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Resurrecting an incomplete lathe project
#1
Many years ago I 'almost' got a lathe project running, with a PMAC-1, using the NC v2.36 software, and an Advantage 500 (I think) panel, with the 8-switch control panel.

Being stubborn, I am going to make another run at it. At the time, NC v2.36 was the choice - is that still appropriate for the PMAC 1? Or does DT have newer, more robust version that will work with the the control I have?

Or, are there other 3-rd party vendors that have software?

Comments on your past experiences with DT NC software, suggestion, etc are appreciated.

Cheers,
Steve
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#2
There is nothing wrong with the 2.36 software, although you will want to get ahold of a version called 2.36(1) which fixes some bugs.

The bigger problem that you will have, assuming that you have an old ISA bus PMAC 1, is coming up with an ISA bus PC and software. When that code came out Windows 2000 was the standard. There is a company called NIXSYS that can sell you a "legacy" industrial PC with and ISA bus with WIN2K installed that will allow you to run NC 2.36 and your old PMAC. This might make sense if your machine is partially/mostly together, you have PMAC/NC experience, and you just want to finish it. If you haven't done anything yet, you don't have much Delta Tau experience and you want a machine that will be supported for a long time, then I would invest in Advantage 900 and a more modern PMAC for the support, IMHO.
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#3
Brian,

Thanks for the info. Where would I acquire a copy of NC v2.36(1)? Delta Tau still have them available? And how do I identify/verify that the software is in fact the 2.36(1), and not what I already have? And on that question, is it possible that I already have that version? Compile dates, version info buried in the exec, what?

The PMACNC-32 disk in front of me says its an '07/13/00' version. Exploring the disk down to the PMACNC32\Release\Disk1 level shows most files with date of '20/04/2000'.

ISA board computers are not a problem, plenty of spares available to me. And plenty of Windows software of various versions.

This project will be using a 7x12 Mini-lathe. It will be a working, SMALL capacity lathe, but mostly a proof-of-concept, for my own personal satisfaction.

As to PMAC experience, the original project was for personal use only, not a business venture, and I worked on/off for maybe 3 years. Yeah, sad to say I spent that much time & never completed it. Any way, at that time I was getting fairly deep into the control, and have kept all my notes from that era. So I am not starting out totally blind.

Cheers
Steve
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#4
Yes you have 2.36... I checked against my release files and that date matches up.
And as mentioned there was a Manual Update (1) that came out with bug fixes... it is just a few files... not a whole install.
So first get your 2.36 installed and working... then email me and I will send you a zip file with the UPDATE files to get up to 2.36(1)
Update files are:
lathe.g 7/9/2002
Ncui32.eng 7/9/2002
Ncui32.exe 7/9/2002
Pmac.dll 7/9/2002
Readme.txt 7/9/2002

I would stay with the NC2.36, works very well. Unless you are doing something very special... it is good basic NC. We have many customers still using 2.36 and love it.

Also sound like you got the Mobo figured out, if not let me know I have excellent source of PMAC friendly motherboards that work perfect with old PMAC ISA cards. Issue with some mobo's is how they implement the ISA bus... it must be available for direct memory access and some newer ones with ISA don't allow this... so drivers are a issue and the PMAC wants direct access due to the speed of sending NC Gcodes from the HMI....

Hope you get it working...
mike
mesposito@deltatau.com
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#5
Just to clarify Unit101's comment: install the 2.36 and then install the four patch files immediately (it entails replacing the four files in a particular directory) before doing completing your integration. You want to work with 2.36(1) from the outset, especially on a lathe.

2.36(1) and the basic PLC programs that are supplied work well. The PLC's take some time to understand, but once you understand them it is actually quite easy to use.

I advise you to get the servos and a limit switches, etc. working at a basic level using the PMAC executive program prior to messing with the NC part of it.
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#6
Mike,
On the subject of motherboards, do you have a method of checking the BIOS settings, to see if they meet the DMA criteria you mentioned?

