Does anyone have ideas for a cheap (lets say <$50) light duty linear actuator with about a 100mm stroke? Position control would be nice, but it’s not really necessary. What I really want is something a little more compact than motor assembly from a CD drive tray.
I imagine such a thing must exist, and Servo City has been teasing me with their light duty linear servos (“Coming Soon” for a few months now). The one pictured doesn’t look like it would have nearly that long of a stroke, but they might be making different versions. Also no clue what the price tag would be.
I had a little back and forth with Haydon Switch & Instrument, which makes sweet little stepper motor/lead screw hybrid linear actuators. Their basic ones are $70 though, and they have a $100 minimum order. Other brands I’ve found have similar or higher prices. It’s like there’s a two inch stroke limit, above which things get way more expensive.
I don’t need anything quite so fancy, but I’m not sure where else to look.
Unfortunately we don’t have any suggestions for you. We’d definitely be interested to hear about it if you do find a source for something like this, though.
I heard back from someone at ServoCity that they really didn’t mean to tease me so, but that the design had been done when one component kept failing in testing, so they’re going through a redesign with no set end date. Oh well.
There doesn’t seem to be any way to get new linear steppers for cheap, but it looks like such things turn up on e-bay occasionally. I just scored this little guy for under $30 shipped:
The motor body is larger than I was hoping for, but it will do the job quite nicely.
It’s an Airpax L92211-P1, and I have a datasheet for it here. The basic specs are 5V, 0.001" per step, and a stroke of about 2.5". I don’t know if this brand is really around any more, but if you don’t mind spending ~$100 you can get similar motors from HSI.
In retrospect I wish I had held out for a “captive” style motor (the e-bay auction wasn’t 100% clear on which kind this was), which keeps the shaft from rotating internally. In this more common “non captive” type of motor, where you have to keep the shaft from rotating externally for it to move linearly.
