The manual I’m reading came with the Razorweld. I purchased the Razorweld as an add on, along with the table. It’s designed to fit together as a CNC system. Forgive me, I’m finding your answer a little confusing. Are you saying that I would be looking for a CFM 50-100% higher than the 6.7 recommended in the manual?
You should be looking for a compressor that can produce 11-12cfm like the one @ds690 recommended. If you use a lower cfm model your compressor will run constantly, producing hot moist air that will be difficult to condition to the levels required for plasma cutting.
Can you cut with a lower cfm model, yes you can… but your cut quality and consumable life will suffer.
If you drop below the flow needed your torch will extinguish.
You will make up the cost of the larger compressor pretty quickly just with the shorter consumable life.
A 60 gal Single Stage realistically runs 10.9cfm at 40psi and Drops heavily at 90psi. You have so many variables depending on if Aluminum Head, Aluminum w/ Cast Sleeve, Cast Head or V-Twin Castiron Head. All cast iron will give you the best % of CFM per Stroke Ration because of heat. If you’re going to the Box store, I would minimally look at an 80gal 2-stage. If you have the Funds and can go for a quality unit that will last 20-30+yrs. you can go 60gal 2-stage if it produces 16cfm at 175psi. Most units do not like to tell you TRUE running CFM at max pressure. A few product lines do like FS Curtis, Max Air, Bell-Air/Chicago Pneumatic. There are a lot of good lines, but remember HEAT is not your Friend. Your 1st 8-15’ of linear run distance from the compressor down the line air cools from the head to room Temp. That is where condensation and water can affect your equipment. Creat water Trap Drops to minimize water in the lines and filter systems. Do not mount the Filter directly to the pump. Waste since the air is still hot at that point. Make sure to often drain the compressor and or put an auto drain plug in the bottom of the tank. They make manual and or Electronic versions. High Humidity can drastically effect water in your system. I strongly Do Not Recommend a Rotary version for small home use. They are designed to wind up and stay running. If you have a lot of start-stop it creates a ton of heat and then condensation which will take out your bearings and ruin a very expensive unit. A way around it is to create a natural Leak in the air system, but that is a waste of air and energy. Rotarys are not as power efficient as a lot of people think. Your Meeter on your power box will be spinning fast!!.
Just know if your going on the affordable side, you can double up tanks for VOLUME, but you will never get the performance out of a Harbor Freight or cheaper brand lines. They just can hold up to heat, or produce enough air in CFM.
This is what am running for my small shop, it is quiet and does a FANTASTIC job. Provides over 20cfm at 150psi, has a built in drier and can easily recover even at 70 psi running continuously. When plasma cutting, the compressor cycles on and off fairly normally providing constant flow. If I did not have this, plan B would have been a 60 gallon (+ plan C adding another 40 gallon tank in line) and then seeing how long I can cut before pausing for the compressor to catch up.