Synth-DIY Yahoo! Groups Archives

Thread

Bernoulli sprayer

2012-12-13 by rolynd33

What speaks against using a bernoulli type sprayer for spray erching ?
I did a seach here but bernoulli did not yield any viable results.

(In essence its just two tubes meeting at an 90° angle ,air is blown into the horizontal tube thus a vacuum is created in the vertical tube drawing up the liquid and then dispersing it in a fine spray at the top. If you dont understand what I am describing , I am not a big explainer :) - just do a quick google search)

It would be simple to construct, fairly large tubes can be used so no clogging of nozzles, no pump needed and no plumbing outside of the tank. All good things to me.

Of cause you will need an air source that means probably a noisy compressor which is a downside. Also the fine aerosol you create must be contained so a tight seal on the tank is needed. The air you blow in must go somewhere so you need an exhaust port probably fittet with a sponge first to catch the larger paricles and then connected to a scrubber bottle to get rid of the rest of the aerosol.

I dont know how much pressure and volume you need but I can produce a fairly good spray just with mouth pressure.

Would the force of the spay cone be too much? Spray pattern too random? Not enough etchant moved?

The idea is simple but I guess there must be something I overlook because no one has thought of this or built one based on this principle.

So, what am I missing here?

Re: [Homebrew_PCBs] Bernoulli sprayer

2012-12-13 by Duane C. Johnson

rolynd33 wrote:

> What speaks against using a Bernoulli type sprayer for spray etching ?
> I did a search here but Bernoulli did not yield any viable results.

Try this:
http://en.wikipedia.org/wiki/Atomizer_nozzle

Duane

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Re: Bernoulli sprayer

2012-12-14 by psykhon@yahoo.com

Its not viable becasuse etchant does not recirculate, you just pump it out of the vessel and to the board but if you try to put it back in, it will loose presure and stops spraying.
To put it back in without pressure loss, it will need a pump capable of more pressure thats in the chamber, so the whole thing becames ilogicall.

Another way is to have LOTS of etchant and a very powerfull air pump to compensate for the volume, Raising cost to an unpractically level

However this is the kind of ideas that migth contribute to something in the future so I dont consider it a waste of time to give it a thougth or two.

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, "Duane C. Johnson" <redrok@...> wrote:
>
> rolynd33 wrote:
>
> > What speaks against using a Bernoulli type sprayer for spray etching ?
> > I did a search here but Bernoulli did not yield any viable results.
>
> Try this:
> http://en.wikipedia.org/wiki/Atomizer_nozzle
>
> Duane
>
> --
> Home of the $35 Solar Tracker Receiver
> http://www.redrok.com/led3xassm.htm [*]
> Powered by \ \ \ //|
> Thermonuclear Solar Energy from the Sun / |
> Energy (the SUN) \ \ \ / / |
> Red Rock Energy \ \ / / |
> Duane C. Johnson Designer \ \ / \ / |
> 1825 Florence St Heliostat,Control,& Mounts |
> White Bear Lake, Minnesota === \ / \ |
> USA 55110-3364 === \ |
> (651)426-4766 use Courier New Font \ |
> redrok@... (my email: address) \ |
> http://www.redrok.com (Web site) ===
>

Re: [Homebrew_PCBs] Re: Bernoulli sprayer

2012-12-14 by Stefan Trethan

I don't think you understand the bernoulli pump, the fluid is not
pressurized, it is "pulled along" by the airstream.
So it can recirculate just fine.

However I suspect there might be trouble with etching uniformity.

ST

Show quoted textHide quoted text

On Fri, Dec 14, 2012 at 5:15 PM, <psykhon@...> wrote:
> Its not viable becasuse etchant does not recirculate, you just pump it out of the vessel and to the board but if you try to put it back in, it will loose presure and stops spraying.
> To put it back in without pressure loss, it will need a pump capable of more pressure thats in the chamber, so the whole thing becames ilogicall.
>
> Another way is to have LOTS of etchant and a very powerfull air pump to compensate for the volume, Raising cost to an unpractically level
>
> However this is the kind of ideas that migth contribute to something in the future so I dont consider it a waste of time to give it a thougth or two.
>
>

Re: Bernoulli sprayer

2012-12-14 by rolynd33

Thats what I thought, no motors no pumps everything nicely contained in the box, just a source of compressed air from the outside going into the box.

