Screw Stepper Motor x 1pcs. Output shaft length: 36mm Stroke 34mm. Step Angle: 18 deg/step. Cable length: 250mm. We maintain the excellent service standards.
Because of the shape and size of a standard servo. The space they need to go is very limited.But why not use a classic (model-maker's) Servo (or the "continuous rotation" type) ?
The leadscrew in that stepper looks rather integral with the motor and it's not clear if the "nut" is made of plastic or metal. The leadscrew has a 2 mm diameter which would normally have a pitch of 0.4 mm, so about 80 revolutions from end to end. A rough count on the photo doesn't look too far from that. I got about 8 revs/second from a similar stepper, so maybe 10 seconds end-end. I measured the shaft torque up to about 2 gm.cms and estimate the leadscrew mechanical advantage around 100 : 1, so perhaps you'd be able to lift up to around 100 grams. However, the linked dc motor gives only around 1.5 revs/sec so it would be the best part of a minute to travel end to end for the same leadscrew. And its torque so high that it could probably destroy the "nut" even if it's made of brass or copper.We might even attempt to remove a stepper motor and connect a DC motor in its place.
From what we read about stepper Motors they are low torque low amps and not really constructed to handle this kind of a load.
With the DC motors (and servo guts), we planned the add 10k slider pots to the length of travel arm to replace the feedback pot in the servo.And its torque so high
Yes, able to tighten upon an object."fingers" are just required to "move"
Yes absolutely, a traditional way to "calibrate" a stepper is to drive it to one of its endstops. An "advantage" of a stepper (although in practice it's usually an enormous DISadvantage) is that the load (or drive) current is the same whether it's moving or not (stalled). Strictly, the inductance of the coils causes the average current to be reduced each time a coil is switched (on), so the current is a little smaller when being driven fast, but that seems to be a very small effect with these micro steppers. The great advantage of dc motors is that as the load increases, their speed drops and the "back emf" (self-generated, reverse voltage) falls. That causes the current to rise which increases the torque and automatically helps to maintain the motor's speed. The only "problem" with that is, if the load is so high that the motor stops (stalls), then the current can rise enormously (perhaps by a factor of 10) which can overheat the motor and/or damage the drive circuit.Is it ok to "stall" steppers at the end of travel, without damaging them?
To me "move" is move (and no more), so IMHO a stepper is unlikely to be satisfactory. I'd call your requirement "manipulation" and for that any serious robot would need pressure sensors. That might be a physical switch or strain gauge, but with a dc motor (or servo) could simply involve monitoring its current drain to detect its speed.Yes, able to tighten upon an object.