Ambient Temperature for 3D Printing

3d Printing / Slicers / Setup / Problems
21

Without researching them, I’m going to presume that those vent openers operate by using either bi-metal expansion/contraction strips or expanding/contracting fluid. After all, that’s how, for decades, furnace thermostats worked. They contained a coiled bi-metal strip that expanded & contracted with temperature. This made the coil tighter or looser. Attached to 1 end of the coil was a switch. Often, the switch consisted of a small glass vial with a bit of mercury in it. There were also 2 wires at 1 end of the vial. When the coil contracted enough, it would tilt the glass vial so that the mercury would roll to the end with the 2 wires and connect them electrically. This would turn the furnace on. When the furnace heat cause the coil to expand enough, it would cause the mercury to roll away from the wires, turning the furnace off.

I venture to say virtually every member of this forum lived in a house with that type of termostat at some point of their life.

22

I remember Minneapolis/Honeywell very well. They were very reliable thermostats too. I can’t ever remember having to fix one.

23

I suspect that a bimetallic strips by their nature won’t provide the driving force required to push a window. These things produce forces in the Kgs! Wax was used for years in car radiators to force open springs and allow the water flow to change according to temperature, hence it suspect that’s more likely.

I have to say peeps, it’s pleasant to discuss with such intelligent and educated people again. Things seem to have devolved into a shouting match pretty much everywhere these days since Google and Facebook took control of just about everything.

can you guess I’m not a fan?

24

They had the advantage that mercury won’t wear out over time, as normal electrical contacts would do. Thousands or make/break connection sparks burn off tiny amounts of regual metal contacts. Mercury to the rescue.

25

The gotcha with mercury is that the stuff can be awfully dangerous if mishandled even in small amounts: amazing to think that it used to be used as a treatment for VD.

Patient: “Doctor, I have a bad case of VD”

Doctor: “Don’t worry, just dip your member in this qucksilver and you’ll be right as rain in a couple of days.”

Patient: “Err… on second thoughts, can I just have some penicillin?”

======= Back to the topic at hand =======

“Elementary Dr. Vax, just as I thought…” Sorry, I’m massacring Sherlock Holmes there.

From this: https://www.window-openers.com/news/…eners-working/

“Automatic greenhouse vents have a piston which gives them the ability to either open or close automatically. When the warmer weather hits, your vents will open and when the temperature drops, the vents will stay closed. Greenhouse vents are very easy to install. The pistons have a specially designed wax which when heated, expands.”

Fiendishly clever guys! In fact, my apartment has radiator thermostats that I believe work in much the same way. The interesting thing is the sheer force exerted on the piston by simple expansion due to heat.

I’ll find a few hours some time soon to modify Hotstuff to control a 12v computer fan to do this electronically though. While it has the “unreliability” of electronics it has the advantage of being able to monitor the temperature anywhere in the enclosure and because the sensors are effectively weightless compared to rest of the hotend they won’t add any notable difference to the print but they it would allow anyone to control the temperature at the sharp end (and also inside the enclosure too, since we can have more than one sensor) within a few degrees with a response time measured in seconds. The disadvantage of wax is revealed in the physics.

Long story short, wax takes time to heat and cool and that means the closer will react quite slowly.

Longer story (if you’re interested) is about the conservation of energy. Heat from the enclosure has to heat the wax, causing it to expand and that drives the piston out. As the wax cools and contracts the piston retracts. Now these things are generating a pushing force in the region of 15 lbs or nearly 7kg which is a LOT. They have to be so they can move the glass pane and wood/metal frame up and down.

I don’t know the math to explain this in detail, but we don’t get work for nothing. Imagine how much power a stepper motor would require to perform this task, several tens of watts I would guess.

The wax is converting heat energy into kinetic energy. We get it for free in a greenhouse because it comes from the sun but in a printer enclosure that has to come from the vented heat generated by all the equipment. Moving 15 Kg (even if a practical application would be moving less because an enclosure would probably be perspex) is still considerable and while that energy will be present, a lot of heat will be “lost” through the case and the metal surrounding the wax. I expect the greatest moving mass here is the piston assembly itself in fact so it will take a considerable time (perhaps too long) for the piston to get hot enough to move and open the vent. As things cool, heat losses will cause the effect to reverse.

