<DocScrutinizer05>
whitequark: ideally traces have strictly vertical edges, that's why orthodox tooling uses endmill. In RL though, no trace ever has a vertical edge, particularly not when etching. So if your Z axis is precise enough to ensure gap width, I don't see a problem with using engraving bits
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<wpwrak>
i'd use an endmill to cut pcbs, though
* DocScrutinizer05
prolly too, since controlling Z-axis is not exactly simple
<DocScrutinizer05>
THIS would be something where you *need* feedback
<DocScrutinizer05>
when you for example use ds-sticky to fix your PCB, and you pressed it a 0.1mm tighter at one end of PCB than on the other, then your traces' gaps also are off at least 0.1mm
<wpwrak>
that's indeed the sort of fun i had when trying to mill traces. for cutting the pcb, i simply add a bit of overshoot. but with traces, you can only go so far ...
<DocScrutinizer05>
with endmill you should keep in mind that they are tiny and you can only go really slow through material to grind with them. Professional CNC mills use up to iirc 100k RPM
<DocScrutinizer05>
I mean the cutting speed is RPM * 2r * Pi. r(adius) of your endmill is what? 0.1mm?
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<DocScrutinizer05>
sounds like a cutting speed like 0.1m/s
<DocScrutinizer05>
for a 10,000 RPM mill. Not really much
<DocScrutinizer05>
when you use a really good cut/travel ratio of 1/10 then you can't move 0.2mm endmill faster than 1cm/s, on a 10000RPM mill
<DocScrutinizer05>
I don't think you can achieve 1/10, I pulled that outa my a....
<DocScrutinizer05>
so more likely you're down to sth like 1mm/s
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<DocScrutinizer05>
will still work, but milling your PCB might take a while ;-)
* DocScrutinizer05
needs to look up the correct english terms for surface speed of a grinding tool like a saw blade or a endmill, and for the amount the cut advances
<DocScrutinizer05>
heck, I prolly don't even know the german terms for that
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<DocScrutinizer05>
just in case I been too fuzzy: when you cut a steel rod with a saw blade, then the saw blade operates at a certain speed in m/s against the rod. And - given a certain pressure you press the blade against the rod and a certain efficiency aka sharpness of the blade - the cut will go deeper in a certain clearly defined ratio for every meter the blade moves across the rod
<DocScrutinizer05>
the ratio is the 1/10 I used in above guesstimate. The pressure is what makes your endmill break since it builds up when you move the endmill through the object to cut
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<DocScrutinizer05>
the sharpness aka efficiency is probably getting too low for the fab, so they decided to sell off those used bits
<DocScrutinizer05>
now in industry time is money and they want fast operation of their machines, thus they use 100,000 RPM CNC and pretty sharp mill bits. For you, using the worn bits, it's "no money but lots of time", so you need to adjust your X/Y speed of your CNC down to really slow. The slower the smaller the tool diameter since that directly reduces grinding speed the tool goes ofer the surface to grind
<DocScrutinizer05>
over*
<DocScrutinizer05>
or across* ?
<DocScrutinizer05>
wpwrak: makes sense?
<wpwrak>
yeah, the duller your cutting edges, the slower you have to go
<DocScrutinizer05>
btw pressure is in force/area where area is the width of your tool * depth you cut into the PCB, so 0.2mm (dia of endmill) * maybe 0.15mm (depth of trench in PCB to cut)
<wpwrak>
with a factory-new 12 mil (0.3 mm) at 6000 rpm, i didn't dare to go faster than 0.5 mm/s. you can probably go faster but each wrong guess costs some USD 15 ...
<DocScrutinizer05>
:nod:
<DocScrutinizer05>
that's why I thought a real feedback of force on tool bit would be really useful
<DocScrutinizer05>
you intentionally break one bit to caibrate the sensor, and that's the last bit you ever broken on that CNC machine
<DocScrutinizer05>
well, at least for that particular type of bit
<wpwrak>
famous last words ;-)
<DocScrutinizer05>
no matter what you cut and how deep you cut and how sharp the bit and how fast the spindle, you always can limit the XY-advance to a safe amount
<DocScrutinizer05>
just your "break distance" of your CNC has to be shorter than the elastic deformation the bit allows
<wpwrak>
hmm, actually you can't because there are other types of mishaps that can break your mill. but yes, keeping the speed reasonably low prevents having to replace mills all too often
<DocScrutinizer05>
to me it feels more like "insanely unbearably low", but yes ;-)
<wpwrak>
excessive speed can also cause vibrations that make the cut uneven
<DocScrutinizer05>
well, after a week even moderately complex PCB should be finalized
<DocScrutinizer05>
;-D
<wpwrak>
oh, one common mistake is to get Z wrong. or to forget about some obstacle, clamp or such. then the mill rushes into whatever at full speed because it things it has no contact with the workpiece.
