Homebrew_PCBs

On Tue, 15 Mar 2005 12:05:40 -0500, uhmgawa <uhmgawa@...> wrote:

>
> Alternatively to avoid intricate pump components having
> to withstand etchant corrosion it would be possible to
> use compressed air to pressurize a container of etchant
> located below board tank level. This again is not 100%
> duty cycle as the etchant must be allowed to gravity
> backflow to the etchant container when said container
> becomes empty. Achieving this could be as simple as locating
> a check valve in the backflow line and bleeding off the
> air pressure in the etchant container. The only thing
> required to automate the process is a float switch in the
> etchant container and a solenoid air valve to alternatively
> pressurize/bleed air to/from the etchant container.

Had the same idea a few days ago. However, will try rotational etcher
first.
Nozzles need quite a lot of volume.

ST

Resend, was dropped..

-------- Original Message --------
Subject: Re: [Homebrew_PCBs] Re:Sprayer pressure
Date: Mon, 14 Mar 2005 09:10:13 -0500
From: uhmgawa <uhmgawa@...>
To: Homebrew_PCBs@yahoogroups.com
References: <1110754728.436.94819.m12@yahoogroups.com> <4235544F.4080809@...>

RMustakos wrote:

> As far a nozzles go, in the US, Home Despot has started carrying 1/2 and
> 1/4 inch irrigation equipment, mass produced plastic (not sure what
> kind), with all sorts of nozzles - mist, 45, 90 180 and 360 sprayers,
> all for 5 for two dollars kind of prices. They screw right into 1/4
> inch tubing, and are made to screw into the side of 1/2 inch tube.

"A" for effort I'd say. However these sprayers are intended
for fluid dispersion in a flat horizontal fan pattern rather
than a projectile cone. Yet the fan nozzles found on
plastic hand-pumped bottle sprayers might be worth a try.
Garden chemical sprayers are another possibility as might be
aerosol can spray nozzles.

Speaking of which, as the fluid delivery doesn't need to be
100% continuous, has anyone given any thought to a piston
pump? Should be easy enough to machine from plastic tube
stock. If conventional o-rings will stand up to the etchant
that could be used as a seal. The other possibility is a
diaphragm pump similar to those used in high-end airless
paint sprayers which does achieve 100% duty cycle.

Alternatively to avoid intricate pump components having
to withstand etchant corrosion it would be possible to
use compressed air to pressurize a container of etchant
located below board tank level. This again is not 100%
duty cycle as the etchant must be allowed to gravity
backflow to the etchant container when said container
becomes empty. Achieving this could be as simple as locating
a check valve in the backflow line and bleeding off the
air pressure in the etchant container. The only thing
required to automate the process is a float switch in the
etchant container and a solenoid air valve to alternatively
pressurize/bleed air to/from the etchant container.

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


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

Stefan Trethan wrote:

> On Tue, 15 Mar 2005 12:05:40 -0500, uhmgawa <uhmgawa@...> wrote:
>
>
>>Alternatively to avoid intricate pump components having
>>to withstand etchant corrosion it would be possible to
>>use compressed air to pressurize a container of etchant
>>located below board tank level. This again is not 100%
>>duty cycle as the etchant must be allowed to gravity
>>backflow to the etchant container when said container
>>becomes empty. Achieving this could be as simple as locating
>>a check valve in the backflow line and bleeding off the
>>air pressure in the etchant container. The only thing
>>required to automate the process is a float switch in the
>>etchant container and a solenoid air valve to alternatively
>>pressurize/bleed air to/from the etchant container.
>
>
>
> Had the same idea a few days ago. However, will try rotational etcher
> first.
> Nozzles need quite a lot of volume.
>
> ST

