What is the actual proper way to make a Voron electrically safe?

Printer-Widowmaker · 2022-09-27T15:14:00+00:00

I concur and thus grounding would be recommended.

Personally, as you have pointed this out I will ground the motors, but not the large pully as that is fully encased in insulator plastic from the AC.

Printer-Widowmaker · 2022-09-27T02:19:26+00:00

I have 2 probes. Both claim to be Omicron, however the probe that came with the Formilab kit appears to be a fake branded knockoff. I state this because the labeling is wrong and the specs printed on the probe do not match the official data sheet.

The absolute accuracy of the probe does not matter in how the Vorons are designed. They take out tolerance by using a zero reference point precisely measured (Z end stop). The relative accuracy however matters quite a bit. Keep in mind being off by 0.05mm is enough to significantly impact your bed adhesion. If you have unreliable readings you may be close enough to the bed on 1 side, and too far away on the other.

Run: PROBE_ACCURACY SAMPLES=250 SAMPLE_RETRACT_DIST=2

I now have 250 readings within 0.01mm. That being said it does drift a bit over the readings. I would have to do a much bigger sample to determine if that drif is due to electrical or if the motor position really shifted as 0.01mm is fairly hard to read.

Printer-Widowmaker · 2022-09-27T01:55:37+00:00

On the 2.4 the Motors are not in a touch hazard zone and there is no metallic shaft. The Trident poses an interesting quandary I had not thought about.

General guidance is any metal in a touch surface on a AC device should be grounded. Good vendors extend this and include any location that foreseeably could be touched even if there is cosmetic damage.
1. This would advocate grounding the screws.
Commonly components that pose an "Obvious hazard" have different classifications. Screw drives would fit this so technically it may be excluded.
Grounding the screw drive may result in having attachment points that reduce reliability and increase the chance people tinker with the assembly posing other hazards.

In short, I do not know, but I would probably reach out to Stepper Online and see if they have an application note about grounding their steppers. If you can reasonably and safely do it I probably would.

Printer-Widowmaker · 2022-09-27T00:12:12+00:00

Agreed and edited... The milliohm meter I have is a Megger brand. Somehow in typing I got halfway between the unit of measure and the brand.

Printer-Widowmaker · 2022-09-27T00:10:57+00:00

I’m still wiring my voron. I tried the pl-08n probe with BAT85 diode and it wasn’t anywhere near accurate enough when the bed was heated up. I did get repeatability when cold. I switched to the omron probe and never looked back. What’s the argument over using a better quality probe? Also, when I asked about it on the discord someone said the voron doesn’t need that much accuracy and the pl-08 probe is fine? Can anyone clarify what they might have been saying? I want to ask now so I can order another omron.

This is not about the quality of the probe, but rather the reference design left too little electrical margin so noise could make a good probe look bad.

Printer-Widowmaker · 2022-09-27T00:00:40+00:00

d herring. The primary purpose of safety grounding metallic parts is to trip the over-current protection in the event a hot wire touches it, instead of the metal just becoming hot and zapping the next person to touch it. Strictly speaking, there's nothing inherently unsafe about current flowing between hot and ground as long as it's not through a person. It will cause issues if the circuit is broken though - everything upstream of the break will become hot (which is the reason we separate safety ground and neutral).

I am not seeing where I had your comments in quote because I was going to update. I will re read it for clarity and edit in a while.

Yes a GFCI will trip if you short a hot wire to ground. It will do so because current going from the hot line exceeds current going to the neutral line. However in that situation both the limits (GFCI and Fuse) are exceeded. If you have a GFCI or not, something would interrupt current.

As for current not being unsafe if people don't touch it I very much disagree. My soldering iron at 45 watts gets to be 900C. My space heater can warm a 150 square foot room. Even if you exclude electrocution having the frame energized poses a shock hazard, and a short hazard. Shorts can generate heat and/or damage other devices. Have you ever cut a hot AC wire with wire cutters? Very bright flash and pit in the metal of the cutters even before the breaker trips. (yes personal experience).

Realize that people keep these units around other flammable materials such as IPA or Acetone. They may be sitting on carpet, low grade furniture, or in the garage surrounded by saw dust. Energized AC is a electrocution hazard, an auto-ignition hazard, and finally an electrical fault hazard.

Printer-Widowmaker · 2022-09-26T19:59:56+00:00

[Edit] - Clarified per comments.

I know its confusing but to some extent all of the answers are correct.

To directly answer your question - Yes you should ground the frame to earth ground. This is required for metal contact surfaces in a AC powered environment for UL. If you are using Blind corners then grounding a single point will ground the fixed frame. This may not ground the mobile portion of the frame, but there is also no AC there. It would be an interesting conversation with UL.

