Reprap Prusa i3 Rework - X END IDLER - With belt tensioner

thingiverse

Mod of the X END IDLER. Added a tensioner for the X carriage belt. installed it, it works. Some suggested that using the other design with 3 bolts is needed for deformations and stress distribution on the z bearings. I didnt see that issue when i assemble it. Also i ran an FEM analysis, and i get the same outcome : it doesn't seem to be a concern. Ran another FEM on the ball bearing holder ("roller puller"), it should be ok as long as you stay below 10Kg of tension force. Less than 2Kg force should be more than enough to get the belt tensioned, so, it's on the safe side and has provision for fatigue. Just print it with the same orientation than on the pictures of the assembled part, and slice it with 1.4mm wall thicknesses. Instructions -- Assembly : Print the X END IDLER and the Roller_Puller Insert a screw in the roller puller, head of the screw goes in the socket (you may need to cleanup the hex socket a little, and to bend very gently the arms while pushing the screw head to its slot). Insert the screw & roller puller into the X_END_IDLER bore, add a nut, et voila you have your belt tensionner -- Careful: The point in having this part is to be able to dose carefully how much tension you want to put. Dont tension the belt too much or you may endup putting too much stress on the tubes that contain your z axis roller bearings. You may want to add a washer before the nut to even out stresses, and to use a nylock nut so that vibration during prints doesnt make it turn and go away. -- Printing I use a full metal extruder, so i printed with ABS at 240°C to get strong bonding (dont go that high if you have a JHEAD you'd destroy the peek) Slicing done with Cura, with infill 30%, wall thicknesses 1.4mm top bottom 1mm. Seems to be rigid enough like that. Printing done with the i3 at 30mm/s external sides, 50mm/s inner sides and 70mm/s infill, and extrusion rate at 110% to get some more chances of layers bonding.