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Lead Screw Pitch

Discussion in '3D printers' started by Jamie Hofer, Oct 16, 2016.

  1. Jamie Hofer

    Builder

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    On the parts store I have noticed conflicting information on the pitch of the lead screw. Would anyone happen to know what exactly the pitch is? It says that the pitch is 2 but in the examples on the RepRap Calculator it says the pitch is 8.
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Builder

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    Pitch is the distance between adjacent threads. Lead is the distance covered along one rotation of a single thread. Starts are the number of individual concentric threads going around the shaft.

    So for an old fashion screw which has a single thread (i.e. single start), pitch = lead. For the screws in the parts store, the pitch is 2mm and there are 4 starts. There are 4 concentric threads running around the screw and they are all 2mm apart. But as each thread runs around the shaft, the next time a specific thread comes into view it is 8mm up from where it started. So for the screws in the shop, pitch = 2mm, the number of starts = 4, and the lead = 8mm.

    RepRap calculator is apparently shortcutting and crossing terms but in most cases you really don't care about pitch. All you generally care about is lead because that determines the distance you advance with each turn of the stepper. So in most cases where it is asking about pitch, it is is probably really asking about lead.
     
    Mark Carew likes this.

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