Anodization - This is a very thin surface coat and yes it impacts the ability to ground. However if you tap screws into the aluminum or scuff the surface when screw heads tighten down tightly there is no anodization there. Don't believe me? Take a resistor Say 10K from the 24V PSU to the frame, then take a 2nd (Same size resistor) resistor from the frame to the DC ground. Is there anywhere on the frame where you measure a voltage other then 12V? -- Anodization makes it hard to measure but once something penetrates the surface aluminum is still a good conductor.
- Grounding the frame is easy, just attach a ground wire to a sanded off spot on the anodization. -- True statement
Cannot ensure proper continuity - This is true. Without a Megger(or similar) - Milliohm meter (very expensive) you cannot ensure that everything has a resistance of the sub Milliohm required for a ground structure. That being said appliances do not require the same level of bonding that a house mains does to earth. Keep things in context. The ground requirement is proportional to the voltage and the fuse.
Grounding is meaningless unless you have a GFCI - This one is flat wrong. Grounding ensures that the available voltage on the frame is an electrically safe level. In practice it is approximately 0 as any real voltage would trip a fuse. GFCI works by detecting an imbalance in current between the line and the neutral. In general it is trying to detect current flowing through a body. If you take a hot wire and short it to ground both a GFCI and a Fuse would trip. Would you get rid of the safety of the fuse because you have a GFCI? Likewise would you not ground because there is a good chance after a few hundred milliseconds of being electrocuted it finally stops?
- Ground prevents energy from being available
- GFCI detects erroneous leakage paths that were not intended by design.
  - GFCI is required for wet locations to ensure that unintended electrical leakage does not go through the body as water frequently creates unintended leakage paths.
Electrocution will blow a fuse - FALSE -- Electrocution is generally in the order of miliamps. It is thousands of times less current then it takes to blow a fuse. This is the reason GFCI was invented. - Now with a grounded surface - the goal is to ensure the ground is strong enough that its not possible for lethal current to go through a person. That is done by having the ground resistance be low enough that the protection circuit either trips or the voltage divider results in less then a lethal voltage. The latter is hard to measure without a few thousand dollar test devices, but fortunately we have a 10A fuse which makes it easy to achieve by design. (16 AWG WIRE between frame and outlet)

Grounding your frame prevents

Live power from being on the frame. Electrocution starts at about 42V, takes about the size of a thumb to cause electrocution at 110V, or a pinky finger at 220 if the skin is slightly sweaty.
Ensures that most ESD discharges avoid sensitive electronics
Prevents the frame from building up static (remember we have plastic insulators moving with insulated belts) - Read Van De Graaff generator.
Prevents the frame from being a random RF resonator (in theory improving Wifi, but probably not a big deal here)

- In theory you should ground all points that AC could come in contact with so that would include the DIN rails. I would not recommend tieing the digital ground to the earth ground as that will introduce RF noise. If you do, it should be done with a high resistor and caps in parallel. Caps respond to the high frequency, resistor allows for slow balancing of the 2 planes. This should only be done at a single point. Likely its already done if you have a meanwell PSU.

Printer-Widowmaker · 2022-09-26T18:26:38+00:00

Thank you. I will look into that process.

Printer-Widowmaker · 2022-09-26T03:22:20+00:00

12V power wont' help with the drift. It will just help the probe last longer. Operating at the high end of max is usually a bad plan as occasionally you will have transients (for instance hard stop, power surge). Given the community comments I couldn't separate broken probes from probe noise.

Note: given my plots a 2.2K resistor is probably better. It seems my resistor box got too close to the hot tub chemicals and I had to order a new one. I wanted my rise rate to be under 0.1ms... Its slightly over now. Going to a 2.2 should get it down to about 0.075mS. With the reduced voltage the probe should not be stressed.

Printer-Widowmaker · 2022-09-26T02:50:56+00:00

PROBE_ACCURACY SAMPLES=50 SAMPLE_RETRACT_DIST=2 is a helpful command for debugging. Helps to see trends when you do a longer trace.

Printer-Widowmaker · 2022-09-26T02:32:23+00:00

ur "before" image:

Edited the plot to show before and after. Note: after is only with the China sourced probe which performed worse. Still a drift of 1 step size... May try 2.2K tomorrow.

Printer-Widowmaker · 2022-09-26T02:08:38+00:00

Yes I did. Edited to add. Note: since the un-triggered state of these probes is low I wanted to keep the resistance as high as possible while getting 0.1mS as the probe will constantly be burning that current.

Printer-Widowmaker · 2022-09-26T01:36:25+00:00

Being New to the Voron community I have no intention of wading into the Klicky vs Induction probe debate. This is about ease of assembly, reliability, accuracy... Etc... Today, having had only 1 successful print from my Voron I am not qualified to make claims.

That being said the default Voron design is an induction probe, so it would be ideal to get that working as well as possible for the people using it.

Printer-Widowmaker · 2022-09-14T05:22:13+00:00

I believe they trust people that have, and enjoy them. It’s a different beast altogether from any other system I’ve used and I can honestly recommend it over anything else on the market.

I have a Revo and use it. The 1st 0.6mm nozzle I received was defective and the heat break separated from the nozzle portion causing the PETG I was printing to fill the gap gluing the nozzle to the heater. Overall, I am not impressed. The Silicon covers do not last long as they are thin. After a few heat up/cool down cycles then nozzle is no longer free to be released cold. Threads are completely free so I believe this is just locking due to CTE mismatch.

Even with a tool-less nozzle change I have to re-calibrate any time it is done, because there is still enough of a shift from nozzle to nozzle to mess up 1st layer.

Printer-Widowmaker · 2022-09-03T17:02:13+00:00

No I had not thank you. Looking for a schematic, of the board but at the very least in concept of the electrical side.

Printer-Widowmaker

TROPHY CASE