The Diagonal rods are the weak point of the printer kit. All six rods had a different length. I noticed this first after I mounted the delta triangle to the delta towers and the triangle was far from being parallel to the printing bed. From other users I read that this is a common issue. And I just can confirm that. I had differences of up to 2.5 mm in the lenght of the diagonal rods.
When I tried to adjust the length of the rods, first I broke one. Though they look like as if they are made of steel, they are not, so I ripped one off. From the weight it feels like steel because the ball joins are made of steel and heavy. Therefore you see one of my rods is thicker - means I used an old umbrella stick tube to join the ball joints.
I took quite a bit of time to improve the diagonal rods:
- I cut them off and glued them all again together to 198 mm using a short piece of tube with a inner diameter of 6mm. I glued them all at the same time to keep the lenghth identical. When two of them have the same length, the others can be adapted, by putting a 6 mm shaft to all of the joint eyes at the same time with the rods of the same lenghth at the outer sides.
- Some of the ball joints were going hard some others wobbled awfully. So I made the wobbling ones going harder by pressing them together using two modified old piston pins of the correct diameter using a bench vise. The hard going ones I moved over a longer period using a drilling machine. Finally I goth them working smooth and precisely, but I have to admit, it would have been better to buy something more accurate.