Both the 27i and 40i from Hobart are very popular plasma cutters with a solid reputation in the metal fabrication world, but there are some major differences between these two plasma cutters aside from cutting capacity. Today we’re gonna break down the different features and limitations of these machines and explain why we strongly feel the Hobart 40i is worth spending the extra $300 on.

Let’s start with the easy stuff, cutting capacity. The Hobart 27i maxes out at 30 amps (despite its name being the 27i) and has a maximum clean cut rating of 3/8 inch on mild steel. The Hobart 40i maxes out at 40 amps and has a maximum clean cut rating of 5/8 inch on mild steel.

Keep in mind these ratings are “maximum clean cut ratings.” This means that the machine can make those cuts almost perfectly with little to no slag. Plasma cutters can be pushed past their “maximum clean cut rating” and still produce good cuts, but they will likely need some clean up with a grinder and such. So realistically the Hobart 27i can cut 1/2 inch mild steel and the 40i can cut 3/4 inch, but the cuts will need to be cleaned up afterwards.

In terms of power I feel the 40i really hits the sweet spot and is perfect for 95% of plasma cutter users. Very rarely do most fabricators work with material over 3/4 inch, so 40 amps of cutting power is perfect. The 27i at 30 amps is a little less of a safe investment in my opinion because you won’t be able to cut anything over 1/2″ which could be a problem for future projects that you don’t know you have yet. For the extra $300 I think the piece of mind of having the extra power is worth it (plus many other advantages of the Hobart 40i which we will explain below).

Another thing to keep in mind is IPM (inches per minute). Being that the Hobart 40i has more power you can expect to cut material faster with that extra power. The manual will show the recommended IPM for different material thicknesses. Take a look at the chart below directly from the spec sheets of the Hobart 27i and 40i. Take note of the IPM rating for cutting a piece of 3/8 mild steel. The 40i will cut 3/8 inch mild steel twice as fast as the the 27i.

One of the big let downs of the Hobart 27i is the lack of a true pilot arc controller. The 27i has what is called a “start only pilot arc,” which gives the user the benefits of pilot arc for a short period of time when they first activate the torch. For example, you can start your cut off the edge of a solid piece of metal and slowly pull into the metal you’re cutting without a problem just like a normal pilot arc system. The problem occurs when you cut something like expanded steel where torch contact is intermittent causing the 27i to cut out after a short period of time.

The Hobart 40i on the other hand has a true pilot arc controller and that allows you to cut expanded steel or rusty material with no interruption. For plasma cutters in this price range we feel a full pilot arc controller is a 100% requirement and that’s why we strongly recommend the 40i.

In terms of duty cycle the 40i has a 60% duty cycle at 40 amps, while the 27i has a 40% duty cycle at 30 amps. Duty cycle on plasma cutters is measured in a 10 minute time period with an operating environment of 104 degrees Fahrenheit. This means that the 40i can operate 6 minutes out of a 10 minute time period, while the 27i can only operate 4 minutes out of a 10 minute period. This means the 40i can operate longer than the 27i, while providing 10 more amps of power.

For the extra $300 investment the Hobart 40i is without a doubt a better machine and provides a lot more features and impressive performance. The fact that the 27i does not have a true pilot arc is a deal breaker for us making the 40i that much better. If you’re gonna spend the money to get a professional grade plasma cutter we highly recommend getting the 40i over the 27i. You won’t regret it.

If you have never used a plasma cutter before be sure to read our comprehensive beginner’s plasma cutting guide. This will help walk you through the entire process of getting your machine hooked up correctly and making cuts safely.

If you are looking for help finding a new machine be sure to check out our list of the best plasma cutters that we recommend. If you need a plasma cutter with a built in air compressor you can view the machines that we recommend here.