Homebrew PCBs

There is a solder paste of some sort that is used on surface mount 
circuit boards.  Once that material hardens (dries, cures, or whatever 
it does) is is hard and conductive?  Could it be used to create a 
trace on a board, and then allow for soldering to it?

Chris

On Fri, 01 Jul 2005 16:48:24 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> There is a solder paste of some sort that is used on surface mount
> circuit boards.  Once that material hardens (dries, cures, or whatever
> it does) is is hard and conductive?  Could it be used to create a
> trace on a board, and then allow for soldering to it?
> Chris


solder paste for SMD is just solder "dust" and flux mixed to a paste. it  
must be soldered (melted) to work, and it would bead up with no copper  
under it.

There is conductive epoxy, and various conductive paints, some of which  
can be soldered to, but i believe it will be a number of years until it  
can be used.

For now i'll concentrate on EDM, as this is most promising.

ST

----- Original Message ----- 

From: "lcdpublishing" <lcdpublishing@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, July 01, 2005 3:48 PM
Subject: [Homebrew_PCBs] Hmm, another thought....


> There is a solder paste of some sort that is used on surface mount
> circuit boards.  Once that material hardens (dries, cures, or whatever
> it does) is is hard and conductive?  Could it be used to create a
> trace on a board, and then allow for soldering to it?

It won't adhere properly to the board surface and will just melt when it is 
heated and form little balls of solder.

Leon 



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I have to admit, the EDM process sounds very interesting.  I am 99% 
certain it could be easily adapted to any existing CNC router (or 
mill).  My fear is the power supply - I don't know enough yet about 
the electronics to make the power supply.  By chance, do you have 
that link to the information you and the other fellow were talking 
about a couple of days ago?  I guess I should look that over to see 
if it is basic enough for me to understand it.

Chris





--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
> On Fri, 01 Jul 2005 16:48:24 +0200, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> > There is a solder paste of some sort that is used on surface 
mount
> > circuit boards.  Once that material hardens (dries, cures, or 
whatever
> > it does) is is hard and conductive?  Could it be used to create a
> > trace on a board, and then allow for soldering to it?
> > Chris
> 
> 
> solder paste for SMD is just solder "dust" and flux mixed to a 
paste. it  
> must be soldered (melted) to work, and it would bead up with no 
copper  
> under it.
> 
> There is conductive epoxy, and various conductive paints, some of 
which  
> can be soldered to, but i believe it will be a number of years 
until it  

> can be used.
> 
> For now i'll concentrate on EDM, as this is most promising.
> 
> ST

I'm in the process of finalizing a power supply circuit designed
specifically for a light-duty CNC.  I should have a 1/2 decent diagram some
time today, I'll post something once I have something to show.  Right now
I'm in the process of making sure I have all the required components and
footprints in QCAD and drawing up those that are missing.

Robert
:)


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de lcdpublishing
Envoyé : juillet 1 2005 12:01
À : Homebrew_PCBs@yahoogroups.com
Objet : [Homebrew_PCBs] Re: Hmm, another thought....


I have to admit, the EDM process sounds very interesting.  I am 99% 
certain it could be easily adapted to any existing CNC router (or 
mill).  My fear is the power supply - I don't know enough yet about 
the electronics to make the power supply.  By chance, do you have 
that link to the information you and the other fellow were talking 
about a couple of days ago?  I guess I should look that over to see 
if it is basic enough for me to understand it.

Chris



Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

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On Fri, 01 Jul 2005 18:00:58 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> I have to admit, the EDM process sounds very interesting.  I am 99%
> certain it could be easily adapted to any existing CNC router (or
> mill).  My fear is the power supply - I don't know enough yet about
> the electronics to make the power supply.  By chance, do you have
> that link to the information you and the other fellow were talking
> about a couple of days ago?  I guess I should look that over to see
> if it is basic enough for me to understand it.
> Chris


<http://cscott.net/Projects/FabClass/final/edesign1.html#schematic>

ST

Thanks!

Will start the investigation into understanding.

