Linear travel

Is that one inch in 1/10th of a second?
What sort of load?

ServoCity (www.servocity.com) has a selection of linear actuators
now.  I doubt they are that fast, though - that is 1 inch in 100 ms.
You could roll your own (mechanical system) using a hobby servo
directly pulling and pushing a linear-moving member.  Even then, it
still won't be that fast.

BRW

On Thu, 19 Jun 2008 13:48:21 -0700 (PDT), BRW


Modern tail rotor servos do 60 degrees in less than 100ms. For
example, Futaba's S9256 is rated at 60ms. They're not cheap nor very
strong, though.

The S9256 is rated at 47 oz*in. If you want a full inch travel, you'd
need an arm length of one inch, giving you a max force of 47 oz, or
13N.

Since the servo has a rotating output, you will need some extra
consideration to get the linear output perfectly linear.
--
RoRo

If you don't have to control to intermediate positions, I think a solenoid
is going to be your cheapest solution.  Any motor that can do that speed
will probably be expensive and require a controller.  All you need for a
solenoid is current.  The solenoids are faster because they don't have to
drive as much mass.

Surplus 12V solenoids with roughly 1" travel are $5 to $10US around here.


Mike Ross

OK I have seen some good answers here. My load is a small sliding lens, and
I can't say exactly how massive it is. The 100 ms is what someone suggested
but I think we can use a slower speed, maybe 250 ms. Still contemplating,
solenoids
are what we will probably use, with a pivot to get more travel. I would like to
use
two for push pull, so we don't have to use a spring. I just didn't know of good
companies to explore linear actuators.

greg

    Suggest investigating concept of "scale".


solenoids

to use

    Ah, another vague actuator requirement.  Try Google.

    There are many different short-distance linear actuator devices available.
If you're going to build stuff, you need to be aware of available parts.
This isn't hard, because most vendors have on-line catalogs.

    Questions to think about?

    - How often is movement required?  If you can allow cool-down time,
    you can use a much smaller solenoid at a low duty cycle.

    - Does power consumption matter?  If this thing has 120VAC available,
    power probably isn't going to be an issue.  If it has to run on an
    AA battery, efficiency will have to be higher.

    - How precise does the stopping point have to be?  5mm?  1mm?  0.01mm?
    Is a mechanical stop with a rubber bumper good enough, or is more
    precise positioning required?

    - Is there a noise issue?  If you slam a solenoid into a hard stop,
    there's going to be a click or a a bang.
    
    - What about size and cost?  This is easier to do if you don't have
    to cram the actuator into a tight spot.  And how many do you need?

    - What's the life cycle? 100 operations? 100,000,000 operations?

A Festo SLTE actuator will probably do the job for you. They're not
cheap, but they're a turn-key solution for linear motion.

http://www.festo.com/INetDomino/us/en/cc7bba1d0b919dfbc125709200547d6a.htm

                            John Nagle

 We will construct it after the type of drive is selected.


Unfortunately Google does not always give what you want.


Thanks for the link. Most all of the actuators I have run into have way too much
power for what we want. I am considerig a 300 rpm gear motor with a arm or
circular
drive feeding an arm. I can set direction and how long of a pulse I need to let
the
motor rest after its traveled.

The servo link was great. I might use a servo but its seems more complicated
using
pulses for control.

I am used to the old analog DC servos.

What I am doing is replacing a Nikon device doing the same thing, but much
faster.

greg

greg

using

Not if you let someone else take care of the complication for you.
You can buy a hobby servo controller that you can command via RS-232.
For example, Pololu (www.pololu.com) or ServoCity sells them.  There
are many other suppliers out there.

BRW

any good

to 100 ms.

     When you ask questions like this, tell us what the load is.
If you need to move 10gm, this is easy.  If you need to move 10Kg, it's
hard, although quite possible.

                    John Nagle