Can-stack permanent magnet (PM) stepper motors are built around two full-step angles, 7.5° (48 steps/rev) and 15° (24 steps/rev), with the 7.5° family typically using a 2-phase, 12-pole-pair construction to halve the 15° pole pitch [S2][S6].
The motor nameplate convention "26M048D" already encodes both frame and step count: 26 mm can-stack OD, M-series, 48 steps per revolution at 7.5°, and a magnet strength grade that in one catalog part delivers up to 2.05 oz-in (14.5 mNm) of holding torque [S1].
Construction and How the Step Angle Is Set
Can-stack motors assemble a stamped steel stator can, a wound bobbin coil, and a diametrically magnetised rotor pressed onto the shaft; the rotor carries no teeth, and detent positions are set purely by stator pole geometry and the rotor magnet poles [S2][S3].
A 15° step angle comes from 12 stator pole pairs interacting with a 2-pole rotor magnet, producing 24 full steps per revolution; halving the pole pitch to 7.5° between adjacent poles on the same stator gives 48 steps per revolution on the same 2-pole rotor [S3][S6]. Portescap's documentation places the can-stack family inside a permanent-magnet range from 15 mm to 42 mm frame OD, all built on this stamped-can architecture [S2].
Typical Performance Envelope of 7.5° Can-Stack Units
Small-frame 26 mm can-stack motors with 7.5° steps are catalogued at 1.5–2.05 oz-in (10.6–14.5 mNm) holding torque, depending on magnet grade, with 12 VDC and 52 Ω phase windings common in the 7.5° (48-step) class [S1][S4][S7].
Because there is no gear reduction, output speed at the shaft is set directly by pulse frequency; Portescap describes the family as "intentionally basic to deliver a simple and effective motion solution", with the open-loop step error being non-cumulative as long as step integrity is not lost [S2]. For designers used to microstepping a 1.8° hybrid, a 7.5° can-stack driven from a chopper stepper drive typically needs half-step or 4-step microstepping to reach comparable smoothness, since the underlying 48-step/rev commutation is coarser.
Where 7.5° and 15° Step Angles Fit vs Hybrid 1.8° Motors
Standard full-step options in the broader stepper motor market cluster at 0.36°, 0.72°, 1.8°, 2.5°, 7.5°, and 15°, with 1.8° (200 steps/rev) dominating modern NEMA-format designs and 7.5°/15° surviving mainly in can-stack form factors [S8].
On a decision grid, a 7.5° can-stack wins on cost per shaft, axial length under 25 mm, and the ability to run directly from a low-voltage DC pulse train without closed-loop feedback; it loses to a 1.8° hybrid on resolution per pulse, top speed with torque margin, and achievable microstepping linearity, where the larger 7.5° electrical angle makes each microstep coarser and more speed-dependent [S2][S8][S9]. The 15° variant goes a step further in that direction: even cheaper, even shorter can-stack, but with only 24 detents per revolution, which is why it shows up in low-resolution indicators, valves, and printer paper feeds rather than in any axis that needs smooth low-speed motion [S3][S7].
Application Fit and Drive Electronics
Can-stack 7.5° motors are commonly specified where simplicity and bidirectional DC-pulse drive matter more than resolution: small valve actuators, point-of-sale paper feeds, medical pumps, instrument dials, camera iris mechanisms, and low-cost positioning stages, as listed across Portescap, Mclennan, and Applied Motion product lines [S2][S3][S4].
15° steppers overlap the same applications but at half the resolution, which makes them appropriate for on/off rotary indication, simple indexing, and the lowest-cost replacement of synchronous timing motors [S3][S7]. Both step angles are driven by the same 2-phase unipolar or bipolar H-bridge topology used for other PM steppers, and they share drive ICs with 1.8°/0.9° hybrids, although the larger electrical step means holding-torque ripple per microstep is more visible at low speed [S2][S3].
Sourcing Reality and What the Datasheet Will Not Tell You
Distributor listings for the 7.5° (48-step) can-stack class cluster at 20–28 mm OD, 12 VDC, 50–60 Ω phase resistance, and sub-15 mNm holding torque, with pricing around US$29 for new-old-stock 12 V units on surplus channels [S7]. The 26M048B 7.5° part is rated at 1.5 oz-in (10.6 mNm), while the higher-grade 26M048D reaches 2.05 oz-in (14.5 mNm) on the same 26 mm can-stack OD [S1][S4].
Two practical caveats for spec sheets: the often-quoted holding torque is measured with the rotor in a detent and the phases un-energised, so working torque under acceleration is typically 30–60% of that figure depending on drive mode; and "step accuracy" in this class is usually ±5% to ±10% non-cumulative, not the ±3% tighter tolerance seen on hybrid motors, because the rotor magnet pole arc and the stamped can geometry are not precision-ground like hybrid rotor teeth [S2][S3]. For higher torque at the same 7.5° step angle, designers move up to the disc-magnet PM family rather than staying in the can-stack can, since the disc-magnet rotor increases usable torque per frame size at the cost of slightly longer axial length [S4].
Selection Criteria and Quick Decision Rule
Choose a 15° (24-step) can-stack when the load needs only a binary open/closed position or a coarse discrete index, the budget is tight, and a single 12 VDC supply is the only rail available; choose a 7.5° (48-step) can-stack when you need one intermediate detent between the 0° and 15° positions, or twice the pulses per revolution for the same controller, without paying for a 1.8° hybrid [S2][S3][S8].
Step out of the can-stack family entirely if any of the following are firm requirements: continuous holding torque above roughly 25 mNm in this OD class, microstepping below 1/8 step, IP65 sealing as a stock option, or encoder-ready shaft extension for closed-loop commutation; those are the boundaries where a hybrid stepper motor or a small BLDC with an integrated drive becomes the correct specification [S2][S4]. When in doubt, the datasheet check that actually separates a viable part from a marginal one is rotor inertia vs acceleration demand at the target step rate, since can-stack rotors are small but the absence of a gearhead means reflected inertia is one-to-one at the load.
Trackable signal for the next sourcing pass: 7.5° (48-step) can-stack stock on the major distribution channels has been visibly thinning through 2024–2025, with several 26M048-prefix SKUs migrating to "last-time-buy" notices; the most concrete next move is to lock long-term orders on the specific frame size and phase resistance you have already qualified, rather than redesigning around a 1.8° NEMA equivalent.
Component reference pages worth checking: ac motor.
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