Homebrew PCBs

Only took five years

http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/

Please give any feed back.

I am working on the laser plotter write up now.

I've only just had a quick glance through but it does look really nice, and cheap too.

Lack of a lathe will hinder my ability to make one though, unfortunately.

--- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@...> wrote:

>
> Only took five years
> 
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> 
> Please give any feed back.
> 
> I am working on the laser plotter write up now.
>

Good work, you have ironed out all the issues that stopped me.

ST

On Sun, Sep 16, 2012 at 1:34 AM, cunningfellow <andrewm1973@...> wrote:
> Only took five years
>
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
>
> Please give any feed back.
>
> I am working on the laser plotter write up now.
>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

You might need a lathe, but you don't need a metal lathe.  A wood lathe
would do.

 

On the issue of the impeller at the bottom (clever repurposing there), would
any angling of the blades help with startup or pressure?  Could you build a
sort of Archimedes screw in the bottom section?

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of tda7000
Sent: Saturday, September 15, 2012 5:35 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Spray etcher completed

 

  

I've only just had a quick glance through but it does look really nice, and
cheap too.

Lack of a lathe will hinder my ability to make one though, unfortunately.

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "cunningfellow" <andrewm1973@...>
wrote:
>
> Only took five years
> 
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> 
> Please give any feed back.
> 
> I am working on the laser plotter write up now.
>





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

Hi Andrew,

Thanks for this, which I found very interesting:

> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/

I doubt if there is an absolute need for the vanes at the bottom of each
rotating tube, which you made from a cut down black plastic toy wheel.

I think that all that would be needed is an end-cap with a hole in the
centre, and for this hole to be somewhat below the surface of the
etchant in the bottom of the tank.  The etchant would flow into the hole
by fluid pressure.  Once in the hole it would be rapidly spun to the
outside, even without vanes.  The vanes would probably help, but I
suspect that only two or four vanes would work nearly as well as 8 or
10, and that the system would still work pretty well without vanes.
Such a pattern of vanes could be made by gluing some baffles into the
bottom of the tube.  They wouldn't need to be particularly numerous or
symmetrical.  Just a single piece of plastic from one side to the other
would work fine, I think.

Likewise, I doubt that the three vertical strips you glued inside the
tube would be necessary, since by the time the etchant has been in the
tube for more than a fraction of a second, it is already spinning with
the tube.  You show the etchant bunched up against each strip, but that
would only be the case if the rotational speed was increasing, which it
is not.  Without these strips, or with much less in the way of strips -
the etchant would be forced against the walls of the tube, with greater
pressure at the bottom due to gravitational force downwards.

Perhaps it would suffice to have a 20 to 25mm PVC tube with an end-cap
with an 8mm diameter hole, and then just loosely stuff the tube with cut
up pieces of plastic pot scourer or similar.  This would allow flow of
etchant along the tube but would quickly cause all the etchant which
enters the hole to spin up to the rotational speed of the tube itself.

I didn't see any lower bearing.  Do you have the end of the rotating
tubes rubbing against the lower plastic framework?  If not, I think that
the whole thing could be self balancing as long as the motor was loosely
mounted, as yours is.  The motor and tube might not be exactly on axis,
but it wouldn't matter.

I wonder if the hole system could be replaced by somewhat flexible
narrow tubes, which exit the PVC tube at various heights.  Each such
flexible tube might flail around somewhat, distributing the drops from
its ends over a larger area of PCB.

With or without the flexible tube approach, I think the problem of
evenly distributing the etchant on the PCB might be solved to some
degree by cycling the speed of rotation.  The exact spray pattern would
depend on rotation speed and this is easily varied from slow to fast
every few seconds via a simple electronic circuit.

Depending on the rotational speed, I imagine you would get more flow
from the lower holes than from the upper ones.  This might be OK,
especially if you staggered the hole spacing to give more holes near the
top, to generally even out the flow pattern.

I had never heard of this rotary spray approach.  I think it is most
intriguing!

I see from your newspaper (The Courier Mail) that you are in Brisbane.
I took a quick look at your page this morning and then went to my
brother's place for lunch.  Lo and behold he had some of the same
plastic containers in his pantry!  The were made by Icon:

  http://www.iconplastics.com.au

near Melbourne.  He recalls he bought them at Bunnings.  I couldn't find
these containers in the Icon catalogue, but I did find they make the
prized plastic crates which are so good for storing LPs and other items.
 These used to be easy to get, but they are quite difficult to obtain
now.  They are on page 7 of the catalogue:

  http://www.iconplastics.com.au/products/materials-handling/

360 x 360 x 270 mm polypropylene "Hobby Box".

I couldn't find an image of the storage box you used, but it looks most
appropriate to the project, because of the relatively clear window on
each side.

