I'd buy a used Millermatic 200 in good shape in a heartbeat. Damn fine
machine, but surely hard to find now. Not sure now about these. Changing
numbers and features every year. The 200 was made for quite a while, IIRC,
finally going to reversible polarity, then to digital controls.
Help me out here. I'm having a brain fart, but it won't come out.
Same current capability (250A @ 40% duty cycle, 200A @ 50% duty cycle) however
there are differences that you may find significant.
#1: the MM250 does not come from the factory equipped with the capability to
connect a spoolgun. You need a module, and those are no longer available from
Miller but there are some still around on shelves. A few years ago when I got
my MM250 I was able to find one (cost me $215.42 which I made back + more on
my first aluminum job). The spoolgun for any of these would be the 30A, which
is a fine quality pro gun.
#2: the MM250 has analog controls and the 251/252 are digital. For myself, I
didn't care, but then I got my welder with an S-sized owner cylinder of C25
for $550 so it was a deal I couldn't pass up.
#3: the MM252 (don't know about the 251, you don't buy those now anyway) allows
presettable preflow/postflow, burnback, spot and delay (stitch) timers. The
MM250 has none of these.
Ernie's former school had a bunch of MM250Xs, which were the first digital
250A welders from Miller, and found that they were essentially lemons. They
wound up trading them all back in and getting 251s. Ernie will tell you to
avoid 250Xs like the plague. That being said, I have seen them in pro welding
shops, so some of them must work OK.
Finally, let me say that I love my MM250. I have made a living with it for
a few years now. It has never once let me down. I upgraded the M25 gun to a
15' version of the same gun, and if I got a chance I'd upgrade to a 400A
Tregaskiss Toughgun as that gun is indestructible and can run 250A in spray
mode all day (not that the machine can do it!).
The Millermatic 35, 200, 250, 250X, 251, and 252 are all the same
output range, with an every evolving feature set.
The 250X, as Grant mentioned, is a lemon, due to a hot spike when you
first pull the trigger that tends to pop the wire back inside the tip
where it usually sticks.
Very frustrating on thin steel with small wires (0.030" or 0.035").
Not so bad with heavier wires.
The 251/252 are more advanced machines since they can work with a spool
gun to become a push-pull system, for aluminum MIG.
That was the best solution we found at South Seattle.
At DIT we have a Millermatic 300 from the same era as the 250X.
It also has a bit of the hot spike problem.
Not as bad as the 250X, but it does have it.
As long as you clip the wire every time, it works fine.
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