Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Thanks, Jon, this was very illuminating after many decades of lathe 
turning practice!
Peter

Am 02.04.2014 19:22, schrieb Jon Elson:
> On 04/02/2014 08:39 AM, Peter Blodow wrote:
>> I don't even know what threading dials are and where they are installed,
>> sorry. I usually cut a thread up to a given length, then stop and
>> retract the tool in one instance. It's a two hand job. I can put the
>> drive directly in reverse for a fraction of a second instead of a brake.
>>
> OK, this apparently is big difference between US and metric
> practice.  US (and old British) lathes in the unified Imperial
> system had standard threads that were all multiples of 8.
> So, we had 20, 24, 32, 40 TPI.  You could disengage the
> half nuts and re-engage on any thread for most of the
> standard thread pitches.  For some odd pitches such as
> pipe threads, you could only engage at one inch intervals.
> The thread dial had various marks so you could be sure
> to engage at the right multiple for the thread you are
> cutting.  It is much faster to open the half nuts, back
> up the carriage with the handwheel and re-engage
> at the right mark on the dial.  I could usually do this
> in about 2 seconds, including backing up the X and
> feeding back in.  I'm sure reversing the spindle and
> then going back to forwards would have to take longer.
>
> But, with the various metric standard pitches, this
> nice multiple relationship probably doesn't hold
> for practical leadscrew pitches.
>
> Jon
>
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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

On 4/2/2014 11:11 AM, Jon Elson wrote:
> On 04/01/2014 11:27 PM, Gregg Eshelman wrote:
>
> Oops, didn't read to the end.
>>
>> Or is there a single board that plugs into one parallel port, can run up
>> to four stepper drives, read up to four TTL quadrature scale/encoder
>> inputs, has an e-stop input, limit switch inputs for 3 or 4 axes, can
>> control spindle on/off and a lube pump *and nothing more than that*?
>>
>>
> Yes, see our Universal Stepper Controller
> 
>
> It does all of these things.  It has a couple more digital
> inputs and
> outputs than you strictly need, but is almost a perfect fit
> to what
> you describe.

That looks like it would work, and be simple/easy since it's a single board.


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gene Heskett]

On Wednesday 02 April 2014 12:26:19 Peter Blodow did opine:

> Am 02.04.2014 14:11, schrieb andy pugh:
> > On 2 April 2014 12:54, Peter Blodow  wrote:
> >> No problem with that, because reversing the drive is done with one
> >> lever, no cranking, no re-engaging, no dial or indicator necessary.
> >> All thread cutting is done this way over here in the shops, I've
> >> never seen any other.
> > 
> > I would imagine that it makes it hard to thread up to a shoulder,
> > especially with a lathe with no spindle brake.
> > (and older lathes with screw-on chucks can often not afford to have a
> > brake)
> 
> It can be challenging, good nerves necessary - I use a 5 Hz setting with
> the VFD to slow things down in such rare instances.
> 
> > Threading dials typically work better on Imperial lathes. With a
> > metric lathe you need to keep changing the thread counter gear.
> 
> I don't even know what threading dials are and where they are installed,
> sorry. I usually cut a thread up to a given length, then stop and
> retract the tool in one instance. It's a two hand job. I can put the
> drive directly in reverse for a fraction of a second instead of a brake.
> Don't like it, though.
> 
> Peter

All this talk  about doing manual threading, along with the pitfalls if 
ones reflexes aren't spot on, makes me want to see both the G76 and g33.1 
(and possibly other spindle/zmotion locked canned cycles, get a little 
smarter.

I have a tendency to start something like that at a slow enough rpms that I 
can visually follow the first cut or two, like when cutting threads up to a 
shoulder, making sure the backout at the end of the cut stroke is done both 
far enough out to clear the shoulder I am cutting threads up to, and has, 
at the first pass, enough clearance to be able to cut up to a thou or so 
from that shoulder on the last spring cut passes.

Seeing that I have it set ok, then the tendency to want to speed it up and 
get a cleaner cut is very hard to resist. But if I do, the thread slides 
sideways and wrecks the threading op because of the lag between the index 
pulse and the actual lockup.

If we have a true ABZ encoder, it seems to me that the zaccel to lock can 
be quantized during an air cutting run, and on the next pass, enable the 
lockup start that far ahead of the index, making adjustments in real time 
such that the desired position is effectively the index pulse.

