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"Twist" on an old method of PCB making.

"Twist" on an old method of PCB making.

2005-03-19 by Dean Batute

Hello all..I think I have yet another new PCB making "twist"!

Many may not know this but I was the FIRST to suggest the idea for
using glossy magazine "stock" for the direct toner method. I did
extensive searching on this group and the rest of the net prior to
making the post a couple of years ago to confirm no one else had
suggested it before (No point in suggesting "old news" ).

Here's an idea for a "twist" (Pun intended) on a different method.

The scratch and etch idea has been tossed around, experimented, and
succcesfully tried by others. All have relied on dragging a sharp
point across a "Blued" or coated circuit board.
The biggest problem was finding a suitable "Resist" that scratched
CLEANLY yet still gave protection from the etchant.

Another idea was the possibility of modifying a plotter somehow to
become a PCB etching machine. I don't think anyone succeeded in this
method because plotters are not strong enough to carry the drill head
or Dremel Flexi-Shaft (not to mention all the other problems).

How about combining the two methods !!!

Pager vibrating motors are VERY small...VERY light... and require
VERY little power to drive them. How about removing the offset
weight, sharpening the shaft to a point, and using the power that
drives the up/down solonoid of the plotter (thru a resistor since
little power is needed) to drive the motor. It'll fit EASILY into the
pen holder (in fact it's probably TOO small and will need an adapter)
and will give a clean "Scratch" thru even the THICKEST of Etch resist
coating. The biggest obstacle will be sharpening the tip.

A little inginuity could figure a mount idea to fix a PCB drill bit
snapped short onto the shaft of the motor (using Epoxy or a small
piece of plastic as a coupler). The critical point will keeping the
bit balanced so it doesn't wobble with relation to the motor. On the
flip side the spinning of the motor should have a gyroscopic effect
to stabalize the motor in relation to the Pen mount to reduce wobble
in that regard.

I'm going to grab some motors Monday and try to fit in some
experiments next week. I don't have any suitable software for PCB
designs but for the purpose of the tests I'll use Corel to plot some
fine detailed text and lines. At least it'll confirm (or deny) the
concept.

There you go...more food for thought.

Thoughts.. ideas...other people's success or failures !!!

Cheers....Dean.

Re: "Twist" on an old method of PCB making.

2005-03-19 by Steve

--- In Homebrew_PCBs@yahoogroups.com, "Dean Batute" <phix_it@y...> wrote:
...
> The scratch and etch idea has been tossed around, experimented, and
> succcesfully tried by others. All have relied on dragging a sharp
> point across a "Blued" or coated circuit board.
> The biggest problem was finding a suitable "Resist" that scratched
> CLEANLY yet still gave protection from the etchant.

Not really. The metal coatings meant for metalworking have worked just
fine. Dykem was suggested here, and I bought another brand at a local
welder's supply and tested it and it worked a treat.

...
> Pager vibrating motors are VERY small...VERY light... and require
> VERY little power to drive them. How about removing the offset
> weight, sharpening the shaft to a point, and using the power that
> drives the up/down solonoid of the plotter (thru a resistor since
> little power is needed) to drive the motor. It'll fit EASILY into the
> pen holder (in fact it's probably TOO small and will need an adapter)
> and will give a clean "Scratch" thru even the THICKEST of Etch resist
> coating. The biggest obstacle will be sharpening the tip.

I had no problems with a small HP pen plotter (forgot the model, 74xx
letter size) scratching through. Bought a metal scratching pen with
replaceable tips, glued one of the carbide tips into an emptied
plotter pen. Then filled it with lead shot and superglued it in place.

Without the weight, it skips. With it and making sure you let the
metal marking fluid dry thoroughly, it works fine. If you don't let it
dry fully, it tears and skips.

Steve Greenfield

RE: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.

2005-03-20 by Brian Schmalz

Yah, I've never had any problem with getting a clean line when I do scratching. My biggest problem is that the line is so incredibly thin and precise that I have a hard time 'covering' any sizable area in any reasonable time. :) I use a carbide tipped scratcher, the thing that's meant to scratch through Dykem.

*Brian

--- In Homebrew_PCBs@yahoogroups.com, "Dean Batute" <phix_it@y...> wrote:
...
> The scratch and etch idea has been tossed around, experimented, and
> succcesfully tried by others. All have relied on dragging a sharp
> point across a "Blued" or coated circuit board.
> The biggest problem was finding a suitable "Resist" that scratched
> CLEANLY yet still gave protection from the etchant.