Chris


--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:

> On Fri, 01 Jul 2005 18:00:58 +0200, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> > I have to admit, the EDM process sounds very interesting.  I am 99%
> > certain it could be easily adapted to any existing CNC router (or
> > mill).  My fear is the power supply - I don't know enough yet about
> > the electronics to make the power supply.  By chance, do you have
> > that link to the information you and the other fellow were talking
> > about a couple of days ago?  I guess I should look that over to see
> > if it is basic enough for me to understand it.
> > Chris
> 
> 
> <http://cscott.net/Projects/FabClass/final/edesign1.html#schematic>
> 
> ST

In a message dated 7/1/2005 9:49:57 A.M. Central Daylight Time,  
lcdpublishing@... writes:

Once  that material hardens (dries, cures, or whatever 
it does) is is hard and  conductive?  Could it be used to create a 
trace on a board, and then  allow for soldering to it?



Chris:  What part of "SOLDER paste" don't you  understand?  (LOL!!!)  The 
stuff is made of flux and thousands of  microscopic balls of SOLDER, would you 
believe!  It is "paste" so it can be  PAINTED on, and it MELTS and "solders 
things" (becomes shiny solder) which  hardens by COOLING to the non-molten state 
when the heat goes away.   SIMPLE!  No, it can NOT be used to "make traces", as 
it would not adhere to  the epoxy board, AND even if it did, it would MELT 
AWAY as soon as you tried to  solder a resistor to it!    (HOPE you don't get 
miffed by my  sense of humor?)


[Non-text portions of this message have been removed]

Jan, worry not, I very much enjoy a good sense of humor!

As I am completely new to electronics and circuit board making etc., 
I have a very open mind to consider anything and everything.  Some 
how a number of years back, I learned that one MUST ASK about 
everything,no matter how trivial.  In this case, I think it is 
pretty obvious I am looking for an alternative method of making 
circuit boards.  Nearly all, if not all, of the current processes 
are subtractive processes, I am just looking at it from a different 
point of view such as an additive process.

But, PLEASE, keep up the humor, it is a whole lot more fun 
investigating this sort of thing when we can share some grins!

Chris



--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
>  
> In a message dated 7/1/2005 9:49:57 A.M. Central Daylight Time,  
> lcdpublishing@y... writes:
> 
> Once  that material hardens (dries, cures, or whatever 
> it does) is is hard and  conductive?  Could it be used to create a 
> trace on a board, and then  allow for soldering to it?
> 
> 
> 
> Chris:  What part of "SOLDER paste" don't you  understand?  
(LOL!!!)  The 
> stuff is made of flux and thousands of  microscopic balls of 
SOLDER, would you 
> believe!  It is "paste" so it can be  PAINTED on, and it MELTS 
and "solders 
> things" (becomes shiny solder) which  hardens by COOLING to the 
non-molten state 
> when the heat goes away.   SIMPLE!  No, it can NOT be used 
to "make traces", as 
> it would not adhere to  the epoxy board, AND even if it did, it 
would MELT 
> AWAY as soon as you tried to  solder a resistor to it!    (HOPE 
you don't get 

> miffed by my  sense of humor?)
> 
> 
> [Non-text portions of this message have been removed]

Chris,

I think I can speak for everyone here when I say that we are ALL looking for
the easiest way to put them thar darned traces on a PC board.  :D

I'm also relatively new to the whole world of electronics, and I've also
tried to find 'that special thing nobody thought of yet'.  Well, I've
learned that pretty much everything has been tried.  The only things not
tested are with new technologies, and those are not readily available.
Etchant, transfer paper, silicone paper, toilet paper, direct transfer, CNC
routing, name it, someone here has tried it.

The nice thing is that the experimentation is an important step.  Just like
the drilling station I'm building, if I had bought the ready-made components
from Xylotex (like that cheater Willem  :P  ), I would not have learned
about center-tap transformers and unipolar/bipolar steppers.

I'm also welding my own frame, so I'm going to get back into that
technology.  Shop class is a few decades behind me now, again, I'll learn
more stuff (unlike that cheater Willem  :P  ).  I'll take longer to get it
running, but I'll have learned a lot from it.  As long as I come out cheaper
than that Sherline kit on Xylotex's site, I'm happy.  Somehow I doubt I'll
blow $1250 USD on this venture.

Did I mention Willem cheated?  He's gonna paint a Sherline blue and say he
built it...

