Re: CNC: Spindle speed control

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "J. Malte Stoeckhert"
<malte.stoeckhert@m...> wrote:

> Hi there,
>
> After doing some research about CAD/CAM/CNC I have one unresolved
> question remaining:
>
> All of the systems/information I have seen so far seems to

disregard

> spindle speed control via g-code which seems funny to me as the
> spindle speed besides the feed rate is an important factor in
> cutting/turning (I'm still a early beginner in metal cutting).
>
> Is there a feasable and financially reasonable solution (I own a
> Sherline mill and lathe)?
>
> Malte

Go to the //groups.yahoo.com/group/Master5 list and check the last
couple of days posts about controlling the speed on a Sherline mill.
The basic concept is to make one of the axis output a PWM signal and
integrate that to create a variable DC voltage. Then you have to
turn that into something that will interface with the speed pot on
the Sherline. The g-code would be a call to that axis (A,B,C) with
an F (feed) rate and that sets the frequency of the pulse train that
ultimately gets turned into a controlled voltage. Someone at some
point had a cicuit posted that was the integration part but I can't
seem to locate it in either group's file section. They are currently
grappling on how to do a soft start/stop when using the direction to
reverse the motor.