Lathe threading

[Bi11Hudson]

A bit late to the party, but I have some input that may clear up a couple of points. 1.5mm is very close to 16 TPI... ... If there is a 127 tooth gear somewhere in the train, there will be a gear of decimal count compounded to it. Bypassing the 127/?, making it simply an idler should convert TPI to pretty close to metric. I can't say how much, haven't thought about it. But a starting point. I use 16TPI/1.5mm as an example but there are many conversions close to each other. Looking to 1.0mm as 25.4 TPI helps.

 

[BenW]

A bit late to the party, but I have some input that may clear up a couple of points. 1.5mm is very close to 16 TPI... ... If there is a 127 tooth gear somewhere in the train, there will be a gear of decimal count compounded to it. Bypassing the 127/?, making it simply an idler should convert TPI to pretty close to metric. I can't say how much, haven't thought about it. But a starting point. I use 16TPI/1.5mm as an example but there are many conversions close to each other. Looking to 1.0mm as 25.4 TPI helps.

That is true and for many threads using a close inch pitch is plenty good enough, but since my lathe has a metric leadscrew it's possible to cut true metric threads if I skip the 127/120 conversion gear. Though for some reason the machine doesn't have a metric Threading chart, so I made one myself.

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