Robert
:)


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de lcdpublishing
Envoyé : juillet 1 2005 17:11
À : Homebrew_PCBs@yahoogroups.com
Objet : [Homebrew_PCBs] Re: Hmm, another thought....


Jan, worry not, I very much enjoy a good sense of humor!

As I am completely new to electronics and circuit board making etc., 
I have a very open mind to consider anything and everything.  Some 
how a number of years back, I learned that one MUST ASK about 
everything,no matter how trivial.  In this case, I think it is 
pretty obvious I am looking for an alternative method of making 
circuit boards.  Nearly all, if not all, of the current processes 
are subtractive processes, I am just looking at it from a different 
point of view such as an additive process.

But, PLEASE, keep up the humor, it is a whole lot more fun 
investigating this sort of thing when we can share some grins!

Chris


Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
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LOL!

That is the same spirit I have with regard to this (electronics 
stuff), it's just fun to learn and experiment with.  However, having 
been in manufacturing for a very long time, I have learned all too 
often, that even though everything has been tried, sometimes it just 
needs a little different spin.  That is what is so great about 
groups like this, you throw out an idea, and see what has been tried 
and what has not been tried. Based on that information, reason out 
the facts from the fumbles, and if there is merit in the concept, 
take yet another approach at it.  

I too cheated with my CNC router, I bought the HobbyCNC stepper 
driver kit to drive the stepper motors, built the kit, had fun, and 
the machine ran.  However, between that and wanting to learn more, I 
have attached myself to a couple of electronics groups where there 
are enough kind people to walk me through some of the technicals.  
The mechanical tasks are still a little fun, but the electronics is 
really been a fun challenge for me - I just can't learn it fast 
enough.

Now I am also getting into pics - very cool devices.  Oddly, while 
reading through the information on them, I was exposed to a lot of 
basic circuits and the infromation provided really helped me a lot.  
Stepper motors for example, with the PICs, I am pretty confident I 
can write the software to drive the motors, and, with the 
information they provided in sample schematics, I almost (that's a 
big almost) think I can make a working circuit to drive either type 
of stepper.  

Even the most fundamental of circuits - gates. I have been 
programming for many years now. But when faced with the basic 
electronic gates, I just couldn't make sense of it.  It wasn't until 
I saw in the pic programming manual the direct relationship between 
using if-and-not-then commands to the gates that it all made sense 
to me. Even though I knew "Gates" in a software sense, I had a heck 
of a time understanding in an electronic sense.

I guess it's like everything else in life, knowledge about one 
thing, always seems to help with knowledge about something 
completely different.

This sure is a hoot though!






- In Homebrew_PCBs@yahoogroups.com, Robert Hedan <robert.hedan@v...> 
wrote:
> Chris,
> 
> I think I can speak for everyone here when I say that we are ALL 
looking for
> the easiest way to put them thar darned traces on a PC board.  :D
> 
> I'm also relatively new to the whole world of electronics, and 
I've also
> tried to find 'that special thing nobody thought of yet'.  Well, 
I've
> learned that pretty much everything has been tried.  The only 
things not
> tested are with new technologies, and those are not readily 
available.
> Etchant, transfer paper, silicone paper, toilet paper, direct 
transfer, CNC
> routing, name it, someone here has tried it.
> 
> The nice thing is that the experimentation is an important step.  
Just like
> the drilling station I'm building, if I had bought the ready-made 
components
> from Xylotex (like that cheater Willem  :P  ), I would not have 
learned
> about center-tap transformers and unipolar/bipolar steppers.
> 
> I'm also welding my own frame, so I'm going to get back into that
> technology.  Shop class is a few decades behind me now, again, 
I'll learn
> more stuff (unlike that cheater Willem  :P  ).  I'll take longer 
to get it
> running, but I'll have learned a lot from it.  As long as I come 
out cheaper
> than that Sherline kit on Xylotex's site, I'm happy.  Somehow I 
doubt I'll
> blow $1250 USD on this venture.
> 
> Did I mention Willem cheated?  He's gonna paint a Sherline blue 
and say he
> built it...
> 
> Robert
> :)
> 
> 
> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
[mailto:Homebrew_PCBs@yahoogroups.com] De
> la part de lcdpublishing
> Envoyé : juillet 1 2005 17:11
> À : Homebrew_PCBs@yahoogroups.com
> Objet : [Homebrew_PCBs] Re: Hmm, another thought....
> 
> 
> Jan, worry not, I very much enjoy a good sense of humor!
> 
> As I am completely new to electronics and circuit board making 
etc., 
> I have a very open mind to consider anything and everything.  Some 
> how a number of years back, I learned that one MUST ASK about 
> everything,no matter how trivial.  In this case, I think it is 
> pretty obvious I am looking for an alternative method of making 
> circuit boards.  Nearly all, if not all, of the current processes 
> are subtractive processes, I am just looking at it from a 
different 
> point of view such as an additive process.
> 
> But, PLEASE, keep up the humor, it is a whole lot more fun 
> investigating this sort of thing when we can share some grins!
> 
> Chris
> 
> 
> Be sure to visit the group home and check for new Links, Files, 
and Photos:

> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links

On Fri, 01 Jul 2005 23:23:41 +0200, Robert Hedan  
<robert.hedan@...> wrote:

>  The only things not
> tested are with new technologies, and those are not readily available.
> Etchant, transfer paper, silicone paper, toilet paper, direct transfer,  
> CNC
> routing, name it, someone here has tried it.

Only EDM, nobody has tried that apart from Curt. There seem to be no  
industrial applications to make PCBs that i can find.
It uses electricity, loads of it, makes fire, under water, and sparks and  
all, that is worth it all by itself, if it does produce a PCB in the  
process i don't mind either. You can't get much better than that. Even  
direct "copper" printing wouldn't be easier as blank PCB without copper is  
very hard to get, so either etch it off or pay more...

By the way, do you have any idea how Willem can build his machine so fast?  
He must have loads of experience... ;-)

ST

Stefan,

I looked over that schematic for the power supply - ouch, my head 
hurts from all the complexity of it.  I think I will have to wait a 
while before I have enough "Smarts" to understand it.  Now if I 
could do all that with a PIC I might have a fighting chance :-)




> Only EDM, nobody has tried that apart from Curt. There seem to be 
no  
> industrial applications to make PCBs that i can find.
> It uses electricity, loads of it, makes fire, under water, and 
sparks and  
> all, that is worth it all by itself, if it does produce a PCB in 
the  
> process i don't mind either. You can't get much better than that. 
Even  
> direct "copper" printing wouldn't be easier as blank PCB without 
copper is  
> very hard to get, so either etch it off or pay more...
> 
> By the way, do you have any idea how Willem can build his machine 
so fast?  

> He must have loads of experience... ;-)
> 
> ST

Well Stephan, 

It seems Willem has a mystery mentor, no idea who that could be...?  :)

I exxaggerratred (<-- wasn't sure on the spelling, so I put 2 of
everything), a bit, his machine isn't up yet.  He's also waiting on
different parts and components.  But by his emails, I'd say he's further
than I am.  That can't be hard, I don't have any 2 parts bolted together
yet.

I'm still at the 'all in my head, waiting on parts' stage.

Robert
:D


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http://groups.yahoo.com/group/Homebrew_PCBs

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I don't think the power supply has to be that complicated for this 
application. Many moons ago I used to own a Sincleir ZX81 computer. The 
Sinclair printer used special paper that was basically a thin coating of 
aliminium over a black background. The printer used a toothed belt to 
drag a metal stylus over the paper and wherever it needed to print a dot 
it applied a voltage to the stylus and vapourised the coating. Being a 
Sinclair product you can be sure the circuitry was very basic. Our needs 
are very similar, the only real difference is that the coating is thicker.

Normal EDM needs a carefully designed power supply because each spark 
removes a very small amount of material. We don't need that kind of 
accuracy so we can use a much higher energy density. I think that if we 
use a large capacitor and keep it charged through a simple linear power 
supply the sparking will be pretty much self regulating. All we need is 
a big beefy transistor to turn on the power when we want to remove 
material. The transistor does not need to switch for every spark, it is 
simply held on for as long as we need to remove copper. As a kid I used 
to cut patterns in aluminium foil using just a 12V car battery as the 
power source and it worked quite well.

