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 when you can't go out and buy a replacement (weekends, holidays, etc.). The worm gear on the motor shaft typically is not the problem. Usually all you need is the pinion gear. There are several similar designs that have been posted, and there is nothing at all wrong with them. I simply preferred to create my own from scratch with a few modifications to suit my tastes. These will fit many door openers including the home versions of Craftsman, LiftMaster, Chamberlain and others. Basically any opener that uses a 41A2817 replacement gear kit or 41C4220A rebuild kit. All three versions have super strong teeth (see print settings section) and improved supports at the roll pin areas so that they should never shear. **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. Both hubs 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 except that it has the holes to save material. There is a side benefit to the holes (see Print Settings section). This is the one I ended up installing and it fit perfectly. I printed it slowly for maximum precision. Any of these will take several hours to print. You will 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. I ordered and received a 41A2817 gear kit as a backup, but it looks like it may remain in my tool box as a "spare" for a long time to come. **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.**