Homebrew PCBs

Hi all,

Having reached all the mechanical milestones for my CNC rig, and now
able to focus purely on the software, I thought I'd write it up and
stick up the photos.

Here it is: http://www.freenet.org.nz/cnc

A masterpiece of precision German/Japanese engineering it most certainly
is *not* :)

But it seems to be working well enough for my modest PCB requirements.

Enjoy!

-- 
Cheers
David

APPLAUSE!!!  Raaahhhhhh.....   :D

WTG dude!    So, are you putting a BMW or Acura logo on that?   :)

"Another thought again was to store CNC milling jobs on PIC16F877-based
smartcards, if I could compress the data well enough to fit into a
smartcard's meagre on-card memory."

Have you considered using 24C128, 256, 512 or 1024 for your smartcards?  You
can I2C them onto your pic.  That's what I might use for my project, not
decided yet.  I might dedicate a slave PIC 18Fxxxx to drive an SD card too.
The nice feature with the 18F is that it can support FAT16 (and FAT32 I
think), so that your SD cards can be browsed/editted from within Windoze.  A
mini disquette with the advantage of high speed and flexible storage size
(from 64M to 8G now I think, check specs).

I just need my motors.  (...Jeopardy tune...)

Any machine that does not explode, implode or catch fire by itself or
electrocute users is a successful project!

Robert
:)



A masterpiece of precision German/Japanese engineering it most certainly is
*not* :)

But it seems to be working well enough for my modest PCB requirements.

Enjoy!

-- 
Cheers
David


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On Mon, 27 Jun 2005 13:04:26 +0200, Robert Hedan  
<robert.hedan@...> wrote:

>
> Any machine that does not explode, implode or catch fire by itself or
> electrocute users is a successful project!
> Robert
>


Not really. It must drill holes in the right places without breaking the  
drill too.

ST

Robert Hedan wrote:
> Have you considered using 24C128, 256, 512 or 1024 for your smartcards?

Yep, but they're not as sexy as PIC16F877-based SilverCards with the
standard credit/ATM card form-factor

> You can I2C them onto your pic

Yep, played with that somewhat a while ago. I2C is a tad slow, but it
does work.

> I might dedicate a slave PIC 18Fxxxx to drive an SD card too.

That's a smart approach - run the CF-driving PIC as an I2C slave talking
to the master PIC. And, CF cards are smaller and store heaps more than
the 24Cxxx I2C ROMs inside the smartcards.

> The nice feature with the 18F is that it can support FAT16 (and FAT32 I
> think), so that your SD cards can be browsed/editted from within Windoze.

That's just too cool!
Have you got a link (or links) for that?
What's the physical connection between PIC and PC?
How big is the FATxx driver code on the PIC18F?

> A mini disquette with the advantage of high speed and flexible
> storage size (from 64M to 8G now I think, check specs).

Yikes - that'll store the milling schedules for heaps of cards!

Anyway, don't get me started - my wife may not appreciate it if I'm up
late at nights reimplementing the CNC controller around an ARM thumb
chip and porting Linux onto it, and driving the CNC via WLAN :P

-- 
Cheers
David

"Not really. It must drill holes in the right places without breaking the  
drill too.  - ST"

We have different standards.   :D


For those of you who are budget-challenged like me, I've been trying to find
an alternative to the $20+ metal cases sold locally.   Looking for a donour?
Old VCRs!!!

I'm about to gut out 4 VCRs that I've been stockpiling in a corner 'cause I
hate throwing away 'things'.    <--  grandmaster packrat

I'm going to check out the transformers for the drilling station and store
the circuits for future scavenging.  The cases make excellent control boxes,
they are already certified, rear power outlet, fuse, ventilation, bla bla
bla.  Just add a fan and slap in your own custom board, bolt on a face
plate, which is WAAAAY easier to do than an entire box, and you should have
a 1/2 decent box.

Robert
:)




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Stefan,

I bet if it used a chicken grill motor, you would fine
something good to say about it. :)

Give the guy his props, he did something we all are
still just talking about.

Myc



--- Stefan Trethan <stefan_trethan@...> wrote:

> On Mon, 27 Jun 2005 13:04:26 +0200, Robert Hedan  
> <robert.hedan@...> wrote:
> 
> >
> > Any machine that does not explode, implode or
> catch fire by itself or
> > electrocute users is a successful project!
> > Robert
> >
> 
> 
> Not really. It must drill holes in the right places
> without breaking the  
> drill too.
> 
> 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
> 
> 
>     Homebrew_PCBs-unsubscribe@yahoogroups.com
> 
>  
> 
> 
> 



		
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The chicken grill motor would have been a stronger substitute for the small
motor David used to roll the cord to lift the drill.