Les


lcdpublishing wrote:

>Stefan,
>
>I looked over that schematic for the power supply - ouch, my head 
>hurts from all the complexity of it.  I think I will have to wait a 
>while before I have enough "Smarts" to understand it.  Now if I 
>could do all that with a PIC I might have a fighting chance :-)
>
>  
>

On Sat, 02 Jul 2005 10:22:38 +0200, Les Newell <lesnewell@...>  
wrote:

> I don't think the power supply has to be that complicated for this
> application. Many moons ago I used to own a Sincleir ZX81 computer. The
> Sinclair printer used special paper that was basically a thin coating of
> aliminium over a black background. The printer used a toothed belt to
> drag a metal stylus over the paper and wherever it needed to print a dot
> it applied a voltage to the stylus and vapourised the coating. Being a
> Sinclair product you can be sure the circuitry was very basic. Our needs
> are very similar, the only real difference is that the coating is  
> thicker.
> Normal EDM needs a carefully designed power supply because each spark
> removes a very small amount of material. We don't need that kind of
> accuracy so we can use a much higher energy density. I think that if we
> use a large capacitor and keep it charged through a simple linear power
> supply the sparking will be pretty much self regulating. All we need is
> a big beefy transistor to turn on the power when we want to remove
> material. The transistor does not need to switch for every spark, it is
> simply held on for as long as we need to remove copper. As a kid I used
> to cut patterns in aluminium foil using just a 12V car battery as the
> power source and it worked quite well.
> Les


It would probably work with a simpler PSU, yes.
However, you need to somehow limit the current at the electrode, or that  
big beefy transistor will get damaged at some point. If you use a resistor  
to do that the power wasted would be great (the guy who designed that  
complicated supply writes). Now if we use less voltage/current anyway it  
might well be acceptable.

The charge current could be pretty much self-regulating if you use a  
transformer supply, i agree. Remember that guy used a rectifer right off  
the mains.
I have two 50V transformers here that i could put in series, they can  
almost continuously supply the current i expect is needed for cutting PCBs.


I'll wait for Curt's operation parameters (what voltage and currents he  
uses for PCBs, and if he uses the boost cct at all), then i will think  
about how to build that supply, and which simplifications to make, if any.

I expect if you go really slow that "light duty" supply might even suffice  
for initial experiments.

ST

Les Newell wrote:

> Being a Sinclair product you can be sure the circuitry was very basic.

Yep.  I had one these. One sign of cheapness--the connector "cable" 
between the keyboard and the mainboard was actually wax paper with 
conductive spray paint. It worked fine until you tried to remove it, and 
discovered you just trashed your $99 computer :-)

-Johnathan

Oh, that kind of power supply.

"As a kid I used to cut patterns in aluminium foil using just a 12V car
battery as the 
power source and it worked quite well."

You do realize how much amperage comes out of a car battery?

Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Les Newell
Envoyé : juillet 2 2005 04:23
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: RE : [Homebrew_PCBs] Re: Hmm, another thought....


I don't think the power supply has to be that complicated for this 
application. Many moons ago I used to own a Sincleir ZX81 computer. The 
Sinclair printer used special paper that was basically a thin coating of 
aliminium over a black background. The printer used a toothed belt to 
drag a metal stylus over the paper and wherever it needed to print a dot 
it applied a voltage to the stylus and vapourised the coating. Being a 
Sinclair product you can be sure the circuitry was very basic. Our needs 
are very similar, the only real difference is that the coating is thicker.

Normal EDM needs a carefully designed power supply because each spark 
removes a very small amount of material. We don't need that kind of 
accuracy so we can use a much higher energy density. I think that if we 
use a large capacitor and keep it charged through a simple linear power 
supply the sparking will be pretty much self regulating. All we need is 
a big beefy transistor to turn on the power when we want to remove 
material. The transistor does not need to switch for every spark, it is 
simply held on for as long as we need to remove copper. As a kid I used 
to cut patterns in aluminium foil using just a 12V car battery as the 
power source and it worked quite well.

Les


lcdpublishing wrote:

>Stefan,
>
>I looked over that schematic for the power supply - ouch, my head
>hurts from all the complexity of it.  I think I will have to wait a 
>while before I have enough "Smarts" to understand it.  Now if I 
>could do all that with a PIC I might have a fighting chance :-)
>
>  
>



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Hi Robert,

Sorry for the late reply. Yes I know all about the current car batteries 
can supply, I still have the scars to prove it (NEVER work on a car 
wearing a metal watch strap). However in this case I was using fairly 
thin wires and they didn't get hot.

