Re: [CAD_CAM_EDM_DRO] losing steps

> Hi All,
> I am putting the finishing touches to my newly built router table,
> and to my surprise, with the power on to the Y motor , I can make the
> motor lose steps, when I put my shoulder into the cross slide.
> Is this normal? the motor is a Pacific scientific 645 oz-in, and I am
> using gecko G201a. and 1 rev of the motor is moving the cross
> slide .8"

If one revolution translates to .8", you really don't have much
mechanical advantage to assist the stepper. Is this some kind
of rack and pinion rather than screw drive?

You can gain some resistance to step loss at low speeds by putting in
timing belt reduction, or going to a somewhat finer pitch screw (maybe
4 turns per inch) although your top speed will drop as a result. Of
course there is no point in worrying about high speed performance
until you have relability at low speeds and at a stop.

Normal sliding contact screws are inefficient, wasting motor power in
friction, however they are also able to dissipate a fair amount of
cutting (or operator shoulder) force in friction without applying it
to the motor. Handwheels on manual machines with acme screws tend to
hold in place in the presence of reasonable cutting forces all by
themselves.

Chris Stratton

-------------------------------------------------
Christopher C. Stratton
Engineer, Instrument Maker, and Horn Player
ccs@... 617 628 1062
http://web.mit.edu/~stratton/www/brassbuild.html