Bubble Etch Tank

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Alec Wright

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Aug 18, 2011, 7:01:45 PM8/18/11
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Seems to have run out of bubbles. It makes a whirring sound though and
gets hot
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Adrian Godwin

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Aug 22, 2011, 3:08:13 PM8/22/11
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Thanks for noting this, alec.

It's possible the tube has popped off the pump or one of the other joints. Could you follow the long PVC tube back to the compressor that's in the cupboard and find out ?

If the compressor has failed I have a spare.

-adrian

Charles Yarnold

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Aug 23, 2011, 6:07:42 AM8/23/11
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I have cleaned and changed the developer and its much happier now.

Had a quick look at the bubbles, didn't have enough time to fix it though.

We have replacement dev, etch, but need to order more stripper.

Sol

Adrian Godwin

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Aug 27, 2011, 4:33:29 AM8/27/11
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I had a look at this on Friday. The pump is working, but blowing air into the tube doesn't make bubbles come out. Air passes into the tube easily though, so I think the pipe has come undone on one of the joints (to antireturn valve and antisyphon device) up under the rim of the tank. The tank needs to be lifted out (which is pretty easy). I didn't have time to do that but will do if it's still not working next time I come in.

I also noticed :

The etchant level is very low and it looked extremely black. Etchant should almost fill the tank : too little can damage the heater. It's not quite that low but is approaching it. There's no benefit to half-filling the tank - it means there's less active etchant available so it will be exhausted more quickly, the board size limit will be smaller and there's a greater danger of exposing the heater. I mention this because Alec had been told by someone that half-full is correct and I'd like to clear up the misunderstanding (I think half-full is an absolute minimum).

The developer heater was on. Not left on and hot, but it came on with the power. As I understand it, the developer doesn't need heating. If someone has found that it does, it would be useful to add that to the wiki. The stripper heater was also on. I don't know whether this is useful or not. Again, more information would be useful.

-adrian

Alec Wright

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Aug 27, 2011, 4:37:13 AM8/27/11
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On Sat, 2011-08-27 at 09:33 +0100, Adrian Godwin wrote:
> I had a look at this on Friday. The pump is working, but blowing air
> into the tube doesn't make bubbles come out. Air passes into the tube
> easily though, so I think the pipe has come undone on one of the
> joints (to antireturn valve and antisyphon device) up under the rim of
> the tank. The tank needs to be lifted out (which is pretty easy). I
> didn't have time to do that but will do if it's still not working next
> time I come in.
>
> I also noticed :
>
> The etchant level is very low and it looked extremely black. Etchant
> should almost fill the tank : too little can damage the heater. It's
> not quite that low but is approaching it. There's no benefit to
> half-filling the tank - it means there's less active etchant available
> so it will be exhausted more quickly, the board size limit will be
> smaller and there's a greater danger of exposing the heater. I mention
> this because Alec had been told by someone that half-full is correct
> and I'd like to clear up the misunderstanding (I think half-full is an
> absolute minimum).
>
> The developer heater was on. Not left on and hot, but it came on with
> the power. As I understand it, the developer doesn't need heating. If
> someone has found that it does, it would be useful to add that to the
> wiki. The stripper heater was also on. I don't know whether this is
> useful or not. Again, more information would be useful.
>
> -adrian
>
>
The stripper heater sounds like a kettle and the stripper steams after
it's been heated. Not sure if this is normal.
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Russ Garrett

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Aug 27, 2011, 8:27:18 AM8/27/11
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On 27 August 2011 09:33, Adrian Godwin <artg...@gmail.com> wrote:
> The developer heater was on. Not left on and hot, but it came on with the
> power. As I understand it, the developer doesn't need heating. If someone
> has found that it does, it would be useful to add that to the wiki. The
> stripper heater was also on. I don't know whether this is useful or not.
> Again, more information would be useful.

When we set it up, I made sure that the set points for all the heaters
were correct (except the tinner which is no longer in use). IIRC the
developer heater is set to ~24 degrees which is the optimum
temperature for the developer. Probably not worth using the heater now
but in winter it's useful.

Resist stripper should be used at 45-50 degrees so that is correct.

--
Russ Garrett
ru...@garrett.co.uk

Adrian Godwin

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Sep 2, 2011, 2:08:04 PM9/2/11
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The problem with the etch tank is that the bubble bar is full of crud
and the air pressure blows the hose off.

I have emptied the tank and left it soaking in the hope it will clear,
but it's probably necessary to poke the holes clean.

The tank needs to be flushed regularly to avoid this happening.
Probably at a minimum when the etchant is changed, but maybe more
frequently (especially if it isn't used, unfortunately).

-adrian

Alec Wright

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Sep 4, 2011, 4:58:22 AM9/4/11
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Adrian, today I tested it out again after its soak and it still blew the
hose off.

I rinsed it out with water a couple of times and then with hydrochloric
acid twice. It seems to be working better now, I've just left it
bubbling away with a solution of hydrochloric and sulfuric acids in it
to hopefully clear it out a bit more.

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Mike Harrison

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Sep 4, 2011, 5:52:54 AM9/4/11
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I find it's easier to just drill a new set of holes.

It's such a hassle taking the bubble bar out that on my tank I've now fixed a new L shaped bubble
bar to the tank lid/basket for easier access.

Adrian Godwin

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Sep 4, 2011, 6:27:59 AM9/4/11
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>>I rinsed it out with water a couple of times and then with hydrochloric
>>acid twice. It seems to be working better now, I've just left it
>>bubbling away with a solution of hydrochloric and sulfuric acids in it
>>to hopefully clear it out a bit more.

Thanks, alec

On Sun, Sep 4, 2011 at 10:52 AM, Mike Harrison <mi...@whitewing.co.uk> wrote:
>
> I find it's easier to just drill a new set of holes.
>
> It's such a hassle taking the bubble bar out that on my tank I've now fixed a new L shaped bubble
> bar to the tank lid/basket for easier access.
>

Good idea. Putting the hose through the lid to supply that would
reduce the need for an antisyphon device, too.

-adrian

Alec Wright

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Sep 7, 2011, 9:04:32 AM9/7/11
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On 4 September 2011 09:59, Alec Wright <ale...@member.fsf.org> wrote:

> On Sun, 2011-09-04 at 09:58 +0100, Alec Wright wrote:
>> Adrian, today I tested it out again after its soak and it still blew the
>> hose off.
>>
>> I rinsed it out with water a couple of times and then with hydrochloric
>> acid twice. It seems to be working better now, I've just left it
>> bubbling away with a solution of hydrochloric and sulfuric acids in it
>> to hopefully clear it out a bit more.
>
> Actually it doesnt seem completely fixed. I'm going to leave it to soak
> in HCl for a few days.
>

That seems to have fixed it now. I've made up a new etchant solution
(the old one was getting a bit weak).

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