I've spent six months (spare time project) building a spray etcher. From
what I've learned, about spray nozzles and spray pumps is they need at
least 1 bar to get reasonable spray patterns and distribution from the
nozzle. For anyone wanting a HCl/CuCl resistant pump capable of > 1bar
and not expensive then I suggest looking into FloJet recreational
vehicle pumps. The other competing brand is Shurflo, but DO NOT use
these pumps as they have a set of stainless steel screws that fasten the
pistons to the diaphragm. According to Shurflo customer support, all
models are constructed in the same way. The heads of the screw will
erode in several weeks as I found out the hard way. Fortunately I was
able to replace the screws with standard M3 machine screws which I
coated the heads in polyethylene plastic. My modified Shurflo pump has
now been operating for several months without problems. I believe the
FloJet brand do not suffer from this drawback as the pistons are
fastened using a different method. There is really no other alternative
to a pump suitable for a hobby spray etching tank. If not then I'd love
to know about it. The pumps are also available in slightly larger
versions intended for industrial use, but double the price.

My spray machine does 1 minute etch per side using CuCl, S.G=1.33, 25°C,
Cu foil thickness 35um, spray pressure 1.9 bar , pump 12.5V at 5.5 Amps
, 3 nozzles spanning a continuous line 300mm across the PCB.

http://www.flojet.com/prodInfoApp/servlet/DisplayProducts?typeId=FRQSP&page=0&catalogId=RV&categoryId=FRMPU&companyId=FLOJET

Adam

On Wed, 16 Mar 2005 09:13:17 +1100, Adam Seychell
<a_seychell@...> wrote:

> For anyone wanting a HCl/CuCl resistant pump capable of > 1bar
> and not expensive then I suggest looking into FloJet recreational
> vehicle pumps.

What is a recreational vehicle? (that term seems silly to me, a bike is a
recreational vehicle too and sure needs no pump.)
What are they used for most often?


The problem with a pump is that i would need to move the boards, or
nozzles, which did you do?

If my maths is OK then i will get a bar at 6000RPM with the rotary machine.
A few days ago i aimed the RPM meter at the proof of concept model and
measured 10000 RPM at a speed that wasn't frightening at all, i think even
more would be possible.
Maybe tomorrow i can do further testing, the lexan and titanium shaft is
already ordered but i have still much to test before it can be put to use.

thanks
ST

Stefan Trethan wrote:

> On Wed, 16 Mar 2005 09:13:17 +1100, Adam Seychell
> <a_seychell@...> wrote:
>
>
>>For anyone wanting a HCl/CuCl resistant pump capable of > 1bar
>>and not expensive then I suggest looking into FloJet recreational
>>vehicle pumps.
>
>
>
> What is a recreational vehicle? (that term seems silly to me, a bike is a
> recreational vehicle too and sure needs no pump.)
> What are they used for most often?
>
>
> The problem with a pump is that i would need to move the boards, or
> nozzles, which did you do?
>
> If my maths is OK then i will get a bar at 6000RPM with the rotary machine.
> A few days ago i aimed the RPM meter at the proof of concept model and
> measured 10000 RPM at a speed that wasn't frightening at all, i think even
> more would be possible.
> Maybe tomorrow i can do further testing, the lexan and titanium shaft is
> already ordered but i have still much to test before it can be put to use.
>
> thanks
> ST
>

I don't know, "recreational vehicle" is just the category they sell the
pumps under. You right, its kind of a broad meaning. The one I was
looking at a while back was this; Unfortunately I bought the Shurflo
instead.

http://www.flojet.com/prodInfo/overview/81000-233_ds.pdf

I agree that there would be more complexity using nozzles/pump sprayer
as either the nozzles or board must move. The concept I used was fix the
PCB horizontal at the roof of a sealed tank, and have the spray nozzles
direct upwards to the PCB. The nozzles are mounted to a pipe that has
wheels at each end. The wheels run along two tracks mounted at each side
of the tank. Drive mechanism consists of belts and a stepper motor
mounted outside the tank. A pulley and shaft mechanically driving the
tanks internal pulleys. If anyones interested I can take photos and put
then to the photo section at Yahoo Homebrew_PCBs.