Further thinking along these lines says we can ask for and get, much more 
zaccel, since zvel isn't straining anything even at 2x the normal running 
speed, auto adjusting the z in the run-up space, say 3 turns of the 
spindle, so that the actual number of steps issued to the motor equals 
encoder pulses for 3 turns.  There is of course more math to it than this 
simplification, but it does seem 100% do-able.

Likewise, similar math could quantify the ballistics of the spindle stop, 
thereby making the desired depth of a peck tap cycle wrapped around a g33.1 
to match up with the reverse timing so the actual stop/reverse will match 
what you fed to the G33.1 as the turnaround point, by initiating the stop 
so it coasts to the correct stop/reverse point.  Yes, I am aware that a 
G33.1 does NOT have a stop cycle, unless its running under my my-lathe.hal 
file.

There, the state change of the dir line initiates a dynamically braked 
stop, and only clocks the new direction thru to the output when the spindle 
is a very few degrees from truly stopped. :)

I could even imagine a lookup table that we would have to fill in the 
blanks, so it might even hit pretty close on the first pass by looking up 
the precount from the index, but that would mean we'll have to measure it 
somehow to fill in the blanks.  But it makes more sense to just let the 
routines measure it and track it themselves.

See what happens when I let my imagination out to play without a chaperon? 
Scary, ain't it. :)

Cheers, Gene
-- 
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-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/02/2014 08:39 AM, Peter Blodow wrote:
>
> I don't even know what threading dials are and where they are installed,
> sorry. I usually cut a thread up to a given length, then stop and
> retract the tool in one instance. It's a two hand job. I can put the
> drive directly in reverse for a fraction of a second instead of a brake.
>
OK, this apparently is big difference between US and metric
practice.  US (and old British) lathes in the unified Imperial
system had standard threads that were all multiples of 8.
So, we had 20, 24, 32, 40 TPI.  You could disengage the
half nuts and re-engage on any thread for most of the
standard thread pitches.  For some odd pitches such as
pipe threads, you could only engage at one inch intervals.
The thread dial had various marks so you could be sure
to engage at the right multiple for the thread you are
cutting.  It is much faster to open the half nuts, back
up the carriage with the handwheel and re-engage
at the right mark on the dial.  I could usually do this
in about 2 seconds, including backing up the X and
feeding back in.  I'm sure reversing the spindle and
then going back to forwards would have to take longer.

But, with the various metric standard pitches, this
nice multiple relationship probably doesn't hold
for practical leadscrew pitches.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/01/2014 11:27 PM, Gregg Eshelman wrote:

Oops, didn't read to the end.
>
> Or is there a single board that plugs into one parallel port, can run up
> to four stepper drives, read up to four TTL quadrature scale/encoder
> inputs, has an e-stop input, limit switch inputs for 3 or 4 axes, can
> control spindle on/off and a lube pump *and nothing more than that*?
>
>
Yes, see our Universal Stepper Controller


It does all of these things.  It has a couple more digital 
inputs and
outputs than you strictly need, but is almost a perfect fit 
to what
you describe.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/01/2014 11:27 PM, Gregg Eshelman wrote:
> Now back to the question, now that it's established exactly what kind of
> signal the scales and encoder put out.
>
> What *hardware* do I need to interface them safely with a PC? I've read
> that it's "simple" to connect "directly" to a parallel port and a garden
> variety LPT can handle two quadrature inputs.
The parallel port (and software encoder counting) has a 
speed limit.
You run a BASE_THREAD at some rate, and the encoder cannot
produce counts even approaching that rate without the risk of
occasionally missing a count.  So, it the BASE_THREAD is at,
say, 5 (which is 50 us or 20 KHz) you can't reliably count
more than, perhaps 15,000 counts/second.  If you have a 10 um
scale, that's a count every .01mm of movement.  15 KHz
is 150 mm/second or 9 m/min (5.9 IPS or 354 IPM).  Not
much of a limit.  But, if the scale is a 1 um, then you are 
down to
15 mm/sec or .9m/min (35.4IPM) which would start to annoy
people.  So, you have to do the calculations for your specific
computer and encoder resolution.

Or, you could get a Mesa or Pico Systems board to handle the
encoder counting in hardware.  This relieves the computer
of the heavy interrupt load of sampling the encoder, and
also gives you better step pulse generation or servo command.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Thanks, Andy,
I now see that I can get as old as a gnu and still learn dazu... Never 
seen anything like that counter, and wouldn't know where to mount it on 
the lathes I know. It's a good idea to make a run out groove that way - 
I usually have to cut it right in the beginning (with a parting tool) 
before threading starts. But that's the way apprentices learn using a 
lathe hereabouts. I have seen dozens of them passing through our shop 
over the years, 3 years each, without anyone mentioning a thread counter.

