Re: DC motor as replacement for Stepper motor

Ramel,

Okay, let's think outside the typical solutions, using what you have
said. This is actually pretty interesting...

You seem to be describing an "escapement" or "pawl" type device.
Escapements were used on early radio control airplanes, and pawl type
feeds are common on old metalworking tools like shapers.

So, Yes, you could duplicate the action of a stepper motor in
a "third world" situation with two homemade solenoids (steal the wire
from a transformer like I used to do when I was a kid) and some sheet
metal to make the pawls. You would also need a gear, or make that as
well from sheetmetal.

Anyway, if you set the pawls up so that the pulling action of the
solenoid advances the gear one "notch"(what you were calling blades),
you have created motion in one direction by simply outputting pulses
from the computer. A second solenoid would be set up in opposition to
the first, to provide motion in the other direction.

You will need to keep whichever solenoid is not currently being used
out of the gear teeth, so that the "other" can provide the desired
motion. This could be done with a "direction" selection solenoid.

(Hey! just had a thought!)
If you set the pawls(the arms of which are spring loaded towards the
gullet of the gear teeth, and free to move "out of the gullet", for
the "return" stroke) up on opposite sides (across the diameter) of
the "driven" gear. Actuate BOTH of them with a single solenoid; AND
had the second solenoid move the dual pawl assembly laterally so as
to engage one pawl whilst disengaging the other, you would have a
STEP and DIRECTION solenoid drive!

I'd imagine this could be put together in an afternoon or two... With
very basic tools, and VERY low cost. Your "drive" force would be that
of the solenoid "pull" force. An open loop system.

It seems so obvious upon reflection, that I wonder if I'm
not "remembering" something I've seen from the past...

Hope this helps.

Ballendo

P.S. Your word "piston" makes me think that this could be also done
with air cylinders, for much higher forces... (but at a higher cost
in time and meterials)

--- In CAD_CAM_EDM_DRO@y..., "Labian, Ramel" <RamelL@p...> wrote:
> hi! what we're trying to do is a customise lathe machine. we build
it from
> scratch. and it must have a computer interface. well it doesn't
need to be
> so complicated. What we had in mind is there is a round disk which
holds
> the blades then a sort of a piston from above <snip>