Les

Robert Hedan wrote:

>Oh, that kind of power supply.
>
>"As a kid I used to cut patterns in aluminium foil using just a 12V car
>battery as the 
>power source and it worked quite well."
>
>You do realize how much amperage comes out of a car battery?
>
>Robert
>:)
>
>  
>

On Sun, 03 Jul 2005 18:43:10 +0200, Les Newell <lesnewell@...>  
wrote:

> Hi Robert,
> Sorry for the late reply. Yes I know all about the current car batteries
> can supply, I still have the scars to prove it (NEVER work on a car
> wearing a metal watch strap). However in this case I was using fairly
> thin wires and they didn't get hot.
> Les


Probably the aluminum burned so fast there wasn't much time for current.
That thing with the watch sounds bad, will remember.

ST

Just a thought, why bother with building a power supply then?  Would a few
car batteries and a car battery charger do the trick?

You can get several working batteries at the scrap yard for a very cheap
price.  Battery chargers are readily available everywhere, I think even in
Australialand.  :P  Several batteries chained together will give you enough
amperage to do some serious cutting to the material, yourself and nearby
landscape.

Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Les Newell
Envoyé : juillet 3 2005 12:43
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: RE : RE : [Homebrew_PCBs] Re: Hmm, another thought....


Hi Robert,

Sorry for the late reply. Yes I know all about the current car batteries 
can supply, I still have the scars to prove it (NEVER work on a car 
wearing a metal watch strap). However in this case I was using fairly 
thin wires and they didn't get hot.

Les

Robert Hedan wrote:

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http://groups.yahoo.com/group/Homebrew_PCBs

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I took a vocational program through highschool.  One thing I will always
remember in auto mechanics is ALWAYS disconnect the positive terminal at the
battery (usually red, from all the blood splattering on it I guess).

I had the chance to see another student showing off his savoir faire at
revving an engine.  He got too close to the alternator connections with his
wrist watch.  The arc melted a passage through the center of his
fancy-schancy watch.  The jolt made him bash his perfect hair on the open
hood of the car and left a really pleasant pattern on his wrist.

He stopped showing off, wearing fancy jewelry and clothes to shop classes
after that.  We all had a good laugh at his expense.  Better him than us we
figured, couldn't have haven't to a more pleasant guy.

(...I conveniently do not mention how I caught fire in the welding classes
though...)

Robert
:D


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Stefan Trethan
Envoyé : juillet 3 2005 13:04
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: RE : RE : [Homebrew_PCBs] Re: Hmm, another thought....


Probably the aluminum burned so fast there wasn't much time for current.
That thing with the watch sounds bad, will remember.

ST


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On Sun, 03 Jul 2005 19:39:37 +0200, Robert Hedan  
<robert.hedan@...> wrote:

> One thing I will always
> remember in auto mechanics is ALWAYS disconnect the positive terminal at  
> the
> battery (usually red, from all the blood splattering on it I guess).


You know it is better to disconnect negative? If you start with positive  
you can easily short it to ground with the wrench while you undo the nut  
on the clamp. Also, there is often no obstructing rubber thingy on it.  
Open circuit is open circuit so that doesn't change anything.

As for using car batteries for EDM, you still need to limit electrode  
current and switch it on/off. You could probably replace the first part of  
the large supply schematic with them, but i think then you can just as  
well go all the way.

ST

Yeah, removing negative is much better, I posted the wrong terminal.  It
also doesn't generate sparks when you're fiddling with it.

Don't rely on which cable is grounded on the chassis though, there are
models that use positive ground just to keep people on their toes.

The best indicator of which cable is which is the small symbol near the
terminal. Don't trust the terminal rubber covers or cable colours 'cause
that can be replaced 'wrong' by a previous owner.

Robert
:)


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Stefan Trethan
Envoyé : juillet 3 2005 13:53
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: [Homebrew_PCBs] Re: Hmm, another thought....