He also could of used the BBQ body as a safety box to protect people from
flying debris.

Robert
:D


		
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> The nice feature with the 18F is that it can support FAT16 (and FAT32 
> I think), so that your SD cards can be browsed/editted from within 
> Windoze.


"That's just too cool!"

- Isn't it?   :)



"Have you got a link (or links) for that?"

- Tadaaa!
<http://www.mikroelektronika.co.yu/english/product/books/picbasicbook/08.htm
>



"What's the physical connection between PIC and PC?"

CAUTION: SPAM ALERT!!!

- That can be anything you want.  You can use the PIC 18F family which now
integrates USB communication.  Mécanique has just released Easy HID which
generates default software template for the PIC and PC through a GUI
interface.  Check it out:
<http://www.mecanique.co.uk/products/usb/easyhid.html>

- But wait, that's not all, you also get access to a budget-priced unique
Vendor ID for your USB product.  USB.ORG has strict compliance requirements
before assigning a Vendor ID which costs between $1500 to $2500.  You can
avoid all that and use Mécanique's Vendor ID and get 10, that's right, -->
TEN <-- Product IDs for the low introductory price of £29.95.
http://www.mecanique.co.uk/products/usb/pid.html



"How big is the FATxx driver code on the PIC18F?"

- Check out the stuff I've uploaded in the Files section, USB folder.  I've
uploaded 2 folders that I generated using Easy HID.



So with a slave PIC 18F4550 you can interface with the PC via USB and manage
a smart card all at the same time.

If you will not market your product, you can leave the default Vendor and
Product ID generated in the code.

Robert
:)


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

- But wait, that's not all, you also get access to a budget-priced unique
Vendor ID for your USB product.  USB.ORG has strict compliance requirements
before assigning a Vendor ID which costs between $1500 to $2500.  You can
avoid all that and use Mécanique's Vendor ID and get 10, that's right,
--> TEN <-- Product IDs for the low introductory price of £29.95.
http://www.mecanique.co.uk/products/usb/pid.html


£29.95 = $54USD
<http://finance.yahoo.com/currency/convert?amt=29.95&from=GBP&to=USD&submit=
Convert>


Robert
:)



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On Mon, 27 Jun 2005 16:54:03 +0200, Mycroft2152 <mycroft2152@...>  
wrote:

> Stefan,
> I bet if it used a chicken grill motor, you would fine
> something good to say about it.
> Give the guy his props, he did something we all are
> still just talking about.
> Myc


While it is true he did more in terms of cnc than myself, i see some  
serious drawbacks too, and if time is put into it i would avoid any  
obvious problems.
The WD40 can says it all.

Also, i didn't quite understand the pic/memory card (?) discussion here,  
not knowing what on earth one would need that for on a CNC. It sounds all  
kind of like Software guys gone CNC which is why i don't really  
participate in the current CNC discussions as it seems a bit removed from  
real world requirements right now. I hope the discussion will turn towards  
mechanically sound, straightforward designs (directly PC controlled) again  
in the future as this is what i'd be most interested in. If it doesn't,  
i'll simply continue to mostly ignore it.

By the way i indeed found another, chicken grill motor today. Had a good  
laugh thinking what i can use it for to annoy you ;-).

ST

Hi,


What else could one use as air pump for bubble agitation?
Because i had so little bubble holes bubbling i connected a rubber ball  
(with one-way valves) instead of the pump.
Surprisingly the bubbler hose works really well if i compress the ball by  
hand. The small aquarium pump just doesn't have enough pressure or flow to  
operate enough of the holes to create a even curtain.


Now i'm looking for a larger pump. There are cheap piston compressors, but  
because i want to run the thing closed loop (take the air from inside the  
etching tank) they are unsuitable with their aluminum cylinder.
I thought about buying a 10 piece lot of small pumps, and connecting them  
together (maybe some series some parallel) to increase the airflow. You  
think that would work?

Any other ideas welcome, i just can't come up with a solution.


ST

On Mon, 27 Jun 2005 16:51:28 +0200, Robert Hedan  
<robert.hedan@...> wrote:

>
> For those of you who are budget-challenged like me, I've been trying to  
> find
> an alternative to the $20+ metal cases sold locally.   Looking for a  
> donour?
> Old VCRs!!!


I've put a few of those aside too thinking the same thing, as well as some  
satellite receivers (smaller cases).
Appear to be pretty nice, and if the PSU is still working you even get  
some voltages filtered and regulated.
But i've yet to find a project to put in one (most projects did go  
directly begind front plates mounted on the bakc of the bench in kind of a  
modular system. The CNC controller is a hot candidate for putting inside a  
VCR/SAT box tho...

