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From: "Harrison, Doug" <dharrison@...>

Couple months, maybe. I will need some help with the layout and component
selection. Will probably produce a few beta versions to make sure we get it
right. Anybody object to using a wall wart to feed the 5vdc supply?

In no real order:

My offer on the parts still stands.

Just to give an idea of the number of some of the parts I have,
in case someone if thinking I have small box of junk...
74-ALS-LS-F-244 Tri-State Octal Line Drivers, Rcvrs.
I have 1,584.

Almost all the parts I have are LS type TTL parts.
It seems they have the advantage as far as drive and sink currents.
They will source 24 ma, this should be able to directly drive many
LEDs and Optoisolators.

The issue of long signal line runs and noise would better be addressed
by differential line drivers than 120VAC, IMHO.
I have a bunch of RS-422 line drivers and rcvrs as well.

I have a bunch of PCB mount relays as well, I'm sure of the rating,
I think they are single pole double throw, they are about a 1/2" cube.

Here is MY take on the interface.
To give the most flexibility and largest address space to the interface
We could make access a 1,2 or 3 step process as necessary.

First Write an address and command string, the only command I can
think of at the moment is read or write.
Something like:
0 1 1 0 1 0 0 1
? ^ +-adderess+
|
0 for read 1 for write
The lower 6 bits are the address for 64 possible locations.
This would allow 512 bits of input/output.

Watch for a ready signal on one input line(If Appropriate)
Read or Write the data.

I would suggest presuming a bi-directional interface and not do the
4 bit crap.
The PS/2 type bi-directional interface has ONLY been around for 13 years.
It SHOULD be supported even in junker type $5.00 hardware.

Use the additional I/O bits on the port for stuff like the ready flag
mentioned above.
The only time I can think of right off the ready bit would be used
would be handshaking for talking to an external CPU or something,
A delay for an A/D converter to do a conversion after a read request,
and to sync up to another external action.

Otherwise this thing would run in a latched state and you could set
up some of the TTL buffers, to pass data straight thru and would
have any input changes instantly show up at the printer port until
you set a new address.

Such a system could easily be built with TTL parts, and with a simple
design based on latches it would be easy to understand and troubleshoot.
A lot simpler than the 8255 btw.

Adding an Eprom directly wired to a pair of 7 segment displays could
decode the address at any given instant and show the number of the
currently active port in decimal digits.
Then again maybe it would change too fast to bother with...

BG Micro has 7500 V optoisolators for 17 Cents.

Marc

In a message dated 2/24/00 2:00:23 PM Mountain Standard Time,
jvicars@... writes:

<< The individual conductors are solid copper, >>
one caution, solid wire is subject to breaking in a shop environment.
bill

From: Jon Elson <jmelson@...>
I would suspect that no manufacturer gets away with this anymore in
industrial equipment,

Both Servo Dynamics and Advance Motion Control make systems that run directly
off the line (no isolation transformer). How they do it? I don't know...

See:


They make several model that run off the line.

and


Some of the PS1600 series supplies are just a bridge and a cap.

Apparently they have some way of "de-referencing" ground (?)

Matt

Couple months, maybe. I will need some help with the layout and component
selection. Will probably produce a few beta versions to make sure we get it
right. Anybody object to using a wall wart to feed the 5vdc supply?

Doug

From: Jon Elson <jmelson@...>
No, there is a G-code for synchronized threading. Apparently, there are
two
very similar codes, one for mills (G84) which is a tapping cycle, which
reverses
the spindle at the end of the move, and backs the tap out of the hole.
This has
apparently been implemented, although it is not in the interpreter
documantation.
I was assured by Fred Proctor (or was it Matt Shaver?) about a year ago
that
GM Powertrain had tested it on one of their big machining centers, and
it worked.

It's true, but this is back in the PMAC/Windows NT days, so it may not be
there now, or work anymore. If someone wants to do this it could probably be
put back in or fixed as required.

