Rotary Table Questions

[RobinHood]

Yes, it is very well made. Genuine Bridgeport 1967-ish vintage in top condition.

Only reason I say “1967-ish” is because I don’t exactly know the year it was made. It did come with the 1967 BP mill - so the mid to late 60s era should be reasonably close.

 

[Susquatch]

All amazing what they all did before there were any computers (other than mainframes)......

 

[Dabbler]

For those wanting to be able to cut 127 gears on the cheap-cheap, Tom Lipton wrote an article on using a 5C spin indexer with a single custom plate to cut them. His secret: use 2 rows of holes.

Here's the link to the original article, and then search for November 1 for the article in question:

"Nothing Too Strong Ever Broke"

Ongoing journal of a life spent designing and building special tools, instruments and mechanical devices for the scientific, medical, metalworking and product development industries. Idea's turned into reality by the mechanical pursuits of Tom Lipton (OX)

oxtool.blogspot.com

There's a trick he used that you need to know: He used a DRO with the 'hole' function, but cut every other hole on the first pass (the 'even' pass, then cut the 'odd' holes on the inner circle on the second pass.

 

[Susquatch]

For those wanting to be able to cut 127 gears on the cheap-cheap, Tom Lipton wrote an article on using a 5C spin indexer with a single custom plate to cut them. His secret: use 2 rows of holes.

Here's the link to the original article, and then search for November 1 for the article in question:

"Nothing Too Strong Ever Broke"

Ongoing journal of a life spent designing and building special tools, instruments and mechanical devices for the scientific, medical, metalworking and product development industries. Idea's turned into reality by the mechanical pursuits of Tom Lipton (OX)

oxtool.blogspot.com

There's a trick he used that you need to know: He used a DRO with the 'hole' function, but cut every other hole on the first pass (the 'even' pass, then cut the 'odd' holes on the inner circle on the second pass.

Very cool! I thought we discussed two circles with alternating holes to make them fit on a smaller plate in another post on this thread, but maybe I was only thinking that in the foggy corners of my own mind! LOL!

I do like the idea of using a spin indexer directly though instead of indexing plates on a rotary table crank.

I also liked Tom's comment on another users post about using three holes. I was surprised to see him discuss accumulating errors. That's the point I was trying to make (far less elegantly) on the RT thread here. I just can't see why an error of a thousandth or so here or there matters at all as long as the error is averaged out over the whole circle instead of accumulated one hole at a time. That thousandth (just an arbitrary small number) doesn't matter at all to the gear tooth spacing and besides, all the other errors from stuff bending probably add up to more anyway.

Good find! Thanks @Dabbler !