But I am not sure if enough etchant can be moved with this method, too much air pressure or volume would be needed and theres still the fact you loose heat when making a fine spray. Its just a wild Idea at the moment and I am exploring its possibilities.

Irregular spray pattern can be compensated by moving the PCB instead. pinned on a slowly rotating disk or if you want double sided etching fixed into a slowly rotating ring.

The disk or ring could be moved by magnetic coupling from the outside. So still no motor inside of the box. The magnets needed on the ring and its stand can be sealed with a bit of epoxy ot silicone. Small neodynium magnets are dirt cheap nowadays.

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan <stefan_trethan@...> wrote:
>
> I don't think you understand the bernoulli pump, the fluid is not
> pressurized, it is "pulled along" by the airstream.
> So it can recirculate just fine.
>
> However I suspect there might be trouble with etching uniformity.
>
> ST
>
> On Fri, Dec 14, 2012 at 5:15 PM, <psykhon@...> wrote:
> > Its not viable becasuse etchant does not recirculate, you just pump it out of the vessel and to the board but if you try to put it back in, it will loose presure and stops spraying.
> > To put it back in without pressure loss, it will need a pump capable of more pressure thats in the chamber, so the whole thing becames ilogicall.
> >
> > Another way is to have LOTS of etchant and a very powerfull air pump to compensate for the volume, Raising cost to an unpractically level
> >
> > However this is the kind of ideas that migth contribute to something in the future so I dont consider it a waste of time to give it a thougth or two.
> >
> >
>

Re: Bernoulli sprayer

2012-12-15 by AlienRelics

Perhaps he thinks the box is sealed and pumping air in will build up pressure.

The original poster already spoke about filtering any atomized etchant out of the escaping air.

Steve Greenfield AE7HD

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan <stefan_trethan@...> wrote:
>
> I don't think you understand the bernoulli pump, the fluid is not
> pressurized, it is "pulled along" by the airstream.
> So it can recirculate just fine.
>
> However I suspect there might be trouble with etching uniformity.
>
> ST
>
> On Fri, Dec 14, 2012 at 5:15 PM, <psykhon@...> wrote:
> > Its not viable becasuse etchant does not recirculate, you just pump it out of the vessel and to the board but if you try to put it back in, it will loose presure and stops spraying.
> > To put it back in without pressure loss, it will need a pump capable of more pressure thats in the chamber, so the whole thing becames ilogicall.
> >
> > Another way is to have LOTS of etchant and a very powerfull air pump to compensate for the volume, Raising cost to an unpractically level
> >
> > However this is the kind of ideas that migth contribute to something in the future so I dont consider it a waste of time to give it a thougth or two.
> >
> >
>

Re: Etching PCB's

2012-12-15 by Roger.Blair

I have done some etching of small brass and copper/bronze parts in the
past, although not etching of PCB's, however this etchant/etching
discussion has me curious... has anyone tried placing a sonicair (type)
electronic toothbrush (extension, without bristles) into an etchant
bath for agitation? Just thinking it might make a simple, but
interesting experiment...
Roger

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

Re: Bernoulli sprayer

2012-12-15 by designer_craig

Guys,just make a splash tank, they are mechanically simple and work very well. All you need is a dasher on the end of a stainless steel or plastic rod (depending on your etchant choice) driven by an old motor. Think of it as an inverted blender. (Hack your wife's blender for the motor) Only takes about an inch of etchant in the bottom of the tank. You do have to build an anti-splash cover seal to keep the etchant in the tank. My last one was built from fiberglassed 1/2" plywood and was a 12" cube.

