How would /diy/ pump ferric chloride for spray etching? Any

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Imagine an impeller like this, but with a few neodymium magnets on the other side, which are attracted by matching magnets on a disc bolted to the HDD motor. I have a small pond pump that works by a similar principle. The impeller and the axle have no direct connection to the driving coils, so the water never gets in contact with the electronics inside it.

Teflon diaphragm pump? Bit expensive though.

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That impeller would then be stuck to one of the walls of a tank like this, which would also have other laser cut acrylic parts in order to function as a pump. At the top of the plate there would be several holes of small diameter, so that the pumped ferric chloride would spray against the board I'm currently etching. This would be repeated on the other side of the tank to etch double faced boards.

>>1084504

Hmm, some pond pumps have the magnets for the impeller completely encased in plastic. They might work out of the box.

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>>1084506
The professional etching machines use regular pumps but with coated inner surfaces. What I'm aiming for is something that could be made into a kit for hobbysts for really fast etching.

>>1084508

Mine does, but the axle is metal. I could replace it with a nylon or ceramic one, but what happens if the ferric chloride attacks the gaskets in the pump? It's fucking gone and I have an electrical short.

>>1084501
why spray the stuff when you can just bathe the board and use a heated magnestir

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Water cooling pumps are almost something I could use. The electrical parts never touch the impeller, but then again the axle is metal.

>>1084509
>>1084501

Look up the sponge method, it will literally speed up etching by 100x and requires a lot less solution.

https://www.youtube.com/watch?v=-2Ajlkik2nI

The only downside is that you need a physically strong resist that won't be wiped away from being rubbed with the sponge, so no permanent markers.

>>1084513
>heated magnestir

Because it will dissolve.

Also, spray etching is much faster.

>>1084510

Take gasket, throw it in the ferric chloride for a while and see if it survives. If not buy or make a gasket which can.

>>1084515
Also should add that they use peristaltic pumps when liquids have to be isolated.

https://en.m.wikipedia.org/wiki/Peristaltic_pump

>>1084518

Peristaltic pumps for dosing ferric chloride are OK, one with a high enough flow suitable for etching would cost as much or more than a teflon coated pump designed for pumping ferric chloride in factories

>>1084507
BTW, I just noticed this one has a piece in the bottom with channels, small holes and a connector with a tube that goes to an aquarium air pump. I think I might make mine like this.

>>1084516
how so? i've been using a glass dish & teflon coated magnetic stir bar for years & theres been no degradation on anything

>>1084520
>This

I use a plexiglass tank with air bubbler stone at the bottom. Also have enough room for a fish tank heater. Works like a charm.

>>1084555
Aren't fish tank heaters made to go only up to 30ºC or so? How long does it take to etch your boards?

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>>1084501
I use these for doping ferric on hot glass. All glass and plastic. Cheap. Works fine.

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use a peristalic pump

https://en.wikipedia.org/wiki/Peristaltic_pump

pic related

>>1084607
They break the tubing over time and the flow rate is really low.

>>1084608

replacing a tiny tube is better than replacing an entire pump due to failure

>>1084609
Why do you think I want to keep the pump motor outside the tank? If that tubing breaks it will spill ferric chloride everywhere, which will also destroy the pump.

Swamp cooler pump

>>1084610

well, dont know what else to suggest then.. try googling it them motherfucker. sheesh

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>>1084612

I only need to figure out an easy pump design to make out of acrylic.

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I think something like this would be ideal.

>mill impeller out of acrylic
>drill holes for small cylindric neodymium magnets
>put the magnets inside it
>cover the holes with epoxy so that it will be flush with the back of the impeller
>glue the pump cover to one of the walls with the impeller inside it
>attach the impeller driver to the other side
>control impeller speed with ESC
>pump will reliably pump forever
>if the motor breaks, just replace with another HDD motor

This would also work for the dry-film developing solution, I believe.

Why not a something like a paint sprayer or sand blaster that's basically a gun and hopper hooked up to an air supply from a compressor?
No moving parts- sand blasters have ceramic tips, most paint sprayers are aluminum with some rubber seals (which could easily be changed to something else).

Didn't man to sage, was left over from a bait thread on other board

Would making a pressure driven sprayer be out of the budget? Seems like pouring the chloride into a pressure tank that can take the acid and attaching an external airpump would be easiest. Then the corrosion never gets near the pump and you use all the same other equipment to apply it.

>>1084614
>easy pump design

If you're unable to find a easy solution, there might not be a suitable one (for stupid people like you at least).

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>>1084757

Some kind of air-lift pump that could be connected to a fishtank air pump would be good.

If it required a big ass compressor it would kind of defeat the purpose of having a small, light and inexpensive etching tank

>>1084780

It's merely a matter of there being no market for such a thing. The PCB manufacturing industry just pays out the ass for industrial equipment. The hobbyist is...well, just a hobbyist. And very few electronicfags, already a bit of a niche, are actually willing to go so far as make a spray-etch tank over simply hassling with or re-doing a fucked-up etch out of a bath now and then.

I'm actually in the same boat as OP (or will be, once I get a few other projects off the table), at least as far as needing an acid-proof pump. I mention this because, frankly, I'm astounded I actually heard of someone else looking to make an etchant tank pump WITHOUT having sought them out myself. Unlike OP, however, I have access to CNC equipment, so ease of manufacture is a non-issue.


