Quote:
Originally Posted by steelerborn
Excellent point Adam. I will look into it, the main reason I did it this way was for simplicity if the motor ever needs to be replaced it would be an easy swap out. I also had the idea of putting a system in place where one could simply disengage the worm gear and allow the arm to be moved manually. Really this was just for fun, and a possible solution to some problems from last season. The anti back driving effect of the worm gear is a huge advantage and allows a mechanical solution to a problem instead of adding in code to achieve the same effect. The bearings on the worm shaft will be thrust bearings however I did not have any thrust bearings in my workspace so I used just standard until I could CAD them sometime this week (only had larger ones from off of an old swerve module). I also did not place any shaft collars on the external parts of the box. Yeah I am a huge fan of Mcmaster, they are huge compared to AndyMark, and I feel like it allows a wider range of materials to do some crazy stuff with. We have had a lot of issues with AndyMark (probably because we are just unlucky). Last season we ordered some transmissions and all of the output shafts were way outside of the tolerances and none of the hubs fit well we had to grind down and press them on. When we bought another set for the real bot everything was fine. Thankfully we got the order in around week 2 and avoided the massive snow storm. Mcmaster is also a company that the students may use even when they are out in the industry so it is a good way to get them to understand how these sites work. This box is in no way attributed to the Bird Brains. We have always been a student designed team with mentors answering some questions. If they want to use this box or anything that I have designed I will usually do a lesson or talk on the design and encourage that they work on their own version, and then help answer their questions. I really hope though that we can get this fabricated to see how it works and functions (don't want them using something that is useless).
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Worm gears by themselves don't necessarily have any anti back-driving properties, they are more efficient in one direction than the other depending on what gears you use and how well the tolerances come out, what grease you use ect. It may not stop back-driving as much as you might think, it would be good to prototype and collect some data. Although a 200/1 reduction with a CIM as the input wont be back-driven very easily anyway.