On reflection, while these openers look like a good idea, I suspect the hysteresis curve would be far too shallow to make them effective. I don’t mind being wrong though because I we need to do all we can to preserve energy.

26

Everyone on the videos I watch about greenhouses swears by them.

27

I’m sure. I’m not allowed a greenhouse but I would have one in a heartbeat if I did. They are superb and as you said, totally “green”.

But the energy in a greenhouse (under direct sunlight) is far greater than that generated inside a small enclosure. The energy we receive from
the sun is astonishing even on an overcast day.

I’ll recode Hotstuff to drive a couple of sensors today (no need for humidity in this application but we could use two sensors, one at the head and an option to have one elsewhere in the cabinet to drive the fan(s).

total BOM should come under the costs of a wax piston but it would be interesting to compare the two. I don’t even have a cabinet!

I expect the problem with a wax piston is the reaction time which relies on the thermal characteristics of the wax - the mass of wax and the metal for the piston will slow it down considerably. A fan system can be adjusted with variable hysteresis (my skills don’t extend to PID) and the response is almost instant.

I wish we could run a proper test though because I love being wrong sometimes as it settles arguments. From my science training (and Richard Feynman) if your experiment disproves your theory then your theory is wrong.

I might be totally wrong but without running the test (hint, hint, cough, splutter) we can’t know for sure.

Marc

EDIT:

Come to think about it something like Hotstuff could also measure for overtemp and even shut the system down or trigger an alarm. You know, in case of a fire etc.

The ATMega 328p that I used in that project isn’t quite up to “fire” standards but there is another slightly more expensive version which would be. Fire/flame sensors are not that expensive and we could even monitor for several types of off-gassing if there was a call for that.

I would still use a dedicated, professionally used smoke detector as a first line of defence but this would be a nice piece of redundancy.

28

So, pretty much as I thought. In this case, the wax is acting as the expansion “fluid”. It is a clever design.

BTW, liquid mercury is not really all that dangerous. Dipping your member in liquid mercury should not cause health issues.

Methyl & gaseous mercury are the real issues. Unfortunately, when liquid mercury is discarded in waste water into lakes & rivers, usually as a result of some manufacturing process, it gets acted on, over years, & gets converted to methylmercury by bacteria. The methylmercury then gets absorbed by plant life in the water, which gets eaten by small animals, which are then eaten by larger & larger animals. All this time, the concentrations go up, so animals higher up on the food chain get higher doses of mercury that’s in an absorbable form.

The gaseous form or mercury is what used to cause millinery workers to go insane. To make beaver pelt hats, the mercury had to be heated quite hot, causing a lot of it to vaporize (liquid mercury will evaporate to some extent at room temperature). The milliners would breath in the fumes, which went straight to their brains. Thus, the term “mad as a hatter”.

29

I always wondered where that term came from. I suppose it wasn’t a good idea to roll it around in your hand as we used to do when I was a kid.
By the way the sun is only indirectly involved in activating the opener, it works by temperature not photovoltaic.

30

As I said, the liquid form is not really dangerous. I doubt that rolling it around in your hand caused any damage.

The sun would be involved in the sense that direct sunlight is quite a bit stronger than indirect, so it would heat up the wax faster.

31

From what I can discern on the videos I’ve seen is that they react quite quickly. I think they tell you all that in the specs for each opener.

32

Speed is a result of the pressure from the expanding wax - but the wax expansion is governed by the amount of energy that it can absorb (or dissipate when it closes).

Any speed tests quoted would be for an outdoor situation which is completely different to our little cabinet. I’m no “poo pooing” the idea only discussing the theory. I would expect (since they have would less weight to shift) it would be possible to manufacture a wax-based one which would be much smaller and therefore, more responsive to changes in temperature.

