

Or, buy a wrist strap that plugs into a grounded outlet and use it before touching the printer.

ps: here's one I just search, it has everything needed to ground it properly so is a few buck more.

https://www.digikey.com/product-detail/en/desco/16310/16-1212-ND/3708689

And a few more to search through:

https://www.digikey.com/products/en/static-control-esd-clean-room-products/static-control-grounding-mats/606

RE: Grounding the printer

@tim-m30

I'll look into the mats.  Thanks for the info!

Scott

RE: Grounding the printer

OK, sorry to beat this dead horse, but I just couldn't help myself. 

Today I checked some of the pins on the power supply.  The power supply case itself isn't connected to the ground pin on the power plug, but there are two other screws that are.  After some other meter checking,  I connected one of those ground screws to one of the screws holding the unit to the MK3 frame.  It all powered up fine.

I then rubbed around in my office chair that's horrible for static build-up, and then went and touched the frame on the MK3 frame.  It let out a nice arc with a pop and sting, but the display didn't even blink.  I repeated several times with the same result.

Then I tried the same while touching the headed bed.  Unfortunately that still causes the display to blank out for a bit.  But I have yet to see the print reset entirely.

Am I wrong to think the power supply case and frame should be connected to ground?  What about the heated bed?  Is there some other hidden surprise I'm going to find later if I keep running this way?

Thanks

Scott

RE: Grounding the printer

This is a quote from EC&M:

"Because 24VDC would normally power 24VDC relays, contactors, and proximity sensors or analog 4mA-to-20mA loops, you must make sure that all metal casings and shields are tied to ground, unless otherwise specified. However, in no way should you connect the AC ground to either the positive or negative connection of the 24VDC power supply."

Note: This also means the heated bed wiring should not be connected to AC ground.

RE: Grounding the printer

Posted by: @robert-rmm200

This is a quote from EC&M:

"Because 24VDC would normally power 24VDC relays, contactors, and proximity sensors or analog 4mA-to-20mA loops, you must make sure that all metal casings and shields are tied to ground, unless otherwise specified. However, in no way should you connect the AC ground to either the positive or negative connection of the 24VDC power supply."

Note: This also means the heated bed wiring should not be connected to AC ground.

Fair enough on the heated bed writing.  I'll leave that alone.  But what about the power supply case and frame - is that statement really saying those shouldn't be connected to earth ground?  Isn't that a safety feature?  Is Prusa connecting any part of the 24VDC power supply to the frame or the PSU case (which are necessarily connected by screws)?

Still don't get it.  Printer is working fine.  But thanks again for the info.

Scott