 - Robin   http://www.firstpr.com.au/pcb-diy/

Here is an idea for a spray etcher, inspired by Steven's project:

  http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/

Lets say we have some PVC glueable tube such as 8mm to 10mm outside
diameter with 1mm to 1.5mm thick walls.  I am not sure where to get this.

Have the motor connected to a straight, rigid vertical section of this
(or perhaps something else thicker, such as wider PVC tube) with the
bottom end either free-floating and self-balancing or running into a
bearing of nylon or similar at the bottom of the tank.

Then, have two straight or somewhat outwardly curved sections of the 8
to 10mm OD pipe, glued to the bottom of this shaft, and rising on either
side like a narrow V shape.  The top ends of the two outer pipes are
sealed shut, such as by heating them and crimping them in a vise.  The
top ends need to be held firmly to the central shaft by some means, such
as more pipes and glue.

The bottom ends of both side pipes are open and perhaps slightly angled
so as they rotate, they are like shallow scoops into the liquid etchant
at the bottom of the tank.  These ends only need to go 5 to 8 mm below
the top surface.  If they go deeper, then they will create unnecessary
disturbance in the etchant at the bottom of the tank.

If the shaft is rotating clockwise, when viewed from above, the right
side-tube is joined to it on our side of the central shaft and the left
side-tube is joined at the far side.

Once the etchant is in the bottom of the tube, it will be forced up the
tube by centrifugal force, due to the V-shaped angle of each tube.

The side tubes have holes drilled in their outer edges, so there are two
rows of spray holes in the entire rotor.  These would be suitably
staggered to achieve a reasonably even set of jets.  Then we modulate
the motor speed with longer slower periods of a few seconds ramping up
to a shorter period of faster speed, so the impact points of the jets
are raised a little due to a faster travel time to the PCB and so
falling less due to gravity.

With sufficient turbulence in the container, this may disperse the
pattern of sprays.

Alternatively, to achieve an even spray pattern, the holes can be more
numerous and smaller, such as 0.7mm or so, so that they don't make such
distinct spray patterns on the PCB.

 - Robin  http://www.firstpr.com.au/pcb-diy/

Early on in the write up I experimented with holding the motor and PVC in a vise and using a file to "turn it down"

It worked but took ages and was messy.

So I decided to just tell people to borrow a lathe.

20 mins on a lathe or 2 hours with a file (and who knows how much you are damaging the motors sintered bearing) it's just not worth it.



--- In Homebrew_PCBs@yahoogroups.com, "Andrew Volk" <amvweb@...> wrote:

>
> You might need a lathe, but you don't need a metal lathe.  A wood lathe
> would do.
> 
>  
> 
> On the issue of the impeller at the bottom (clever repurposing there), would
> any angling of the blades help with startup or pressure?  Could you build a
> sort of Archimedes screw in the bottom section?
> 
>  
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of tda7000
> Sent: Saturday, September 15, 2012 5:35 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: Spray etcher completed
> 
>  
> 
>   
> 
> I've only just had a quick glance through but it does look really nice, and
> cheap too.
> 
> Lack of a lathe will hinder my ability to make one though, unfortunately.
> 
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com> , "cunningfellow" <andrewm1973@>
> wrote:
> >
> > Only took five years
> > 
> > http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> > 
> > Please give any feed back.
> > 
> > I am working on the laser plotter write up now.
> >
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

> Robin Wrote:
>
> I doubt if there is an absolute need for the
> vanes at the bottom of each rotating tube
> <SNIP>

Early versions didn't have vanes.

They had startup reliability problems.

The vanes fixed the startup issues.

The BEST solution for the bottom is
a radial that is a conical shape with
a very slight axial inflow.

I knew people would complain about
needing a lathe.  I didn't want to
make an impeller that needed a 5
axis CNC machine to make :D

(The toy wheel was something to make
it easy for the average person to do)

> <SNIP>
> Likewise, I doubt that the three vertical
> strips you glued inside the tube would be
> necessary
> <SNIP>

Without the strips you do get banding.

I think it was Alien Relics here that tried
to make his tube with a spiral of holes
and found his banding was the exact distance
of the spirals.

RoelCNC made his tubes with a bottom bearing
and it does not have such banding. (even
without the dams/strips)

This indicates to me the out of round
condition is causing the issue.


> <SNIP> 
> I didn't see any lower bearing.  Do you
> have the end of the rotating tubes rubbing
> against the lower plastic framework?

No lower bearing.  Thats why care is needed
in the building to keep it round.

> <SNIP>
> I think the problem of evenly distributing
> the etchant on the PCB might be solved to
> some degree by cycling the speed of
> rotation.

I have done this speed modulation and it did
even out the banding.

I have also used a gear head motor to slowy
cycle the PCB holder up and down.

Neither is now neccesary now I have the
banding issues sorted at the source.


