Index plate .STL file wanted

[Darren]

It will do spiral milling, but it will also do differential indexing so that 127 tooth gear would have been possible without messing around making new plates. I'm definitely not going to be making my own ring and pinions though.

I almost put a 4bt into my 85 Toyota but other things took priority at the time.

 

[140mower]

I almost put a 4bt into my 85 Toyota but other things took priority at the time.

..... Funny how life stands in the way of a good time isn't it? It's hard finding that balance between being responsible and "wanna see something funny? Here, hold my beer".

 

[Darren]

..... Funny how life stands in the way of a good time isn't it? It's hard finding that balance between being responsible and "wanna see something funny? Here, hold my beer".

My 1786 ongoing projects get in the way of each other. I'm going to be having a clearance sale so my projects can be other peoples projects who have the same problem as me.

 

[140mower]

My 1786 ongoing projects get in the way of each other. I'm going to be having a clearance sale so my projects can be other peoples projects who have the same problem as me.

That's a familiar sounding story.....
BTW.... I have this old truck out back, it only needs a little tlc.........

 

[Susquatch]

but it will also do differential indexing so that 127 tooth gear would have been possible without messing around making new plates.

Never heard of that. How does that work Darren?

 

[Darren]

The worm drives the spindle as normal, but an extension shaft can be driven by the spindle, connected to change gears, witch in turn drives the indexing plate shaft. So instead of being in a fixed position, the index plate can actually rotate at a ratio to the spindle as the crank is turned. So two different ratios are at play. Indexing prime numbers can be done pretty accurately.

This video explains it very well:

 

[Susquatch]

This video explains it very well:

Thanks Darren. Very cool.

In my mind's eye, I had imagined creating a table and manually correcting the numbers as they flipped over or under the next closest integer.

This is a cool way to do the same thing using a compound (feedback) gear train to correct exactly instead of the closest integer.

Does yours have the same huge side shaft that this one has? And why is that needed anyway? It just makes everything awkward and ungainly.

 

[Darren]

The BS-2 has a MUCH more compact system than his. I suspect the reason for such long extensions has to do with the ability to back drive the index head from the mill table for spiral milling. Normally you'd have a driveshaft arrangement.

I found it in another video showing his table drive setup:

 

[PaulL]

The plates are mostly about making the user believe the accuracy is better than it really is.

That depends on what kind of accuracy you want. Hole to hole you're likely to see some variance, but the error won't accumulate as you go from hole to hole, meaning you do fine for most gear teeth, etc.
Ie, you'll wind up with 127 teeth in the end, but with minor variance on their exact positions.
Whether that's sufficient for the task is another question entirely.