Adam

Stefan Trethan wrote:

>
>
> The problem with a pump is that i would need to move the boards, or
> nozzles, which did you do?
>

I added some pictures of the etcher I made. Its under
Photos > Etching Equipment

http://photos.groups.yahoo.com/group/homebrew_pcbs/lst?.dir=/Etching+Equipment&.src=gr&.order=&.view=t&.done=http%3a//briefcase.yahoo.com/

Recreation vehicle = travel trailer/motorhome with self
contained utilities. The pump provides house pressure to
the sink/shower/toilet, etc. from an internal storage tank.

Norm

Adam Seychell wrote:

> Stefan Trethan wrote:
>
>>On Wed, 16 Mar 2005 09:13:17 +1100, Adam Seychell
>><a_seychell@...> wrote:
>>
>>
>>
>>>For anyone wanting a HCl/CuCl resistant pump capable of > 1bar
>>>and not expensive then I suggest looking into FloJet recreational
>>>vehicle pumps.
>>
>>
>>
>>What is a recreational vehicle? (that term seems silly to me, a bike is a
>>recreational vehicle too and sure needs no pump.)
>>What are they used for most often?
>>
>>
>>The problem with a pump is that i would need to move the boards, or
>>nozzles, which did you do?
>>
>>If my maths is OK then i will get a bar at 6000RPM with the rotary machine.
>>A few days ago i aimed the RPM meter at the proof of concept model and
>>measured 10000 RPM at a speed that wasn't frightening at all, i think even
>>more would be possible.
>>Maybe tomorrow i can do further testing, the lexan and titanium shaft is
>>already ordered but i have still much to test before it can be put to use.
>>
>>thanks
>>ST
>>
>
>
> I don't know, "recreational vehicle" is just the category they sell the
> pumps under. You right, its kind of a broad meaning. The one I was
> looking at a while back was this; Unfortunately I bought the Shurflo
> instead.
>
> http://www.flojet.com/prodInfo/overview/81000-233_ds.pdf
>
> I agree that there would be more complexity using nozzles/pump sprayer
> as either the nozzles or board must move. The concept I used was fix the
> PCB horizontal at the roof of a sealed tank, and have the spray nozzles
> direct upwards to the PCB. The nozzles are mounted to a pipe that has
> wheels at each end. The wheels run along two tracks mounted at each side
> of the tank. Drive mechanism consists of belts and a stepper motor
> mounted outside the tank. A pulley and shaft mechanically driving the
> tanks internal pulleys. If anyones interested I can take photos and put
> then to the photo section at Yahoo Homebrew_PCBs.
>
>
>
> Adam
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
>

--
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On Wed, 16 Mar 2005 13:44:08 +1100, Adam Seychell
<a_seychell@...> wrote:

>
> I agree that there would be more complexity using nozzles/pump sprayer
> as either the nozzles or board must move. The concept I used was fix the
> PCB horizontal at the roof of a sealed tank, and have the spray nozzles
> direct upwards to the PCB. The nozzles are mounted to a pipe that has
> wheels at each end. The wheels run along two tracks mounted at each side
> of the tank. Drive mechanism consists of belts and a stepper motor
> mounted outside the tank. A pulley and shaft mechanically driving the
> tanks internal pulleys. If anyones interested I can take photos and put
> then to the photo section at Yahoo Homebrew_PCBs.
> Adam

Thanks for the photos, wow, you certainly put a lot of work in that!
I think i might have seen pictures of your machine before, but then it was
still under construction?

It is HUGE now, it seems it lives outside? Not a problem with the weather?

ST

Stefan Trethan wrote:

> On Wed, 16 Mar 2005 13:44:08 +1100, Adam Seychell
> <a_seychell@...> wrote:
>
>>I agree that there would be more complexity using nozzles/pump sprayer
>>as either the nozzles or board must move. The concept I used was fix the
>>PCB horizontal at the roof of a sealed tank, and have the spray nozzles
>>direct upwards to the PCB. The nozzles are mounted to a pipe that has
>>wheels at each end. The wheels run along two tracks mounted at each side
>>of the tank. Drive mechanism consists of belts and a stepper motor
>>mounted outside the tank. A pulley and shaft mechanically driving the
>>tanks internal pulleys. If anyones interested I can take photos and put
>>then to the photo section at Yahoo Homebrew_PCBs.
>>Adam
>
> Thanks for the photos, wow, you certainly put a lot of work in that!
> I think i might have seen pictures of your machine before, but then it was
> still under construction?
>
> It is HUGE now, it seems it lives outside? Not a problem with the weather?