Peter



Am 02.04.2014 16:12, schrieb andy pugh:
> On 2 April 2014 14:39, Peter Blodow  wrote:
>
>> I don't even know what threading dials are and where they are installed,
> Here is a typical one:
> http://www.practicalmachinist.com/vb/attachments/f25/5191d1216225324-thread-dial-specs-9-junior-9-inch-thread-dial.jpg
>
> It simply counts the leadscrew threads as they go past. On an Imperial
> lathe you can normally re-engage the half-nut on any mark for an even
> TPI and on any numbered mark for any odd TPI.
>
> So, cutting a thread you engage the nut (on a numbered mark for an odd
> TPI) and let the carriage move down the lathe.
> At the shoulder you disengage the nut and either let the tool cut a
> run-out groove or try to do a synchronised retract on the feed screw.
> You then move the carriage back past the start of the thread, watch
> the thread gauge rotate, and re-engage the nut on a suitable mark.
>
> On an Imperial lathe there is a single fixed gear on the counter. On a
> metric lathe there are sometimes three gears, and you set the counter
> to the right height to engage the correct one. The problem is in
> knowing which is the correct one
>
> This is a picture of the tell-tale from a metric lathe with 56T and
> 60T gears, you can see that some pitches can only be re-engaged at one
> particular mark. others at even marks, and some at any mark.
> http://members.optushome.com.au/terrybrown/Media/Projects/LatheP1695.jpg
>


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[andy pugh]

On 2 April 2014 14:39, Peter Blodow  wrote:

> I don't even know what threading dials are and where they are installed,

Here is a typical one:
http://www.practicalmachinist.com/vb/attachments/f25/5191d1216225324-thread-dial-specs-9-junior-9-inch-thread-dial.jpg

It simply counts the leadscrew threads as they go past. On an Imperial
lathe you can normally re-engage the half-nut on any mark for an even
TPI and on any numbered mark for any odd TPI.

So, cutting a thread you engage the nut (on a numbered mark for an odd
TPI) and let the carriage move down the lathe.
At the shoulder you disengage the nut and either let the tool cut a
run-out groove or try to do a synchronised retract on the feed screw.
You then move the carriage back past the start of the thread, watch
the thread gauge rotate, and re-engage the nut on a suitable mark.

On an Imperial lathe there is a single fixed gear on the counter. On a
metric lathe there are sometimes three gears, and you set the counter
to the right height to engage the correct one. The problem is in
knowing which is the correct one

This is a picture of the tell-tale from a metric lathe with 56T and
60T gears, you can see that some pitches can only be re-engaged at one
particular mark. others at even marks, and some at any mark.
http://members.optushome.com.au/terrybrown/Media/Projects/LatheP1695.jpg

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Am 02.04.2014 14:11, schrieb andy pugh:
> On 2 April 2014 12:54, Peter Blodow  wrote:
>
>> No problem with that, because reversing the drive is done with one
>> lever, no cranking, no re-engaging, no dial or indicator necessary. All
>> thread cutting is done this way over here in the shops, I've never seen
>> any other.
> I would imagine that it makes it hard to thread up to a shoulder,
> especially with a lathe with no spindle brake.
> (and older lathes with screw-on chucks can often not afford to have a brake)
It can be challenging, good nerves necessary - I use a 5 Hz setting with 
the VFD to slow things down in such rare instances.

>
> Threading dials typically work better on Imperial lathes. With a
> metric lathe you need to keep changing the thread counter gear.
I don't even know what threading dials are and where they are installed, 
sorry. I usually cut a thread up to a given length, then stop and 
retract the tool in one instance. It's a two hand job. I can put the 
drive directly in reverse for a fraction of a second instead of a brake. 
Don't like it, though.

Peter

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[andy pugh]

On 2 April 2014 12:54, Peter Blodow  wrote:

> No problem with that, because reversing the drive is done with one
> lever, no cranking, no re-engaging, no dial or indicator necessary. All
> thread cutting is done this way over here in the shops, I've never seen
> any other.

