Re: Electronic Lead Screw & Power Cross Feed | Poor CNC ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

> I think this sums it up.
>
> Eleminate the change gears.
>
> I cut mostly aluminum so would like to be able to adjust the feed

rate

> and I cut stainless. I need two feed rates at any particular time.
>
> Putting a stepper or servo or even a windshild motor on the

leadscrew

> an then a speed pot would handle about 98% of my needs.
>
> but if I can add a simple interface to the mix, then presto !
> electronic leadscrew.
>
>
> Now, also considder that one does the add. It will be a servo or
> stepper almost exclusivly.

DeskCNC uses a quadrature encoder with an index pulse to
electronically gear a spindle to axes motion. This permits multiple
start threading, back flank constant chip load cutting, and tapered
threads. We use a 500 line encoder on Sherline lathes. this
permits you to slow the spindle down to an appropriate speed for
cutting even larger diameter threads. You can even turn the spindle
by hand and the axes will stay geared to the rotation of the spindle
( within 1/2000 of a rev).

One of the points that seems to have been missed in the discussion
of threading over the last few weeks is that manual threading is a
pita. It takes very good coordination to avoid smashing into a
shoulder or to catch the halfnut at the correct time for 7-12 passes.

An electronic leadscrew does not eliminate this problem.

A CNC lathe, with two axes to work with, permits an inexperienced
operator, or a clumsy one to still make good threads.

With our software, programming a multiple pass thread is less
complicated than figuring out which change gear to use on a manual
lathe.

Fred Smith - IMService