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Magnetic Drive Etchant Pump

C

Chris Jones

Jan 1, 1970
0
D

D from BC

Jan 1, 1970
0
How about an aquarium pump with all plastic parts?

Good Luck!
Rich

Yeah...I spotted some mag drive aquarium pumps on the net. I suspect
they're good for salt water aquariums. All plastic inside.

I did try pumping etchant with a scrap car windshield wash pump....I
don't know if I burned out the motor due to overheating or the etchant
messed up the mechanics..
I got the motor smokn hot...
I should have cracked open the pump to find out what failed.

I wonder if a 12V windshield wash pump can be submersed in cold fresh
water (or oil) for more continuous lifespan.


D from BC
 
R

Rich Grise

Jan 1, 1970
0
Yeah...I spotted some mag drive aquarium pumps on the net. I suspect
they're good for salt water aquariums. All plastic inside.

I did try pumping etchant with a scrap car windshield wash pump....I
don't know if I burned out the motor due to overheating or the etchant
messed up the mechanics..
I got the motor smokn hot...
I should have cracked open the pump to find out what failed.

I wonder if a 12V windshield wash pump can be submersed in cold fresh
water (or oil) for more continuous lifespan.

No. Even submerged, washer pumps aren't rated for continuous duty.

And it'd have to be submerged in the etchant, so it would eventually
disappear anyway. ;-)

Good Luck!
Rich
 
B

Barry Lennox

Jan 1, 1970
0
It's for agitation and flow...
I'd like to try to get a river of etchant flowing down the board.
I think I read somewhere that there's a risk of over-etch.
However, I'm not making brain implants.

Spraying would be more pro but I don't think I need my boards that
good.. A little rework is tolerable.

I'm interested in using minimal amounts of etchant that way I don't
have to play with a tank.
It's safer and quicker to handle small amounts of etchant..

I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

Heating of the tank and etchant was done by a sheet of about 3mm alloy
held against one glass side with plastic clamps.The other side of the
alloy sheet has about 10-12 WW power resistors epoxied to it, these
are connected to a variable DC supply set to provide whatever heat is
required.

The PCB is lifted out via a length of thin fishing line attached to a
tiny hole in one corner.

It was important to have a solid lid, otherwise the room filled with
etchant vapour.

Barry
 
L

ludo

Jan 1, 1970
0
I'm currently looking around for a mini magnetic drive pump to pump
etchant..

Kinda like this
http://www.petsolutions.com/Mag-Drive-Water-Pumps+I25002515+C49.aspx

Any pointers?
D from BC

I've been using things like these:
http://www.commodityaxis.com/ProductData.aspx?id=49 model VA80 etc. Found
at pet shop here for a similar price (~$10). Internally, the magnet runs
on a stainless steel pin, which does corrode away eventually. I use it
maybe twice a month and they last about 2-3 years. If you go this way,
wash the innards carefully after etching and do add some oil on the pin
when it's in storage.

I park it in a shallow glass bowl next to the pcb, and put a piece of 8mm
fuel hose on the exit and loop it back down so it points at the pcb. 30mil
tracks are no problem. My artwork doesn't allow much better, usually.

Haven't tried floating the pcb as recommended by others here, but will now.

L
 
N

Nico Coesel

Jan 1, 1970
0
Rich Grise said:
No. Even submerged, washer pumps aren't rated for continuous duty.

And it'd have to be submerged in the etchant, so it would eventually
disappear anyway. ;-)

And don't forget about Nylon. Ferric Chloride also attacks Nylon.
 
D

D from BC

Jan 1, 1970
0
On Fri, 10 Aug 2007 08:40:53 +1200, Barry Lennox
I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

Heating of the tank and etchant was done by a sheet of about 3mm alloy
held against one glass side with plastic clamps.The other side of the
alloy sheet has about 10-12 WW power resistors epoxied to it, these
are connected to a variable DC supply set to provide whatever heat is
required.

The PCB is lifted out via a length of thin fishing line attached to a
tiny hole in one corner.

It was important to have a solid lid, otherwise the room filled with
etchant vapour.

Barry

I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

_______ __
/______/| _/ 6mm
| ||
|/\/\/\||
| * * ||
| * * ||<leak
|=============tube====<aquarium air pump>

The tube is the bubbler and also the tank bottom end piece.
D from BC
 
D

D from BC

Jan 1, 1970
0
I've been using things like these:
http://www.commodityaxis.com/ProductData.aspx?id=49 model VA80 etc. Found
at pet shop here for a similar price (~$10). Internally, the magnet runs
on a stainless steel pin, which does corrode away eventually. I use it
maybe twice a month and they last about 2-3 years. If you go this way,
wash the innards carefully after etching and do add some oil on the pin
when it's in storage.

