On 2013-11-04, BottleBob wrote:
On Sunday, November 3, 2013 7:59:26 PM UTC-8, DoN. Nichols wrote:
I have (and use) a small CNC lathe (The Emco-Maier
Compact-5/CNC). I also have a Bridgeport which started live as a
stepper-based CNC, which I was converting to servo motors, before a fire
set me back a ways. I'll get back to that as time goes on.
Don:
Coincidentally, I had a little Yellow Compact Lathe (NOT CNC though).
Mine is yellow -- though later ones were gray or red (or
perhaps a combination of the two).
It could have been a lot faster with a better choice of CPU. It
runs from a 6502 (what was used in the Apple ][ and the Commodore Pet
among other home computers. In particular, while it has Carbide inserts
for many things including threading, it is necessary to slow the spindle
speed down to about 200 RPM or lower for moderately coarse threading such
as 20 TPI or 1 mm pitch. Leave the spindle speed faster, and it
displays an error message on the CRT (if present -- that is an option),
and some error number on the LED readout display. Turn down the
spindle speed, and it starts threading. The spindle has an index plate
to show it where it is in its rotation, and the lathe has to compute
at which index hole it makes its next step. (And, it does everything
internally in metric units, though it will accept commands in inch
units. And it is a little more precise in metric units. Steps of
0.01mm or 0.002" and when stepping manually in inch mode. sometimes it
is two ticks before the next figure displays, sometimes one.
And the program format is insanely picky. Decimal point
location is implied, not displayed. and if you lose a space out of a
line of code, everything is multipled by 10 because of the position.
Here is what the start of a program looks like:
================================================== ====================
%
N` G` X ` Z ` F` H
00 90
01 92 1904 00
02M03
03 84 1900 - 5000 15 00
04 84 1650 - 1000 10 05
05 01 1850 - 1000 10
06 25 L 22
================================================== ====================
and the end:
================================================== ====================
21M30
22 01 1900 - 4832 10
23 00 1900 - 1000
24M17
M
================================================== ====================
The 'M' standing alone on the last line tells it that the program is in
metric units. Inch units have a '"' there instead.
[ ... ]
But some other things which I started doing on the little CNC
lathe turned out to be a lot quicker on the Clausing, using a bed
turret, and Geometric die head among other things.
I now see what you and Lloyd meant with your suggestion for going with
"A minority of 'Home Shops'..." as regards CNC machines.
Indeed. And several of the others in the local metalworking
club have modified small lathes or desktop mills to be CNC as well.
Enjoy,
DoN.
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