33

The gaseous form or mercury is what used to cause millinery workers to go insane. To make beaver pelt hats, the mercury had to be heated quite hot, causing a lot of it to vaporize (liquid mercury will evaporate to some extent at room temperature). The milliners would breath in the fumes, which went straight to their brains. Thus, the term “mad as a hatter”.

I remember many years back doing a tour of a pottery and there was something similar there - lead maybe? - which drove workers insane hence the term “potty”. @Ender5r you might know more about this than I, my chemistry is has gone a bit ferric-oxide over the years. (Bad-dum—tiss!)

34

Many years ago, both lead & mercury were used in pottery. The high temperatures could cause all kinds of chemical reactions that are not exactly pro-human.

35

I can’t find them - but I’ve found what appears to be a pretty decent manufacturer of these things so I’ve dropped them a line with our query and invited them to join in here if they have time.

Thanks for all the respectful comments here, I’m not used to it these days! It’s a real pleasure to chat with people who (a) know their stuff and (b) don’t shout, swear, and spit out their dummies when someone doesn’t agree.

EDIT: these dudes - https://www.vernatherm.com/

36

While chemistry (obviously) isn’t really my thing, I find it remarkable how long it took people to wake up to the fact that certain chemicals, even in their elemental forms are so amazingly toxic if misused. The route of entry is also important, something that wasn’t lost on the producers of Erin Brockovich who made a rich, but otherwise deceptive former paralegal appear to be some heroine by taking on a huge chemical company. The gotcha is the film portrays hexavalent chromium (Cr6) as being carcinogenic by ingestion (which it’s not) it’s hugely toxic by inhalation. This is presumably how the potters and hatters came into contact and there’s no surprise that they went mad/potty. I love etymology.

Lead seems nasty no matter how it gets into us. I worked with far, far too much of it as a kid and I can’t help wondering if one or more of my kids suffer as a result.

In fact, lead was used until at least the 1950s as lead arsenate to control insects in — wait for this — orchards! Use continued until (I think) the 1980s and probably later in Argentina in the tobacco regions and (surprise) the kids there are getting horribly sick. Not to mention they also get lead (and maybe arsenic too, I’m not sure now) from a local volcano which spews the crap into their water table and the poor there can’t get clean water with the lead removed.

37

"Toxicity

Hexavalent chromium compounds are genotoxic carcinogens. Due to its structural similarity to sulfate, chromate (a typical form of chromium(VI) at neutral pH) is transported into cells via sulfate channels.[SUP][7][/SUP] Inside the cell, hexavalent chromium(VI) is reduced first to pentavalent chromium(V) then to trivalent chromium(III) without the aid of any enzymes.[SUP][7][/SUP][SUP][8][/SUP] The reduction occurs via direct electron transfer primarily from ascorbate and some nonprotein thiols.[SUP][7][/SUP] Vitamin C and other reducing agents combine with chromate to give chromium(III) products inside the cell.[SUP][7][/SUP] The resultant chromium(III) forms stable complexes with nucleic acids and proteins.[SUP][7][/SUP] This causes strand breaks and Cr–DNA adducts which are responsible for mutagenic damage.[SUP][7][/SUP] According to Shi et al., the DNA can also be damaged by hydroxyl radicals produced during reoxidation of pentavalent chromium by hydrogen peroxide molecules present in the cell, which can cause double-strand breakage.[SUP][8][/SUP]

Both insoluble salts of lead and barium chromates as well as soluble chromates were negative in the implantation model of lung carcinogenesis.[SUP][7][/SUP] Yet, soluble chromates are a confirmed carcinogen so it would be prudent to consider all chromates carcinogenic.[SUP][6][/SUP][SUP][7][/SUP]

Chronic inhalation from occupational exposures increases the risk of respiratory cancers.[SUP][7][/SUP] The most common form of lung malignancies in chromate workers is squamous cell carcinoma.[SUP][7][/SUP] Ingestion of chromium(VI) through drinking water has been found to cause cancer in the oral cavity and small intestine.[SUP][7][/SUP] It can also cause irritation or ulcers in the stomach and intestines, and toxicity in the liver.[SUP][7][/SUP][SUP][9][/SUP] Liver toxicity shows the body’s apparent inability to detoxify chromium(VI) in the GI tract where it can then enter the circulatory system.[SUP][7][/SUP]

