A handwheel turns a screw to advance the center spindle of this movable lathe head. Explore the wheel-and-spindle motion and calculate axial travel from the screw lead and number of handwheel turns.
Movable Lathe Head Screw-Travel Calculator
Enter a declared screw lead, handwheel turns and initial center-spindle extension. The worksheet reports ideal axial travel and final extension. It does not infer the historical screw pitch or rate machine accuracy, load, backlash, alignment or safe extension.
Equation Used
- The handwheel and screw rotate together.
- The spindle is constrained to rectilinear motion along the head axis.
- The declared screw lead is constant and backlash is neglected.
- Strength, fit, alignment, thrust capacity, allowable extension and historical dimensions are excluded.
Each complete handwheel turn advances the center spindle by one screw lead in the ideal model. Change the lead and turn count to compare the resulting travel.
Handwheel rotation advances the center spindle
Brown movement 285 shows the movable head of a turning lathe. Turning the wheel rotates a screw and produces rectilinear motion of the spindle whose end carries the center.
The animation keeps the handwheel, screw thread and center spindle connected. Its dimensions are illustrative; the displacement follows the entered lead and turn count.
Positioning the turning-lathe center
The movable head supports and positions the work with a center that can advance or retract along the lathe axis. Historical fit, clamping and load details vary and are not inferred here.
Declared screw lead converts turns to travel
Declared-geometry example
For a declared 4 mm/rev screw, five handwheel turns produce 20 mm of ideal axial travel. Starting from 20 mm extension gives 40 mm final declared extension.
Travel, accuracy and usable extension
Screw lead determines ideal travel per turn. Actual positioning accuracy and usable spindle extension also depend on backlash, fit, alignment and the construction of the lathe head. Those properties require machine-specific information beyond the three inputs here.
Movable-head questions
Is this a Swiss-type sliding headstock?
No. The cited movement is a screw-adjusted movable lathe head carrying a center spindle.
Is 4 mm/rev historical?
No. It is only the default declared lead for exploring the exact relation.
Does final extension indicate a safe setting?
No.
Movable lathe-head references
- Henry T. Brown, Five Hundred and Seven Mechanical Movements, item 285: identifies the movable turning-lathe head and states that the wheel drives a screw to move the center spindle rectilinearly.
- THK official ball-screw overview: modern reference confirming screw lead and rotation are used to define travel; product-specific accuracy and load claims require product data.
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