He's a smart cookie;)

Stefan Trethan wrote:

> On Wed, 16 Mar 2005 13:44:08 +1100, Adam Seychell
> <a_seychell@...> wrote:
>
>
>>I agree that there would be more complexity using nozzles/pump sprayer
>>as either the nozzles or board must move. The concept I used was fix the
>>PCB horizontal at the roof of a sealed tank, and have the spray nozzles
>>direct upwards to the PCB. The nozzles are mounted to a pipe that has
>>wheels at each end. The wheels run along two tracks mounted at each side
>>of the tank. Drive mechanism consists of belts and a stepper motor
>>mounted outside the tank. A pulley and shaft mechanically driving the
>>tanks internal pulleys. If anyones interested I can take photos and put
>>then to the photo section at Yahoo Homebrew_PCBs.
>>Adam
>
>
>
> Thanks for the photos, wow, you certainly put a lot of work in that!
> I think i might have seen pictures of your machine before, but then it was
> still under construction?
>
> It is HUGE now, it seems it lives outside? Not a problem with the weather?
>
> ST

When I was designing the tanks, I always had the intention of it living
outside, since something this big would take up to much valuable garage
space. Installing it somewhere like the bedroom or kitchen is not
something even I would attempt. Because PCB fabrication is a wet process
, it seemed only natural to make the equipment survive the outdoors.
All metal fasteners, hose clamps, mounting brackets, et, are stainless
steel/or aluminum, while all the plastics are UV resistant, and the wood
has five coats of paint :) Maximum PCB panel size is A4 (300x200mm).
BTW, there is still more work to do on the PTH chemistry and many other
little problems to fix.

On Wed, 16 Mar 2005 20:51:41 +1100, Adam Seychell
<a_seychell@...> wrote:

>
> When I was designing the tanks, I always had the intention of it living
> outside, since something this big would take up to much valuable garage
> space. Installing it somewhere like the bedroom or kitchen is not
> something even I would attempt. Because PCB fabrication is a wet process
> , it seemed only natural to make the equipment survive the outdoors.
> All metal fasteners, hose clamps, mounting brackets, et, are stainless
> steel/or aluminum, while all the plastics are UV resistant, and the wood
> has five coats of paint Maximum PCB panel size is A4 (300x200mm).
> BTW, there is still more work to do on the PTH chemistry and many other
> little problems to fix.

Well, it seems _very_ complex from the pictures (and PTH explains some of
it).

Way more than i need for now, for sure.

What i meant with the weather was mainly temperature, you couldn't leave
something like that outdoors in the winter here, it would freeze. (not to
speak of how hard it would be to etch a PCB with snow on the unit).

I assume the climate where you live is different and allows that.

Very nice work though...
How is the uniformity of the spray-etch?
What's your etch time?

ST

> Well, it seems _very_ complex from the pictures (and PTH explains

some of it).

> Way more than i need for now, for sure.

Don't know if you have seen this, but it might give you some ideas?
www.radixgmbh.de/d_101_Radix_Spruhatzer_DuoSpray227.htm


Regards
James

On Thu, 17 Mar 2005 15:13:22 -0000, James RM <tvi@...> wrote:

>
> Don't know if you have seen this, but it might give you some ideas?
> www.radixgmbh.de/d_101_Radix_Spruhatzer_DuoSpray227.htm
> Regards
> James

I was aware of that, thanks.
I'm actually making a very similar machine with a few changes.
What i don't like about the commercial machines is the poor bearing
situation and motor parts possibly exposed to etchant.

You can buy ready-made sprayers at ebay germany, which look much nicer
than the one from radix (tupperware box??). Also, they are cheaper. They
would not have been too expensive for me, but i simply think there are a
few things i would like different.

thanks
ST