Note that all i've seen have a metal lid, but a 2-prong plug, so you'd  
either need to safety isolate everything or ground the chassis.


ST

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

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, June 27, 2005 4:53 PM
Subject: [Homebrew_PCBs] air pumps


> Hi,
>
>
> What else could one use as air pump for bubble agitation?
> Because i had so little bubble holes bubbling i connected a rubber ball
> (with one-way valves) instead of the pump.
> Surprisingly the bubbler hose works really well if i compress the ball by
> hand. The small aquarium pump just doesn't have enough pressure or flow to
> operate enough of the holes to create a even curtain.
>
>
> Now i'm looking for a larger pump. There are cheap piston compressors, but
> because i want to run the thing closed loop (take the air from inside the
> etching tank) they are unsuitable with their aluminum cylinder.
> I thought about buying a 10 piece lot of small pumps, and connecting them
> together (maybe some series some parallel) to increase the airflow. You
> think that would work?
>
> Any other ideas welcome, i just can't come up with a solution.

If it's only for occasional use, why not pump up an old car wheel and tyre. 
That should have plenty of pressure and capacity to etch a few boards. Can't 
be a closed system, of course.

Leon 



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On Mon, 27 Jun 2005 18:11:47 +0200, Leon Heller  
<leon.heller@...> wrote:

>
> If it's only for occasional use, why not pump up an old car wheel and  
> tyre.
> That should have plenty of pressure and capacity to etch a few boards.  
> Can't
> be a closed system, of course.
> Leon


closed system is main requirement or i would use shop air. I'm not  
spreading any more etchant mist than needed.

thanks

ST

Old computer cases are a wonderful and very cheap device too!



--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan 
<robert.hedan@v...> wrote:
> "Not really. It must drill holes in the right places without 
breaking the  
> drill too.  - ST"
> 
> We have different standards.   :D
> 
> 
> For those of you who are budget-challenged like me, I've been 
trying to find
> an alternative to the $20+ metal cases sold locally.   Looking for 
a donour?
> Old VCRs!!!
> 
> I'm about to gut out 4 VCRs that I've been stockpiling in a 
corner 'cause I
> hate throwing away 'things'.    <--  grandmaster packrat
> 
> I'm going to check out the transformers for the drilling station 
and store
> the circuits for future scavenging.  The cases make excellent 
control boxes,
> they are already certified, rear power outlet, fuse, ventilation, 
bla bla
> bla.  Just add a fan and slap in your own custom board, bolt on a 
face
> plate, which is WAAAAY easier to do than an entire box, and you 
should have
> a 1/2 decent box.
> 
> Robert
> :)
> 
> 
> 
> 
> 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

Forgive me, I am sure this has already been discussed but...

I don't know if air is required or not so keep that in mind.

From the little I have read so far, you need agitation, not actually 
air.  Air is just a way of moving the liquid around for the 
agitation. It also seems that most of the rigs for this are vertical 
to accomodate the rising air.

Would this work...

A shallow, flat tank, sitting horizontal.  Across the center is a 
pivot point and at one end a very small, slow spinning gear motor 
with a cam on it. The cam rubs against the bottom causing the tank 
to rock back and forth.  This would cause the liguid to move back 
and forth in a wave motion.

Adding a couple of standoffs to the circuit board before putting it 
in the solution could be used to keep the board off the bottom of 
the tank.  

If nothing else, it might be relaxing to watch it rock back and 
forth :-)

Chris

On Mon, 27 Jun 2005 18:36:17 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> Forgive me, I am sure this has already been discussed but...
> I don't know if air is required or not so keep that in mind.
> From the little I have read so far, you need agitation, not actually
> air.  Air is just a way of moving the liquid around for the
> agitation. It also seems that most of the rigs for this are vertical
> to accomodate the rising air.
> Would this work...
> A shallow, flat tank, sitting horizontal.  Across the center is a
> pivot point and at one end a very small, slow spinning gear motor
> with a cam on it. The cam rubs against the bottom causing the tank
> to rock back and forth.  This would cause the liguid to move back
> and forth in a wave motion.
> Adding a couple of standoffs to the circuit board before putting it
> in the solution could be used to keep the board off the bottom of
> the tank.
> If nothing else, it might be relaxing to watch it rock back and
> forth
> Chris


been there, done that, results uneven esp. 2-sided difficult.

thanks anyway.

ST

--- Stefan Trethan <stefan_trethan@...> wrote:

> 
> By the way i indeed found another, chicken grill
> motor today. Had a good  
> laugh thinking what i can use it for to annoy you
> ;-).
> 

Hi Stefan,

I have the same reaction, I see a chicken grill motor
and laugh thinking about you and your many uses for
this indispnsible little device.