> <SNIP>
> went to my
> brother's place for lunch.  Lo and behold
> he had some of the same plastic containers
> in his pantry!  The were made by Icon:
> 
>   http://www.iconplastics.com.au
> 
> near Melbourne.  He recalls he bought them
> at Bunnings.

Yes the one I used was "icon" brand from
bunnies (where lower prices where just at
the begining)

Some thoughts that come to mind from reading you excellent article:

Add some vertical oscillation to the PCB mounting system to overcome the problem of blocked, burred or miss-drilled jets.
Add a short section of hollow centre submerged Archimedes screw to the bottom of the tube to ensure starting.

Malcolm

 
I don't suffer from insanity I enjoy it!
Mene, mene, tekel, upharsin
The writing is on the wall.


________________________________

 From: cunningfellow <andrewm1973@...>
To: Homebrew_PCBs@yahoogroups.com 
Sent: Sunday, September 16, 2012 12:34 AM
Subject: [Homebrew_PCBs] Spray etcher completed
 

  
Only took five years

http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/

Please give any feed back.

I am working on the laser plotter write up now.


 

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

Nice job.
I built a splash etcher years ago and found the trick is to get some randomness to the splash.  I did this by making the radial edge of the splashier paddle very irregular.

I am wondering if some external surface features on your tubes may make a finer spray pattern.  I got this idea from cleaning paint rollers with the garden hose. With the water hose stream you can spin up the rollers really fast but the interesting thing is the fine spray of water that departs the spinning roller.  All the little hairs of the roller nap act like little emitters.   I saw a likely roller cover at the home center a few weeks ago, the tube was PVC but not sure about the nap.  It would have to be tested to see its resistance to the chemistry.

Craig   

--- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@...> wrote:

>
> Only took five years
> 
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> 
> Please give any feed back.
> 
> I am working on the laser plotter write up now.
>

I see it's turned up on Hackaday now:

http://hackaday.com/2012/09/16/etching-brass-and-copper-with-the-etchinator/


--- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:

>
> Nice job.
> I built a splash etcher years ago and found the trick is to get some randomness to the splash.  I did this by making the radial edge of the splashier paddle very irregular.
> 
> I am wondering if some external surface features on your tubes may make a finer spray pattern.  I got this idea from cleaning paint rollers with the garden hose. With the water hose stream you can spin up the rollers really fast but the interesting thing is the fine spray of water that departs the spinning roller.  All the little hairs of the roller nap act like little emitters.   I saw a likely roller cover at the home center a few weeks ago, the tube was PVC but not sure about the nap.  It would have to be tested to see its resistance to the chemistry.
> 
> Craig   
> 
> --- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@> wrote:
> >
> > Only took five years
> > 
> > http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> > 
> > Please give any feed back.
> > 
> > I am working on the laser plotter write up now.
> >
>

Congratulations, and very good work you did on this project.

However, I still think that the most simple spray etching system is like the Kepro tanks.

I did used those machines in the 80s; now I am trying to replicate and refurbishing a broke tank and manifolds, but I remember that you could do hundreds and hundreds of PCBs without any "shading" or "banding" effects on the copper.

For those interested in those systems, this place has very useful photographs:

http://www.cnczone.com/forums/273303-post306.html

Regards.



--- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@...> wrote:

>
> Only took five years
> 
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
> 
> Please give any feed back.
> 
> I am working on the laser plotter write up now.
>

On 16-09-12, cunningfellow  <andrewm1973@...> wrote:     
> Only took five years
> 
> http://www.instructables.com/id/The-Etchinator-low-cost-spray-etcher/
>  
> Please give any feed back.
> 
> I am working on the laser plotter write up now.

Looks like a very nice design. Can't wait to see the laser plotter :)

How many watts does the motors need to be?


--
Emil

> Emil Johnsen wrote:
> <SNIP>
> How many watts does the motors need to be?

Motors I have at the moment pull only 9
watts each.  Some others I had pulled
even less.

Your mileage may vary depending on where
the motors peak efficiency is.  High RPM
motors will bog down and draw too much
power at the slow 3000 RPM.

That is why a big diameter 5 pole motor
is a good idea.

First of all you have made an excellent article !

regarding a sophisticated impeller/fan . There a lot of activity / enthusiasts that are building at home made 3D printers (also there is a group on yahoo). Also are available commercial services for this. On a such a printer can be made this impeller fairly easy . Also I am interested to participate on this "improvement" since I was planning for a long time ago to build a spray etcher...
Regards,
Daniel

This kind of turbine would work ?
http://grabcad.com/library/francis-turbine-runner--1


--- In Homebrew_PCBs@yahoogroups.com, "Daniel" <dandumit@...> wrote:

>
> First of all you have made an excellent article !
> 
> regarding a sophisticated impeller/fan . There a lot of activity / enthusiasts that are building at home made 3D printers (also there is a group on yahoo). Also are available commercial services for this. On a such a printer can be made this impeller fairly easy . Also I am interested to participate on this "improvement" since I was planning for a long time ago to build a spray etcher...
> Regards,
> Daniel
>

> Daniel wrote:
>
> This kind of turbine would work ?
> http://grabcad.com/library/francis-turbine-runner--1
> 

I may try play with a 3D printer to improve the
impeller.

