Craftsman/Liftmaster/Chamberlain 41A2817 main gear

thingiverse

Does the interior of your garage door opener resemble the first photo? These garage door opener gears often strip at the most inconvenient times, making it impossible to get a replacement when you need it (weekends, holidays, etc.). The worm gear on the motor shaft is usually not the problem. You'll likely only need the pinion gear to fix the issue. There are several similar designs that have been posted, and they work just fine. I simply preferred to create my own from scratch with a few modifications to suit my tastes. These custom gears will fit many door openers, including home versions of Craftsman, LiftMaster, Chamberlain, and others. Any opener using a 41A2817 replacement gear kit or 41C4220A rebuild kit should work well. All three versions have super strong teeth (see print settings section) and improved supports at the roll pin areas to prevent them from shearing. **Specs-** Outside diameter: 69.85mm (2.75") Number of teeth: 32 Pressure angle: 20 degrees Tooth angle: 7 degrees from axis Face width: 13mm Bore diameter: 13mm Roll pin slot width: 5mm Top and bottom hub height: 7.5mm Material: I used PETG, but nylon would be great if you can print with it. Design1- (gear) A basic gear with raised hubs that are heavily reinforced where the torque from the roll pins will be applied. The hubs are also filleted for stress relief. Design2- (gearA) A similar design to #1 except that recesses and holes were added to save material. Design 3- (gearB) Similar to #1, but with holes to save material. There is a side benefit to the holes (see Print Settings section). This design worked well for me and fit perfectly after I printed it slowly for maximum precision. Any of these gears will take several hours to print. You'll want to print them as close to solid as possible. **Slight update 12/28/19-** After a few weeks of usage, I decided to check the gears to see how they are holding up. So far so good, and this particular opener gets used a lot. There is a very slight burnishing where the gear and worm teeth are contacting, but otherwise nothing of note. I added some disk brake wheel bearing grease to the lubricant already present for good measure and will check it again in a month or so. **Further update 3/8/20-** I checked the gear again this morning. After more than four months of service, the gear still only has a slight burnishing where the worm and gear teeth contact, and no noticeable wear otherwise. So it appears that it may be a good runner for years to come. **And yet another update 10/12/20-** Still working perfectly. Used daily with no signs of unusual wear or other problems. I hope this helps you. Thanks for looking.