For the record, OP, my current thinking has me just using a magnetically-coupled impeller on ceramic bearings. But I'm looking for a high-flow, low-pressure pump; the opposite of your needs. Might still work, depending on nozzle design and desired pressure.

>>1084813

Do you need the bearing, though? The impeller will just stay in the etchant and it will reduce friction by itself. All it really needs is a ceramic axle

bigclive on youtube had something like this, he openend up an led showerhead and its basically a motor with a magnetically coupled impeller, maybe you can use that to pump the liquid? only part exposed would be the impeller

the drain pumps for ice makers and some fish tank pumps are isolated from the metal, the motor shaft etc and use magnets.
The impeller and chamber part is made out of HDPE and HDPE is pretty solid against lots of shit.

More:
--air power your pump by tying 2 small shit impellor or water wheel style pumps back to back with air pushing, you can put the things in a tank of the shit so you don't need to worry if gaskets go to shit, just set up something to let air out of fluid line for when shit wears out if you need. or just make sure the air powered side is low pressure enough to not push air into the fluid line as seal goes bad.

Seals: Tried faucet packing teflon material? its like a thick wire of the stuff, but of course flexible as shit. Teflon might last.

I like that idea of a tank of the shit with an air pump pressurizing the space above it to push fluid into your hose.

I don't know what kind of pressure you need, if you get a shitty plastic centrifugal or impeller pump, replace shaft with plastic (you'll likely have to somehow key the shaft to make up for lack of metal fusing) and put the pump underwater, but shaft going up through top of reservoir tank motor could be mounted outside.

theres a few out of my ass at the crack of dawn

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>>1084855
forgot pic

>>1084856
and you can get glass straw, tube or pipe online cheap so that only the tubing downstream would be vunerable

>>1084856
How does the solution get back into the reservoir?

>>1084855

The problem isn't really the pressure. If the pump can elevate the fluid 30cm or so it has enough pressure to make it squirt through a few pin holes in the form of small droplets. It will etch the board faster than a bubble etch tank, and cheaper than a pro spray etcher.

I think the magnetically coupled impeller milled out of acrylic driven by an HDD motor should be enough. I need to do a proof of concept. I think that if I had the ESC I could drive the motor, and if I bought the magnets and paid someone to mill the impeller and pump cover it would probably work.

It could be turned into a commercial product, either as a complete kit the buyer could build on his own, or as a retrofit kit: glue the mag-drive centrifugal pump into one of the walls in your tank, stick the motor to the other side and there you go, your bubble etcher is now a spray etcher and you can do boards in less than 3 minutes, develop dry film, wash the board and do everything else, since the same pump will work for all of those tasks.

>>1084501

whats the speed difference between spray and just letting it dribble over the board ?

>>1084501
PERISTALTIC PUMP


If you need one right fucking now, you can pick one up at your local drug store in the form of a nerf super soaker. Otherwise just order one from china.

>>1084614
thingiverse might have one

>>1084608
How long do you need a pump to last really? Months of continuous use? It's not like OP is churning out pcbs on an industrial scale.
>>1084610
If you know when your tubing breaks, you can replace it before it fails.

Or what if you do this: what if you put your motor inside it's own tank


Also did you try googling ferric chloride pump? I found a bunch of DIY ones

>>1084969
>Also did you try googling ferric chloride pump?

Yes, they were all professional pumps coated with whatever or really stupid like pumping it directly with a windwasher pump (which has a metal axle)

>peristaltic pump

Flow rate is too low

>>1084591
Yea, the heater doesn't make it real hot, but better than room temp and I figure it helps replace some of the heat lost by the evaporation/bubbling process.
Time really depends on the board. But it's way faster than just leaving it sit. Never measured time, always went by a sample etching.

>>1084501
Do you have a compressed air supply? You could make a venturi pump out of plastic.

>>1085559
Nope.

I'll have one for an aerograph (when I buy one), I wonder if it would be powerful enough?

>spray etching
>perilstatic is not enough flow.
Wow you are fucking retarded dude seriously.
You don't deserve help desu

>>1085632
Show me a peristaltic pump that can actually be used for spray etching.

No one even uses them for pro etching, because it's a retarded fucking idea.

>>1085633
Literally any one you like 'could' be used with an appropriate nozzle.
They don't use them in commercial tanks because then they don't get to sell you a new bit when the old one breaks.
I use them all the time for pumping stuff that we simply aren't allowed to use other pumps for because of decontamination effort and cost.
Anyone with a holesaw, bit of plywood, handful of fucking skate bearings and you can make your own for practically nothing that will pump at whatever pressure or volume you dare to dream.
They are too easy to build and too easy to maintain. You would be stupid not to do it.

>>1085640
Bu..but muh unicorn pump

>>1085822
Great argument retard

>>1086068
Hey, I'm not the retard who thinks he's going to mill a complex shape out of a notoriously difficult to work with plastic, Not use an axial bearing, use a motor with completely wrong characteristics for the application, not even think about mitigating the drag in a shitty magnetic coupling, and rejecting good ideas because I'm sold on the idea that I am smarter that everyone else. But yeah I just took the bait from your dumb ass so I must be pretty stupid

>>1086412
And I forgot to sage.