Group Project: Dividing Head - Organization and Design

[ErichKeane]

It doesn't really matter to me, presumably I could re-make the plates any time I wanted something more. We are doing 40-1, right? So each full rotation represents 9 degrees.

72 holes means we can index to the .125 of a degree.
36 holes is 1/4 of a degree.
15 degrees is 24 holes, which means .375 of a degree. The problem here is that we couldn't get even-degrees.

36 seems like a nice sweet spot, that if I had to have a preference I would be fine with.

However, if we're leaning toward 15 degrees, I'd likely prefer every 20 degrees (18 holes), as that at least gets us every 1/2 degree.

 

[Brento]

I think a 1/2 degree is fine with me. I wouldnt need anything crazier. I doubt i would need anything more accurate.

 

[rwm]

My understanding is that the index plate for the spindle does not involve the worm? It is for direct indexing?
I do not envy the person who will do the engraving and stamping...
R

 

[Shotgun]

@Ianagos signed up for making the indexing plates, because he has the CNC, but I'm pretty sure that @Flyinfool is talking about the quick indexer/backing plate.

@Ianagos, would you be able to volunteer to make the Quick Index Plate with positions every 5 degrees? I'd be happy if this part was not marked, or just "sparsely" marked (every 30 degrees?) Marking every 5 degrees would be really busy.

 

[Flyinfool]

You are misunderstanding me.
I am not talking about the index plates that you use while making gears and such that feed thru the worm. I am talking about the quick index plate mounted to the spindle nose its self for quick common spacing's.
The plates for actual use of uncommon spacing that feed thru the worm will cover most counts up to 100 positions.

This is the index plate I am referring to shown with 72 positions.

 

[ttabbal]

Quick indexing is usually limited. IMO, it stops being "quick" if you have loads of positions. 72 seems like overkill. I would think you would usually use 4, 6, 8, 12, 16 maybe. After that it seems like you start getting into areas where you need to precision of the worm and plates.

I could be wrong, I don't own one, so feel free to correct me.

The CAD model is looking good! Thanks for all the work you're putting into it.

 

[Shotgun]

I like your thinking, @ttabbal. Being off by 0.1 degree doesn't mean much over 60, when you're just trying to cut a hex head on a bolt. But, it is a big error if you're trying to hit every 1 degree to make a gear.

It is a bit late to throw this idea out, but if we had chosen 30 or 60 teeth for the worm gear, then we could have made the quick indexer with just a ping between the gear teeth.

 

[Flyinfool]

The more I work on this the more I think 72 at 5° intervals is to much. 10° or 15° sounds better and will be less of a pain for whomever is making it. I am leaning to 15° so that 45° will be one of them. This will allow quick hex or octagons.

This is what it would look like at 15° and 24 index points.
I like this much better.

 

[Flyinfool]

It is to late to easily go to a 30:1, that would almost be starting over with a clean sheet of paper. BUT From a distance it looks like it might be possible to go to a 60:1. that would make the gear just under 5 inch Dia, and stretch the length of the bottom of the base and the trunion by about an inch. I think there is room to do that. The problem with 60:1 is that you are getting closer to the ratios of a rotary table where when you are indexing there will be MANY turns of the crank plus some number of holes on the indexing plate. leading to the possibility of counting the turns wrong, and just a lot of cranking in general.

Yes I am a cranky old man.....

I think we are good at our 40:1.

This quick index is easy to remove when not needed, just 2 set screws.

 

[Shotgun]

This is what it would look like at 15° and 24 index points.
I like this much better.

Me, too.

Except that no matter how hard I tried, I couldn't get the model to spin.

I'd like to see what you have in mind for the Quick Indexing Pin. I envisioned nothing more than a pin through the locking plate. That's all my Atlas has.