Well, I've had the Tevo Tarantula for about 3 months and by rights, I'm behind most owners in doing upgrades to the "Spider". According the Facebook page, most owners are printing and purchasing upgrades for the printer right from the start. I have printed some items out to house the power unit and the circuit board. Not really upgrades, more ascetics.
If you search the Internet for upgrades for the printer, you will find a list of many things to do. The first thing I've chosen is get the Dual Z Axis. This kit will keep the movement of the "Z" axis moving completely level and parallel to the heat bed, thus, the print is smoother looking. Having two -Z- axis motors with the threaded rods can help ensure stability of the -X- axis during print and can, overall, reduce wear on the mechanical components.
I purchased this Banggood Dual Z Axis. At the time of this writing, the kit sells for $52.13 CAD. I was lucky enough to get the kit for about $10.00 less.
As you can seen by the images above the kit doesn't have much to it. (Large image is missing the stepper motor). The other images show the kit installed and the installation follows the same lines as the first z-axis motor and screw assembly. There is an excellent video by ruiraptor titled TEVO Tarantula 3D printer - HOW TO improve your printer - Part 13 (DUAL Z MOTOR). This video walk the installer step by step thru the installation and the fine tuning so it will work correctly with the original z-axis motor and screw.
There are three ways to connect the motor to the circuit board. The motor wire that comes with the kit allows the motor to be connected in parallel, serial or extra driver. The video shows the Pros and Cons of each type of connection. I chose to connect the motors by way of parallel. It seemed to be the most straight forward method.
Every little tweak and add-on to this printer seems to make it better and better. The next upgrade to the printer will probably be the replacement of the Y-axis rubber wheels to the metal ball bearing rail. With that, an upgrade to the heat bed frame. Stay tuned.