Can you use it to etch pcb's? Maybe use it to rotate
pcbs's in a spray etcher?

Just trying to help, see you've got me thinking about
it now.....

Myc

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

From: "lcdpublishing" <lcdpublishing@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, June 27, 2005 5:36 PM
Subject: [Homebrew_PCBs] Re: air pumps


> Forgive me, I am sure this has already been discussed but...
>
> I don't know if air is required or not so keep that in mind.
>
>>From the little I have read so far, you need agitation, not actually
> air.  Air is just a way of moving the liquid around for the
> agitation. It also seems that most of the rigs for this are vertical
> to accomodate the rising air.
>
> Would this work...
>
> A shallow, flat tank, sitting horizontal.  Across the center is a
> pivot point and at one end a very small, slow spinning gear motor
> with a cam on it. The cam rubs against the bottom causing the tank
> to rock back and forth.  This would cause the liguid to move back
> and forth in a wave motion.
>
> Adding a couple of standoffs to the circuit board before putting it
> in the solution could be used to keep the board off the bottom of
> the tank.
>
> If nothing else, it might be relaxing to watch it rock back and
> forth :-)

I do the same thing, manually. There was design for something like your 
suggested tank in the ARRL Handbook a few years ago. The etchant was kept 
hot with a heat lamp over the tank.

Leon 

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"Also, i didn't quite understand the pic/memory card (?) discussion here,  
not knowing what on earth one would need that for on a CNC. It sounds all  
kind of like Software guys gone CNC...  - ST"


We are looking at alternative solutions.  Some of us like myself will use
PC-side software (Mach 2 in my case) to drive the drilling station via
parallel cable.  You can't assume everyone else will take the same approach.

Some have chosen a different route; converting a JPEG of the circuit into
data.  This data does not have to be converted each and every time, I'm
assuming it could be a lengthy process and/or tedious.

The easy solution is to download the data onto PIC-side memory only once and
access it from there.  That leaves the PC available to use by other members
of the family; I have a multi-PC network, that isn't a problem for me.

He was originally thinking of using the PIC RAM or a compact flash card.  I
suggested using a card edge connector with a memory chip on a tiny circuit
(Nintendo-cartridge style).  The 24Cxxxx series of memory chips are easy to
use and very cheap; much more so than the smart card.  Here's one I threw
together to hold a PIC 16F628 (exclusively for I/Os requested from an I2C
network of PICs) and a 24Cxxxx memory chip:
<http://www.xavierkamial.com/Videos/External%20memory%20card.jpg>

It all boils down to alternative solutions to the same dilemma; how to drill
relatively precise holes, possibly in a repetitive manner if need be.  Some
of us are designing the basic system; a drilling station.  Some of us are
taking the extra step and designing a light CNC machine; able to route,
drill, change tools automatically (I'm working on something  :)  ), vacuum
dust, monitor quality, trackpin insertion, solder paste application, pick 'n
place and who knows what other process.

Some of us are limitted by budget, skill and tools.  We are bound to have
solutions of varying degrees of technology.  Diversity, that's what I like
in all the ideas brought forth.  See, that "drill raised by a string on a
shaft" idea, I hadn't even thought of that.  It's a darn garage door opener,
all he needs is a remote control.

Robert
:)


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David, I just wanted to say that in any group there is a lot of talk 
about how to do thing "right" or "best" and sometimes it is nice to 
see how to do something "just so it works"

Congrats on getting the thing up and running.

One question: What are the trays rolling or sliding on?

Robert Hedan wrote:
> The chicken grill motor would have been a stronger substitute for the small
> motor David used to roll the cord to lift the drill.

Not a stepper motor though, so not the same precise control over drill
height :P

> 
> He also could of used the BBQ body as a safety box to protect people from
> flying debris.
> 
> Robert
> :D
> 
> 
> 		
> __________________________________ 
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> 
> 
> 
>  
> 
> 
> 
> 
> 
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> 
> 
> 
>  
> 
> 
> 
> 
> 

-- 
Cheers
David

Robert Hedan wrote:
>>The nice feature with the 18F is that it can support FAT16 (and FAT32 
>>I think), so that your SD cards can be browsed/editted from within 
>>Windoze.