I would imagine that it makes it hard to thread up to a shoulder,
especially with a lathe with no spindle brake.
(and older lathes with screw-on chucks can often not afford to have a brake)

Threading dials typically work better on Imperial lathes. With a
metric lathe you need to keep changing the thread counter gear.

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Am 02.04.2014 13:06, schrieb andy pugh:
> On 2 April 2014 11:29, Peter Blodow  wrote:
>> There is no problem in disengaging the half nuts,
>> re-arranging things and closing again. Multiple pass cuts are, of
>> course, always done by retracting the tool und reversing the drive.
> The point is that you have to reverse the drive rather than disengage
> the nut, wind back the carriage, re-engage the nut on the
> thread-counter and do the next pass.
No problem with that, because reversing the drive is done with one 
lever, no cranking, no re-engaging, no dial or indicator necessary. All 
thread cutting is done this way over here in the shops, I've never seen 
any other. With my lathe, it is all done with one lever, so I can back 
out, reverse with high speed, then again cut with low speed, all with a 
turn of my right hand. The left hand is for setting the cutting depth.
> You can't disengage the nut during a mutli-pass threading operation
> when using the non-native thread pitch.
Yes I can, but why? Only in case of emergency, to replace the tool or 
sharpen it etc. (Easy to do with large threads, small ones with a 
magnifying glass). The nut stays closed until the thread is virtually 
all done, multi-pass or multi-thread, regardless.
>
> (Actually, I believe that it is just about possible if you wind back
> to a stop and do something else clever that I once read about).
>
> I wonder if there is scope for a microprocessor thread dial, that
> lights an LED when the opportune moment to engage the nut arrives?
All this is not necessary and only a likely source of errors.
Peter


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[andy pugh]

On 2 April 2014 11:29, Peter Blodow  wrote:
> There is no problem in disengaging the half nuts,
> re-arranging things and closing again. Multiple pass cuts are, of
> course, always done by retracting the tool und reversing the drive.

The point is that you have to reverse the drive rather than disengage
the nut, wind back the carriage, re-engage the nut on the
thread-counter and do the next pass.
You can't disengage the nut during a mutli-pass threading operation
when using the non-native thread pitch.

(Actually, I believe that it is just about possible if you wind back
to a stop and do something else clever that I once read about).

I wonder if there is scope for a microprocessor thread dial, that
lights an LED when the opportune moment to engage the nut arrives?

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Not really, Jon, all the metric/Whitworth-conversion is done within the 
feed gear box. I can select between 60 metric and imperial feed rates 
each. I switch metric to imperial with the flic of one lever. This is 
done, however, by a combination of gear wheels (34/26*79/41) to avoid 
the use of a giant 127 teeth wheel. This gives a slight error of 0.8% in 
case of metric screw cutting which, however, has never led to 
difficulties. This means, the machine has been actually designed for 
Whitworth threads. There is no problem in disengaging the half nuts, 
re-arranging things and closing again. Multiple pass cuts are, of 
course, always done by retracting the tool und reversing the drive. For 
each pass, I give the tip a tenth mm additional feed with the top slide 
screw to make sure it will cut mainly in forward direction.

The screw itself is, as I said before, 4 threads to the inch (6.35 mm 
pitch) although inches were never used in Italy. My machine is a 
Graziano SAG 12 (italian brand), very convenient for automation because 
of the magnetic clutch speed selection.

Best regards
Peter

Am 01.04.2014 18:43, schrieb Jon Elson:
> On 04/01/2014 10:32 AM, Peter Blodow wrote:
>> Until the early 1990ies, many lathes were produced in Germany with inch
>> screws and a 127 teeth gear wheel to drive them in order to end up with
>> metric threads.
>>
> But that means you can't disengage the half nuts and
> re-engage them
> for the next threading pass.  Seems like a very hard way to go
> for production, although perfectly acceptable for rare cases
> where
> you need a thread the lathe can't provide.
>
> Jon
>
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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[andy pugh]

On 2 April 2014 05:27, Gregg Eshelman  wrote:

> Recommend something? I've searched some and findings range from "Yeah,
> TTL quadrature outputs can be connected to a parallel port." (without
> the author giving any specific details) to "Here's a schematic and a
> BOM, now get out your soldering iron." to "Buy this expensive board that
> does *anything*, of which you'll only use one function."

You can connect your scales to a parallel port using wires. For
neatness and reliability you might also want to use plugs.

Any additional components just reduce the probability of damaging the
port and/or motherboard.