<DocScrutinizer05>
probably a very good tactics is to use a 1mm or even 3mm endmill for everything that doesn't need to get any finer than that
<DocScrutinizer05>
sure, that's human error
<wpwrak>
and then sometimes parts of a piece come off and strike the mill. or, worse, stay attached to it.
<DocScrutinizer05>
that's bad
<wpwrak>
yes, always pick the largest mill that can do the job :)
<DocScrutinizer05>
and you should try to find tool path that avoids creating such loose blobs
<wpwrak>
sometimes the toolpath is fine but the adhesive is too weak
<DocScrutinizer05>
I guess advance speed goes up diameter^4 or sth like that
<DocScrutinizer05>
higher circumference speed, higher force allowable
<wpwrak>
luckily, my mill detects such things fairly quickly. so it must have some sort of sensor.
<wpwrak>
one limiting factor is the mill's torque and the amount of vibration the talk can tolerate
<DocScrutinizer05>
200W should create enough torque
<wpwrak>
e.g., i wouldn't try my 1/8 in (3.2 mm) mill on a PCB
<wpwrak>
yeah, whitequark's machine is pretty powerful
<wpwrak>
mine has only 10 W (in the spindle motor)
<DocScrutinizer05>
that's a bit low
* DocScrutinizer05
wonders how much has his Proxxon "dremel"
<DocScrutinizer05>
40W
<wpwrak>
well, it's intended for light work. also, a weak spindle motor means a lower chance for self-disassembly ;-)
<DocScrutinizer05>
self-WUT?
<wpwrak>
i.e., the sooner or the later we'll hear whitequark curse about the mill cutting into the table ;-)
<DocScrutinizer05>
"look, I can shoot away the floor as well!" ?
<DocScrutinizer05>
that's why you *always* use a 10mm decent victim material
<wpwrak>
what we need is an industrial robot (the kind that has an arm with many degrees of freedom) with a high-powered laser cutter ;-)
<DocScrutinizer05>
yes!!!
<DocScrutinizer05>
since ~2years I'm googling for really powerful cutter lasers every now and then
<DocScrutinizer05>
haven't found anything better than "cuts plastic sticky foil" so far
<DocScrutinizer05>
really good IR laser (LED) >100W is hard to find, even new from manuf
<DocScrutinizer05>
at some shipyards the not only cut 50mm steel sheets by laser, they even weld whole ships by laser robots
<DocScrutinizer05>
they*
<DocScrutinizer05>
those are awesome tools, really :-)
<DocScrutinizer05>
a few 100kW
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<DocScrutinizer05>
basically those shipyards became giant makerbots during the last few decades
<DocScrutinizer05>
I guess they wouldn't find the right focus and PWM adjustment to make a PCB though ;-)
<wpwrak>
maybe you should make friends there. i'm sure they discard old equipment every once in a while ...
<DocScrutinizer05>
the precision is probably in the mm range at best
<DocScrutinizer05>
hardly ever they discard those lasers
<DocScrutinizer05>
just like Queen Mary doesn't discard the engine
<DocScrutinizer05>
I guess the laser weighs dozens of tons
<wpwrak>
if they upgrade to a new generation of machines, why would they keep the old ones around forever ?
<roh>
lasers have some disadvantages at price end.
<roh>
and one doesn usually need the precision
<DocScrutinizer05>
seems increased precision is outweighing that
<DocScrutinizer05>
aiui nowadays 100m+ ocean liners are completely built on CNC laser cutting and welding
<DocScrutinizer05>
portal XYZ actuators that move a bot arm with some more degrees of freedom to anywhere of the cross secion of that ocean liner
<DocScrutinizer05>
and for sure laser cutting of steel sheets of several meters length and height, and up to 100mm thickness
<DocScrutinizer05>
to cut out appertures for doors and windows, and so on
<DocScrutinizer05>
then weld the cut sheets into place, also with laser
<DocScrutinizer05>
I have no detailled info, just a TV report about contemprary laser usage
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<whitequark>
DocScrutinizer05: (unbearably slow) yes, this is exactly my concern, safe surface speed for this 0.2mm endmill means a very trivial pcb routes for like 1.2 hours
<whitequark>
which is absurd
<DocScrutinizer05>
well, go for 100,000 RPM then ;-)
<DocScrutinizer05>
or don't cut trenches with 0.2mm when you could cut them 1mm wide as well
<whitequark>
well... a spindle for 60000 rpm would set me back about $700
* whitequark
did a fun check for the accuracy of his cnc machine
<whitequark>
I took a chunk of PCB and milled the laminate away, leaving just the bare copper
<whitequark>
seems to have worked out very well
<whitequark>
... grh, wpwrak can rejoice: I've just milled into my table a little bit :/
<whitequark>
DocScrutinizer05: wpwrak: is it important to use deionized water for etching/developing solution, or is regular boiled water OK?
<DocScrutinizer05>
I'd think reasonably clean tap water is ok
<DocScrutinizer05>
except...
