Print cooler bracket for Ramps 1.4

thingiverse

When you are using a direct drive extruder in combination with a small nozzle (0.3 or less) the stepper motor needs to deliver a relative high torque to assure a constant material flow. In my case the DRV 8825 stepper driver std. setting of Vref ca. 0.7 to 0.8 Volt was not enough to deliver enough power to my small NEMA 17 extruder motor (type 42BYGHW609, 4,08 Kg/cm holding torque) I had to increase Vref up to1.1 Volt to make the MK8 drive gear turning at a stable rpm independent of the extrusion speed (higher speed increases counter pressure increase by hot end). But at Vref 1.1 the DRV8825 driver turns significant more hot. Although the driver is rated to run up to 150'C before shutdown. Running IC at high junction temperature will always reduce lifetime of the part and influences its performance. This bracket is dimensioned for a 30mm 12V DC cooler Mount it on the Ramps with 2 40 mm M3 screws in the 2 holes: one on top of the MOSFET connector, the other one just in front of the 2 Fuses. Use the dia. 3mm plastic washers (slt added) to prevent damage/shortcut on Ramps PCB by the M3 nuts The 30 mm fan mounts on top of the 2 extensions and blows an effective air flow on the extruder driver position area. Print Settings Printer Brand: RepRap Printer: Prusa i3 Rafts: No Supports: No Resolution: 200um Infill: 40%, linear Notes: Part printed in PLA 1,75mm extruder temp 210'C heated bed 69'C print speed 40 mm/s nozzle: 0.3 mm How I Designed This Solid works Using parametric design software from scratch. based on actual available mounting holes , needed minimum bracket height on ramps 1.4 to give space on fuses. Actual cooler airflow tested at design height of cooler No temp measurements done, effectiveness based on sensing with finger tip to assure only a mild heat-up of heatsink. design 2 4mm circles at 48 mm center-center distance do offset of 1.5 mm of both circles extrude up to 33mm sketch rectangle covering 50% of both holes extrude up to 3 mm : no merging split parts on inner 4mm hole surface and subtract the 2 'half moons' in both holes sketch both cooler extensions and draw 4mm holes extrude both extensions up to 3 mm filet all inner corners on R1 to make the part more resilient