BSA ball-screw actuators
A ball screw replaces the sliding nut of a lead screw with recirculating balls: efficiency goes from roughly 30–40% to over 90%, so the same motor delivers two to three times the thrust, and backlash and wear drop with it. The BSA is the LYNX family you choose when a Z or precision axis needs high thrust, high duty cycle, or tighter repeatability than a lead screw gives.
Two frame sizes cover the range. BSA 45 rides on a NEMA 17 motor with 50, 100, and 250 mm travels and a 7 kg rating; BSA 60 on NEMA 23 with 100, 250, and 500 mm travels and a 15 kg rating. Both come with a 5 mm lead (100 mm/s, maximum thrust) or a 10 mm lead (200 mm/s), in parallel-mount or inline-motor configurations, stepper or servo. Every variant is a stock part number with a 2–3 week lead time.
BSA versus LSA: when the ball screw earns its price
The lead-screw LSA 45 and LSA 60 cost about $175–$200 less per axis and hold position by friction when power is off, which makes them the default Z axis in most of the systems the engine builds. The BSA wins when any of these is true: the axis runs continuously (ball screws don't heat and wear the way a sliding nut does at high duty), the thrust requirement is near the top of the lead-screw envelope, or the application needs micron-level repeatability. One trade-off to design for: a ball screw is not self-locking, so a vertical BSA axis holding a load without power needs a motor brake, which the engine adds to the quote when you say the axis is vertical.
How the engine sizes a ball-screw axis
Thrust is computed from acceleration, gravity (if vertical), and process force; it is converted to motor torque through the lead and a 90% screw efficiency, and checked against the motor's torque curve at the rpm your speed and lead demand, with a minimum 25% margin. Critical speed and column loading are checked against travel. Ask for a BSA by name, or describe the axis and let the engine decide between BSA and LSA — it prints the reason either way.
All 18 BSA ball-screw actuators
| Part | Travel (mm) | Rated load (kg) | Max speed (mm/s) | Motor | List |
|---|---|---|---|---|---|
| BSA 45 50mm Inline Stepper | 50 | 7 | 200 | Stepper | $925 |
| BSA 45 50mm Parallel Mount Stepper | 50 | 7 | 200 | Stepper | $1,025 |
| BSA 45 50mm Parallel Mount Servo | 50 | 7 | 200 | Servo | $1,125 |
| BSA 45 100mm Inline Stepper | 100 | 7 | 200 | Stepper | $1,025 |
| BSA 45 100mm Parallel Mount Stepper | 100 | 7 | 200 | Stepper | $1,125 |
| BSA 45 100mm Parallel Mount Servo | 100 | 7 | 200 | Servo | $1,225 |
| BSA 60 100mm Inline Stepper | 100 | 15 | 200 | Stepper | $1,325 |
| BSA 60 100mm Parallel Mount Stepper | 100 | 15 | 200 | Stepper | $1,425 |
| BSA 60 100mm Parallel Mount Servo | 100 | 15 | 200 | Servo | $1,525 |
| BSA 45 250mm Inline Stepper | 250 | 7 | 200 | Stepper | $1,250 |
| BSA 45 250mm Parallel Mount Stepper | 250 | 7 | 200 | Stepper | $1,350 |
| BSA 45 250mm Parallel Mount Servo | 250 | 7 | 200 | Servo | $1,450 |
| BSA 60 250mm Inline Stepper | 250 | 15 | 200 | Stepper | $1,475 |
| BSA 60 250mm Parallel Mount Stepper | 250 | 15 | 200 | Stepper | $1,575 |
| BSA 60 250mm Parallel Mount Servo | 250 | 15 | 200 | Servo | $1,675 |
| BSA 60 500mm Inline Stepper | 500 | 15 | 200 | Stepper | $1,875 |
| BSA 60 500mm Parallel Mount Stepper | 500 | 15 | 200 | Stepper | $1,975 |
| BSA 60 500mm Parallel Mount Servo | 500 | 15 | 200 | Servo | $2,075 |
Rated load and speed are catalog maximums for the configuration shown; "—" means the figure depends on the motor curve at your speed — the engine computes it. All prices are U.S. list, single quantity.
Not sure which one?
Describe the task — payload, travel, speed, orientation. The engine picks the family and the variant, shows the torque and inertia math, and prices the whole system.
Frequently asked
What is the difference between a ball screw actuator and a lead screw actuator?
A lead screw drives a sliding nut (30–40% efficient, self-locking at fine leads, lower cost). A ball screw drives a recirculating-ball nut (over 90% efficient, far more thrust per watt, minimal backlash, long life at high duty) but will back-drive, so vertical axes need a brake.
Which BSA lead should I choose?
5 mm for maximum thrust and resolution at up to 100 mm/s; 10 mm when the axis needs 200 mm/s. The engine selects the lead from your speed target and shows the torque margin for both.
Can a BSA be used as a vertical Z axis?
Yes, and it is the right choice for heavy or continuous-duty Z moves. Specify vertical and the engine adds the gravity torque and a brake to the BOM.
What is the lead time?
BSA 45 and BSA 60 are stock configurations at 2–3 weeks; a STEP file is available for every variant.