<DocScrutinizer05>
for H2O2 you don't want to add impurities of any kind usually
<whitequark>
nay, H2O2 isn't my cup of tea
<DocScrutinizer05>
but then, who would mix H2O2 with H2O?
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<DocScrutinizer05>
ooh right, prolly illegal in Russia
<whitequark>
H2O2? yes, hard to obtain
<DocScrutinizer05>
use Plutonium instead ;-P
<whitequark>
lol
<whitequark>
btw have you ever used "liquid tin" ?
<DocScrutinizer05>
nope
<whitequark>
I've bought a bottle to try it out
<DocScrutinizer05>
liquid silver here
<whitequark>
it's a chemical tinning solution
<DocScrutinizer05>
ooh that one
<whitequark>
you put the pcb inside for 20 minutes and tin precipitates from the solution
<whitequark>
on the copper
<DocScrutinizer05>
yeah I think I tried that once a 40 years ago
<DocScrutinizer05>
result was some metallic dirt on PCB that sticked to the fingers when touching it, instead of to the copper
<whitequark>
well chances that in those 40 years they managed to build it better
<whitequark>
or maybe not, no idea really
<DocScrutinizer05>
I guess carefully drying the PCB and tin without touching surface, then spraying PCB with flux, then "curing" the whole thing with a blue welding flame....
<DocScrutinizer05>
but then, you probably could reach better results with solder paste
<whitequark>
well, the shop had a demo board tinned with this solution, it looked pretty rad
<whitequark>
definitely not "sticked to fingers better than to copper"
<DocScrutinizer05>
fake?
<whitequark>
lol I seriously doubt that
<whitequark>
those guys (gals actually) have very high-quality supplies and I shop there for years
<DocScrutinizer05>
prolly some current can do wonders anyway
<DocScrutinizer05>
ooh, you say they prepared that themselves?
<whitequark>
yea
<DocScrutinizer05>
well, then...
<whitequark>
another funny thing: I've bought several aerosols by cramolin there. I've not found a single place on the web to buy them, at least in single bottles
<whitequark>
Cramolin, have you heard it? it's a .de company
<DocScrutinizer05>
not unknown that companies cheat though, like acme solder co winding stannol solder wire on their acme hub for doing the demo video
<whitequark>
make very nice (and absurdly expensive) aerosols. flux-off is particularly nice but they have several dozens of them for all imaginable purposes
<DocScrutinizer05>
never heard of cramolin
<DocScrutinizer05>
here we call that "Kontakt Chemie"
<DocScrutinizer05>
dunno if it's a different localized name for same gue
<whitequark>
ooooh yes. exact same package design, guess it's a different name
<whitequark>
also explains why I wasn't able to find it anywhere
<DocScrutinizer05>
dang, that make a LOT of sense ¡
<whitequark>
highly active, duh!
<whitequark>
oh, you mean an acid and a base at the same tim
<whitequark>
*time
<whitequark>
wait, where did you find those ingredients? I can't find any in the pdf at "TDS"
<DocScrutinizer05>
IDS
<whitequark>
no such link
<DocScrutinizer05>
that page throws error from that linkl
<DocScrutinizer05>
damn JS
<DocScrutinizer05>
crap
<DocScrutinizer05>
from main page click on "multifoam 77"
<DocScrutinizer05>
MULTISCHAUM 77 12x400 ML de,fr >>> IDS
<DocScrutinizer05>
IDS is a link
<whitequark>
... okay, there is no multifoam 77 link on the main page
<DocScrutinizer05>
o.O
<whitequark>
no "multifoam" or "77" at all
<whitequark>
oh, if I switch to DE then there is
<DocScrutinizer05>
it's there in english as well
<whitequark>
I need to switch "language on label" to DE, not site language
<DocScrutinizer05>
but links never work as expected
<whitequark>
anyway, I think I understand the reason
<whitequark>
see, it's "ingredients", not "components". they wrote what they mixed in the solution, not what results
<whitequark>
so perhaps some of the components only are soluble in acidic environments, but after they're mixed together, they form something else which doesn't care about pH
<whitequark>
and at that point you can add your base
<DocScrutinizer05>
anyway Kontaflon 85 is my personal recommendation for lubricant for special cases. Really amazing stuff
<DocScrutinizer05>
sprayed the board of my pinball machine with it, and after that the balls were twice as fast, and no more wear on the paintings and varnish
<whitequark>
neat
<whitequark>
you have a pinball machine?
