Miller Dynasty 400 Review – An Absolute Beast

Miller Dynasty 400 Review

The big dog for TIG applications, the Miller Dynasty 400 is truly top of the line in every sense. We are lucky enough to have one of these in our shop, and we’ve gotten a lot of use out of it. This article will cover our thoughts on this brilliant machine, and if it’s worth the hefty price tag.

The Dynasty machines are a great line of TIG welders, but many shops don’t have the need for a 400-amp beast. The 210 and 280 Dynasty’s are more commonly seen in shops, and they can handle plenty of large jobs in their own right. They are also much cheaper than the 400.

Miller Dynasty 400 In Action
Aluminum Golf Cart Repair With The Dynasty 400

Dynasty 400 – High Amperage Applications

In our shop we do a ton of high amperage TIG welding. We build ski racks with heavy walled aluminum, and often have the machine set at 300 amps. We also do a lot of heavy repair work that requires high amperages. The Dynasty tackles these projects with ease, and never overheats on us.

The problem with a lot of lower end TIG machines is that they don’t perform well with high heat applications. Some machines are capable, but the duty cycles are atrocious. They overheat within a few minutes of welding and take a while to cool down.

At 250 amps, the dynasty 400 has a 100% duty cycle – which means it can weld indefinitely without needing to cool down. At 300 amps, it has a 60% duty cycle – which means it can weld for 6 out of 10 minutes before needing to cool down. Once you reach 400 amps, you can only weld for short periods before it needs a rest, but we rarely use the full 400 amps for day to day projects.

The Dynasty 400 also features a high-end power management technology. This means that it can be plugged into power sources from 208 volts to 575 volts. This is ideal for welders with different power outlets at their shop, and allows you to run the machine smoothly in many situations.

Wireless Control

Our Dynasty machine model is the full wireless setup version. It sits on a nicely fabricated cart runner that can be wheeled around easily. The “Coolmate” 3.5 water cooler sits below the machine and is capable of cooling torches with ratings up to 600 amps. It has a 3.5 gallon capacity, and is best utilized with Millers specialty coolants instead of plain distilled water.

The 400 also has a dedicated 120 volt outlet to power the attached Coolmate. When you switch the machine on, it will begin starting  the water cooler instantly. Additionally, the dynasty 400 only runs the Coolmate when it is necessary. This saves power because the water cooler isn’t constantly running when it doesn’t need to be. It will only cool your torch when it detects that you are actually welding.

The wireless foot pedal has changed the game for us and makes TIG welding so much more enjoyable. Gone are the days of tripping over the wire or getting it wrapped around objects.

Aluminum TIG Beads
Aluminum TIG With The 400

The foot pedal is robust yet lightweight, and it cuts out extra wires that can get in the way for shop workers. It sends instantaneous signals to the 14 pin connector attached to the machine – it is always super accurate. The cart has its own slot where the foot pedal can be stored safely while not in use.

We do recommend being careful with the pedal, as the setup costs about an extra thousand dollars. It is durable and gets knocked around sometimes, but we make sure not to be too rough with it.

Arc Characteristics/Settings

The TIG arc on the Dynasty 400 is amazing. It really shows how mediocre some lower end machines are. It is buttery smooth and it is something that you just have to try for yourself.

We have found that the arc characteristics on aluminum is where the machine really shines, even with straight argon gas. When you pair helium with the 400, it can produce some incredible looking welds. We tend to stick with argon because helium is a lot more expensive. With the amount of cylinders we go through, we like to save some cash by not buying helium all the time.

For aluminum, this machine has an extended AC balance which dictates how much cleaning action is employed. Cleaning action is essential for aluminum welding, and better cleaning rates lead to higher quality welds.

This machine also has some insane settings – to the point where I can’t even understand when they would be necessary. The pulse controls on the DC side are ridiculous. It has infinite pulse settings and can perform pulses up to 5000 times per second. I wouldn’t recommend that for the sake of your long term vision, but it is capable of it.

On the AC side of things, Miller has added advanced waveform technology. These new additions mean that the Dynasty has a faster freezing aluminum puddle, deeper penetration, and quick travel speeds. The wetting action is remarkable, and you will notice how fast the aluminum puddle forms compared to other machines on the market. This allows you to work faster and add filler metal at rapid rates.

Often overlooked, the 400 has top notch Stick welding capabilities. It has lots of DIG which is great for cellulose rods, and its “hot start” feature allows you to start more stick welds without sticking your rod to the piece. This makes it a breeze for teaching beginners how to run their first stick beads.

Aluminum TIG Beads
More Aluminum Beads With The Dynasty

Price Tag

The cost of the Dynasty 400 alone is $8,300. This does not include the water cooler or any other components. To buy the complete setup with the running cart is about $11,300. This includes the Coolmate water cooler, wireless foot pedal bundle, all hoses and lines, TIG torch, ground clamp, and multiple coolants.

Our shop dropped in on the complete setup, and it paid for itself in less than 6 months of work. All the employees in the fab shop love it, and the structural department just wishes they could get their hands on it. Unfortunately, we are too busy to teach those guys how to TIG weld. They can stick to their beam fabrication for the time being.

This being said, not every shop is going to need 400 amps worth of machinery. The smaller Dynasty 210 retails for about $4,000, and it is plenty capable of many projects. 210 amps can tackle some big projects, so we aren’t trying to downplay that machine. It all depends on which metals you plan on welding, and especially how thick they are. Heavier gauges require more amperage, and vice versa. Even though we enjoy the 400, we rarely bump it up to the full amperage. Our heaviest projects will top out at around 320 amps.

I can only see justifying this purchase if you plan on making money with your TIG skills. The ultimate goal is to at least recuperate the price tag, and hopefully make a lot more income than that. Someone who has loads of cash could put the 400 in their garage to mess around with, but this machine is really meant for professional welding applications that require advanced machine settings.


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