Using welder as power source for ECM
 

I'm thinking of picking up a cheap welder to use for a little
home-brewed electrochemical machining (aka electro-etching). Has
anyone tried this? Which would be more appropriate for this
application, a CC or a CV machine?

Thanks.
Bert

Bert wrote:

I'm thinking of picking up a cheap welder to use for a little
home-brewed electrochemical machining (aka electro-etching). Has
anyone tried this? Which would be more appropriate for this
application, a CC or a CV machine?

I believe that a transformer-based CV machine is basically a transformer with a
big capacitor bank. At any rate, my wirefeed has a bunch of honkers in it. CC
stick machines I believe have transformers that are wound to maximize
inductance. But either would work fine if you aren't suddenly varying the load.
The reason stick machines are CC is that if the weldor varies the arc the
current will try to stay as much as possible the same so the weld doesn't vary
as much. For a fairly constant load, I'd imagine either would work OK. What kind
of current and voltage are you looking for?

GWE

On Sat, 11 Jun 2005 19:11:58 +0000, Bert wrote:

I'm thinking of picking up a cheap welder to use for a little
home-brewed electrochemical machining (aka electro-etching). Has
anyone tried this? Which would be more appropriate for this
application, a CC or a CV machine?

Unless you mean "Electrical Discharge Machining", or EDM, you've
been seriously disinformed. Electro-etching takes milliamperes at
less than ten volts. You could do it with a couple of flashlight
batteries. If you're really talking about electro-etching, then I
might suggest that you might do a little studying on the subject.
http://www.google.com/search?q=electroetch

Electrical Discharge Machining, on the other hand, is one of the things
that drops my jaw in awe, and could, conceivably, take the kind of power
that's necessary for real welding.
http://www.google.com/search?q=%22el...e+machining%22

Thanks,
Rich

From a book entitled " Non-traditional machinging Procsesses ",
" The ECM process requires low voltage DC. Voltages from 5v to 15 v
are usually used but may go as high as 30 v in certain cases.
Currents from 100 to 20,000 amp are being used with even higher
currents being considered for the future.

A welder would have a higher voltage than you need, but might work for
doing some experimenting. You might also consider Microwave Oven
transformers with a rewound secondary.

Dan

Grant Erwin wrote:

Bert wrote:

I'm thinking of picking up a cheap welder to use for a little
home-brewed electrochemical machining (aka electro-etching). Has
anyone tried this? Which would be more appropriate for this
application, a CC or a CV machine?

I believe that a transformer-based CV machine is basically a transformer with a
big capacitor bank. At any rate, my wirefeed has a bunch of honkers in it. CC
stick machines I believe have transformers that are wound to maximize
inductance. But either would work fine if you aren't suddenly varying the load.
The reason stick machines are CC is that if the weldor varies the arc the
current will try to stay as much as possible the same so the weld doesn't vary
as much. For a fairly constant load, I'd imagine either would work OK. What kind
of current and voltage are you looking for?

GWE

At this point, I would guess somewhere between 10 and 50 V, and
probably 5-10A as a minimum, possibly much more depending on how much
area needs to be etched (and how patient I am). I expect some
experimentation will be involved. I may end up needing a step down
transformer to get the voltage in the right range.

Bert

" wrote:

From a book entitled " Non-traditional machinging Procsesses ",
" The ECM process requires low voltage DC. Voltages from 5v to 15 v
are usually used but may go as high as 30 v in certain cases.
Currents from 100 to 20,000 amp are being used with even higher
currents being considered for the future.

A welder would have a higher voltage than you need, but might work for
doing some experimenting. You might also consider Microwave Oven
transformers with a rewound secondary.

Dan

Those numbers seem in line with the info I've run across so far. The
industrial machines run with very small (sub-mm) gaps between
electrode and work. My setup will be a bit cruder with a substantially
larger gap, so I imagine I'll need to bump up the voltage quite a bit.
And I'll be working at lower currents, at least initially -- until I
get a handle on the process -- but I should still end up with much
higher material removal rates than during my earlier experiments with
a 12V/6A battery charger. I'll keep the microwave transformer in mind
in case the welder doesn't work out. Thanks.

Bert