Well, it is not a 'compensation'. You need to install a spindle
encoder, with an
index channel, and hook it up to an encoder input on the STG board (or
whatever
you are using). EMC computes where the Z axis should be relative to
spindle
position.

Another way to look at this is "electronic gearing". The EMC (and other
controls that thread) start up the spindle and then "sync" or "slave" the
other axis (usually Z) to the spindle encoder. This explains why the Z axis
must travel a short distance before you can cut the workpiece.

Matt

Doug, I would definitely be interested in a board like this. When might we
expect to see this available?
Patrick

John Guenther wrote:

Is there any probability that EMC will be ported to RedHat 6.0 or 6.1 in the near future?

We have a port to Linux 2.2.13/RT Linux 2.0, which should work with the
Red Hat 6.X distributions. We'll put a new release on the FTP site for
both the Linux 2.0.36 and 2.2.13 platforms this weekend.

--Fred

From: Jon Elson <jmelson@...>

The turning center G-code is G33, for constant lead threading, and it
doesn't
require you to back up the spindle to return the tool to the start end
of the thread
to take another pass. G34 does variable lead threading, which sounds
like an
obscure thing to do.

The Threading commands are G32 and G76. The G33 was an obscure command on
the Fanuc 5T to allow for more precise cutting of odd lead(pitch) threads.
The control only supported 4 decimals for pitch & this was an attempt to add
more. In the Fanuc 6T the G33 was eliminated & the G76 was added. The G32
and G33 are single pass threading commands & require that you program the
X(diametral) start point as the tool progresses into the work. The G76
command is a one or two line command that automatically calculates infeed
angles and makes multiple passes. You program only the start point in X and
it calculates the end position based on your depth of cut spec & number of
passes.

Our free threading program is designed to generate a tool path very similar
to the G76, and do it for a machine that may not support the G76 (or even a
manual machine). There is a write up on our web site at


The program also generates the tool path geometry in a fashion that can be
imported into Vector and Vector will then flawlessly generate the G code for
each pass.

We are kicking off a special lease-license that is designed especially for
the home shop/hobbyist user. The program allows you to rent to own Vector
licenses. It is rather unique & we are offering special terms to the
Cad-Cam-EDm-DRO listserve members. Normal term is 7 months, for this group
through the end of the month 5 month terms. Please call us for details as
the info will NOT be placed on our web site till at least tomorrow.

Now, of course, this is how the 3-phase variable speed drives
work, but when you are driving 230 Volt motors, you at least
know there are hazardous voltages there.

Jon

It might also explain why 3ph VSD's go up in smoke so often.

Doug

I'm guessing about 1.5 hour for one-off assembly. If we go with a standard
layout and build several it could be as little as a half hour. She is
working on boards of similar complexity right now. We bid them at $17.60
each. A good PCB layout helps.

Doug

I wrote:
Subject: Re: Quiet spindle motor?

[I was wondering if anybody knew where I could get a 1/10 hp AC-DC
universal motor that was nice and quiet? The Dayton spindle motor on my
MaxNC 10-2 makes too much noise for home use, but I'd like to use it in my
basement. Is this a function of the brushes, or the sleeve (as opposed to
ball) bearings? I've had much bigger motors that ran much quieter- any
suggestions? I could also use a 1/5 hp motor, for my other machine.]

Chris Stratton stratton@... wrote:

I've got a sherline with the older AC motor, that is also on the noisy
side. Contributions seem to come from the fan, brushes, relatively low
switching rate of the control, the fairly high RPM you find on these
small machines, and the fact that they vibrate a lot more for a given
imbalance than a heavy cast iron machine would.

Could you just put it in a foam-lined plywood & plexiglass box with
isolation feet (machine-box and maybe box-table)?

[I've had the same thought- no doubt this would help, although I'd have to
balance the anti-noise effect of the foam and plywood with the restriction
of visibility from the plex. I was planning to do this anyway. Isolating
the machine from the structure would also help. But I'd like to start with
a quieter motor, if possible- then I might be able to run it at night.]

Craig C Chamberlin <ccc@...>

You can buy the current Sherline motor and control box separately...Price
is $US150-175. It is very quiet.