I park it in a shallow glass bowl next to the pcb, and put a piece of 8mm
fuel hose on the exit and loop it back down so it points at the pcb. 30mil
tracks are no problem. My artwork doesn't allow much better, usually.

Haven't tried floating the pcb as recommended by others here, but will now.

L

I checked out that link..Looks like a fresh water pump....

I think the salt water pet pumps have a better chance at being
nonreactive to etchant.
Like on:
http://www.aquariumproducts.com.au/category50_1.htm
"Magnetic Drive pumps are ideal for salt water aquariums and live fish
holding tanks. These true Mag-drive pumps are completely sealed and do
not have shaft seals to wear out. Only a single casing O-ring is used
and prevents the liquid from leaking. They are manufactured using the
latest engineering plastics to prevent corrosion. The permanently
split capacitor start ( PSC ) motors are totally enclosed fan cooled (
TEFC ).Continuously rated, Class E insulation, Thermal overload
protection and suitable for indoor use."

D from BC
 
J

John Popelish

Jan 1, 1970
0
D said:
On Fri, 10 Aug 2007 08:40:53 +1200, Barry Lennox


I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

_______ __
/______/| _/ 6mm
| ||
|/\/\/\||
| * * ||
| * * ||<leak
|=============tube====<aquarium air pump>

The tube is the bubbler and also the tank bottom end piece.
D from BC

If you can come up with a way make it entirely of glass and
silicone tub caulk (the kind that stinks of acetic acid),
you should be able to make a very stable assembly. Glass
and silicone bond to each other very strongly.
 
B

Barry Lennox

Jan 1, 1970
0
On Fri, 10 Aug 2007 08:40:53 +1200, Barry Lennox


I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

Agreed, That's exactly why the whole thing is made from glass. No
plastic-RTV bond anywhere.

The only tricky bit is drilling the glass tube, but it can be done
with the right drill, care and a little practice helps too.

I also have a friend who blows glass for a uni lab. He reckons it's
easier to heat the glass tube where you want the hole, and just pick a
little hole out with an old nail or similar. Sounds doable but messy
to me.
 
R

Rich Grise

Jan 1, 1970
0
Agreed, That's exactly why the whole thing is made from glass. No
plastic-RTV bond anywhere.

The only tricky bit is drilling the glass tube, but it can be done
with the right drill, care and a little practice helps too.

I also have a friend who blows glass for a uni lab. He reckons it's
easier to heat the glass tube where you want the hole, and just pick a
little hole out with an old nail or similar. Sounds doable but messy
to me.

It sounds to me like it'd be much less messy than drilling! You'd need
a sufficiently small flame, of course, and use Pyrex so it doesn't
crack from the differential expansion. (or is that a dumb thing to say
because it's so glaringly obvious?) :)

Cheers!
Rich
 
B

Barry Lennox

Jan 1, 1970
0
On Fri, 10 Aug 2007 08:40:53 +1200, Barry Lennox
[snip]
I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

Heating of the tank and etchant was done by a sheet of about 3mm alloy
held against one glass side with plastic clamps.The other side of the
alloy sheet has about 10-12 WW power resistors epoxied to it, these
are connected to a variable DC supply set to provide whatever heat is
required.

The PCB is lifted out via a length of thin fishing line attached to a
tiny hole in one corner.

It was important to have a solid lid, otherwise the room filled with
etchant vapour.

I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

Agreed, That's exactly why the whole thing is made from glass. No
plastic-RTV bond anywhere.

The only tricky bit is drilling the glass tube, but it can be done
with the right drill, care and a little practice helps too.

I also have a friend who blows glass for a uni lab. He reckons it's
easier to heat the glass tube where you want the hole, and just pick a
little hole out with an old nail or similar. Sounds doable but messy
to me.

It sounds to me like it'd be much less messy than drilling! You'd need
a sufficiently small flame, of course, and use Pyrex so it doesn't
crack from the differential expansion. (or is that a dumb thing to say
because it's so glaringly obvious?) :)

Quite probably, but I'd give the whole job to my friend, he reckons
it's less than a 10 minute job !

Barry
 
D

D from BC

Jan 1, 1970
0
40:53 +1200, Barry Lennox
[snip]
I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

Heating of the tank and etchant was done by a sheet of about 3mm alloy
held against one glass side with plastic clamps.The other side of the
alloy sheet has about 10-12 WW power resistors epoxied to it, these
are connected to a variable DC supply set to provide whatever heat is
required.

The PCB is lifted out via a length of thin fishing line attached to a
tiny hole in one corner.

It was important to have a solid lid, otherwise the room filled with
etchant vapour.

I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

Agreed, That's exactly why the whole thing is made from glass. No
plastic-RTV bond anywhere.