Of 2,345 unsafe products in 2015 listed by the EU Commission for Justice, Consumers and Gender Equality some 64% came from China, and 23% were clothing articles, including leather goods (and shoes) contaminated with hexavalent chromium.[SUP][10][/SUP] Chromate-dyed textiles or chromate-tanned leather shoes can cause skin sensitivity.[SUP][10][/SUP]

In the U.S., the OSHA PEL for airborne exposures to hexavalent chromium is 5 µg/m[SUP]3[/SUP] (0.005 mg/m[SUP]3[/SUP]).[SUP][11][/SUP][SUP][12][/SUP] The U.S. National Institute for Occupational Safety and Health proposed a REL of 0.2 µg/m[SUP]3[/SUP] for airborne exposures to hexavalent chromium.[SUP][13][/SUP]

Hexavalent chromium is present in drinking water and public water systems.[SUP][3][/SUP][SUP][4][/SUP] Based on the findings of the National Toxicology Program (NTP)—which is headquartered in the National Institute of Environmental Health Sciences (NIEHS)—in 2014, California established a state-wide drinking water standard of 10 parts per billion (ppb)—micrograms per liter (MCL) of 10 ppb—“specifically for hexavalent chromium, not total chromium.”[SUP][14][/SUP][SUP][15][/SUP][SUP][16][/SUP]

For drinking water, the United States Environmental Protection Agency (EPA) does not have a Maximum Contaminant Level (MCL) for hexavalent chromium."

https://www.osha.gov/hexavalent-chromium

38

Replying to the O/T post.

For drinking water, the United States Environmental Protection Agency (EPA) does not have a Maximum Contaminant Level (MCL) for hexavalent chromium.

My post specifically states that the route is critical - and it’s inhalation that is toxic. There is ample evidence that Cr6 is highly carcinogenic if inhaled and this is seen in worked exposed to it. Nothing there is new and all of this was known when Erin Brockovich managed to extort millions from PG&E (because it was simply cheaper to settle than it was to fight dozens of cases).

Cr6 is converted to Cr3 by HCl in the gut although this wasn’t accurately reflected in the Wikipedia article you’ve pasted in, but it’s discussed here: Ingestion of chromium(VI) in drinking water by human volunteers: absorption, distribution, and excretion of single and repeated doses - PubMed with volunteers given a dose of 5-10 milligrams Cr6 per liter of deionized water which is a massive amount.

That Cr6 is hugely genotoxic, causing carcinogenesis in workers exposed to atmospheric Cr6 is not in doubt but there is no evidence that ingestion of small amounts of Cr6 is harmful in drinking water.

The rate of all cancer types in and around the area implicated by the PG&E leakage covered by the movie and the lawsuits has remained at statistically similar level as reflected by the rates of the same cancers across the USA. Brockovich was full of it and the crucially movie’s writers knew that, that much is evidenced in the Act 1 -> 2 turning point where Brockovich (Julia Roberts) is shocked to hear from Dr. Frankle (Randly Lowell) how bad this is, but read carefully:
[INDENT=2]FRANKEL
Yes. There’s straight-up chromium – does all kinds of good things for the body. There’s chrom 3, which is fairly benign, and then there’s chrom 6, hexavalent chromium, which, depending on the amounts, can be very harmful

ERIN
Harmful, like – how? What would you get?

FRANKEL With repeated exposure to toxic levels – God, anything, really – from chronic headaches and nosebleeds to respiratory disease, liver failure, heart failure, reproductive failure, bone or organ deterioration – plus, of course, any type of cancer. He rattles it off coolly. Just facts. Erin’s stunned.

ERIN So that stuff – it kills people.