Craig

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, "rolynd33" <roland.rasch@...> wrote:
>
> What speaks against using a bernoulli type sprayer for spray erching ?
> I did a seach here but bernoulli did not yield any viable results.
>
> (In essence its just two tubes meeting at an 90° angle ,air is blown into the horizontal tube thus a vacuum is created in the vertical tube drawing up the liquid and then dispersing it in a fine spray at the top. If you dont understand what I am describing , I am not a big explainer :) - just do a quick google search)
>
> It would be simple to construct, fairly large tubes can be used so no clogging of nozzles, no pump needed and no plumbing outside of the tank. All good things to me.
>
> Of cause you will need an air source that means probably a noisy compressor which is a downside. Also the fine aerosol you create must be contained so a tight seal on the tank is needed. The air you blow in must go somewhere so you need an exhaust port probably fittet with a sponge first to catch the larger paricles and then connected to a scrubber bottle to get rid of the rest of the aerosol.
>
> I dont know how much pressure and volume you need but I can produce a fairly good spray just with mouth pressure.
>
> Would the force of the spay cone be too much? Spray pattern too random? Not enough etchant moved?
>
> The idea is simple but I guess there must be something I overlook because no one has thought of this or built one based on this principle.
>
> So, what am I missing here?
>

RE: [Homebrew_PCBs] Re: Bernoulli sprayer

2012-12-15 by Jeff Heiss

Any pictures of your tank available?

Jeff

_____

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of designer_craig
Sent: Saturday, December 15, 2012 10:41 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Bernoulli sprayer

Guys,just make a splash tank, they are mechanically simple and work very
well. All you need is a dasher on the end of a stainless steel or plastic
rod (depending on your etchant choice) driven by an old motor. Think of it
as an inverted blender. (Hack your wife's blender for the motor) Only takes
about an inch of etchant in the bottom of the tank. You do have to build an
anti-splash cover seal to keep the etchant in the tank. My last one was
built from fiberglassed 1/2" plywood and was a 12" cube.

Craig

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "rolynd33" <roland.rasch@...>
wrote:

>
> What speaks against using a bernoulli type sprayer for spray erching ?
> I did a seach here but bernoulli did not yield any viable results.
>
> (In essence its just two tubes meeting at an 90° angle ,air is blown into

the horizontal tube thus a vacuum is created in the vertical tube drawing up
the liquid and then dispersing it in a fine spray at the top. If you dont
understand what I am describing , I am not a big explainer :) - just do a
quick google search)

>
> It would be simple to construct, fairly large tubes can be used so no

clogging of nozzles, no pump needed and no plumbing outside of the tank. All
good things to me.

>
> Of cause you will need an air source that means probably a noisy

compressor which is a downside. Also the fine aerosol you create must be
contained so a tight seal on the tank is needed. The air you blow in must go
somewhere so you need an exhaust port probably fittet with a sponge first to
catch the larger paricles and then connected to a scrubber bottle to get rid
of the rest of the aerosol.

>
> I dont know how much pressure and volume you need but I can produce a

fairly good spray just with mouth pressure.

>
> Would the force of the spay cone be too much? Spray pattern too random?

Not enough etchant moved?

>
> The idea is simple but I guess there must be something I overlook because

no one has thought of this or built one based on this principle.

>
> So, what am I missing here?
>

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

Re: Bernoulli sprayer

2012-12-15 by cunningfellow

> rolynd33 wrote:
>
> What speaks against using a bernoulli type
> sprayer for spray erching ?

Volume.

You don't need a mist.

You want fairly large droplets.

Re: Bernoulli sprayer

2012-12-16 by rolynd33

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

Show quoted textHide quoted text

>
> > rolynd33 wrote:
> >
> > What speaks against using a bernoulli type
> > sprayer for spray erching ?
>
> Volume.
>
> You don't need a mist.
>
> You want fairly large droplets.
>

At the moment I am etching with a bubbler tank and ferric, this works ok for pcb but I have begun fabricating small parts from sheet metal. As I am using 0,5mm thickness and it needs to be through etched undercut on fine details becomes a problem. I use double sided etching and have cranked up the temperature of the etchant to 55°-60°C to speed up the process but dimensional accuracy is not where I want it to be.
(BTW: I am using toner transfer with the oracal 651 plotter vinyl and I am getting better and more consistent results than with the thin glossy magazine and catlouge paper I used before. I use the transparent one for double sided designs.)