The only tricky bit is drilling the glass tube, but it can be done
with the right drill, care and a little practice helps too.

I also have a friend who blows glass for a uni lab. He reckons it's
easier to heat the glass tube where you want the hole, and just pick a
little hole out with an old nail or similar. Sounds doable but messy
to me.

It sounds to me like it'd be much less messy than drilling! You'd need
a sufficiently small flame, of course, and use Pyrex so it doesn't
crack from the differential expansion. (or is that a dumb thing to say
because it's so glaringly obvious?) :)

Quite probably, but I'd give the whole job to my friend, he reckons
it's less than a 10 minute job !

Barry

I had my polycarbonate pieces cut by laser within 10 minutes.
It's one of the main reasons why I like polycarbonate projects.


D from BC
 
C

Chris Jones

Jan 1, 1970
0
Rich said:
On Fri, 10 Aug 2007 08:40:53 +1200, Barry Lennox
[snip]
I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

Heating of the tank and etchant was done by a sheet of about 3mm alloy
held against one glass side with plastic clamps.The other side of the
alloy sheet has about 10-12 WW power resistors epoxied to it, these
are connected to a variable DC supply set to provide whatever heat is
required.

The PCB is lifted out via a length of thin fishing line attached to a
tiny hole in one corner.

It was important to have a solid lid, otherwise the room filled with
etchant vapour.

I tried something similar except I made it out of polycarbonate and
sunk the thing in a bath of hot tap water.
The bubbler was a polyethylene tube at the bottom with holes punched
in it.

Etchant leaked out from around the tubing.
I tried to silicone seal around polyethylene tubing...Futile... :(
I might get it going again once I glueweld in some polycarbonate
tubing.

Agreed, That's exactly why the whole thing is made from glass. No
plastic-RTV bond anywhere.

The only tricky bit is drilling the glass tube, but it can be done
with the right drill, care and a little practice helps too.

I also have a friend who blows glass for a uni lab. He reckons it's
easier to heat the glass tube where you want the hole, and just pick a
little hole out with an old nail or similar. Sounds doable but messy
to me.

It sounds to me like it'd be much less messy than drilling! You'd need
a sufficiently small flame, of course, and use Pyrex so it doesn't
crack from the differential expansion. (or is that a dumb thing to say
because it's so glaringly obvious?) :)

Actually I would not use Pyrex - you need to get it much hotter than
ordinary (soda) glass in order to melt it. Think oxy-torch instead of
Bunsen burner. And it can still crack if you don't cool it slowly and
gently. Quartz has a really low coefficient of thermal expansion, but then
that is even harder to melt than Pyrex.

Chris
 
B

Benj

Jan 1, 1970
0
Barry said:
I saw a very effective etching tank that used minimal etchant. It was
a *very* thin vertical tank made from two sheets of glass, but the
side "walls" were only strips of glass. 5 mm thick. The cunning part
was the bottom was 5 mm dia glass tube, with about 10 holes drilled
along it's length. One end was blocked off, and the other fed, via PVC
tubing, from an aquarium pump.

The drilling took some time and care with a special glass drill (Lee
Valley has them) but it was the only tricky part of the whole tank,
and the results were worth it.

It was all bogged together with RTV intended for aquarium tank
construction.

You guys are making this ALL to complex!

I've got LOTS of etching tank setups. Cheap and effective. I build a
tall thin (about 1 inch gap) somewhat wider than the circuit board
you wish to etch out of plexiglas. Make it rather taller than the
boards. It's easy to glue with solvent glue and you put a couple of
cross pieces on each end for feet. Fit a L shaped piece of PVC pipe
(capped) into the bottom and up the side. Drill two rows of small
holes in the bottom leg. (Use a PC board drill! ... You ARE making
PCBs right?) down one side of the tank (inside) you hang a glass fish
tank heater to heat the etchant. These heaters usually have a temp
control which you turn up to get some decent heat. Supply some air to
the bottom pipe from say an air brush pump and you are in business!
The bubbler etches nicely (works better with other etchants than
Ferric Chloride but does work with that too.) Basically just a plastic
tank partly filled with etchant covering the board, heated with the
heater and stirred with bubbles. Build one, you'll love it.

Yeah, they get all stained with ferric Chloride after a while but who
cares the things cost very little to make if you have some access to
plastic scraps of some kind. Glass? We doan need no stinking glass!
Just make sure the seams are nice and tight all around before you
start to try it with etchant.

OR if you insist, my previous setup was a pyrex baking dish mounted on
a hotplate for heating which was mounted on a pivoting board and
gearmotor that gently rocked the dish so etchant sloshed form one end
to the other. Believe me the bubbler is MUCH better!

Benj
 
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