<DocScrutinizer05>
I had
<DocScrutinizer05>
quite some time ago
<DocScrutinizer05>
I lost everything, several times
<whitequark>
I recall... li-ion fire
<DocScrutinizer05>
:nod: but there the pinball machine already been gone
<DocScrutinizer05>
yesterday I seen a TV report about those old machines, and I pondered getting one again
<DocScrutinizer05>
console games never got the hook in me, but pinball... I started playing when I been 6 years old, or even earlier
<DocScrutinizer05>
I used a beer crate to stand on when playing
<DocScrutinizer05>
and after some 30min some of the personal of that bowling noticed me and chased me out
<DocScrutinizer05>
a game been 10 Pfennig back when
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<DocScrutinizer05>
ooh, btw s/LiIon/NiMH/ though that's a suspicion only
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<DocScrutinizer05>
NiMH seem more dangerous to me than LiIon
<whitequark>
oh okay
* whitequark
has just peeled the film from a polycarbonate sheet
<whitequark>
it is beautiful.
<DocScrutinizer05>
since they have no good emd-of-charge detection properties, I seen them heat up insanely high several times, in chargers
<DocScrutinizer05>
the hotter those NiMH get, the lower the tempreature
<whitequark>
resistance?
<DocScrutinizer05>
so when the charger misses the delta-V, it goes al the way till disaster
<DocScrutinizer05>
eeek
<DocScrutinizer05>
the hotter those NiMH get, the lower the voltage
<whitequark>
(misses dV) unless it has a heat sensor, and it better have one!
<DocScrutinizer05>
fastchargers are supposed to stop when they detect decay of voltage caused by battery heatup
<DocScrutinizer05>
yeah, pretty few have, and for sure the vacuum cleaner that prolly started that fire had any such fancy stuff
<DocScrutinizer05>
it actually just had a series resistor and a 5mm barrel connector for external power supply
<whitequark>
do you have any appliances not posing a fire hazard? :D
<DocScrutinizer05>
yeah, my smoke detectors ;-P
<whitequark>
haha
<whitequark>
okay, I'm off to get labeling paper, deionized water, more airtight containers and stuff
<whitequark>
fortunately it's all within 5 subway stops so not going to take too much time
<DocScrutinizer05>
wich surprisingly reminds me to get a CO2-fire-extinguisher
<DocScrutinizer05>
the power extinguishers are a disaster in themselves
<DocScrutinizer05>
powder*
<DocScrutinizer05>
you extinguish the flames, then you tear down the building since the powder ruined everything
<whitequark>
could skip extinguishing the flames then
<DocScrutinizer05>
thus: CO2 extinguisher
<DocScrutinizer05>
(halon extinguishers are forbidden - a shame)
<whitequark>
are they? my father installed a bunch on a power plant here in moscow
<whitequark>
well, maybe .de regulations are stricter
<DocScrutinizer05>
I just found some, for exorbitant pricetag, exclusively approved for use in air- and spacecraft
<DocScrutinizer05>
this one says "not flamable when used according to instructions" - which is a pretty poor joke
<whitequark>
haha
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<DocScrutinizer05>
in english: >>Non-flammable* formulation. * criteria according aerosol directive.<<
<DocScrutinizer05>
while DUST OFF 360 SUPER says >>A non-flammable formulation in all conditions. <<
<DocScrutinizer05>
>>Designed for critical applications, where 100% safety is an absolute must.<< lol
<DocScrutinizer05>
DUST OFF HF (HIGH FLOW) (mine): >>. A non-flammable pressurised gas, designed for applications where absolute safety is a must, it can even be used on energised equipment, when there is a risk for discharges.<<
<whitequark>
I'd be really wary of "non-flammable*"
<DocScrutinizer05>
this site is so abysmally bad. incredible. Select "English" on top right. Tick "Duster Spray" in left side menu. With "Language on product label ": German you see 6 products. with English you see only 3
<DocScrutinizer05>
OOOH, on PRODUCT label. OMG
<DocScrutinizer05>
"sorry, this spray is not available in english language" lol
<whitequark>
haha
<DocScrutinizer05>
mhm, now i got it, finally
<DocScrutinizer05>
tetrafluoroethane 75-10%0
<DocScrutinizer05>
Dimethylether 5-10%
<DocScrutinizer05>
nfc why they need 5-10% dimethylether in that stuff
<DocScrutinizer05>
mine is tetrafluoroethane with 5..10% 1,1-Difluoroethane
* DocScrutinizer05
notices much Fluor around him lately
<DocScrutinizer05>
whitequark: I don't think the Kontakt chemie stuff ever had Butane/Propane in their duster sprays
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<whitequark>
huh
<whitequark>
I've dissolved 250g of (NH4)2S2O8 and the water is much much colder
<whitequark>
specifically 9°C with room at 24°C
<whitequark>
8° even
<DocScrutinizer05>
sure
<DocScrutinizer05>
normal, no?
