I haven’t used a Mk2, but I have the Mk3Pro. (the high powered one.)
I use it mainly for reactive metals, which it does beautifully. In
point of fact, it’s much better at welding niobium than the Rofin
Starweld (the $30,000 one…) I used previously. (So, no, it’s not a
tack welder, and it’s not a toy.)
That being said, it does take a bit of getting used to, and it has
some issues with silver. (Yes, the 3Pro has enough power to weld
silver. Getting a decent bead is a trick I have yet to master, but
silver’s no treat with a laser either.) I hate to admit it, but I do
use it a lot for tacking things down before soldering, but it
seems silly to have the blinking thing and not use it for whatever I
can. I don’t do repairs generally, so I’ve never tried it with
retipping, or anything like that.
The one thing I really miss from a laser is the ability to open the
beam out and ‘smooth’ the weld. No such trick for the PUKs.
If you’re looking at buying one, get the pro, and get their
microscope. I already had a spare binocular microscope, so I decided
to save some money and just get a shutter to fit my existing scope.
Major pain, and I’m still not entirely happy with the results.
(entirely my own stupid fault. Get their scope. Trust me.) The pro
has more power than the standard Mk3. Definitely useful, both for
deeper welds, and faster cycle time between shots.
As far as the electrodes go, yeah, you chew them up. The good news
is that it’s possible to buy.020" Ceriated tig electrodes, and use
those. Much cheaper. I have a little jig I use to get a decent grind
on them on my power-hone. I normally sharpen up a whole batch of
them (say 20 or so) blow through both ends of all of them, and then
resharpen in one batch. Seems to save time. The good news, (such as
there is any) about the electrode points is that the duller the
point gets, the broader the weld bead becomes. (you loose depth)
there are some situations where a wide bead is more useful, so it’s
not entirely a bad thing. (And for some things, like tacking, you
just don’t care, so it’s a non-issue.)