More important than the scales for determining what hardware would be
appropriate is what type of axis motors you are trying to control.

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Dave Cole]

Do yourself a favor and do not go the cheapest route.   You will burn 
more time and find more frustration by going cheap.
If you look for and find an "exact fit", chances are you will need one 
more input or one more output beyond what you bought.

You will know exactly how many inputs and outputs you will need when you 
are done with the conversion.  :-)

Until then, you just "think" you know how many you need.

Things I can think of you may want to add:..  An MPG, an analog output 
to control the spindle speed, a probe sensor input, etc.

(I think that Teco supports Modbus, but you will have to tell us if it 
works properly or not.)

Dave

On 4/1/2014 11:27 PM, Gregg Eshelman wrote:
> Now back to the question, now that it's established exactly what kind of
> signal the scales and encoder put out.
>
> What *hardware* do I need to interface them safely with a PC? I've read
> that it's "simple" to connect "directly" to a parallel port and a garden
> variety LPT can handle two quadrature inputs.
>
> If I get a low profile PCI dual LPT card I'll be good to go for the
> existing three axes and have a spare input for a 4th axis.
>
> I'm not interested in a DIY project to connect the scales. (The rest of
> the refit/rebuild has been enough DIY already.) I'd like to just buy
> something to plug into the LPT ports and connect the scales and encoder
> to the other side - and have it usable with LCNC. Preferably without
> having a ton of extra features aside from interfacing the scales and
> encoder.
>
> Recommend something? I've searched some and findings range from "Yeah,
> TTL quadrature outputs can be connected to a parallel port." (without
> the author giving any specific details) to "Here's a schematic and a
> BOM, now get out your soldering iron." to "Buy this expensive board that
> does *anything*, of which you'll only use one function."
>
> The BOB I have has I/O for e-stop, spindle on/off and limit switches.
> That will run off the built in LPT on the PC, or a port on the PCI card
> if that will work better. (It's a better BOB than the very basic one
> which came with the steppers, drives and power supplies kit.)
>
> Might use the spindle control relay on the BOB to run the lube pump
> since the VFD has an RS232 connection. (I need to look up software for
> that, and if LCNC supports whatever comm protocol TECO uses.)
>
> Can LCNC work with doing I/O on several LPT and COM ports at the same time?
>
> Or is there a single board that plugs into one parallel port, can run up
> to four stepper drives, read up to four TTL quadrature scale/encoder
> inputs, has an e-stop input, limit switch inputs for 3 or 4 axes, can
> control spindle on/off and a lube pump *and nothing more than that*?
>
> In other words exactly and only what is required to operate a basic 3 or
> 4 axis CNC machine tool - without a ton of added cost feature creep.
>
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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

Now back to the question, now that it's established exactly what kind of 
signal the scales and encoder put out.

What *hardware* do I need to interface them safely with a PC? I've read 
that it's "simple" to connect "directly" to a parallel port and a garden 
variety LPT can handle two quadrature inputs.

If I get a low profile PCI dual LPT card I'll be good to go for the 
existing three axes and have a spare input for a 4th axis.

I'm not interested in a DIY project to connect the scales. (The rest of 
the refit/rebuild has been enough DIY already.) I'd like to just buy 
something to plug into the LPT ports and connect the scales and encoder 
to the other side - and have it usable with LCNC. Preferably without 
having a ton of extra features aside from interfacing the scales and 
encoder.

Recommend something? I've searched some and findings range from "Yeah, 
TTL quadrature outputs can be connected to a parallel port." (without 
the author giving any specific details) to "Here's a schematic and a 
BOM, now get out your soldering iron." to "Buy this expensive board that 
does *anything*, of which you'll only use one function."

The BOB I have has I/O for e-stop, spindle on/off and limit switches. 
That will run off the built in LPT on the PC, or a port on the PCI card 
if that will work better. (It's a better BOB than the very basic one 
which came with the steppers, drives and power supplies kit.)

Might use the spindle control relay on the BOB to run the lube pump 
since the VFD has an RS232 connection. (I need to look up software for 
that, and if LCNC supports whatever comm protocol TECO uses.)

Can LCNC work with doing I/O on several LPT and COM ports at the same time?

Or is there a single board that plugs into one parallel port, can run up 
to four stepper drives, read up to four TTL quadrature scale/encoder 
inputs, has an e-stop input, limit switch inputs for 3 or 4 axes, can 
control spindle on/off and a lube pump *and nothing more than that*?

