Hey there
@Standard Modern 10” : I have the imperial version of that lathe and have pretty much rebuilt/remade a significant portion of it. A 127 tooth 16DP is going to be just over 8 inches in diameter - that will be pretty big!
My "plan" for adding change gears to my lathe to cut metric threads would be to reduce the 127 tooth gear using a 20 or 22 DP cutter for the gear and effectively reduce it to under 6 inches in diameter. I have the plans for most of the build to convert an imperial lathe to metric but have not explored the other way as I have no data on the "metric" version.
Questions:
Is the lead screw metric?
What are the gears driving the current quick change gear box? The imperial version is: 48 Teeth to 83 Teeth to 48 teeth the lead screw is 8 TPI
In order for me to change up the threading I need to make the 127 tooth gear (will first need to make a 127 hole diving plate for my rotary table) and then make some idler gears to change the 22DP gear back into the current arrangement - further tooth comparisons are leading me to believe the gears are 20 degree PA and not 14.5 PA ...alas...but ....not an issue if I remake them all to the 14.5 PA
If you have some pictures of the lathe and the arrangement of the drive gears that would be great. I have a few things done up in ACad for making an idler bracket etc
Oh yes - I am just North of Barrie so not that far