Homebrew PCBs

Hi Adam

>
>
>Markus Zingg wrote:
>> 
>> Acording to Bungard the etching process of THEIR machines is total
>> uniform - as oposed to the (el cheapo) machine I unfortunately first
>> bought. I must admitt though that I don't have first hand experience
>> with their machines. As soon as time permits - that's currently a bit
>> a problem :) - I will take a closer look at this. I may end up buying
>> one of those Bungard machines but we will see.
>> 
>
>
>What is the price of the Bungard etching machine ?

The MK2 costs EUR 249
the Turbo EZ is EUR 437 and 
the Turbo DZ is EUR 550

I haven't made up my mind yet wether I'm going to buy one of those or
not. I'm currently held busy elsewhere and will get back to this topic
and a decision as soon as time permits. I mean building one myself is
also going to cost money so the result of a homebuilt one either would
have to be better or then I must be sure that time and money will
result in a lower price (which based on the exeperience with building
the through plating machine I somehow doubht).

>> 
>> I totaly agree on this one. IMHO serious (fine artwork) kind of PCB's
>> can't be etched with those. I had one myself but it's sitting on the
>> shelf now.
>
>Yep. :)
>
>
>
>> I agree here too, but I think that the rotary principle is suffiently
>> good to do this. Again, I can't proofe this at the very moment.
>
>If you end up buying the machine please keep the group informed 
>on how well it works. I would be very interested to know.

Will do so.

>> This sounds like a good concept (and thanks for the pointer to the
>> nozzles).
>
>I actually put the wrong link to the nozzle. It should be
>http://www.bete.com/metric/products/pages/nf.htm
>At the moment I'm looking at getting a total of 6 x NF10 with 65 
>degree fan angle and in 303 stainless steel. Just confirmed the 
>price at AUD$10.45
>Because its an alkaline etchant I'm allowed to use stainless 
>steel. Let me know if you want to know more details on the 
>etching chemistry. It is electrically regeneratable.
>See http://www.elo-chem.com or google search "elo-chem"
>
>
>> Please keep us up to date on your progress. Etching is
>> really the only step left here that does not work too well at the
>> moment. 
>
>Yep, I know what you mean. Once you get everything else working 
>great, the quality of the etching step suddenly becomes an issue.
>
>>>I haven't yet found a solution for the pump.
>> 
>> Yes, I figure this is getting difficult. Have you ever considered
>> building the pump also? I was thinking about having a PVC tube formed
>> as a circle and then some kind of rotor equiped.....
>
>I know the pump your talking about. I read all the other replies 
>too. It appearing that the only pump to use is the magnetic drive 
>centrifugal pump. The one I have in mind is the MD-70RZ(T), see;
>http://www.iwakiwalchem.com/iwaki/literature/Specsheets/MD5570100.pdf
>My uncle is a sales rep for Iwaki pumps, so if he will discount I 
>will seriously think about taking the plunge.
>
>According to the graph it should pump 20 L/minute at 1.5 bar. 
>Using this information the nozzle type can be calulated.
>
>The challenge now is to design the spray nozzle configuration so 
>it etches uniformly. I've been told there is no simple solution 
>for working out all the variables. There are things such as the 
>number of nozzles, nozzle to nozzle spacing, distance from the 
>panel, amount of overlap of the spray pattern, the fan angle, the 
>jet incident angle to the panel, the linear sweeping speed of the 
>jets, ect. Its one of those things that you just have to play 
>with until you get it right. I might have to buy some cheap 
>phenolic copper clad to experiment with.
>
>Adam

The biggest chalange with home built machines that you design yourself
is  (IMHO) that you always must take the risk of buying parts to just
try if it works out well and there is some (not so low) percentage of
stuff that you buy where you end up with the conclusion that it does
not work well hence the money for it is most often lost. It's quite a
lot easier to build something after plans or such based on other
peoples experience than develop all by yourself although the latter is
undoubtly much more fun. 

With regard to the rotary spray etcher I really somehow doubht if it's
worth the effort to design one bymyself because the prices - although
not really cheap - are still in a range where building one myself
could turn out to be a bad deal. This was very different with the
through plating machine where nothing in a compareable pricerange (and
quality of course) was available. This statement is however not really
related to your plans of building the kind of machine you are thinking
of cause I do agree that this machine will be much closer to what they
use in professional board shops.

Markus