<whitequark>
I remember this effect from my classes, just wasn't expecting to observe it
* DocScrutinizer05
forgot to get milk for the weekend, with all the Kontakt chemie stuff :-S
<whitequark>
it's just 3pm or 2pm there
<DocScrutinizer05>
yep, but my shopee closing at 14:00 the latest
<whitequark>
wow
<whitequark>
that is inconvenient
<DocScrutinizer05>
now I have to walk 1000m to get milk of inferior quality :-(
<whitequark>
euuugh
<whitequark>
isopropanol *stinks*
<DocScrutinizer05>
yep
<whitequark>
I would even say reeks
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<DocScrutinizer05>
I once worked for a cleaning service where we cleaned a whole school's carpets (YES!), and the water vacuum needed iso spraying every 5 min to destroy the foam building up
<DocScrutinizer05>
then continue vacuuming and dpread the fumes into the air
<DocScrutinizer05>
spread even
<DocScrutinizer05>
was real fun :-S
<whitequark>
I wonder if it's intentionally flavored to make sure no one drinks it
<DocScrutinizer05>
no, i'm sure it really smells terrible
<DocScrutinizer05>
genuine stinker
<DocScrutinizer05>
hmm, maybe not: >>Isopropyl alcohol is denatured for certain uses, in which case the NFPA 704 rating is changed to 2,3,1.<<
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<whitequark>
wiki says it has a peculiar odor
<whitequark>
"more pungent than ethanol"
<whitequark>
pungent indeed
<DocScrutinizer05>
LOL >>The chewing of cordite, as a form of chewing gum was far from unknown in the late 19th and early 20th centuries. The sweet taste made it attractive, and it gave the user feelings similar to those produced by alcohol. (Due to its explosive qualities, however, several fatalities were reported, from chewing too strenuously.(Ref: http://trove.nla.gov.au/ndp/del/article/3281990 among other sources.))<<
<whitequark>
hahaha
<DocScrutinizer05>
I wonder wtf goes on with that stuff. I thought nitroglycerine was toxic in all but the smallest dosages
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<whitequark>
hrm, I wonder
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<larsc>
exploding chewing gum?
<whitequark>
hrm, I might want to get glasses out of proper glass and not polycarbonate
<whitequark>
with all this UV and stuff
<viric>
I hate non-glass glasses
<viric>
I only once had non-glass glasses, and in a week, they were scratched.
<whitequark>
these are quite scratch-resistant, I couldn't scratch them once in about three years
<whitequark>
maybe foru
<whitequark>
*four
<viric>
Maybe I'm careless enough about glasses, that I need glass ones
<viric>
My brain learned that I can place them anywhere anyhow, just not hit them
<viric>
and that's fatal for polycarbonate.
<whitequark>
I'm more worried that they're made from the same material I use for exposing PCBs specifically because it's UV-translarent
<whitequark>
(fatal for polycarbonate) maybe your polycarbonate is shitty or something
<viric>
:)
<viric>
can be
<whitequark>
because I never cared to think where I place my glasses and nah, they're smooth
<viric>
I didn't know about the UV
<whitequark>
I'm actually breaking the frame before scratch or break the lens
<viric>
I see, quite the opposite of my experience
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<whitequark>
okay, now I made a 5% solution of NaOH and it is pretty damn hot
<whitequark>
I wonder why is enthalpy of dissolution so different
<whitequark>
in sign even
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<DocScrutinizer05>
I have another interesting question for you: what happens to Cu2C2 when something happens. I don't see any gas or sth in there
<whitequark>
C2?
<DocScrutinizer05>
:nod:
<whitequark>
like Cu=C=C=Cu ?
<DocScrutinizer05>
probably
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<whitequark>
or Cu-C≡C-Cu
<DocScrutinizer05>
err Cu(II)
<whitequark>
regardless of it, this should be really unstable if it even exists
<whitequark>
ok, then the former
<whitequark>
weird
<DocScrutinizer05>
nah! Cu(I)
<whitequark>
hrm
<whitequark>
a bit less weird
<DocScrutinizer05>
Cu(II) is even more instable
<whitequark>
"A stable and stoichiometric Cu2C2 phase in nanoparticle form has been synthesized using activated reactive evaporation technique."
<whitequark>
>< whitequark> regardless of it, this should be really unstable if it even exists
<DocScrutinizer05>
sure, but what *happens*?
<whitequark>
okay, when you mix carbides with H2O you get acetylene and metal hydroxides iirc
<whitequark>
Cu2C2 + H2O -> Cu2O + H2C2
<DocScrutinizer05>
ooh
<whitequark>
then Cu2O + H2O -> ...
<whitequark>
in reality it happens in one stage of course
<whitequark>
actually, hm
<whitequark>
no, it'll just precipitate as Cu2O because it's not soluble in water
<whitequark>
so acetylene and copper(I) oxide
<whitequark>
er
<whitequark>
yes
<DocScrutinizer05>
haha! >>Thermal decomposition of copper acetylide in vacuum is not explosive and leaves copper as a fine powder at the bottom of the flask, while depositing a fluffy very fine carbon powder on the walls.<<
<whitequark>
yup, I guess it's exploside because it results in very fine pyrophoric particles
<whitequark>
like, it's a self-propagating volumetric explosion
<DocScrutinizer05>
must be extremely hot
<DocScrutinizer05>
actually to me that sounds like it evaporates carbon
<DocScrutinizer05>
the german wikipedia has much less info
<DocScrutinizer05>
>>it is interesting as a curiosity because it is one of the very few explosives that do not liberate any gaseous products upon detonation.<< been completely missing in german wikipedia. That's why I wondered what happens
<DocScrutinizer05>
when you would pack it without H2O and without any air and place it into a containment, it wouldn't make that containment burst, right?
