Thunderbolt 3 Expansion?

I have a 2017 27" iMac, and one of my few complaints is that there are only 2 Thunderbolt 3 ports on its, but 4 USB 3! I also have a 2017 MBP that only has Thunderbolt 3. I am trying to fall in line with Apple by switching to Thunderbolt 3, but it's very easy to run out of ports. Right now, all of my USB and Thunderbolt ports are being used. I've been looking for a dock, but I've only found docks that will simply swap out the used Thunderbolt port, in other words, you have to plug in the dock to Thunderbolt, and the dock only has one Thunderbolt port.

Has anyone found a way to add more Thunderbolt 3 ports to their iMac?

Hi,

I had a mid-2011 27 inch iMac that had thunderbolt 2. I bought an OWC TB2 dock (https://eshop.macsales​.com). After plugging in the dock, I still had 2 TB2 connections available (1 on the iMac, 1 on the TB2 dock). I liked the OWC dock because it not only added USB ports, but it also had a Firewire port (I still have a couple of legacy Firewire devices). I hooked 2 Seagate TB2 external drives to the dock, booting the iMac from an SSD I installed in one of the drives. I ran the system this way for several years. The iMac booted and operated very fast.

I now have a 2017 27 inch retina iMac. It has TB3, so I bought an Apple TB3 to TB2 converter to hook the OWC dock to. I know OWC has a TB3 dock but I still wanted to use the dock I have. The TB2 dock still works wonderfully. I've got one of the Seagate external TB2 drives still hooked to the dock and boot from it and several USB 3 external drives as backup devices. I hook the other iMac TB3 port to an Akitio (https://www.akitio.com​/products) Thunder3 Raid box with two 1 TB hard drives raided for video editing. The Akitio also has 2 USB 3 ports, an ethernet port, an SD card slot, and another TB3 port which I've got a TB3 to TB2 converter plugged in to hook to a Buffalo TB2 1TB hard drive to store my pictures.

If I were to buy another dock, I would have no fear buying the OWC TB3 dock. The TB2 dock I have had been replaced by OWC after they found a problem with the USB ports disconnecting hard drives that were attached to them. The replacement dock has worked without a problem.

I know the OWC docks trade one TB port for another, not really giving you any more TB ports. But, I've bought TB devices that had at least 2 ports on them so I could daisy chain the devices. I've got 3 TB2 devices daisy chained on one TB3 converter and haven't noticed any degredation. Hope this info is helpful. Feel free to ask questions.

Mark