You know it is better to disconnect negative? If you start with positive  
you can easily short it to ground with the wrench while you undo the nut  
on the clamp. Also, there is often no obstructing rubber thingy on it.  
Open circuit is open circuit so that doesn't change anything.

As for using car batteries for EDM, you still need to limit electrode  
current and switch it on/off. You could probably replace the first part of  
the large supply schematic with them, but i think then you can just as  
well go all the way.

ST


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http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
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While on the subject -

Keep in mind when doing jump starting this Winter, come cars are 
being switched over to 24 volt system (not positive it is 24Volts, 
but something higher than 12 volts).




--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan 
<robert.hedan@v...> wrote:
> Yeah, removing negative is much better, I posted the wrong 
terminal.  It
> also doesn't generate sparks when you're fiddling with it.
> 
> Don't rely on which cable is grounded on the chassis though, there 
are
> models that use positive ground just to keep people on their toes.
> 
> The best indicator of which cable is which is the small symbol 
near the
> terminal. Don't trust the terminal rubber covers or cable 
colours 'cause
> that can be replaced 'wrong' by a previous owner.
> 
> Robert
> :)
> 
> 
> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
[mailto:Homebrew_PCBs@yahoogroups.com] De
> la part de Stefan Trethan
> Envoyé : juillet 3 2005 13:53
> À : Homebrew_PCBs@yahoogroups.com
> Objet : Re: [Homebrew_PCBs] Re: Hmm, another thought....
> 
> 
> You know it is better to disconnect negative? If you start with 
positive  
> you can easily short it to ground with the wrench while you undo 
the nut  
> on the clamp. Also, there is often no obstructing rubber thingy on 
it.  
> Open circuit is open circuit so that doesn't change anything.
> 
> As for using car batteries for EDM, you still need to limit 
electrode  
> current and switch it on/off. You could probably replace the first 
part of  
> the large supply schematic with them, but i think then you can 
just as  
> well go all the way.
> 
> ST
> 
> 
> Be sure to visit the group home and check for new Links, Files, 
and Photos:

> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links

On Sunday 03 July 2005 01:39 pm, Robert Hedan wrote:
> I took a vocational program through highschool.  One thing I will always
> remember in auto mechanics is ALWAYS disconnect the positive terminal at
> the battery (usually red, from all the blood splattering on it I guess).

They were wrong.  You want to disconnect the _ground_ wire first,  and connect 
it last.

I speak from having managed a retail battery store for several years,  and 
changing out a LOT of them.

Hi Roy,

You missed a subsequent post where I said I made a 'mistrake', I meant the
negative.  Then I yapped on about the reasons why.

Robert
:D


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Roy J. Tellason
Envoyé : juillet 4 2005 08:52
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: [Homebrew_PCBs] Re: Hmm, another thought....


On Sunday 03 July 2005 01:39 pm, Robert Hedan wrote:
> I took a vocational program through highschool.  One thing I will 
> always remember in auto mechanics is ALWAYS disconnect the positive 
> terminal at the battery (usually red, from all the blood splattering 
> on it I guess).

They were wrong.  You want to disconnect the _ground_ wire first,  and
connect 
it last.

I speak from having managed a retail battery store for several years,  and 
changing out a LOT of them.








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On Monday 04 July 2005 09:55 am, Robert Hedan wrote:
> Hi Roy,
>
> You missed a subsequent post where I said I made a 'mistrake', I meant the
> negative.  Then I yapped on about the reasons why.
>
> Robert
>
> :D

No,  I just hadn't gotten to it yet...		:-)

> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> De la part de Roy J. Tellason
> Envoyé : juillet 4 2005 08:52
> À : Homebrew_PCBs@yahoogroups.com
> Objet : Re: [Homebrew_PCBs] Re: Hmm, another thought....
>
> On Sunday 03 July 2005 01:39 pm, Robert Hedan wrote:
> > I took a vocational program through highschool.  One thing I will
> > always remember in auto mechanics is ALWAYS disconnect the positive
> > terminal at the battery (usually red, from all the blood splattering
> > on it I guess).
>
> They were wrong.  You want to disconnect the _ground_ wire first,  and
> connect
> it last.
>
> I speak from having managed a retail battery store for several years,  and
> changing out a LOT of them.
>
>
>
>
>
>
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>