ACME vs lead screw

[Harry CrowtherParticipant @harrycrowther39896]

Hi,

I was wondering if anyone knows the difference between a 'trapezoidal lead screw' and a 'ACME lead screw'? Or is ACME the brand name?

[Harry CrowtherParticipant @harrycrowther39896]

[Brian GParticipant @briang]

They are both trapezoidal Harry. Generally I think the difference is whether the machine is imperial or metric. Acme (named for the Acme Machine Company) has a thread angle of 29 degrees and dimensioned in inches, whilst ISO trapezoidal threads have a thread angle of 30 degrees and are dimensioned in mm. I suspect however that in the long tradition of mixing standards you can get metric machines using the Acme thread form or imperial machines using the ISO form.

Brian

[Zane CrowtherParticipant @zanecrowther67531]

There isn't much difference as mentioned above, its just that the American ACME form has an angle of 29 degrees, while the metric trapezoidal is 30 degrees. So trapezoidal lead screws are more common in the UK.

[JasonBModerator @jasonb]

You will also find that ACME is made in imperial pitches given as tpi or threads per inch whereas the Trapezoidal come sin metric pitches eg 2mm , 3mm etc.

I would not say TR screws are more common in the UK as there are still a lot of old machines running imperial ACME screws but anything new and metric will have TR

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