Miller 375 X-treme Plasma Cutter

Cheap, fun, and easy – yup it’s what I shopped for in a prom date, unfortunately I never got all three. In the case of the Miller Spectrum 375 X-treme plasma cutter you get exactly that. While cheap is a relative term, the cost of owning a plasma cutter has dropped by about 50% in the last few years. As far as fun goes, if you can dream it up, you can cut it with this machine, from brackets, tabs, and frame work, to decorative household items for the Mrs., the Miller Spectrum 375 X-treme takes the guess work out of cutting altogether. With its simple multi-voltage plug, auto air regulator, and built in thermal protection, this little blue beauty couldn’t be easier.

The Miller Spectrum 375 X-treme lives us to its name and is truly the mighty-might of the plasma cutting world. It measures a svelte 13”x8”x6” and tips the scales at a feather-weight 18 pounds. But don’t let its size fool you, this little blue devil will easily slice through thick metal that bigger, more expensive units will struggle with. It’s so light and small, that Miller provides a shoulder strap attachment to allow you to tote it around the job site with you. Portable, powerful and limited only by your power and air connections. 

The Miller Spectrum 375 X-treme plasma cutter ships in a durable plastic carrying case that has room to hold spare parts, manuals, accessories and more. The Miller Spectrum 375 X-Treme is also big on versatility too, with a very innovative multi-voltage, twist-lock plug, allowing it to be used with both 110 volt and 220 volt power sources. 

Another nice feature of the Miller 375 X-treme is that it operates without high frequency, thus no need to unplug computers or worry about ruining digital controls as in the past. 

Features at a glance: 

• Connects to either 110 or 220 VAC by simply changing plug ends  
• Convenient carrying case with enough room to bring extra parts, MVP plugs, consumable box, gloves, eye protection, etc.
• Weighs in at 18 pounds - need we say more? 
• LVC™ (line voltage compensation) provides peak performance power under variable conditions (power fluctuations up to +/-15%) for steady cuts and cleaner ending cuts.
• Convenient LED indicators for pressure, power, cup and temperature
• Ergonomic torch with safety trigger, and improved swirl ring and cup.
• Standard air connection on back panel for easy gas or air hookup.
• Factory pre-set air – no need to adjust the air pressure. Unit automatically regulates the proper internal air pressure to the torch.
• Gas/air filter/regulator inside the power source provides added protection during transportation.
• Starts without high-frequency so it will not interfere with or damage controls or computers.

The Test

We sparked up our Miller 375 X-treme plasma cutter and first tested how it dealt with varying air supplies. The 375 X-treme requires 4.5 cfm @ 90 psi to operate, which is well within the limits of most medium-sized 110v hobbyist air compressors. Our first test was done with a 2 hp 33 gallon 110V Craftsman compressor that was rated at 6.2 cfm @ 90 psi and the 375 X-treme performed just fine. Our second test was conducted using 5 h.p. 80 gallon 220v compressor rated at 9.2 cfm@ 90 psi. The Spectrum 375 X-treme performed with no noticeable difference between the two compressors, only that the larger compressor kicked on only once during use and turned back off after a minute or so. The smaller compressor kicked on after only 30 seconds of cutting and ran continuously during use, but never fell behind or affected the Spectrum 375 X-treme’s function.
 
Our next battery of trials focused on the variances between 110V and 220V power sources and to see how each would affect its cutting capabilities. We plugged the Miller Spectrum 375 X-treme plasma cutter into the ol’ 110 outlet and pulled out a piece of ½” plate steel. We cranked the plaz cutter up to the 110V max setting and let her rip. It did indeed cut through ½” plate just fine, but we had to move very slowly. The cuts were even and with minimal slag considering the thickness of the steel we were cutting.  We pushed the machine to its 110v limits and found that it performs exactly as advertised.
 
The Miller 375 X-treme is only rated to sever 5/8” and will cleanly cut ½”, so I decided to get a piece of ¾” plate, crank the little machine on high while plugged into 220v, and see what it could do. The 375 X-treme tried as best it could, but it couldn’t get through the ¾” steel in one pass, and just made a nasty gouge in the plate. It did however buzz right through ½” plate repeatedly with no problems.
 
Our next test was to check the Miller’s duty cycle, so I started repeatedly cutting 1-foot sections out of ½” plate. After a few foot-long passes, the 375 X-treme simply paused for 20 seconds or so with the thermal light lit on the front panel, and then went right back to cutting with no problems. 
 
We also tested to see how cleanly it would cut thin metal when using a roller guide. In essence, we wanted to see if we could make a slag-free cut with the machine. We then chocked up a piece of 10-gauge steel and made a fast pass at it. The Miller 375 Xtreme made a cut so smooth, that it might be mistaken for a shear cut – very nice.

Our last test was to actually put the Miller Spectrum 375 X-Treme plasma cutter to work on a real project. As is often the case, I jabbed and ribbed the boss just enough to get him to do something that he wouldn’t normally do, such as cutting into the pristine fenders on his ’74 FJ40 Land Cruiser. He’s been whining about building a set of more durable tube-fenders anyhow, and I just needed to push him over the edge.  Rick was a bit apprehensive, but once the cut lines were drawn on the fenders, and the Miller 375 X-Treme was up and running, he sliced through his pristine Land Cruiser with reckless abandon.  The Spectrum 375 X-Treme cut perfectly clean lines in the fenders and barely disturbed the paint.  Care must be taken when cutting thin metal such as fenders, as a slight bobble, twitch or sneeze will take off metal you wanted to leave attached.  Even in the hands of novice users such as Rick and I, the Miller Spectrum 375 X-treme made us look like pros. 

Preparing the boss’ fenders by grinding away the paint to secure a good ground.	A last glance before it begins.	Making the first cut. Hand-controlled cutting with the torch works well, but the smallest movements translate into cut metal immediately.
Using a wheel-guide, the plasma cutter makes very straight, precise cuts.	4″ of pristine FJ40 fender now relegated to the scrap heap.	Notice how the paint is barely disturbed and how clean the cuts are. With a steady hand or a roller guide, there is no slag and no metal to clean up.

The Verdict 

The Miller 375 X-treme plasma cutter is so small, it’s almost cute (I get to keep my man card even though I just called a tool “cute”, because I’m actually using a manly plasma cutter). But don’t let the size fool you – this is a powerful plasma cutter that can just as easily be used by a weekend hobbyist as it can by a professional metal worker. It’s powerful, accurate, precise and very user-friendly. There is only one adjustment to be made on the Miller 375 X-treme, which is the power setting – everything else is regulated automatically by the plasma cutter itself – a very handy feature. The LED indicators for pressure, power, cup and temperature allow faster troubleshooting, but we we only able to get the air pressure light to come on when deliberately dropped the air pressure.
 
The Miller 375 X-treme plasma cutter rips through its rated metal thickness like a frat boy through a freshly tapped keg. It’s light enough to be set on top of a work bench and the power cord and hoses are long enough for it to be set far away from the work being accomplished.
 
Overall, if you are looking for a portable machine with more than enough power to handle just about anything on your rig, around your house or even on most job sites, then the Miller 375 X-treme plasma cutter might be just what you need. For the price, convenience, simplicity, portability, and power this little guy will be in my shop for a long time.  
 
At time of publishing, the Miller 375 X-treme plasma cutter will set you back about $1,600 (we bought on eBay for about $1,300 with free shipping), which is right inline with other comparable units.