In other words exactly and only what is required to operate a basic 3 or 
4 axis CNC machine tool - without a ton of added cost feature creep.

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/01/2014 02:57 PM, Gregg Eshelman wrote:
> On 4/1/2014 7:01 AM, John Kasunich wrote:
>> On Tue, Apr 1, 2014, at 09:52 AM, Dave Cole wrote:
>>> Actually 127 Pulse/rev works ok.
>>>
>>> If you have 5 TPI screws it works out to:  0.2 / 127 = 0.00157" per
>>> pulse.   If you count all of the edges of the full quad signal (which is
>>> normal) you can divide that by 4 which is approximately .00157/4 =
>>> .000393 in/count.
>>>
>> 127 is an odd encoder count, but I understand why:
>> 0.000393" is 0.01mm.
> So as it is I can get 0.01mm precision on the Z axis with its 5 TPI
> ballscrew?
>
>
You get .01mm RESOLUTION, but the servos need to have some
deflection from the commanded position, which requires some
jitter and deflection.  Depending on how great your servo amps
are, the following error may be kept
to just a couple encoder counts, or it could be quite a bit 
more.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Dave Cole]

Electrically, yes if you use a microstepping drive.  :-)

But if your ball screw has slop in it, then no.  :-(

Dave



On 4/1/2014 2:57 PM, Gregg Eshelman wrote:
> On 4/1/2014 7:01 AM, John Kasunich wrote:
>> On Tue, Apr 1, 2014, at 09:52 AM, Dave Cole wrote:
>>> Actually 127 Pulse/rev works ok.
>>>
>>> If you have 5 TPI screws it works out to:  0.2 / 127 = 0.00157" per
>>> pulse.   If you count all of the edges of the full quad signal (which is
>>> normal) you can divide that by 4 which is approximately .00157/4 =
>>> .000393 in/count.
>>>
>> 127 is an odd encoder count, but I understand why:
>> 0.000393" is 0.01mm.
> So as it is I can get 0.01mm precision on the Z axis with its 5 TPI
> ballscrew?
>
>
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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

On 4/1/2014 9:32 AM, Peter Blodow wrote:
> Am 01.04.2014 15:01, schrieb John Kasunich:
>> 127 is an odd encoder count, but I understand why:
>> 0.000393" is 0.01mm.
>>
>> I wonder if this mill was used to make metric parts
>> and they wanted the control and readout to use
>> metric units natively?
>>
> Until the early 1990ies, many lathes were produced in Germany with inch
> screws and a 127 teeth gear wheel to drive them in order to end up with
> metric threads.
> Peter

My mill was at one point owned by AC Delco, so circa 1990 they likely 
were doing metric parts. The linear scales are 0.0004" resolution which 
could be 'close enough' to the Z axis' 0.000393"

I have a small form factor Dell Pentium 4 with one PCI slot. Could add a 
dual LPT low profile card to it, in addition to the built in LPT and two 
RS232 ports. It has a video card in its AGP slot.

Or I have a 3 Ghz LGA775 CPU Dell Optiplex GX520 SFF with only one PCI 
slot (GX520 is the "stripper" model with two DDR2 and one PCIe x16 slots 
unpopulated.)

I also have three up-market mini desktop Dell Optiplex boxen with PCIe 
x16, one PCIe x1 and one PCI slot, two of them with an x16 video card. 
Only an LPT and one RS232 on those.


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

On 4/1/2014 7:01 AM, John Kasunich wrote:
> On Tue, Apr 1, 2014, at 09:52 AM, Dave Cole wrote:
>> Actually 127 Pulse/rev works ok.
>>
>> If you have 5 TPI screws it works out to:  0.2 / 127 = 0.00157" per
>> pulse.   If you count all of the edges of the full quad signal (which is
>> normal) you can divide that by 4 which is approximately .00157/4 =
>> .000393 in/count.
>>
>
> 127 is an odd encoder count, but I understand why:
> 0.000393" is 0.01mm.

So as it is I can get 0.01mm precision on the Z axis with its 5 TPI 
ballscrew?