Re: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.

2005-03-20 by Stefan Trethan

On Sun, 20 Mar 2005 10:01:58 -0600, Brian Schmalz <brian.s@...>
wrote:

>
> Yah, I've never had any problem with getting a clean line when I do
> scratching. My biggest problem is that the line is so incredibly thin
> and precise
> that I have a hard time 'covering' any sizable area in any reasonable
> time. I use a carbide tipped scratcher, the thing that's meant to
> scratch
> through Dykem.
> *Brian


the rotary scribe would make a wider line.

ST

RE: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.

2005-03-20 by Brian Schmalz

Quite true, but wouldn't you have a difficult time controlling the width of it's 'path'? If there were a really good way to 'set' the resulting width, I can see it being very useful to my process - if I could say I wanted a .003 line width out of the rotating scribe, and it were very uniform, it would certainly speed up my scratching process, even if I had to slow down the linear speed of the plotter head to let the scribe do it's work.

*Brian

-----Original Message-----
From: Stefan Trethan [mailto:stefan_trethan@...]
Sent: Sunday, March 20, 2005 10:19 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.



On Sun, 20 Mar 2005 10:01:58 -0600, Brian Schmalz <brian.s@...>
wrote:

>
> Yah, I've never had any problem with getting a clean line when I do
> scratching. My biggest problem is that the line is so incredibly thin
> and precise
> that I have a hard time 'covering' any sizable area in any reasonable
> time. I use a carbide tipped scratcher, the thing that's meant to
> scratch
> through Dykem.
> *Brian


the rotary scribe would make a wider line.

ST



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Re: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.

2005-03-20 by Stefan Trethan

On Sun, 20 Mar 2005 10:23:55 -0600, Brian Schmalz <brian.s@...>
wrote:

>
> Quite true, but wouldn't you have a difficult time controlling the width
> of it's 'path'? If there were a really good way to 'set' the resulting
> width,
> I can see it being very useful to my process - if I could say I wanted
> a .003 line width out of the rotating scribe, and it were very uniform,
> it
> would certainly speed up my scratching process, even if I had to slow
> down the linear speed of the plotter head to let the scribe do it's work.
> *Brian


i guess it depends on how far off center the scribe is...

ST

Re: "Twist" on an old method of PCB making.

2005-03-20 by onenastyviper

Hi guys.

I am using an HP 7475A for scratching using a modded pen and solid
tungsten-carbide bit (a bit from a Wickes tile scribe) any ideas on
how to sharpen this bit??
Also, what are the advantages to adding weight to the bit?? How much
max weight?


PK

RE: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.

2005-03-20 by Brian Schmalz

PK,
The way I sharpen my carbide tip is to rub it back and forth, while turning it, on a diamond hone. Kind of like manually sharpening a pencil by using sandpaper. Then I check the tip under a magnifying glass to see how far it's gotten. I've never added any weight to my scratcher, but it sounds like a good idea.

*Brian

-----Original Message-----
From: onenastyviper [mailto:oneNastyViper@...]
Sent: Sunday, March 20, 2005 12:46 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: "Twist" on an old method of PCB making.




Hi guys.

I am using an HP 7475A for scratching using a modded pen and solid
tungsten-carbide bit (a bit from a Wickes tile scribe) any ideas on
how to sharpen this bit??
Also, what are the advantages to adding weight to the bit?? How much
max weight?


PK







Be sure to visit the group home and check for new Bookmarks and files:
http://groups.yahoo.com/group/Homebrew_PCBs
Yahoo! Groups Links

Re: "Twist" on an old method of PCB making.

2005-03-21 by Steve

I think it would take a diamond or ceramic hone to sharpen. Can you
get a flat ceramic hone? As the other poster says, turn while rubbing.
Doesn't really matter if it is off center a bit after you are done.

How much weight? I just filled all the empty space in my pen with
small lead shot. The advantage was that before I weighted it down it
had occassional skips where it wouldn't quite scratch all the way
through the coating.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, "onenastyviper"
<oneNastyViper@h...> wrote:
>
> Hi guys.
>
> I am using an HP 7475A for scratching using a modded pen and solid
> tungsten-carbide bit (a bit from a Wickes tile scribe) any ideas on
> how to sharpen this bit??
> Also, what are the advantages to adding weight to the bit?? How much
> max weight?
>
>
> PK