--- In Homebrew_PCBs@yahoogroups.com, "hjf2k2" <drgenio@h...> wrote:
in time, they too suffered from the lack of control. You would not
have any way of knowing if it's too fast till you break the tools.
With a controlled axis, you simply tell it how fast to feed in
inches per minute. For small drills, the difference between 1 IPM
and 2 IPM will be the difference between a broken tool and a tool
that will drill all the holes.
For a stepper size reference, my CNC router uses 160 oz-in motors -
direct drive to ball screws running dry. The way system is very
basic, UHMW plastic against aluminum. It developes around 50 pounds
of cutting force - very approximate value.
These 160 oz-in motors are running at 44 volts and 1.5 amps through
a unipolar chopper driver. I can get rapid speeds up to 150 IPM but
only with some pretty slow accell/decell ramps.
That should give you some parameters to start with.
> > Bad idea,would
> >
> > You will have no control over the force - with a spring, you
> > simply get a single feedrate for everything. Believe me,a .010"
> > diameter drill requires a much different feedrate than a .125"strength.
> > diameter drill.
>
> Why? If I compress the spring a little more, I'll have more
> Or so I think. So I can put a screw to adjust the spring tensionfor
> the different bits (I use .75 and 1mm bits anyway...)there
>
> > There is no quick and easy answer on motor sizing,
> Well, I'll be making my machine with whatever I have handy. I can't
> seem to find a supplier of ball screws for my country (I'm sure
> are, but anyway the price will be too high), so I'd have to buildit
> with a regular threaded and nuts. I don't mind the efficiencyeither,
> I don't care if it's a little oversized. I ask this as I haveWhile similar methods have been used on drilling machines WAY BACK
> absolutely no idea about stepper motors.
>
> hjf
in time, they too suffered from the lack of control. You would not
have any way of knowing if it's too fast till you break the tools.
With a controlled axis, you simply tell it how fast to feed in
inches per minute. For small drills, the difference between 1 IPM
and 2 IPM will be the difference between a broken tool and a tool
that will drill all the holes.
For a stepper size reference, my CNC router uses 160 oz-in motors -
direct drive to ball screws running dry. The way system is very
basic, UHMW plastic against aluminum. It developes around 50 pounds
of cutting force - very approximate value.
These 160 oz-in motors are running at 44 volts and 1.5 amps through
a unipolar chopper driver. I can get rapid speeds up to 150 IPM but
only with some pretty slow accell/decell ramps.
That should give you some parameters to start with.