On 9/6/22 23:42, John Dammeyer wrote:
Hi Ralph,
The reason I ask is the replies are often like yours with an incorrect
assessment of features.
https://www.centroidcnc.com/centroid_diy/images/centroid_acorn_cnc_controller.pdf
I think 8 inputs is quite different from the 3 home inputs you mentioned. A
quadrature encoder input for spindle feedback and therefore tapping is another
3 inputs and apparently on the DB-9 is also the ability in addition to 0-10V
spindle speed the CW/CCW direction capability. And I count 8 relay outputs and
4 motor channels, not 3.
Bari has mentioned about costs. He's right about that.
The Mesa 7i95 with Ethernet connection to the PC and a choice of user
interfaces with or without touch screen. Cost is $295 compared to by the time
you add some relays and a power supply the cost is probably more for the Linux
System.
But, and it's a gigantic huge but, the response is often "I don't want to learn
another OS and have to figure out what to do with Linux".
Assuming then that the end user installs limits and shares a home with one on
each axis he's got 6 inputs tied up. Adds a touch sensor which can share a
tool height sensor input. Maybe also a small rotary table with a stepper for
that 4th axis. A relay output for coolant control which is an extra cost for
the LinuxCNC system. And VFD on the spindle along with an encoder.
So far we haven't exceeded the I/O on either system. Costs are somewhat comparable.
However, after that introductory carrot, the price for the Acorn jumps by another $159
for the "Mill Pro" which now lets you use that rotary table and do Rigid
tapping. So now the Acorn is well above the price of the LinuxCNC system. We'll ignore
the price of the PC for now since both are required (along with motors, belts, pulleys,
limit switches etc.).
If you go out and buy a laptop it probably comes with Windows 10. Finding an
inexpensive laptop with hard wire (verses WiFi) internet connection is getting
harder. Not sure about the touch screen side of things. Either laptop or a
monitor.
So price wise, MESA $295 plus some relays and a power supply so say $400. The
Acorn $329+ $159= $488. So Acorn more expensive but turnkey compared to trying
to install LinuxCNC on a new piece of hardware, trying to figure out what a HAL
and INI file do, which user interface to install and so on...
The question still stands. For that simple 3 axis + rotary table mill why buy
LinuxCNC? We're not adding a tool changer or power drawbar because it's a
hobby system or used occasionally in a small shop to make 5 of something.
There are user groups for both types of systems. For that matter cost wise
there's also MACH4 with the Ethernet SmoothStepper or a few other similar
interfaces. Cost wise also in the $400 range.
So why LinuxCNC?
John
Let me say it again John, I'm a bit of an outlaw. Been called a JOAT and
accused of walking
on water. (Which explains my business name if suppliers want one.) None
of which is 100% true.
For me the choice is a no brainer.
Any job I want to do only costs me the hardware to build it. Nobody is
standing there with
a hand out that needs green grease or the job won't get done.
LinuxCNC facilitates getting the job done simply because it comes with
no limits AND no
warranty.
MBA's hate that, they've nobody to sue when their wild hair fails. MBA's
and I rather famously
don't get along. They are always looking for an edge, which often is of
questionable legality.
I don't tolerate that at all well.
The only limit I've found in linuxcnc is this users lack of imagination.
If /I/ can imagine it, /I/ CAN do it.
Only for the cost of the hdwe.
I imagined carving this vise screw, but it would need a rotary axis of
considerable speed. And an air supply to clear the cuttings.
A 5/1 worm drive for $70 on fleabay, $130 for a 3NM 3 phase
stepper/servo. Some machining to
make a foot to put it on the 6040's table, another $70 for a
surprisingly nice tailstock, printed a socket
to hold the stick, and I had a 400+mm long B axis. Problem solved.
Driving it with LinuxCNC is NOT a problem.
Jameco had some teeny 12 volt air compressors for a $7 bill. 5 of them
supplies plenty of air, printing
the intake filtration and manifolds gives me plenty of air to run a
mister kit dry. A pwm to control
their speed? Couple hours in hal and an $11 H-bridge, works great and I
cannot hear it over the
rest of the mills noise.
Designing the shape of the buttress tooth in OpenSCAD and converting
that into g-code to carve
wood took a bit of study. Needing a 7 degree load face, and not wanting
to write that code, was
about 2 days, designing a wedge to put under the mills spindle motor,
printing it and installing it,
gaining a much needed 30mm under the tool while I was at it.
The list goes on. Other solutions cost lots of money, a lot like paying
rent. And my attempts to help
defray its costs? Several offers of help with buildbot $ or gear have
been made, all simply ignored.
TANSTAAFL guys. Somebody has to buy the beer and peanuts. ;o)>
-----Original Message-----
From: Ralph Stirling [mailto:ralph.stirl...@wallawalla.edu]
Sent: September-06-22 5:34 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Acorn CNC
What kind of machine does the potential Acorn buyer plan to control?
Most of these newer controls are aimed at vanilla 3-axis cartesian
machines. They generate step/dir pulses, and have three home inputs,
and not a lot else. LinuxCNC really shines when you have more complex
I/O needs, unusual kinematics, tool changers, integration with external
elements (bar feeders, robots, etc) and the like. I haven't seen any of
the newer open source or low cost controllers address these more sophisticated
applications.
-- Ralph
________________________________________
From: John Dammeyer [jo...@autoartisans.com]
Sent: Tuesday, September 6, 2022 5:06 PM
To: Enhanced Machine Controller (EMC)
Subject: [Emc-users] Acorn CNC
CAUTION: This email originated from outside the Walla Walla University email
system.
If I was to offer an reason to go LinuxCNC to someone who is attracted to an
Acorn system what would I say.
Other than the Acorn is really just a cape for a BeagleBone Black. But the
user interface is all via Ethernet so a
PC of some sort is still required.
There appear to be so many CNC systems out there now. Even LinuxCNC now
suffers from too many user
interfaces to the point where is the Tormach really still LinuxCNC or is it
something different too?
Comments?
John
"ELS! Nothing else works as well for your Lathe"
Automation Artisans Inc.
www dot autoartisans dot com
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Cheers, Gene Heskett.
--
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soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
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