The mobo's I have were selected so that they would accept a full-length PMAC, without interfering with caps, headers, etc. I currently have available an AOpen AX6BC (recommended to me by a Delta Tau integrator in Florida), a Tekram S3AP-A, and an eMachines mb.

For operating systems, I have Win95, Win95(SR1), Win98, Win98SE, WinXP home, WinXP Pro, or Win NT4.0 available.

Recommendations are always welcome, and thanks for the help.

Cheers,
Steve
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#7
2.36 runs perfectly in Windows 2000 (which was the defacto 2.36 environment) if you can get it, I believe it also runs in NT. Not sure about XP. Don't run it in 98 or 95.
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#8
If needed I have archived the last updated full version of this software with the compatible PEWIN32 and PLOT32 (with full documentation) at:
http://ftp.support.deltatau.com/DT-USA/nc%202.36-2.38/

The "readme.txt" describes each entry in this folder. Keep in mind this is very old obsoleted software and is offered without warranty or support. Having said that I will try to answer any reasonable questions posted on this Forum.
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#9
(03-24-2014, 12:41 PM)steve.milici Wrote: If needed I have archived the last updated full version of this software with the compatible PEWIN32 and PLOT32 (with full documentation) at:
http://ftp.support.deltatau.com/DT-USA/nc%202.36-2.38/

The "readme.txt" describes each entry in this folder. Keep in mind this is very old obsoleted software and is offered without warranty or support. Having said that I will try to answer any reasonable questions posted on this Forum.

Steve,

I have looked over the files, and have a question about there being 3 lathe.g files (lathe.g, latheB.g, & latheC.g). What is the difference between them, and what should I use for my very basic lathe application?

Mike E sent me the 4) update files that included a read.me file, which was somewhat confusing.

Quote:This manual upgrade package has the following change:

- The DNC button has been removed from the function key
sub menu that appears under program "PRG: function key

- The file lathe.g must be modified and downloaded so that
the new pmac code for G40,G41 and G42 is present. This is
REQUIRED and MUST BE DONE NO EXCEPTIONS!!! Users of latheb.g
and lathec.g can replace the G40,G41 and G42 code that is in
their respective files with the code located in the supplied
lathe.g

The way it is stated in the readme almost sounds like I am to modify the NEW lathe.g, then download it into my application. That doesn't make sense. So my presumption is that the lathe.g has already been modified, and I am to just replace my existing lathe.g with the new one?

Cheers,
Steve
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#10
Do not modify lathe.g. Simply replace the old lathe.g with the new one, same with the other three files. Perhaps rename the original files something like xxx_old.xx and then you will have them around. The four files serve as a bug patch. I recommend using lathe.g and not one of the others. The other lathe types mimic certain standards on other types of machines.

If you do this, all will be well. The primary fix that this patch accomplishes is making tool nose radius comp work correctly.
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#11
I've decided to go with WinXP for my operating system (as opposed to NT 4.0, which doesn't allow Fat32, or USB), and will be doing initial servo tuning with the motors dis-mounted from the lathe.

I still have to mount the spindle encoder, and get the gibs adjusted to eliminate (most of) the slop in the saddle & cross-slide. When I am comfortable with that, and all limit switches working, I will mount the motors and servo tune the fully assembled lathe.

When that is done I'll need to decide which of the DT Operator Control Panels to use: I have both the style with 8) rotary switches, which I 'think' is called the Advantage 500, and one with 4) rotary switches, which I 'think' is an Advantage 600??

On my many-years-ago attempt, I tried using the 8) switch OCP, and had to modify the ncpanel.plc. I liked the functions available with the 8, but not if I cannot make the system work.

Cheers,
Steve
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#12
Changed my mind on Op system - going with NT4.0, as XP w/SP3 was very slow.

SERVO TUNING:

Does 'PMAC Tuning Pro' work with my PMAC(1) non-turbo? And if so, is it available/better than using the tuning in PEWin?

From my past experience, and reading manuals, I still have questions about the procedures, and optimum results. For a step move, setting the size & time seem not to be a problem, but the values for a parabolic move are less clear. I changed the move size to several shaft revolutions - is that good/bad/or just different? Changing the time for the parabolic move gives different max FE, with the same PID settings. Wasn't expecting that.