<whitequark>
I don't think so
<whitequark>
but, there is always some air
<whitequark>
unless you work hard to remove it all
<whitequark>
actually, no, I think it still could burst... chances that the result products are much less dense than source
<whitequark>
I don't know shit about crystallic lattices of former and latter, but intuition says it'll be less densely packed afterwards
<DocScrutinizer05>
hah, so it might "explosively" expand by - say - factor 2 :-)
<DocScrutinizer05>
which might have whole new usecases since the expanding material isn't gaseous
<DocScrutinizer05>
it might be way more effective on solid materials like steel etc than any "usual" explosive
<DocScrutinizer05>
while same time it should have a really low explosion radius
<DocScrutinizer05>
you probably could blast a 1mm hole into usual glass with it
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* DocScrutinizer05
makes notice to get copper(1)chloride, ammonia, and some good old carbide
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<wpwrak>
CNC milling was yesterday. now you'll introduce CNC precision explosive deposition ;-)
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<whitequark>
haha
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<whitequark>
huh. I wasn't too greedy with chemicals this time and the results are fascinating
<whitequark>
5% NaOH removes resist *very* fast
<whitequark>
30% etchant also works marvelously
<wpwrak>
so it's back to chemistry then ?
<whitequark>
for now, since the cheap endmills haven't arrived yet (and won't get there any time soon), and I'm sure as hell not going to buy a dozen of $15 ones
<whitequark>
well, there's the engraver trick, but I couldn't find engraver bits which ship fast as well
<whitequark>
plus either way it is so very slow
<whitequark>
I'll eventually compare chemistry with milling
<whitequark>
anyway. most of my grief was caused by the fact that I used USSR-formula photoresist, and it is well known (as I'm aware now) for being ridiculously shitty
<whitequark>
I'm now trying with proper imported resist
<wpwrak>
i suspect that chemistry wins in the end. milling has the enormous benefit that you can make traces and cut the pcb in the same process, thus eliminating any offset, but that's about all it has going in its favour
* whitequark
nods
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<whitequark>
a combination of hot plate and stirring is ideal for etching... now only where to get that for a sane price
<whitequark>
and preferably NOT with 110V input yet again
<whitequark>
does this look like a disaster or is it just me ?
<whitequark>
oh wait, no t° regulation
<wpwrak>
hmm, my catv link is very sick. 58% packet loss to the next hop
<wpwrak>
let's see if resetting the modem helps ...
<wpwrak>
kewl. that did the trick :)
<wpwrak>
whitequark: maybe find a source for HCl. then you don't need to cook your acid
<whitequark>
okay, etching is *very* slow. I'm doing it for 18 minutes already
<whitequark>
there's a lot of bubbles, so it is likely due to the fact it's not being stirred
<whitequark>
(HCl) eugh. not really wanting to work with it.
<wpwrak>
i suppose a bottle of vodka + a 5 liter of HCl from your local industry supplies store may be cheaper than equipping a chemical work-around lab :)
<whitequark>
so far every chemical I need is a little bit corrosive, but that's it. hcl is outright dangerous.
<wpwrak>
of course, already 1 l would last you for years. if they have it in such small quantities :)
<wpwrak>
yes, HCl is a little corrosive. i noticed when i tried to store it under the kitchen sink ;-)
<wpwrak>
now it has a nice safe place outside
<wpwrak>
(bubbles) you have to stir/move the pcb ... if you just let is sit there it's likely to take a day or so ... and etch at places you never thought the acid could enter
<whitequark>
yeah, that pisses me off
<whitequark>
hence search for magnetic stirrer
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<wpwrak>
that's why a fast acid is convenient. you can make HCl+H2O2 about as fast as you can handle.
<whitequark>
actually a nonheated one would likely do the job, that's much cheaper
<wpwrak>
most of the non-HCl-based processes are slow at ambient temperature
* whitequark
wonders what is the motive of wpwrak advising him to use more dangerous chemicals ;)
<wpwrak>
HCl isn't *that* bad
<whitequark>
well, 35% hcl is
<whitequark>
I'm not working with it again unless I absolutely need that
<wpwrak>
i.e., i'm not telling you to use a 1000 liter basin of FOOF heated to 1 C below boiling temperature ;-)
<larsc>
and with sharks swimming in there ;)
<larsc>
radioactive sharks
<wpwrak>
with lasers
<whitequark>
I don't think *anything* can swim in FOOF
<whitequark>
literally anything
<whitequark>
I'm not even sure what are you going to use for storage at 1°C below boiling temp
<wpwrak>
i guess it all depends on the time scale :)
<wpwrak>
directed gravitational fields ?
