A scroll chuck uses a rotating Archimedean scroll engaged with jaw teeth so guided jaws move radially in unison. This calculator compares two separate constant-pitch scenarios; it does not describe one scroll whose pitch varies between the two values.
Spiral-Grooved Face Plate · Two Selected Pitch Scenarios
Compare two separate ideal constant-pitch Archimedean-scroll scenarios and synchronized radial jaw increments.
Equation Used
- Each comparison uses an ideal Archimedean scroll with its own constant radial pitch.
- All selected jaws remain engaged with the same comparison scroll and are guided radially.
- Scroll angle is accumulated relative rotation from a selected reference.
- Twice radial increment is labeled as a selected opposed-span change, not a guaranteed workpiece diameter range.
- Tooth geometry, backlash, wear, runout, clamping force, usable stroke and safety are excluded.
Former pitch-range wording is corrected: the two entered pitches define separate comparison scrolls, not one variable-pitch Archimedean scroll.
Two selected ideal scenarios
For each selected constant pitch p, scroll rotation θ gives ideal radial increment Δr=pθ/360°. The plan view overlays the low- and high-pitch constructions and their synchronized jaw-radius envelopes.
What the calculator determines
Select two comparison pitches, accumulated scroll angle and jaw count. The calculator reports the smaller- and larger-pitch radial increments and the corresponding twice-radial span changes.
Selected comparison ledger
For each scenario: Nrev=θ/360°; Δr=pNrev; selected opposed-span change=2Δr.
Selected-input example
At one scroll revolution, the separate 4 and 6 mm/rev scenarios give ideal jaw increments of 4 and 6 mm and opposed-span changes of 8 and 12 mm.
Kinematics, not chuck accuracy or capacity
Actual chuck performance depends on tooth geometry, jaw numbering and assembly, clearances, backlash, wear, guide error, scroll runout, jaw stiffness, gripping diameter and load. Equal commanded travel does not establish concentricity or clamping force.
Questions
Does a real Archimedean scroll have low and high pitch?
Not in this comparison. Each result is a separate constant-pitch scenario.
Does jaw count change travel?
No. In the stated ideal model it changes the number and angular spacing of synchronized jaws, not radial increment.
References & Further Reading
- Wikipedia contributors. Chuck (engineering). Wikipedia
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