The main problem with the Tevo Tarantula series is that it is based on the infamous single frame design of prusa i3 variant which most of them has an issue of swaying to the rear or at least where the weight is.

Tarantula's weight are more towards the back and as a result, a high skew angle were produced and it is noticeable; skew angle at 1.423 degree off of a 20 x 20 x 100mm cube

This part here is to support the tower of the frame by pushing forward to make it very close to 90 degree as much as possible for the z axis (between y min and y max)

The "top long.stl" if you're going to use the stock acrylic motor mount but still wanted to use this rear tower support, I made this so that the acrylic are also supported by the rear support

You might need to file down the t-slot nut holder so it can go into the slot without problems

You might need to file some of the parts by at least 1mm thickness because the supplied stock acrylic is about 21mm instead of 20mm following aluminum profile

• 2 x 50cm 8mm diameter threaded rods
• 2 x at least 20cm 8mm diameter threaded rods
• 14 x nuts compatible to your threaded rods
• at least 8 spring washers 4 on each sides
• at least 5 m4 x 10 screws
• at least 5 t-slot nut, printable one are here http://www.thingiverse.com/thing:1289978
• print every part requiring one of them each for each side
• recommended to have long spirit leveler or long metal ruler

On mounting the bracket, make sure the diagonal 50cm threaded rod can slide freely from top and bottom bracket so that you have a good clearance over this. After you've identified the clearance as in can slide into the hole easily, tighten down the nut holding the bottom bracket on the horizontal bar while still testing out the diagonal bar clearances.

Once the bottom bracket at horizontal bottom bar has been tightened, screw in the threaded rod making it locking to the horizontal bar, followed by tightening the nut on top of the bottom bracket holding down the diagonal

Top Section
Try to tighten from both angle at the same time top and bottom part of the tower while checking the tower angle. Adjust to suit your accuracy liking