<wpwrak>
(HCl) i guess it depends on ventilation. if you have good ventilation and can store it outdoors, you should be fine.
<whitequark>
I live in an apartment without a balcony
<wpwrak>
i.e., i don't see any unusual amount of corrosion in the area where i do my etching. and i keep the etchant (which contains HCl at a low concentration, certainly < 10%, probably < 5%) around for reuse
<wpwrak>
the pure HCl, on the other hand, gets stored outside, so the vapours can escape
<wpwrak>
ah, no balcony complicates all this
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<wpwrak>
maybe find some chemist you can ask about ways to store chemicals indoors
<whitequark>
I can already tell you the answer: "don't"
<whitequark>
either that or they're a really bad chemist :]
<wpwrak>
naw, it's HCl. it's used everywhere.
<whitequark>
well, not in places people live
<wpwrak>
well, you wouldn't want to live in a microwave oven either, yet you may have one in your kitchen ...
<whitequark>
unlike HCl, microwave oven can be turned off :)
<wpwrak>
especially toilet cleaners seem to be pretty potent in this regard
<whitequark>
that fails my "repeatability" requirement, who knows what else is in that can
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<wpwrak>
it's usually written on it. but yes, you'd have a process that largely depends on a specific set of products. of course, since they all try to accomplish the same, the formulas may be very similar.
<wpwrak>
my main concern would be additives that react with peroxide. so another question for the chemist you should befriend
<wpwrak>
another problem would be the thickener. that's probably the main additive. but since you'll dilute the critter with peroxide anyway, is should become a bit more liquid, too
<whitequark>
ewwww
<whitequark>
no, I'm definitely not using a process so hard to reproduce exactly
<whitequark>
since reproducibility here is my #1 goal
<wpwrak>
not that hard. buy toilet cleaner X, add the usual peroxide. chances are you'll be able to get cleaner X for a very long time. besides, you need only small quantities. so a bottle will last a good while, even if it's less efficient than pure HCl
<whitequark>
it's not as much about using same process for X years, as for understanding it thorougly and sharing it
<wpwrak>
i think you'll want to look for customer comments on toilet cleaners, comments where people say they had some nasty stains and already tried a number of cleaners that didn't work
<wpwrak>
well, you could share it in russia :)
<wpwrak>
let's see if anyone has done that before ...
<whitequark>
most pipe cleaners here use NaOH anyway
<whitequark>
and it has very nasty dark color due to it being ridiculously dirty
<wpwrak>
you still have to be present to check when it's done. so you may as well stir a little while waiting ...
<wpwrak>
also, if you have a decent mixture, the process is fast. someone who has to sit and wait for an hour is clearly doing something terribly wrong.
<wpwrak>
e.g., with a sufficiently aggressive mixture, i've had it etch a board clean in < 1 minute. note that, at such a rate, a) this is no longer an exact process, and b) heat becomes an issue
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<wpwrak>
normally i prefer more leisurely speeds in the 10-15 minutes range
<whitequark>
DocScrutinizer05 will be delighted to learn that the liquid tin coating not only doesn't stick to fingers, but also survives light scratching by tweezers
<whitequark>
the overall pcb quality is far below what I eventually want to have, though... there's poor adhesion of dry photoresist to the copper for some reason, flawed etching process and the printer apparently doesn't quite have enough resolution
<whitequark>
neither of the adjacent tqfp pads you can see should be joined
<DocScrutinizer05>
seen that, thought you had some obstacle in your exposure system
<whitequark>
the photomask has a thinner line where they've been joined, I guess it's 0.1mm instead of 0.2mm or somesuch
<whitequark>
and exposure wasn't ideally perpendicular to the board
<whitequark>
it's really a photomask defect, not so much as exposure or developing one
<whitequark>
likely inkscape shat all over my photonegative when I used it to move the picture to the top of the page... its pdf import seems to be botched. it also ate a "finest" dimension rectangle I had
<whitequark>
I think my negatives printed directly from .ps didn't have this kind of defect
<whitequark>
DocScrutinizer05: my photoprocess is negative... obstacle would result in *missing* pads
<whitequark>
not joined
<whitequark>
anyhow. as I'm trying them the first time, I'm really delighted with performance of the mask and liquid tin
<whitequark>
mask is quite easy to work with and has nice thickness, I'd say 1/2 to 2/3 of factory made mask
<whitequark>
they claim that the same mask is used in real fabs, I can believe that
<DocScrutinizer05>
it looks preety awesome
<DocScrutinizer05>
pretty even
<whitequark>
it's completely even. the only difference with fab-made mask I can spot is lower thickness
<DocScrutinizer05>
how do you create solderstop mask?