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/01/2014 10:32 AM, Peter Blodow wrote:
>
> Until the early 1990ies, many lathes were produced in Germany with inch
> screws and a 127 teeth gear wheel to drive them in order to end up with
> metric threads.
>
But that means you can't disengage the half nuts and 
re-engage them
for the next threading pass.  Seems like a very hard way to go
for production, although perfectly acceptable for rare cases 
where
you need a thread the lathe can't provide.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Jon Elson]

On 04/01/2014 08:01 AM, John Kasunich wrote:
>
> 127 is an odd encoder count, but I understand why:
> 0.000393" is 0.01mm.
>
> I wonder if this mill was used to make metric parts
> and they wanted the control and readout to use
> metric units natively?
>
Yup, any time I see encoders with 127 or 2540 or similar 
counts, I
immediately think they had metric/imperial conversion in mind.

On lathes, they even put 127 tooth gears in the train to make
metric threading work.

Jon

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Peter Blodow]

Am 01.04.2014 15:01, schrieb John Kasunich:
> 127 is an odd encoder count, but I understand why:
> 0.000393" is 0.01mm.
>
> I wonder if this mill was used to make metric parts
> and they wanted the control and readout to use
> metric units natively?
>
Until the early 1990ies, many lathes were produced in Germany with inch 
screws and a 127 teeth gear wheel to drive them in order to end up with 
metric threads.
Peter

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[John Kasunich]

On Tue, Apr 1, 2014, at 09:52 AM, Dave Cole wrote:
> Actually 127 Pulse/rev works ok.
> 
> If you have 5 TPI screws it works out to:  0.2 / 127 = 0.00157" per 
> pulse.   If you count all of the edges of the full quad signal (which is 
> normal) you can divide that by 4 which is approximately .00157/4 = 
> .000393 in/count.
> 

127 is an odd encoder count, but I understand why:
0.000393" is 0.01mm.

I wonder if this mill was used to make metric parts
and they wanted the control and readout to use
metric units natively?

LCNC uses floating point math and can convert units
with no problems, but back in the day they might have
wanted to stick to integer math.  Having the encoder
counts be a nice round number in mm was probably a
benefit.

John Kasunich

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Dave Cole]

Actually 127 Pulse/rev works ok.

If you have 5 TPI screws it works out to:  0.2 / 127 = 0.00157" per 
pulse.   If you count all of the edges of the full quad signal (which is 
normal) you can divide that by 4 which is approximately .00157/4 = 
.000393 in/count.

That seems adequate to me.

Dave

On 4/1/2014 1:59 AM, Gregg Eshelman wrote:
> Specs on the rotary encoder.
> 3=Quadrature with index
> 25=0.25" bore
> 127=127 pulse/rev Probably way too coarse. Apparently super Z axis
> accuracy wasn't real important on this mill back in 1990.
>
> All three ball screws are 5 TPI.
>
> On 3/31/2014 7:22 AM, Dave Cole wrote:
>> The scales should not be a problem. TTL encoder inputs are common on the
>> Mesa boards.
>> You will need to look up that BEI encoder to find the specs.
>> TTL or differential line driver are common.
>>
>> I've been using the Mesa 7i43 with a 16 in 8 out I/O board ( 7i37TA) and
>> either the servo (7i33TA)  or the stepper interface board, but the 5i25
>> gives more bang for the $ if you have a PCI slot available.   The 7i37
>> is very flexible regarding sourcing or sinking inputs and outputs which
>> is really nice for retrofits.
>>
>> Dave
>>
>> On 3/31/2014 1:02 AM, Gregg Eshelman wrote:
>>> Anilam System A-10 pinout
>>>
>>> pin 1: A chan (white)
>>> pin 2: NC
>>> pin3: COM (black)
>>> pin4: B chan (green)
>>> pin5: NC
>>> pin6: +5V (red)
>>> pin7: marker pulse (brown)
>>> pin8: NC
>>>
>>> Specs I've found is they're 10 micron, 0.0004" resolution, square wave
>>> TTL output.
>>>
>>> I have 1600 oz/in stepper motors on the mill. The Z axis has a rotary
>>> encoder on its ballscrew.
>>>
>>> BEI MODEL
>>> M153-25-127
>>> DATE CODE 9021
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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

Specs on the rotary encoder.
3=Quadrature with index
25=0.25" bore
127=127 pulse/rev Probably way too coarse. Apparently super Z axis 
accuracy wasn't real important on this mill back in 1990.

All three ball screws are 5 TPI.

