Ender 3 CR20 Belt clearance upgrade by Propeller3D

Last crawled date: 3 years, 2 months ago

This is a modification that lowers the belts on the x and y axis so they are running inside the extrusions on the motor side. This is a quick fix and not the ultimate solution. Hopefully this will spark some ideas to others that can improve on it and maybe make a better solution.
I have a CR20 but this should also fit the Ender 3 and maybe other creality printers.
By default the belts are not quite parrallel with the axis which will make them rub against the extrusions and also create some other problems. This is a bad design by creality and I haven't seen this flaw on other printers.
Mathematically speaking the belt will not be long enough when the trolleys are close to the edges which will make the weakest point bend/flex a little which is probably the motor brackets (they are pretty weak). The belts are pretty unstretchable. Having the brackets bend/flex will cause the belts to want to travel from side to side on the pulleys.
This is a clip on that pushes the belt down into the extrusion. You will need to remove the aluminium bed and y axis trolley to fit it. The x axis can be mounted without removing the x axis trolley if you loosen or remove the left upper wheel nyloc nut. The belt holds the clip in place. Pull on the belt and if the clip wants to move out a little when you pull leave it there since it will want to stabilise into that position anyway.
Make sure that the clip and belt is centered inside the extrusion, there is sideways adjustability. The belt may chafe a little where it goes through the extrusion because it is the same dimension as the hole in the extrusion, this should fix it self after a while when the rubber wears off a little.
The size of the hole where the belt goes into the clip on the x axis is not quite aligned, this is done to fasten it better.
The idler pulleys can be adjusted down a bit, since they are bigger they will not be a problem. I drilled out some bigger holes for the screws on the x axis idler bracket to allow more adjustment of the position.