I had an aftercooler on my old I.R. compressor. Worked amazing. Compressor went out, so I just got a new Quincy 2 stage-60 Gal.
But I cant do aftercooler because it will void warranty.
Has anyone used the aftercooler after the tank?
It still seems like it would help cool the air going to table.
Yes, many of us. There is an entire thread where the pros and cons of both configurations is being discussed.
Initially I set mine up between compressor and tank but it lowered the rpms, so I moved it to after.
Air Compressor aftercooler Info thread - Projects - Langmuir Systems Forum
I will help, but it won’t give you the same “max” benefit as between the pump and tank.
I too have a Quincy 2stg 60 gal and plumbed up a derale trans cooler with a water trap after it and it definitely catches a serious amount of water. Even when the RH is 30% and DP is in the 40s it’ll catch enough to pop off the auto drain after a cycle or two.
I’ve ran my compressor in sub freezing temps despite their warnings, foolish maybe but necessary at the time. Do regular maintenance on it including oil analysis every year and after 10 years it’s still pumping like new. Only real thing I’ve had to do is retension the belts once and replace the check valve once due to… you guessed it, corrosion. I wouldn’t hesitate to void the warranty and put an after cooler in, I wish I had done it when it was brand new. That check valve is a massive PITA to source, but no way was I spending a couple hundo with Quincy unless I had to. Found one on eBay for $45, after trying it bought 3 more to keep in a drawer that I’ll end up never using now.
The benefits outweigh the cost of repairs and consumables otherwise. But that’s just one man’s opinion.
The aftercooler, as part of the system doesn’t have the capacity to do any more or any less work to remove water whether it is mounted before or after the tank. You are getting more water out of the cooler before the tank because there is more water in the air before the tank.
You will get the same amount of water out of the system (tank+cooler) no matter the order of your setup. That being the case, your decision is if you want the tank to do the job it was intended and designed to do, removing most of the water, and use the aftercooler as a backup (aftercooler mounted post tank)… or use the aftercooler to remove most of the water, and use the tank as a backup(aftercooler mounted pre tank).
The benefits to mounting the aftercooler post tank are:
Shorter cycle times due to less blow by.
Less wear and tear on the compressor.
Lower compressor head temps.
Less waste of compressed air due to discharge at end of cycle (all the air in the aftercooler and lines between the backflow valve is discharged)
Your aftercooler will last longer due to not being subjected to hot air and pulsing loads.
You won’t void your warranty on your compressor.
Benefit to mounting the aftercooler pre tank.
Dryer air in the tank resulting in decreased possibility for corrosion of the tank walls.
Many. And I would say most if not all are happy with their set-ups and have dry air to their plasma machines (including myself and several members of this forum who have had it both ways). Nearly everyone reports less water being trapped when the cooler is after the tank for the reasons stated very well by Eric.
So it is like the saying from “Dirty Harry”: “Do you want to put the cooler before the tank and void your warranty but get dry air or put it after the tank and get dry air without voiding your warranty?”
“DO YOU FEEL LUCKY?” 
Thank you!!!