Anycubic i3 Mega bed belt tensioner (Y axis)

thingiverse

For the stock Anycubic i3 Mega it is hard to get the right belt tension especially for the bed/Y axis. There are many different tensioners available and I already printed some and wanted to use a linear rail mod for the bed including a belt tensioner but finally decided to do otherwise. For now I'll keep the linear rods and designed a new tensioner that is screwed in as replacement for the original belt mount right underneath the bed mount using the original M4 screws. While printing the first version I noticed those screws are M4 ones and not M3 as in my print. Luckily before creating this thin I updated the models for M4 threaded heat inserts. The same principle is used on my CoreXY print head and works fine. For belt routing please check the photos. The ends coming out of the respective parts are fixed with zip ties and cut to proper length. Additionally you need a square M3 nut with 5.5*5.5*1.8 mm that slides into the slot on top of the main body. Then use a 30 mm socket cap screw and guide it through the spanner into the hole in the main part so that it screws into the square nut and can be tightened. EDIT 31.05.2023: Added a shorter version as the original one loses a cm travel distance in -Y (to the front). You can shorten the belt so that the spanner including the zip tie in front of it moves into the main part when tightened. Depending on the printer model you might raise the GT2 idler and motor pulley about 2 mm to get everything into the same plane.