Craig

[I checked on that- I even got the Sherline folks to hold their motor up to
the phone and turn it on- it was quieter than mine. Unfortunately, the
Sherline DC motor is considerably larger and heavier than the one I'm
replacing, and I'm afraid it will weigh down the z-axis unduly. It is also
considerably slower, running at ~3000 rpm instead of 10,000 rpm in the
motor I'm replacing. I suppose I could change the pulley system to be 1/1
instead of the 1/3 reduction it now uses, but rigging a counterweight
system would be difficult. And what with tax and shipping, the thing is up
over $200 already.]

Jon Elson <jmelson@...> wrote:
My recollection from the ad photos is this is a 'sewing machine' type
motor.

[Right- they are easy to slow down with electronic speed controllers.]

Journal bearing can be much quieter than ball, although good ball
bearings
can also be fairly quiet. Brushes, themselves don't make much noise.
The shortcomings of those type motors are probably in two areas; a
minimal number of armature windings and commutator segments, and
no, or minimal balancing of the armature.

[Is this what makes them noisy?]

I know that brush-type motors can be made quiet, as I have some in my
mill. Don't look for an AC/DC
universal motor. Instead, find a DC permanent magnet motor of modest
size and use that. You might also check out the Surplus Center
'treadmill' motors, but these may be a bit too large and heavy.
With a different (larger) pulley on the motor, a motor with lower
speed can give the same range of spindle speeds, but the slower motor
is most likely to be quieter than the sewing machine motor, which needs
to run fast to produce any torque.

Jon

[Thanks, Jon, Chris, and Craig. This gets me somewhat farther along. I
suppose I can find a DC motor the right size and change my pulleys (if I
can find the right ones for those skinny little belts) - but what kind of
transformer would I need to run it on a more or less continuous basis? How
much should I expect to spend? I'd like to switch my other one (the 1/5 hp)
over as well, but the speed control for this one is controlled by
software, so that if I wish to preserve that feature I'd have to replace
like with like.]

Andrew Werby


Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff

Fred,


Servo To Go users,

The EMC includes a software interface to the Servo To Go that should work with both Model 1 and Model 2 boards. The source We don't have a Model 2 board here, so we haven't tested it. We took the
latest driver from Servo To Go's web site, which handles both models,
and ported it. It works for the Model 1. Testers, please...

--Fred

Jan-release RH5.2 K2.0.36
Tried now to put some voltage on the DAC's. Which 'minerror' put very high a can run a program, when jogging (+ -) an axis seeing on a scoop the change in voltage (+ -).

Tried also STG- linux- program:
Changed bit A1 =P1/45 = + X limit , nothing happens
Changing bit A2=P1/43 = - X limit , indication in TkEmc X goes red.
Changing bit A3=P1/41 = X amp fault , indication in TkEmc X goes red.
Same thing happens with Y and Z axis.
Was this also the fact in stgmod.o ? I remember changing bit A7 to go out of Y-limit when working which my (broken) model 1 board or is my STG Configuration out of date?
Jan.

Doug,

If you deliver a board such as you are you are talking about, which works with CNCPro, I would be happy to pay to have your wife
assemble it...

So, an estimate of the cost of an assembled board...ballpark...would be good, it is it possible.

Regards,

Craig

Carlos Guillermo ,wrote

I ordered 4 of those motors. They look nice, but I missed the fine

print

about them being brushless!
This model senses the rotor position from extra tracks on the

encoder wheel,

instead of the hall sensor setup I'm familiar with. Can you point

me to the

brushless motor control chips you mentioned, and maybe also an

appnote

sample circuit?