I was looking into methods that give less undercut and as far as I could discern spray etching gives the least undercut, right?

I have no experience with building a spray etcher and as far as I was able to see its difficult and costly to get the right pump and on the rotating tube type its not the easiest part to get them to run smoothly set the right speed and get the impeller to function perfectly.

As I already have a compressor I wanted to explore the idea of a sprayer without motors and pumps which would be a little easier to build and uses no costly parts. But the consensus here and the fact that no one has build a system this way leads me to the conclusion that this would not be the way to go.

I will be looking into the splash etching tank idea and do a little research into this direction.

Regards

Re: Bernoulli sprayer

2012-12-16 by designer_craig

Jeff,
I built the tank back in 1975 and used it off and on for many years. Back in 2000 I was down sizing due to an upcoming move and got rid of it with a lot of other stuff. I could find no photos but I did draw up a sketch a while back. Go to the files section of the forum and look under Craigs-files. I used this etcher with annonium persulfate becasue I had an easy supply of the stuff. The company I worked for had a captive PCB shop and used the AP as part of the process. I had an imersion heater to get it up to the 140F etching temp. Fresh hot etchant would do a board is 30 to 60 seconds.

Don' know if I would use it with Feric Chloride becasue of the mess that the stuff makes, stains everyting it touches. CuCL2 should work fine as well but out side because of the HCL fumes. AP is so clean to work with.

There are photos of my spin coater and pcb drill in the photo section under Craigs photos

Craig

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:
>
> Any pictures of your tank available?
>
>
>
> Jeff

RE: [Homebrew_PCBs] Re: Bernoulli sprayer

2012-12-16 by Jeff Heiss

I like the splash etcher drawing. What does SS stand for in the SS paddle?
How would you compare the performance of a splash ether to other etch tanks
like wave, bubble, or spray?

Jeff

_____

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of designer_craig
Sent: Sunday, December 16, 2012 1:23 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Bernoulli sprayer

Jeff,
I built the tank back in 1975 and used it off and on for many years. Back in
2000 I was down sizing due to an upcoming move and got rid of it with a lot
of other stuff. I could find no photos but I did draw up a sketch a while
back. Go to the files section of the forum and look under Craigs-files. I
used this etcher with annonium persulfate becasue I had an easy supply of
the stuff. The company I worked for had a captive PCB shop and used the AP
as part of the process. I had an imersion heater to get it up to the 140F
etching temp. Fresh hot etchant would do a board is 30 to 60 seconds.

Don' know if I would use it with Feric Chloride becasue of the mess that the
stuff makes, stains everyting it touches. CuCL2 should work fine as well but
out side because of the HCL fumes. AP is so clean to work with.

There are photos of my spin coater and pcb drill in the photo section under
Craigs photos

Craig

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff Heiss" <jeff.heiss@...>
wrote:

>
> Any pictures of your tank available?
>
>
>
> Jeff

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

RE: [Homebrew_PCBs] Re: Bernoulli sprayer

2012-12-16 by Andrew Volk

My guess is that SS is Stainless Steel.

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Jeff Heiss
Sent: Sunday, December 16, 2012 11:35 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] Re: Bernoulli sprayer

I like the splash etcher drawing. What does SS stand for in the SS paddle?
How would you compare the performance of a splash ether to other etch tanks
like wave, bubble, or spray?

Jeff

_____

From: Homebrew_PCBs@yahoogroups.com <mailto:Homebrew_PCBs%40yahoogroups.com>
[mailto:Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> ]
On Behalf Of designer_craig
Sent: Sunday, December 16, 2012 1:23 PM
To: Homebrew_PCBs@yahoogroups.com <mailto:Homebrew_PCBs%40yahoogroups.com>
Subject: [Homebrew_PCBs] Re: Bernoulli sprayer

Jeff,
I built the tank back in 1975 and used it off and on for many years. Back in
2000 I was down sizing due to an upcoming move and got rid of it with a lot
of other stuff. I could find no photos but I did draw up a sketch a while
back. Go to the files section of the forum and look under Craigs-files. I
used this etcher with annonium persulfate becasue I had an easy supply of
the stuff. The company I worked for had a captive PCB shop and used the AP
as part of the process. I had an imersion heater to get it up to the 140F
etching temp. Fresh hot etchant would do a board is 30 to 60 seconds.