> "Have you got a link (or links) for that?"
> 
> - Tadaaa!
> <http://www.mikroelektronika.co.yu/english/product/books/picbasicbook/08.htm

Thanks

> "What's the physical connection between PIC and PC?"
> 
> CAUTION: SPAM ALERT!!!
> 
> - That can be anything you want.  You can use the PIC 18F family which now
> integrates USB communication.  M\ufffdcanique has just released Easy HID which
> generates default software template for the PIC and PC through a GUI
> interface.  Check it out:
> <http://www.mecanique.co.uk/products/usb/easyhid.html>
> 
> - But wait, that's not all, you also get access to a budget-priced unique
> Vendor ID for your USB product.  USB.ORG has strict compliance requirements
> before assigning a Vendor ID which costs between $1500 to $2500.  You can
> avoid all that and use M\ufffdcanique's Vendor ID and get 10, that's right, -->
> TEN <-- Product IDs for the low introductory price of \ufffd29.95.
> http://www.mecanique.co.uk/products/usb/pid.html

Hmm, feels easier to put up a SLIP driver and a cut-down TCP/IP stack,
these already exist for 18F, and address the rig via an IP address. This
appeals to me more as a Linux guy.

Or, even easier, I could just extend my existing serial control protocol
to allow for download/storage/management/execution of milling schedules.
And if I want it to look like a filesystem to the host PC, I can always
wrap it in FUSE.

A respected friend/mentor is always saying "do the simplest thing that
could possibly work".

> "How big is the FATxx driver code on the PIC18F?"
> 
> - Check out the stuff I've uploaded in the Files section, USB folder.  I've
> uploaded 2 folders that I generated using Easy HID.
> 
> 
> 
> So with a slave PIC 18F4550 you can interface with the PC via USB and manage
> a smart card all at the same time.
> 
> If you will not market your product, you can leave the default Vendor and
> Product ID generated in the code.
> 
> Robert
> :)
> 
> 
> 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:
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> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

-- 
Cheers
David

Stefan Trethan wrote:
> While it is true he did more in terms of cnc than myself, i see some  
> serious drawbacks too, and if time is put into it i would avoid any  
> obvious problems.
> The WD40 can says it all.

If you've got any constructive suggestions for evolving the mechanical
design to something better, using only easily-available materials and
non-specialised tools/techniques, I'm all ears.

> Also, i didn't quite understand the pic/memory card (?) discussion here,  
> not knowing what on earth one would need that for on a CNC.

Need and convenience are two different things.

Makes sense to me for a CNC to have milling jobs stored on it, which can
be selected via a keypad and LCD interface. That kind of stuff is way
easier for me than the mech work.

> It sounds all  
> kind of like Software guys gone CNC

You noticed? :P

> I hope the discussion will turn towards  
> mechanically sound, straightforward designs (directly PC controlled) again  
> in the future as this is what i'd be most interested in.

The floor is yours. We're listening. Refer first paragraph of my reply.

-- 
Cheers
David

Stefan Trethan wrote:
> On Mon, 27 Jun 2005 18:11:47 +0200, Leon Heller  
> <leon.heller@...> wrote:
> 
> 
>>If it's only for occasional use, why not pump up an old car wheel and  
>>tyre.
>>That should have plenty of pressure and capacity to etch a few boards.  
>>Can't
>>be a closed system, of course.
>>Leon
> 
> 
> 
> closed system is main requirement or i would use shop air. I'm not  
> spreading any more etchant mist than needed.
> 
> thanks
> 
> ST
> 

I've never notice actual mist from bubbling etchant. However, if your 
trying to minimize gaseous fumes then a sealed system is the only 
option. Bubbles do create a lot of splashes and fine droplets that will 
travel a surprising long distance. If you can sufficiently cover the 
etchant so that droplets run back in to the tank, then that should solve 
most of your problems. My spray etcher does creates a heck of lot of 
mist and it is not "closed loop". There is an air bubbler in the spray 
chamber for aerating the etchant and I get virtually no etchant escaping 
even though the "air" is continuously escaping. By far most etchant 
escapes from spillage as I withdraw the PCB. The trick was to install a 
double walled opening. The theory is that mist will immediately settle 
upon contact with a surface. So you all you have to do it make sure the 
mist is very likely to contact a surface.

Now you won't be limited to corrosion resistant air pumps. And even 
aquarium pumps don't like acid. They usually have a zinc screw 
connecting the diaphragm to the oscillating arm, and I've found the 
valve flap material breaks down too. I can guarantee you'll get more 
problems then you'll solve trying to recirculate the etchant chamber gases.

Adam

On Tue, 28 Jun 2005 00:17:05 +0200, David McNab <david@...>  
wrote:

>
> If you've got any constructive suggestions for evolving the mechanical
> design to something better, using only easily-available materials and
> non-specialised tools/techniques, I'm all ears.
>

Al on Al bearing will not last, and WD40 will not help 'cause the drilling  
dust will turn it into grinding paste. The electronics are just barely  
moving it, but you kow that already.
I hope the drill is steady enough on this mount not to break drills. I  
hope the X/Y is precise enough height-wise to mill.