Thanks,
Carlos Guillermo

I did the same thing myself,after checking back I found that there
was no fine print about them being brushless in the catalog,only on
the data sheet,live & learn as they say.Anyway after finding out what
I had I started looking for a
driver solution
here are some of the options Im looking at now

brushless DC motor controller
Unitrode UC3626 or UC3625 sold by Texas insturments

$4.53-$5.15 from Arrow Electronics
Motorola MC33035 $3.36 Arrow
Allegro A3932SEQ or A3933SEQ(both drive high side mosfets
directly)$5.81
still looking motorola looks ok unitrode or allegro starting to look
better

high side driver
Intersil HIP4083(3x) or HIP4086(6x) $3.65 & $7.17 Arrow

power amp (all n-channel)
Texas insturments TPIC1310 3-HALF H-BRIDGE (2.5A continuous 12A pulse)
$3.60ea from

there are a lot of options out there from other makers,most will read
ttl level encoders &/or hall inputs,check the data sheet to be sure
some take a PWM speed input most like a voltage level,all the ones
Ive seen so far need a direction+speed input,almost all of the data
sheets have examples using a switch for direction & a pot to set the
speed(stand alone use)
the option Im working on is
PC->DAC+8255->UC3625->HIP4086->TPIC1310->motor then
encoder->LS7266R1->PC
price on a 4 axis setup adds up fast but is still 1/4 what a
comercial kit is going for most places
btw arrow seems to be mostly an oem dealer but if you bug them enough
they will sell "samples"
hope this helps
BFP

There are two more aspects to remember in this matter:
If you are using a notebook machine, you can not install a ISA card so it would be
better using the LPT port.
And, if you are going to use this board / port for driving step and dir signals to a
stepperamplifier or servoamplifier. Then, what will be the best way to do this. Either to
have a long cable between the pc and the optocupler board or have a long cable
between the opto-board and the amplifier. This will be a bigger problem with large
machines. (This cables can be 3 to 10 yards long.)
Just a matter to remember.
Ernst

stratton@... wrote:

From: stratton@...

Oh, now we're really going off the deep end. We were talking about

a

suitable transformer for some 24 W stepper motors. Yes, if you use

a

5 KVA transformer, you will have no trouble providing 75 Watts to 3
motors, and you will also prevent thieves, tornados and tsunamis

from

stealing/blowing/washing away your CNC control!

I'm not sure they are 24 watt motors. They may be rated to dissipate
24 watts as heat, but how much electrical energy can they convert to
mechanical energy? I suspect more than that.

Well, if a standard stepper driver is used, with some method to limit
current (ie.
resistors or chopper drive) then the motor power dissipation at idle is
provably
more than the maximum mechanical power output of the motor.
Actually, a motor with extremely small inductance and a very carefully
designed
chopper drive might be able achieve more power out than the idling
power,
but it could be quite tricky to obtain. Most steppers have very large
inductance, which affects performance even at very low speeds.

The only way to get more power out, is to have some mechanism to raise
motor
current with increasing speed. There have been some systems that do
things
like this, but they are not used, to my knowledge, on the small, home
shop
CNC setups.

Jon

"Harrison, Doug" wrote:

From: "Harrison, Doug" <dharrison@...>

Sometimes it gets tempting to just buy IRF640's rated for 200 volts
and simply rectify the line...

Chris

Depending on what kind of isolation your amps have, this might
work
fine. I read of one manufacturer that does this.

I would suspect that no manufacturer gets away with this anymore in
industrial equipment,
due to OSHA and NFPA (electrical code) requirements. This is just
too dangerous. It means that any part of your circuit is potentially
'live', and can't be touched, probed by line-powered instruments,
etc. I certainly wouldn't have such a design in anything I will use
or service. But, especially since the motor is likely to be mounted
on a moving part of the machine, and connected by cables, it is just
too likely that a cable could get cut or pinched, and blammo!
If the machine was well grounded, it might not cause any personal
injury, but the motor driver and other equipment, like the computer,
would get blasted.

Now, of course, this is how the 3-phase variable speed drives
work, but when you are driving 230 Volt motors, you at least
know there are hazardous voltages there.

Jon

"D.F.S." wrote:

From: "D.F.S." <dfs@...>

From: Jon Elson <jmelson@...>

"D.F.S." wrote:

The threading does not use some fixed value for spindle speed, it
measures
spindle rotation with a spindle encoder, and each sampling interval

it

computes
a new carriage position based on the spindle position.

