Excellent report, Don !
Should be required reading for all interested in CNC.

Bob Swinney
"DoN. Nichols" wrote in message
...
On 2008-07-15, RB wrote:

[ ... ]

Now I'm looking at a EMCO COmpact5 CNC mill/lathe. It's not the F1, but
I have not determined what generation it is.

What I'd want it for is to learn basic CNC programming, and to make
things like firing pins for pistols. It looks like a fun toy.

It should work nicely for that.

It seems to be complete, powers up, DRO shows on the screen and the
numbers move when you bump the servos via the manual controls.
Has a chuck, maybe some collets, includes the milling head. Also a
steady rest. The machine was in use by a recently deceased benchrest
rifle builder. He also has a much larger CNC machine that looked to be
his workhorse. This little one is pretty clean. Asking price is $700

Not bad.

What kind of toolpost does it have?

The options are a quick-change of the Dickson style, or a turret
which handles six tools (three bar shanked tools for normal turning, and
three round shanked tools for drilling, boring and internal threading.
The latter will only be present on the later machines. A machine with
the quick-change toolpost could be any of the three firmware versions
(each with modifications to the CPU board, including progressively
more memory and more complex functions from a single instruction.

I've searched the web and found surprisingly little about these
machines. I did find this http://www.emco.co.uk/home&hobby.htm
which is most useful.

Does anyone here own and use one?

Yes to both.

Suggestion of things to look for / at to evaluate it?

Well ... the sure way to tell which you have is to pull the back
cover, pull out the CPU board, and check the version labels on the
EPROMs. There are three EPROMs on the system. The earlier one had
smaller EPROMs plugged directly into the CPU board. The newer ones have
a daughterboard which plugs into the original EPROM sockets plus into at
least one socket originally for a logic chip -- whose functions were
moved onto the daughterboard. I think that it is possible to convert an
older board to the newer by just adding components -- including RAM
chips -- plus changing the firmware. But I have not yet tried this with
my old board. The CPU happens to be the old 6502, so don't expect too
much power or speed out of the computer part. (Unless you are looking
at the Compact-5/CNC-PC, which uses a PC with a special card to do the
control, and just provides power and the stepper motor drivers in the
box.

Another clue is that the oldest version at least has keys which
don't have the contour on the sides that good newer keyboards have, just
a shallow cup in the center. The colors of the keys are slightly
different, but it is too late to look that up tonight. E-mail me for
more information -- but *don't* send attachments like photos, or the
e-mail will probably be automatically refused. The e-mail address in
the "From: " header above, and in the .sig below is valid. I don't play
with munged addresses.

Another clue is the spindle motor switch. On the earlier
system, the switch was simply a rocker switch with ON and OFF. On the
newer one it is either a rocker switch with ON/OFF/CNC so the program
can start and stop the spindle. Some of the later ones have a
different style of switch, but since I don't have one of those, I
forget what it looked like -- rotary switch, perhaps?

Things to watch out for?

Earliest version keyswitches have serious key bounce problems.
I replaced my system board with a newer one (expensive) which got me the
newer firmware and a lot more other features.

Most of them have a tape drive for storing programs which uses
tiny tapes which are quite hard to find. I have a replacement drive
which will use 3.5" floppies -- but which will require me to make a new
mounting bezel for it. (Then again -- floppies are now getting hard to
find, too. :-)

Overall usability for the intended purpose?

Reasonable -- especially with the last firmware package. An
example of differences is the G-code which turns in the earlier one
makes a single pass at the depth of cut already established. The last
one lets you start just clear of the workpiece and tell it to cut from
*here* to *here* (Z-axis) and to then return to the start, step in by
*this* much, and repeat until you get to the final depth specified.

There are similar ones for threading.

And the older version which would require a lot of commands to
make multiple passes to get to final diameter has fewer total
instructions in the available memory.

One thing to watch out for (in all versions) is that you can't
turn odd diameters. The minimum step size is 0.001" in inch mode, and
0.01mm in metric mode. But this corresponds to the radius of the
workpiece, not the diameter, so you can only make pieces which vary by
0.002" or 0.02mm. Note that the metric mode steps are smaller, so you
may want to convert everything to metric dimensions (you can't mix
metric and inch in a single program).

Does the price seem right based on what I've mentioned?

I would consider it to be a good price if you have the
quick-change toolpost (with at least four holders -- one for the parting
blade and three for other square-shanked tools -- with one with a V
bottom for round shanked tools as well), or the turret toolpost.

A bonus is The collet adaptor for the spindle. This would make
your firing pins easer to make than doing it with a chuck.

Prices seem to normally be above this. based on observed eBay
auctions.

BTW What does the chuck look like? The newer ones look like the
3-jaw chucks for larger lathes, while the older one is operated
with what looks like a Jacobs chuck key, geared to turn a plate
just behind the jaws. There are also a 4-jaw chuck, and a 4-jaw
universal chuck (nice when dealing with thin-walled parts where
a 3-jaw chuck would be more likely to distort the workpiece).

Good Luck,
DoN.

--
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