>> Also, i didn't quite understand the pic/memory card (?) discussion here,
>> not knowing what on earth one would need that for on a CNC.
> Need and convenience are two different things.
> Makes sense to me for a CNC to have milling jobs stored on it, which can
> be selected via a keypad and LCD interface. That kind of stuff is way
> easier for me than the mech work.
>

If you are Software guys, then why on earth would you even suggest JPEG  
for storing a layout. One would assume you know better as software guys  
not to use a lossy compression meant for photos on line art/ B&W. The  
_only_ image format that would make sense is a lossless one where you can  
put in 2 color and get out 2 color with sharp edges, be it GIF or PNG or a  
non-compressing format like BPM.

Why would anyone want to use a picture as basis for the data when there  
are formats meant for that which the CNC coftware can output? Especially  
with the simplcity of drill files it seems pretty crazy to detect them  
holes from a picture.



>> It sounds all
>> kind of like Software guys gone CNC
> You noticed?
>

I really think you are going a very peculiar route with that CNC.  
Nonetheless i wish you only the best of luck. I just hope it doesn't turn  
out like those fancy, but not functional, webpages that are nowadays made  
by some software guys.

ST

On Tue, 28 Jun 2005 00:50:28 +0200, Adam Seychell  
<a_seychell@...> wrote:

>
> I've never notice actual mist from bubbling etchant. However, if your
> trying to minimize gaseous fumes then a sealed system is the only
> option. Bubbles do create a lot of splashes and fine droplets that will
> travel a surprising long distance. If you can sufficiently cover the
> etchant so that droplets run back in to the tank, then that should solve
> most of your problems. My spray etcher does creates a heck of lot of
> mist and it is not "closed loop". There is an air bubbler in the spray
> chamber for aerating the etchant and I get virtually no etchant escaping
> even though the "air" is continuously escaping. By far most etchant
> escapes from spillage as I withdraw the PCB. The trick was to install a
> double walled opening. The theory is that mist will immediately settle
> upon contact with a surface. So you all you have to do it make sure the
> mist is very likely to contact a surface.
> Now you won't be limited to corrosion resistant air pumps. And even
> aquarium pumps don't like acid. They usually have a zinc screw
> connecting the diaphragm to the oscillating arm, and I've found the
> valve flap material breaks down too. I can guarantee you'll get more
> problems then you'll solve trying to recirculate the etchant chamber  
> gases.
> Adam


well, i have taken the pump apart, cleaned it, and you were right the  
liquid did affect it, it "sticks" the valve flaps. They are silicone so i  
wouldn't worry and the screw was protected with silicone too.


In a way i want to run it open loop and avoid all the problems, but in a  
way i also want to avoid the fumes. If there is enough droplets in the air  
to clog the pump it will corrode my tools. My tank is more or less  
airtight, with a rubber seal.


Now the pump works better again, and would even be strong enough to power  
the bubbler (tho i can use shop air open loop).

What i wonder is if there is a way to make sort of a filter, maybe a  
bottle with cotton wool in it or something like that to catch the  
droplets. Maybe it would help to soak it in some weak NaOh, and let dry,  
to neutralize and droplets.

What do you think?

ST

James Newton wrote:
> David, I just wanted to say that in any group there is a lot of talk 
> about how to do thing "right" or "best" and sometimes it is nice to 
> see how to do something "just so it works"

Ack on that!

> Congrats on getting the thing up and running.

Thanks!

> One question: What are the trays rolling or sliding on?

Refer earlier post titled "CNC mill X-Y tracks". Aluminium angle riding
on aluminium angle, temporarily lubricated by WD40 (CRC).

I'm told in no uncertain terms that this is very not ideal, so when I
get the milling software working I'll rework the bottom tracks and add
strips of cutting-board plastic (thanks for earlier suggestions to look
in a $2 shop).

-- 
Cheers
David

Stefan Trethan wrote:

> On Tue, 28 Jun 2005 00:50:28 +0200, Adam Seychell  
> <a_seychell@...> wrote:
> 
> 
>>I've never notice actual mist from bubbling etchant. However, if your
>>trying to minimize gaseous fumes then a sealed system is the only
>>option. Bubbles do create a lot of splashes and fine droplets that will
>>travel a surprising long distance. If you can sufficiently cover the
>>etchant so that droplets run back in to the tank, then that should solve
>>most of your problems. My spray etcher does creates a heck of lot of
>>mist and it is not "closed loop". There is an air bubbler in the spray
>>chamber for aerating the etchant and I get virtually no etchant escaping
>>even though the "air" is continuously escaping. By far most etchant
>>escapes from spillage as I withdraw the PCB. The trick was to install a
>>double walled opening. The theory is that mist will immediately settle
>>upon contact with a surface. So you all you have to do it make sure the
>>mist is very likely to contact a surface.
>>Now you won't be limited to corrosion resistant air pumps. And even
>>aquarium pumps don't like acid. They usually have a zinc screw
>>connecting the diaphragm to the oscillating arm, and I've found the
>>valve flap material breaks down too. I can guarantee you'll get more
>>problems then you'll solve trying to recirculate the etchant chamber  
>>gases.
>>Adam
> 
> 
> 
> well, i have taken the pump apart, cleaned it, and you were right the  
> liquid did affect it, it "sticks" the valve flaps. They are silicone so i  
> wouldn't worry and the screw was protected with silicone too.
> 
> 
> In a way i want to run it open loop and avoid all the problems, but in a  
> way i also want to avoid the fumes. If there is enough droplets in the air  
> to clog the pump it will corrode my tools. My tank is more or less  
> airtight, with a rubber seal.
> 
> 
> Now the pump works better again, and would even be strong enough to power  
> the bubbler (tho i can use shop air open loop).
> 
> What i wonder is if there is a way to make sort of a filter, maybe a  
> bottle with cotton wool in it or something like that to catch the  
> droplets. Maybe it would help to soak it in some weak NaOh, and let dry,  
> to neutralize and droplets.
> 
> What do you think?
> 
> ST

If tools are corroding several meters away then it must be HCl gas, 
rather than splashes or wouldn't travel so far. What etchant are you 
running ? There should be almost no oder from a open jar of etchant at 
room temp. Keep HCl concentration under 2 Molar. If your stuck with a 
fuming etchant,(i.e an open container of etchant will corrode steel in 
its vicinity) then you have to keep it sealed. All I can recommend is 
keep the place well ventilated during etching, and seal air tight when 
not in use. You must of course also eliminate exterior splashes due to 
bubbles.

On Tue, 28 Jun 2005 13:57:56 +0200, Adam Seychell  
<a_seychell@...> wrote:

>
> If tools are corroding several meters away then it must be HCl gas,
> rather than splashes or wouldn't travel so far. What etchant are you
> running ? There should be almost no oder from a open jar of etchant at
> room temp. Keep HCl concentration under 2 Molar. If your stuck with a
> fuming etchant,(i.e an open container of etchant will corrode steel in
> its vicinity) then you have to keep it sealed. All I can recommend is
> keep the place well ventilated during etching, and seal air tight when
> not in use. You must of course also eliminate exterior splashes due to
> bubbles.


I use CuCl, but maybe my fumes fear needs explaining:

Years ago, when i still used HCl H2O2 Tray etching with way too high  
concentrations of all, i forgot a small etchant tray on a workbench with a  
nice new set of drills (and other stuff) about half a meter away. After  
several days (maybe even weeks) when i discovered the situation the drills  
did not look new any more :-(.

This was a open tray, and i haven't discovered problems with my etcher  
(rubber seal, but not really airtight just a lid) so far. There is no odor  
with the current etcher when it is just standing around, but when the pump  
is pumping like 100l/h of air through those 100l will have some fumes in  
them and will definitely leave the etcher.

On another occassion i discovered it is not good to store steel spray cans  
near a closed PE bottle of HCl, the can seam started rusting. This was  
after months.


I will put a few experimental nails around the etcher, and try to put all  
tools further away, then it will be fine to run open-loop i hope. When any  
of the nails start to rust i must do something.

thanks

ST

hi,


Does anyone use those milling bits to cut out boards? The ones with the  
diamond pattern all over the business end which look otherwise just like  
PCB drills.

If this works well then i can wait until i have my CNC and use the  
sheetmetal shears until then, otherwise i must make a shaft for that  
carbide saw somehow. Pretty hard to do without lathe and the last attempt  
was a bit too much out of round.

I'm worried about the huge amount of material that is milled away,  
wouldn't that dull the bit quickly?

ST

Metal corrosion as a result of etchant gas emanations:

I have a overhead fan for a kitchen stove waiting for this very purpose.  I
know it will corrode, but at least it will be the only thing that will
corrode.  I bought it on liquidation for $40.

I can use the ventilation area for spray painting and all sorts of stuff,
and it's real easy to install.

Robert
:)


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

David McNab wrote:
> If you've got any constructive suggestions for evolving the mechanical
> design to something better, using only easily-available materials and
> non-specialised tools/techniques, I'm all ears.

Unsure of what you consider easily available but again
I'd recommend one of the many tooling suppliers.  The
latest Enco flyer has their perpetual "sale" on drill
rod, cored bronze rounds, and acme threaded rod and nuts.
Depending upon scale I'd hazard the bill of materials
for a basic XY set of ways to set you back about $10-30.
No affiliation with Enco other than they get far too
much of my money.