Don' know if I would use it with Feric Chloride becasue of the mess that the
stuff makes, stains everyting it touches. CuCL2 should work fine as well but
out side because of the HCL fumes. AP is so clean to work with.

There are photos of my spin coater and pcb drill in the photo section under
Craigs photos

Craig

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com>
<mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff Heiss" <jeff.heiss@...>
wrote:

>
> Any pictures of your tank available?
>
>
>
> Jeff

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

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

Re: Bernoulli sprayer

2012-12-16 by cunningfellow

>> Jeff Heiss wrote:
>> I like the splash etcher drawing. What
>> does SS stand for in the SS paddle?
>> How would you compare the performance
>> of a splash ether to other etch tanks
>> like wave, bubble, or spray?

> Andrew Volk wrote:
> My guess is that SS is Stainless Steel.

Yes SS is stainless.

The OP used Amonium Persulfate so SS is OK.
If you are etching other metal such as steel
or brass then you will be using FeCl3 and
stainless is not an option.

Also etching thick brass (rather than
relatively easy PCBs) then spray is the way
to go. Float etching is an option as well
apparetnly but I never had the same success
as spraying.

If you are worried about difficulty of
buidling tubes and you are down under I
can help you out. (no idea where you are
from)

RE: [Homebrew_PCBs] Re: Bernoulli sprayer

2012-12-17 by Jeff Heiss

I'm in the USA in Philadelphia. I understand the pros use spray etching. I
think I will look at other peoples spray setups and see what they have going
on.

Jeff

_____

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of cunningfellow
Sent: Sunday, December 16, 2012 6:46 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Bernoulli sprayer

>> Jeff Heiss wrote:
>> I like the splash etcher drawing. What
>> does SS stand for in the SS paddle?
>> How would you compare the performance
>> of a splash ether to other etch tanks
>> like wave, bubble, or spray?

> Andrew Volk wrote:
> My guess is that SS is Stainless Steel.

Re: Bernoulli sprayer

2012-12-17 by designer_craig

SS = stainless steel.

The Splash tank is about as agressive as a good spray tank and has more action than a bubbler. Wtih a spray thank you could do both sides at once. To do the same on a splash tank you need two dashers, one on each side of the board.

Craig

Show quoted textHide quoted text

--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:
>
> I like the splash etcher drawing. What does SS stand for in the SS paddle?
> How would you compare the performance of a splash ether to other etch tanks
> like wave, bubble, or spray?
>
>
>
> Jeff
>
>
>
> _____
>
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of designer_craig
> Sent: Sunday, December 16, 2012 1:23 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: Bernoulli sprayer
>
>
>
>
>
> Jeff,
> I built the tank back in 1975 and used it off and on for many years. Back in
> 2000 I was down sizing due to an upcoming move and got rid of it with a lot
> of other stuff. I could find no photos but I did draw up a sketch a while
> back. Go to the files section of the forum and look under Craigs-files. I
> used this etcher with annonium persulfate becasue I had an easy supply of
> the stuff. The company I worked for had a captive PCB shop and used the AP
> as part of the process. I had an imersion heater to get it up to the 140F
> etching temp. Fresh hot etchant would do a board is 30 to 60 seconds.
>
> Don' know if I would use it with Feric Chloride becasue of the mess that the
> stuff makes, stains everyting it touches. CuCL2 should work fine as well but
> out side because of the HCL fumes. AP is so clean to work with.
>
> There are photos of my spin coater and pcb drill in the photo section under
> Craigs photos
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff Heiss" <jeff.heiss@>
> wrote:
> >
> > Any pictures of your tank available?
> >
> >
> >
> > Jeff
>
>
>
>
>
> [Non-text portions of this message have been removed]
>