On 3/31/2014 7:22 AM, Dave Cole wrote:
> The scales should not be a problem. TTL encoder inputs are common on the
> Mesa boards.
> You will need to look up that BEI encoder to find the specs.
> TTL or differential line driver are common.
>
> I've been using the Mesa 7i43 with a 16 in 8 out I/O board ( 7i37TA) and
> either the servo (7i33TA)  or the stepper interface board, but the 5i25
> gives more bang for the $ if you have a PCI slot available.   The 7i37
> is very flexible regarding sourcing or sinking inputs and outputs which
> is really nice for retrofits.
>
> Dave
>
> On 3/31/2014 1:02 AM, Gregg Eshelman wrote:
>> Anilam System A-10 pinout
>>
>> pin 1: A chan (white)
>> pin 2: NC
>> pin3: COM (black)
>> pin4: B chan (green)
>> pin5: NC
>> pin6: +5V (red)
>> pin7: marker pulse (brown)
>> pin8: NC
>>
>> Specs I've found is they're 10 micron, 0.0004" resolution, square wave
>> TTL output.
>>
>> I have 1600 oz/in stepper motors on the mill. The Z axis has a rotary
>> encoder on its ballscrew.
>>
>> BEI MODEL
>> M153-25-127
>> DATE CODE 9021

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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Gregg Eshelman]

On 3/31/2014 6:22 AM, andy pugh wrote:
> On 31 March 2014 07:02, Gregg Eshelman  wrote:
>
>> Specs I've found is they're 10 micron, 0.0004" resolution, square wave
>> TTL output.
>
> That should work with any hardware, including the parallel port.

Got a datasheet from BEI on the encoder.

3=Quadrature with index
25=0.25" bore
127=127 pulse/rev

127 seems to be rather coarse, especially considering the stepper is 200 
full steps/rev and is geared down via cogged belt. Apparently whomever 
specced out this mill wasn't looking for high precision on the Z axis.

BEI no longer make an encoder this style with only 127 PPR. 500 is the 
minimum.


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[andy pugh]

On 31 March 2014 07:02, Gregg Eshelman  wrote:

> Specs I've found is they're 10 micron, 0.0004" resolution, square wave
> TTL output.

That should work with any hardware, including the parallel port.


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Re: [Emc-users] What hardware to interface with these linear scales and rotary encoder?

[Dave Cole]

The scales should not be a problem. TTL encoder inputs are common on the 
Mesa boards.
You will need to look up that BEI encoder to find the specs.
TTL or differential line driver are common.

I've been using the Mesa 7i43 with a 16 in 8 out I/O board ( 7i37TA) and 
either the servo (7i33TA)  or the stepper interface board, but the 5i25
gives more bang for the $ if you have a PCI slot available.   The 7i37 
is very flexible regarding sourcing or sinking inputs and outputs which 
is really nice for retrofits.

Dave

On 3/31/2014 1:02 AM, Gregg Eshelman wrote:
> Anilam System A-10 pinout
>
> pin 1: A chan (white)
> pin 2: NC
> pin3: COM (black)
> pin4: B chan (green)
> pin5: NC
> pin6: +5V (red)
> pin7: marker pulse (brown)
> pin8: NC
>
> Specs I've found is they're 10 micron, 0.0004" resolution, square wave
> TTL output.
>
> I have 1600 oz/in stepper motors on the mill. The Z axis has a rotary
> encoder on its ballscrew.
>
> BEI MODEL
> M153-25-127
> DATE CODE 9021
>
> I have the old Acra mill set where it will be used, got the variable
> speed drive rebuilt (and through much shopping around and patience for
> good deals got all the new parts, good quality, for a bit under $100).
> Motors mounted with new pulleys and belts, using adapter plates I had a
> guy in Kentucky make for around $50. (One of those need a CNC mill to
> make parts for the CNC mill so it could make the parts...) Also have a
> new TECO VFD with an RS232 module that I hope to be able to use for
> direct computer control of on/off and direction.
>
> My latest part acquisition, which I didn't even know I had until I
> brought the lot home and started digging, is an ELO 15" 1024x768
> capacitive touch screen LCD industrial monitor. Brand spanking new!
> (Though a discontinued model.) Bought an auction lot of 18 ex-government
> Dell desktop computers and assorted keyboards, mice, smart card readers,
> keyboards with built in smart card readers - and this box I didn't open
> because it was raining while loading the truck. Bg smile on my face
> when I opened the box last night, even bigger when I tested it today and
> it worked. It'll fit perfectly in the old Anilam control box with space
> below for an e-stop and other controls. That alone made the $107 for the
> lot worth it. :)
>
> Getting closer, sooo much closer to being a working machine again! :)
>
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