St Mary Spin Rolls

St Mary Spin Rolls & Rotary V-Blocks - the original....the best!

St Mary Spin Rolls & Rotary V-Blocks were invented & patented by John Kopczynski Sr, the founder of Ascension Industries Inc.

Spin Roll Fixtures For Grinding

525M 10 edit525M 8

St. Mary's unique Spin Roll work holding fixtures provide low-cost, precision cylindrical grinding or other machining capabilities. A patented design, employing three intermeshing contact rolls, assures precise, repeatable, automatic linear positioning and concentricity up to .0002".

Available in 9 manual and motorized models, Spin Rolls mount easily on many standard shop machines, including most internal, cylindrical (ID & OD) or surface grinders, drill presses, finishing, cutting, chucking, and other machine tools.
Standard models accommodate workpieces from 1/64" to 3" diameter and 5/8" to 5" lengths, with an optional mounting bracket on Model 525-P for lengths up to 20".

Workpieces can be loaded quickly, easily and accurately, allowing the Spin Roll to be used efficiently for both prototype and production machining.

Automatic concentricity (within .0002"), linear positioning, and precise duplication for any number of workpieces are assured by the Spin Roll's three intermeshing contact rolls which revolve and rotate the cylindrical piece on its own circumference.

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Rotary V-Block Inspection Fixture Spin Rolls


With St. Mary's Rotary V-Block fixtures, the concentricity and straightness of circular or round shafted objects can now be inspected quickly, (to within .00005) safely and accurately by a practically unskilled operator!
Just insert the workpiece between the three intermeshing contact rolls and against the end stop which has been adjusted to the length required. The workpiece rotates on its own circumference, achieving precise concentricity while maintaining linear positioning. Because of the greater ratio of diameter of rolls to diameters of workpiece, the workpiece makes many revolutions per turn of the rolls.

The rolls in the Spin Roll Rotary V-Block are especially lapped for true roundness. The female contact rolls are mounted on dead centers and the intermeshing (or clamp) roll is mounted on a permanently sealed bearing. The rolls are so true that only a slight turn of the clamping roll provides for accurate checking of any diameter by means of a mechanical or electronic indicator or optical comparator.

The Spin Roll Rotary "V" Block loads, locks and releases quickly and simply by means of its adjustable spring loaded arm. Assures exact duplication on multiple runs.

A Micro Rotary V-Block Spin Roll Model MRV-10 is also available for inspection of small circular parts requiring true concentricity (within .00005).

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To purchase St. Mary's Spin Rolls, call 716-693-9381 or e-mail  This email address is being protected from spambots. You need JavaScript enabled to view it. Ascension Industries provides full service & support for every product we sell. For evaluation, calibration and repair service for your spin rolls, submit a  Spin Roll Repair Form.