Is this something EMC does "Out of the Box"?

I figured this would be the Best approach, but thought EMC could only
pre-calculate the positions of all the axis at any given instant, and
compensate to try and force everyting back into sync.
The only "Correction" is if things fall far enough out of sync, past
a defined parameter, was to simply stop with an error.

This is not the way EMC works?

No, there is a G-code for synchronized threading. Apparently, there are
two
very similar codes, one for mills (G84) which is a tapping cycle, which
reverses
the spindle at the end of the move, and backs the tap out of the hole.
This has
apparently been implemented, although it is not in the interpreter
documantation.
I was assured by Fred Proctor (or was it Matt Shaver?) about a year ago
that
GM Powertrain had tested it on one of their big machining centers, and
it worked.

The turning center G-code is G33, for constant lead threading, and it
doesn't
require you to back up the spindle to return the tool to the start end
of the thread
to take another pass. G34 does variable lead threading, which sounds
like an
obscure thing to do.

I don't believe this is implemented, but if G84 has been done, G33
should be no
problem to add.

Where is this compensation feature documented or is it a DIY kind of
function?

Well, it is not a 'compensation'. You need to install a spindle
encoder, with an
index channel, and hook it up to an encoder input on the STG board (or
whatever
you are using). EMC computes where the Z axis should be relative to
spindle
position.

I'll have to look into a control for my motor.
What is the usual speed variation that can be acheived had with one of

these controls?
I would presume there is only a limited frequency change that will
properly operate a motor designed for a fixed frequency.

Not really. Cooling is the major problem, as most AC motors use
self-driven cooling
fans. If you provide your own, constant-speed cooling fan, then the
motor can be
run down to nearly zero RPM. With external cooling, it should be no
problem at
all to run from 15% to 150 % or so of rated speed. You get constant
torque up
to 100% rated RPM, then constant power above that.

I built my own PWM servo amps, since I didn't know where to get them

surplus at the time. It was a great education in control systems

theory

I have a lot to learn, maybe it's time to pick my lessons.

I'll build one if necessary, or if the cost appears too high to me,
but
I presume from that statement you NOW know of a source for surplus
servo amps?

Well, they do come on the surplus market from time to time, not
necessarily
cheap, often hard to get documentation, etc. But, I've seen them on
eBay
and such places. I have made my design available to other people (about

20 individuals, so far) as a semi-kit. See my web page at :

for more info.

Jon

Andrew Werby wrote:

From: Andrew Werby <drewid@...>

[I was wondering if anybody knew where I could get a 1/10 hp AC-DC
universal motor that was nice and quiet? The Dayton spindle motor on
my
MaxNC 10-2 makes too much noise for home use, but I'd like to use it
in my
basement. Is this a function of the brushes, or the sleeve (as opposed
to
ball) bearings? I've had much bigger motors that ran much quieter- any

suggestions? I could also use a 1/5 hp motor, for my other machine.]

My recollection from the ad photos is this is a 'sewing machine' type
motor.
Journal bearing can be much quieter than ball, although good ball
bearings
can also be fairly quiet. Brushes, themselves don't make much noise.
The shortcomings of those type motors are probably in two areas; a
minimal number of armature windings and commutator segments, and
no, or minimal balancing of the armature. I know that brush-type motors

can be made quiet, as I have some in my mill. Don't look for an AC/DC
universal motor. Instead, find a DC permanent magnet motor of modest
size and use that. You might also check out the Surplus Center
'treadmill' motors, but these may be a bit too large and heavy.
With a different (larger) pulley on the motor, a motor with lower
speed can give the same range of spindle speeds, but the slower motor
is most likely to be quieter than the sewing machine motor, which needs
to run fast to produce any torque.

Jon

Who was looking for big surplus xfmrs...how big is "big: to you? I have
thousands, mostly small, but some are a couple hundred VA.

They are all "dry" (no oil), for electronic equipment, not pole pigs for the
power grid.

Murray