# Cutting acme threads on a lathe



## sasanifab (Jan 11, 2021)

Now that I got my threading situation figured out..... I’d like to try my hand at some acme threads. I understand that the tooling is different and that there are standard and metric varieties. In the manual it says that a change gear is required for Dp and Mp. Is this the change required for acme threading ? I included a picture of what I mean. If this is true , I’m going to need a m1 157 tooth gear. Does anyone make these ?


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## sasanifab (Jan 11, 2021)

I used the standard gear change , that is tbi....as acme threads are measured this way . Is this incorrect ?


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## Illinoyance (Jan 11, 2021)

Diametral pitch and Module are for cutting worms.  Use the standard threading setup.  Acme threads have a 29* included angle.  Metric trapezoidal threads have a 30* included angle.  Acme is specified in threads per inch.  Metric is specified by the pitch in mm.


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## dmacritchie (Jan 22, 2021)

Good Morning I don't mean to hijack this thread but im trying to understand acme threads as i have a worn out cross slide nut, is ther such a thing as metric acme threads thanks for any help


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## Illinoyance (Jan 22, 2021)

Yes, there is a metric equivalent. It has an included angle of 30* instead of 29* for Acme. Thread depths are different also. It is referred to as a trapezoidal thread. If you don't have Machinerys Handbook I suggest you visit Maryland Metrics. You can download a file that lists nearly every thread form, metric and Imperial.


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## dmacritchie (Jan 23, 2021)

thank you i will


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