Marv,

Excellent explanation and especially helpful for pointing out the near zero error solutions using plate #1. I like thumbing through my Machinery's Handbook just to familiarize myself with just knowing what is available.

The 127 gear is probably the most important gear of all for an exact conversion of an imperial threading lathe into a metric threading lathe. My 12" swing geared-head lathe has this gear in the gear train behind the headstock (photo 3 and 4 at Homemade Change Gears) where there is plenty of room to accommodate this large gear.

Thank you for the explanation of "compound indexing". I could remove my 127 tooth gear and use it as an indexer to create a 127 hole plate for a direct indexing jig.

Regards,

Paul