<whitequark>
it's dry film solder mask, so almost same process as resist
<DocScrutinizer05>
niiiice
<DocScrutinizer05>
i was almost "don't cheat me, that's not a selfmade PCB!"
<DocScrutinizer05>
the magnet stick will ruin your PCB
<whitequark>
wat?
<whitequark>
oh, you mean mechanically scratch it
<DocScrutinizer05>
yes
<whitequark>
mm
<whitequark>
what if I make a "table" out of e.g. acrylic for pcb (or stir bar) to lie on?
<DocScrutinizer05>
I see......
<DocScrutinizer05>
before my inner eye....
<DocScrutinizer05>
a set of two plastic tubs
<DocScrutinizer05>
in one you milled a huge number of 1mm holes with your CNC
<DocScrutinizer05>
to the bottom
<DocScrutinizer05>
this sits on top of the other tub
<DocScrutinizer05>
in which your PCB sits
<whitequark>
yeah, same idea, I think I'll just keep it all in one container and use a sheet of acrylic (with holes as you suggest) to separate
<whitequark>
on tiny legs
<DocScrutinizer05>
and there's a tube from lower to upper tub that has foam in it, climbing up frpm the lower to the upper tub
<whitequark>
I place the pcb under the table, I place the stirrer on top of the table, voila
<DocScrutinizer05>
hmmmm
<whitequark>
(if I place pcb on top, it's going to either close up all the holes, or, if I flip it, the etchant will be distributed only thorugh the holes => very uneven)
<DocScrutinizer05>
I don't think this will "mix" or move in any way the liquid under the table
<whitequark>
it's easy to check. I just need to put a drop of dye under the table
<whitequark>
or, actually I have another idea
<DocScrutinizer05>
yeah, and then you got that mega expensive mega useless magnet stirrer
<whitequark>
a set of "legs" for PCB
<whitequark>
so you drop pcb into etchant "face" down and the legs keep it above the stirrer
<DocScrutinizer05>
hmm, that *might* work
<whitequark>
the legs would be just a set of acrylic blocks with a slot milled in, where the pcb goes
<whitequark>
should snap on just with friction
<DocScrutinizer05>
I'd still prefer aquarium equipment
<whitequark>
eh?
<DocScrutinizer05>
bubbles and tubes
<whitequark>
oh, you want to have two tubs and a pump
<whitequark>
well
<DocScrutinizer05>
yes, bubble pump
<whitequark>
there's some merit to bubbles for other etching process, namely CuCl2
<whitequark>
because oxygen restores the etchant to its virgin state
<DocScrutinizer05>
meh, any slow spinning motorized toy or tool plus a 1m of cord will do
<DocScrutinizer05>
to rock the etching tub
<DocScrutinizer05>
like once per 2..4 seconds. when you can adjust the speed of the rocking movement, all the better
<whitequark>
mmm
<whitequark>
and what to heat it with?
<DocScrutinizer05>
well, I'd preheat the bath and use some isolating measures to avoid it cooling down too quickly
<wpwrak>
you could use the mill. make a fire what burns below 660 C to heat the acid. use the mill's head to nudge the jar from time to time
<wpwrak>
if you do this .. don't forget to make a video and post it on youtube ;-)
<DocScrutinizer05>
or use blue or black tub and place it under a 500W light
<whitequark>
...
<wpwrak>
(heat) or get a bunch of low-ohm through-hole resistors and make an array. they can go pretty hot before they degrade.
<DocScrutinizer05>
right! just mount one side of your tub to your CNC spindle (don't turn spindle), then move Z axis up and down all you like
<DocScrutinizer05>
yeah, resistors is what most DIY dudes use
<DocScrutinizer05>
I'd just place the tub on an electro heating plate, place the heating plate on a board, place the board on the CNC mill and lift it at one endor even place a rod as "axis" under the board and press down one side of board with the CNC mill
<DocScrutinizer05>
doesn't need a single screw or welding or cutting up stuff
<DocScrutinizer05>
probably all you need is to be found in your kitchen already, except the CNC mill
<DocScrutinizer05>
a further 10 min and you're down to 15bucks
<whitequark>
wpwrak: stirrer: $130, working lungs: priceless
<DocScrutinizer05>
ooh, you already are
<whitequark>
yeah
<whitequark>
actually, maybe I should just give up and have a 110V strip in my house
<wpwrak>
you probably inhale more chloride when you open the tap ;-)
<whitequark>
wpwrak: afaik moscow ozonates water instead of chlorinating. either way, it doesn't even stink of cl2, and people are pretty good at detecting it in tens of ppms
<wpwrak>
just buy a car wash and have it refitted ;-)
<whitequark>
just buy a pcb fab :p
<DocScrutinizer05>
honestly the next simplest thing to "stirr" after rocking the tub is to have some tilted plane below the etching liquid surface and a bubblestone from aquarium under the lowest point of that tilted plane
<DocScrutinizer05>
and you even could use your PCB for the tilted plane, face down