I would like to try an axial inflow radial out.

> 
> I would like to try an axial inflow radial out.
>
Do you have a link or image about it?  I understand that you consider that would be needed exactly the opposite impeller that I have proposed?

Andrew,

You have done a great job of writing this up, and it is evident that you have done a LOT of experimenting along the way to validate and refine the design. Thanks for sharing this.

I am curious about "the BEST solution for the bottom [which] is a radial that is a conical shape with a very slight axial inflow." I am not sure if I am picturing correctly what you mean. I am envisioning something like the following cross-section, except at a much shallower angle than my crude ascii-graphics suggest (note that this will need a fixed font to show correctly):

|\        /|
| \      / |
|  \    /  |
|   |  |   |
----   -----

What I am attempting to show is a cross-section of a short "plug" that goes in the end of the tube. This plug would have a smaller-diameter hole at the bottom to let the fluid in, but the "inner walls" of this plug would slope up at a shallow angle. Thus, when the fluid enters the bottom, it would be forced to flow up the shallow slope by centrifugal action, and in the process would suck in more fluid. Or at least that is my theory. :)

Is this what you have in mind for "the best solution"? If not, any chance of a drawing to show what you have in mind?

Thanks again for an excellent write-up!


--- In Homebrew_PCBs@yahoogroups.com, "cunningfellow" <andrewm1973@...> wrote:

>
> > Robin Wrote:
> >
> > I doubt if there is an absolute need for the
> > vanes at the bottom of each rotating tube
> > <SNIP>
> 
> Early versions didn't have vanes.
> 
> They had startup reliability problems.
> 
> The vanes fixed the startup issues.
> 
> The BEST solution for the bottom is
> a radial that is a conical shape with
> a very slight axial inflow.
> 
> I knew people would complain about
> needing a lathe.  I didn't want to
> make an impeller that needed a 5
> axis CNC machine to make :D
> 
> (The toy wheel was something to make
> it easy for the average person to do)
> 
> > <SNIP>
> > Likewise, I doubt that the three vertical
> > strips you glued inside the tube would be
> > necessary
> > <SNIP>
> 
> Without the strips you do get banding.
> 
> I think it was Alien Relics here that tried
> to make his tube with a spiral of holes
> and found his banding was the exact distance
> of the spirals.
> 
> RoelCNC made his tubes with a bottom bearing
> and it does not have such banding. (even
> without the dams/strips)
> 
> This indicates to me the out of round
> condition is causing the issue.
> 
> 
> > <SNIP> 
> > I didn't see any lower bearing.  Do you
> > have the end of the rotating tubes rubbing
> > against the lower plastic framework?
> 
> No lower bearing.  Thats why care is needed
> in the building to keep it round.
> 
> > <SNIP>
> > I think the problem of evenly distributing
> > the etchant on the PCB might be solved to
> > some degree by cycling the speed of
> > rotation.
> 
> I have done this speed modulation and it did
> even out the banding.
> 
> I have also used a gear head motor to slowy
> cycle the PCB holder up and down.
> 
> Neither is now neccesary now I have the
> banding issues sorted at the source.
> 
> 
> > <SNIP>
> > went to my
> > brother's place for lunch.  Lo and behold
> > he had some of the same plastic containers
> > in his pantry!  The were made by Icon:
> > 
> >   http://www.iconplastics.com.au
> > 
> > near Melbourne.  He recalls he bought them
> > at Bunnings.
> 
> Yes the one I used was "icon" brand from
> bunnies (where lower prices where just at
> the begining)
>

> Andrew "awakephd" wrote:
>
> <SNIP>
>
> Is this what you have in mind for "the
> best solution"? If not, any chance of a
> drawing to show what you have in mind?
> 

Files > Etchinator > Impeller.png

I hope this picture conveys the idea.

Also not shown in the hidden detail is a
tapered conical plug in the centre.  It
just looked messy and confusing when I
tried to add that to the drawing.

I needs either a lot of experimenting to
get the optimal shape OR someone much
much smarter than I am do some math.

Finally it probably needs some shark
teeth painted on it.  Apparently people
dig that kind of thing.

> Daniel wrote:
>
> Do you have a link or image about it?
> I understand that you consider that
> would be needed exactly the opposite
> impeller that I have proposed?


Daniel,

See

Files > Etchinator > Impeller.png