I don't recall if you have access to machine tools but
for such a project even use of a small lathe will not
only make the result more accurate but easier to
accomplish.

-- 
uhmgawa@...        www.gnu.org

Hi Stefan,

Yes I use them regularly. They last a suprisingly long time. If you are 
only cutting through one thickness of board you can feed at quite a high 
rate as well. You do need a reasonable spindle speed. Mine is about 
10000RPM which is probably a little slow. I don't know how well a Dremel 
type tool will handle the side loads though. If the spindle chatters in 
slack bearings you are likely to break the cutter.

BTW use good extraction because it does produce quite a lot of dust.

Les

Stefan Trethan wrote:

>hi,
>
>
>Does anyone use those milling bits to cut out boards? The ones with the  
>diamond pattern all over the business end which look otherwise just like  
>PCB drills.
>
>If this works well then i can wait until i have my CNC and use the  
>sheetmetal shears until then, otherwise i must make a shaft for that  
>carbide saw somehow. Pretty hard to do without lathe and the last attempt  
>was a bit too much out of round.
>
>I'm worried about the huge amount of material that is milled away,  
>wouldn't that dull the bit quickly?
>
>ST
>  
>

On Tue, 28 Jun 2005 22:09:45 +0200, Les Newell <lesnewell@...>  
wrote:

> Hi Stefan,
> Yes I use them regularly. They last a suprisingly long time. If you are
> only cutting through one thickness of board you can feed at quite a high
> rate as well. You do need a reasonable spindle speed. Mine is about
> 10000RPM which is probably a little slow. I don't know how well a Dremel
> type tool will handle the side loads though. If the spindle chatters in
> slack bearings you are likely to break the cutter.
> BTW use good extraction because it does produce quite a lot of dust.
> Les


I hope the proxxon IB-E will do (15k), it has ok bearings. if not i've got  
to make a spindle...

Thanks for the been there doing that information.


Plan on using a dedicated shop vac for extraction.

ST

Stefan Trethan wrote:
> On Tue, 28 Jun 2005 13:57:56 +0200, Adam Seychell  
> <a_seychell@...> wrote:
> 
> 
>>If tools are corroding several meters away then it must be HCl gas,
>>rather than splashes or wouldn't travel so far. What etchant are you
>>running ? There should be almost no oder from a open jar of etchant at
>>room temp. Keep HCl concentration under 2 Molar. If your stuck with a
>>fuming etchant,(i.e an open container of etchant will corrode steel in
>>its vicinity) then you have to keep it sealed. All I can recommend is
>>keep the place well ventilated during etching, and seal air tight when
>>not in use. You must of course also eliminate exterior splashes due to
>>bubbles.
> 
> 
> 
> I use CuCl, but maybe my fumes fear needs explaining:
> 
> Years ago, when i still used HCl H2O2 Tray etching with way too high  
> concentrations of all, i forgot a small etchant tray on a workbench with a  
> nice new set of drills (and other stuff) about half a meter away. After  
> several days (maybe even weeks) when i discovered the situation the drills  
> did not look new any more :-(.
> 
> This was a open tray, and i haven't discovered problems with my etcher  
> (rubber seal, but not really airtight just a lid) so far. There is no odor  
> with the current etcher when it is just standing around, but when the pump  
> is pumping like 100l/h of air through those 100l will have some fumes in  
> them and will definitely leave the etcher.

> On another occassion i discovered it is not good to store steel spray cans  
> near a closed PE bottle of HCl, the can seam started rusting. This was  
> after months.
> 
> 
> I will put a few experimental nails around the etcher, and try to put all  
> tools further away, then it will be fine to run open-loop i hope. When any  
> of the nails start to rust i must do something.

Thats a cleaver test. The HCl is weired in that low concentrations  < 
0.1M won't release any HCl. Yet, if the concentration is high then HCl 
likes to escape. You can see this at the extreme when opening the lid of 
a bottle of the concentrated acid.

So by lowering the acid say by half, you can dramatically reduce the 
release of corrosive fumes. I'm not sure of the exact concentration you 
used initially that reduced your drill bits into rust, but going by your 
description I could easily see this happening.

Hi,

Nice to see someone having a go.

Why would you gear the stepper motors 1:1 and introduce more backlash in
addition to the leadscrew nut?

Regards,

Terry


| Hi all,
|
| Having reached all the mechanical milestones for my CNC rig, and now
| able to focus purely on the software, I thought I'd write it up and
| stick up the photos.
|
| Here it is: http://www.freenet.org.nz/cnc
|
| A masterpiece of precision German/Japanese engineering it most certainly
| is *not* :)
|
| But it seems to be working well enough for my modest PCB requirements.
|
| Enjoy!
|
| --
| Cheers
| David