The standard equipment on the Tevo Tarantula leaves quite a bit to be desired. I noticed that the stock x-axis motor mount was flexing when I would tension the belt, so I decided to create a more sturdy mount for that motor. I have seen a couple of versions of this here on Thingiverse, but my design is more solid and, in all probability, like most of my designs, over-engineered.

To install this, you will need the following hardware:

8x m4 x 10mm screws (4 of which come with the standard mount)
8x m4 T-slot nuts (4 of which come with the standard mount)
4x m3 x 35mm screws
7x 4mm washers (you cannot fit a washer on one of the eight m4 screws)
4x m3 washers
2x 5mm nylon spacers (one of which is used on the standard mount)

Installation should be obvious from the CAD drawing and is similar to the standard mount with the exception of the front plate. All four m3 screws go through both halves of the mount into the stepper motor. The idler pulley is sandwiched between the two halves of the mount with a 5mm nylon spacer on either side of the pulley. The m4 screws go through the plates so that the t-slot nuts are on the inside, with washers between the screw and the plates.

There are two "top" plates here. Version 1 is the strongest, but I found that it interfered with the mounting of the oldham coupler and the z-axis drive rod, so I modified that to version 2. You may want to print the v2 top plate if you think your rod is going to get in the way :)

I went through four designs when modeling the top plate, so in the photos of this installed, I have not yet replaced the (intermediary) v2 plate with the (final) v2 - I simply removed the two outer mounting screws, so... go by the CAD drawing and not the actual photographs.

In the photo I've uploaded of my test tower, you can the vast improvements with each modification I've made. From left to right, the first tower is prior to my latest upgrades. The second tower is after installing the no-sanding oldham coupler (not my design). The third tower is after installing this upgraded motor mount.