Why don't you cut your own worm gear. This guy does it here and build a rotary table.
http://madmodder.net/index.php?topic=7488.0
http://madmodder.net/index.php?topic=7488.0
Why don't you cut your own worm gear. This guy does it here and build a rotary table.
http://madmodder.net/index.php?topic=7488.0
It may be worth it to buy the worm and worm gear in the standard ratio of 40:1, because the tables that give the info. for turns and holes on the dividing plate are easily available in most machinist's handbooks. The other common ratio, especially in larger units is 90:1, and this table of info is much less available. A good reason not to select a straight toothed spur gear is that there is only a slight line contact between the worm and gear, hence much faster wear to the gear and worm resulting in backlash. To further complicate things, the spur gear you would select will be of diametral pitch, while it would need to be circular pitch, which is not available commercially, and which you would not be able to cut the worm to match it without a stack of odd change gears, some probably prime numbers not available commercially, and not possible to cut with a dividing head that does not have a differential indexing feature, which most do not.If I figured this out correctly. It would take 40 turns of the crank to turn the spindle once And you have a plate with various hole patterns of different numbers. You select a plate with the pattern of holes to to equal the distance in degrees the handle gets turned to give you the correct divisions on the spindle. Am I in the neighborhood here?
So , if you used a 30:1 set of gears, you have to figure the hole patterns to do the same job with the new ratio, correct?