Re: [CAD_CAM_EDM_DRO] Re: Electronic Lead Screw & Power Cross Feed | Poor Man's CNC ?

Hi,

It was a good write-up and mentioned a few points that seem to have been
lost on this list with a strive for perfection.

The lathe CNC folk seem to believe in a need for ball-screws with everything
and then throwing away handwheels. This is not necessary.

I own a Harrison CNC/Manual lathe built for education market during the
80's. It was originally installed in a local technical college in 1981 at a
cost of £18,000 ($31,349) which was more than the price of a family house in
my area. I point this out to show this was not a cheap machine and one of
the largest manufactuters of lathes in the world didn't see the need to fit
ball-screws.

It does not have ball-screws on either axis, needing a little adjustment of
the cross-slide leadscrew nut whenever cutting towards the operator is
required, not very often. I can get the backlash down to a repeatable 0.01mm
and can program this out. What the CNC folk seem to forget is it is bad
machining practice to machine towards the tailstock so a ball-screw on the Z
axis is not necessary with creative programming.

The machine is also fitted with a screw cutting gearbox and handwheels so it
can be used as a totally manual machine although I have never used it in
this manor as I manually machine using the CNC controller I have stepper
movement via a speed and direction 4 key keypad and DRO feedback. Should I
need to screw-cut, it is a simple matter of keying in a small program
quicker than it would take to change gear ratios.

I have another straight turning machine of about the same size that would
benefit from an electronic leadscrew as it does not have a gearbox or change
wheels.

I beleive this subject has a place on this list and urge you to keep it here
rather than starting another list.

Regards,

Terry

> What a good write-up .
> Cheers BW
>
> Cam