FRANKEL Oh, yeah. Definitely. Highly toxic, highly carcinogenic. Bad, bad stuff.[/INDENT]

Note how even the screenplay alludes to Cr3 as being benign - but it doesn’t say that Cr6 when present in the water table is essentially safe because we convert it to Cr3. (Whoops.) If they’d been honest at this point, there wouldn’t have been a movie that made Brockovich into a hero, rather one that exposed the totally unbalanced nature of US litigation which would have potentially exposed Brockovich as just another “lawyer” who is keen to exploit the system.

It’s a movie, it’s not necessarily supposed to tell the truth; U571 misled everyone about the recovery of the first working engima machine. The TRUE story is even more interesting but far longer, but after much outcry, they did add a footnote explaining who really captured it.

Much the same can be said for glyphosate (often called RoundUp) after that was “implicated” by the IARC and caused an upset not unlike the MMR debacle, only this one has made ambulance chasing firms like the one Brockovich was with millions in fees: taken from the damages awarded to plaintiffs with horrible cancers.

A lot of people hate on glyphosate because they don’t understand it. Save me the citations, I’ve probably read them already or the papers they are based on, and I’ve written extensively on this subject. Yes you can drink it, no it won’t give you cancer and no, it’s not a beverage either so you’re not supposed to drink in the first place. Indian farmers who did attempt to commit suicide (after being driven in to crushing debt by corrupt seed suppliers, also Indians it’s worth noting) just succeeded in making themselves vomit at worst. If there are any carcinogens in Roundup or the products associated with it, the balance of probability points to the surfactants which have to the best of my knowledge, not actually been fully assessed.

The IARC has been infiltrated by corrupt scientists, much as I hate to admit that such a thing exists, and this too has been exposed by good journalists. Unfortunately people hate on Monstanto because of the association with Agent Orange during the Vietnam war. Glyphosate was a once-in-a-lifetime discovery that’s been given a bad name by a well-funded anti-science lobby that, for its own selfish interests ($$$) wants to set modern agriculture back centuries.

Now, can we quit with the copypasta and return to the topic at hand please?

39

What a cute and cynical word: copypasta!

Who diverged from the 3d printing topic first?

I would like to believe that the participants in the forum are of above average intellect, citizens of Lake Wobegon?

I suspect some among us may be even climate deniers…

The environment is relevant to all of us, cosmonauts in the pale blue dot. At a more regional level, I am concerned about the potential hazards of 3d printer materials, filaments and resins.

I may be the emperor of copy and paste:

Chromium-6 in Tap Water: Why the 'Erin Brockovich' Chemical Is Dangerous | Live Science “Chromium-6 in Tap Water: Why the ‘Erin Brockovich’ Chemical Is Dangerous”

You are free to choose the red or the blue pill and believe what you choose to believe, opinions are not facts…

Are some reduced odor or epoxy free resins safer? Inquiring minds need to know…

40

@marcdraco - Steering more towards 3D printing but still questions on “safety”, perhaps you can shed some light on a couple of topics I’ve tried to research in the past? [LIST=1]

  • Regarding the safety of PTFE ("teflon" as I understand it) at 3D printing temperatures: I know there was a lot of concern about teflon coated pans at stovetop temperatures (190-250C as I understand it). The 3D printing literature -- most by rather dubious manufacturers -- claim that printing below 240C with their PTFE-lined heatbreaks is not a risk. Some articles on PTFE safety -- no more convincing -- claim that household pets, particularly birds, can be harmed by heating teflon up to lower temperatures. I've read that PTFE tubing can offgas neurotoxins that are, at the very least, not healthy. Can you point to any definitive information? I personally go with all-metal hotends for printing above PLA temperatures, but I don't want to spread alarmist information.
  • Regarding the emission of ultra-fine particles. Concerning PLA and PETG, my understanding is that they emit low amounts of UFPs and that a laser printer or microwave emits much higher levels. However, I did find mention of a NASA study that was researching 3D printing in space that indicated that dried filaments of each type emitted far lower levels of UFPs than filament of the same type that had absorbed moisture. Again, I don't want to be alarmist, but drying filament helps with a number of problems. Lowering UFPs would be an added bonus. [/LIST] I hope you don't mind the questions, but you seem well versed in safety topics.