Should I decrease the time (on the parabolic move) so that I am pushing the system ALMOST, but not quite to its limit? Or should I slightly increase the move time from that almost-at-its-limit value ?

Some of the manuals on tuning show a finished parabolic move with FE down to 10 cts - is that realistic on a full-sized machining center? Just curious.

If I were to be able to achieve that low FE during tuning, should the displayed FE (on NC32 'position' screen) be 0.0000 after a move? Or would I likely see some error?

Thanks,
Steve
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#13
In my opinion primary benefit of the parabolic move is for setting the velocity feedforward and acceleration feedforward gains. For the test to be of any benefit in this regard the velocity and acceleration during the test have to be significant enough to have a measurable effect on the system. Specifically, for a machining center, you should push at least as hard as you would expect the machine to perform circular interpolation, i.e. for a given circle radius at a given federate, determine how one of the axes would move and approximate this with the parabolic move and then some. It should certainly be at least one rev of the motor for a rotary motor, IMHO.

Without knowing what the mechanics of your system are and what 10 cts translates into, it is hard to say if you can achieve that or not. Many commercially available VMC's ball bar test to better than 50 millionths of an inch, some better than that (lathes typically even better), so clearly the following error of the servo is better than that in those examples. The highly specialized machines that I work on have following errors during a parabolic move of better than 1 millionth of an inch. In your case, if you have a rotary servo driving a screw and your encoder is on the motor and is roughly 2000 to 5000 cts/rev I would expect that you would achieve better than +/- 10cts unless you are pushing the system beyond the torque limits of the motor or the motor bearings or ball screw nut bearings are poor. This is because a typical modern servo motor behaves pretty ideally. Keep in mind that the motion of the carriages will be worse than this, as the mechanics of the rest of the machine will add additional error.
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#14
Note that the tuning program in the 2.38 software is for the most part identical to the Pro version. installing the Pro version on the same computer with the 2.38 can cause issues with competing dlls.
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#15
Brian,

The question concerning performance of a real machining center was one of curiosity, as there is a lot of mass to move around, compared to a small lab motor like was used in the text write-ups.

My project is a small bench-top lathe, sold by Harbor Freight, Grizzly, etc. It has only a 7" swing over the ways, and 12" travel in the Z.

Both axes are driven by PM brushed DC motors, driven by AMC 30A8 amps.
And yes, those amps are over-kill, but they are what I had on hand. The Z is direct coupled to the ball-screw. Encoder is on motor end, 500 PPR, 4X decode in Ivar, with 5TPI pitch on ball-screw: 10,000 cts/inch.

Last night when doing the parabolic tuning, I set the move size/speed to what now turns out to be probably twice as fast as any turning operation I would actually command. With that said, I was able to get the max FE on the move to around 10-12 cts. Then going into the NC32 program and using the hand-wheel to move Z, I was always getting a FE ('Position' screen on NC32) of .0015", unless I reversed direction, when FE would go to zero, due to backlash. Is this to be expected, on this 'hobby' type lathe? Or are there other areas I need to address?

And I have yet to get a good balance of Motion Applet/I-var settings for max acceleration rates, time to S curve, etc. I either get wind-up when using the hand-wheel, motion after jog pb released, or hand-wheel 'cogs'
aggressively if I set up to have motion stop when jog pb's released.

Steve
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#16
If I understand, the encoders are on the motors, so backlash will not affect following error per se. If you can achieve +/- 10-12 cts in PEWIN, then you should see .0010" to .0012" in NC under the same conditions. If it literally only displays one of the two numbers then there might be something set incorrectly with respect to the display.

To get the right "feel" for the hand wheel, you have to correctly trade off the distance per click, the hand wheel jog speed, and the jog acceleration. If the speed and acceleration are too low then it will be too easy to turn the hand wheel faster than the machine can move, causing it to "wind up" as you describe. Same for the PB's. I suggest setting the hand wheel step sizes small and work your way up. The wind up is a bummer, as it leads to crashing tools into things.
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