I have decided worm gears are the way to go for what I need. My question is, is there some setup i can make that eliminates the backlash? If you have any drawings or online articles, please share.
I have decided worm gears are the way to go for what I need. My question is, is there some setup i can make that eliminates the backlash? If you have any drawings or online articles, please share.
Well, you could use the same trick as is used to preload double nuts for a ball screw: buy two worms (or cut the one in half) and shim them apart. The idea is that you want to stretch the pitch just a wee bit. You would need a good worm bearing housing set up that holds the two halves completely and firmly captive.
The joint between the two halves would be right at the tangent to the wormwheel, but that should not be a major concern.
I guess if you cut one worm in half, you are going to lose the thickness of the saw cut (or abrasive wheel cut), but that cannot be helped. If you purchase two worms, then you might have to spend some time facing them to get the pitch right. The keyway will ensure that they stay lined up at the same phase angle all the time.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Hu's suggestion is the most mechanically sound.
Another option is to weight or springload the moving side of the mechanism to hold the worm so it is always running tight on one side of the gearface only, this method has the benefit of being self compensating. It has the drawbacks of always working on only face (wear X2). Also is best suited for lighter work as heavy work or quick direction changes may overcome the springs/weights and cause chatter or worse. Yes you could use REALLY heavy springs but it a severly amplified rate of wear to the worm system.
www.integratedmechanical.ca
Here are a couple of websites for worm gear and gear backlash. One describing what Hu mentioned in his post.
http://www.manufacturingtalk.com/news/hoc/hoc111.html
http://www.antibacklashgear.com/
Wayne Hill