Dividing And Indexing Head Project

I'd forgotten about the handle! I got mine on the auction site. It was an introductory one for a stupid low price. I have a 6" Phase II on a larger mill now. Got it from the same auction site. The Phase II is sweet. Sometimes it makes sense to pay more.
Larry
 
Ianagos said:
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
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I have tried that and failed miserably.

The other thing is I want this build easy for any hobbyist to be able to do. I don't think making the gears will accomplish that. for this reason, using acquired gears will be the plan. getting gears from an old gear box seems the best idea to keep the simplicity desired.
 
Once this build starts, this project will move to a new thread in members projects. I will let you all know when this happens.
 
mark_f said:
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?
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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.
Using a commercially available gearbox is problematic due to most of them being not of even ratios because of the need to use odd numbers of teeth to avoid the same teeth meshing over and over at nearly every revolution, that is odd ratios are used to cause a "hunting" action so that wear is spread over all the teeth in the gear train.
 
I have done a lot of research on the dividing head lately and you are somewhat correct that ideally , 40:1 would be the way to go. You are missing the point of the project. This will be how any hobbyist can make a pretty good dividing head at a MINIMAL cost and not be too difficult. Yes, I could go to Boston gear and order a worm set for 150 to 250 dollars, but then I might as well go the extra couple hundred and buy a Chinese dividing head.

I have found dividing heads with many different ratios. some of the really old simple ones had odd ratios. some of the new imports have a ratio other than 40:1. I am guessing that is why there are so many plate sets that work on various heads. If the 40:1 was a standard (which it sort of is) you would only need one chart. All the companies do something to make their plates proprietary, be it the mounting method, the size or where they get mounted. My plates will be proprietary because of the ratio. It is all a mute point. There is absolutely nothing wrong with the 30:1 ratio. I have already figured the needed hole patterns for most of the common hole circles encountered and they will also cover many more. I intend to keep developing the needed plates to cover most divisions. There is no problem as long as the plates and chart made are used on a 30:1 dividing head.

This thread is done . there will be a new thread started in members projects to cover the building of a simple dividing head.
 
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