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Messages - Chestermarine

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11
Modbus / Re: Struggling with RS485 & Teco 7300CV
« on: March 24, 2011, 07:35:28 PM »
Hello GD:

Have you seen the free download " RS232 Analyzer.msi " program at www.commfront.com ?

I just downloaded it to play/practice learning more about my own Modbus setup. It sounds like a pretty powerful tool.

Regards,
John
   

12
Brains Development / Re: multi axis selection for MPG panel
« on: March 24, 2011, 04:42:19 PM »
Hello Professor:

Sounds to me like this is a job for a PLC, but then I am just a beginner myself with the Brains. I would like to suggest you have a look at the Cubloc PLC, www.cubloc.com.  Pretty nice hardware for a very reasonable cost, as compared to Automation Direct. 

I am using one to actuate panel buttons, Led's, and Mach screen buttons on my own mill retrofit. You still need to write Brains for the final input to Mach. The Cubloc PLC can run any kind of Basic, and/or ladder logic program you can dream up to tweak a Mach brain, plus turn a lot of stuff on and off; feedrate override Potentiometer (something I consider a necessity on a CNC mill), outputting to a LCD, or Mini touch screen, and more. 

Regards,

John

13
Hello gumby:

That's quite a laundry list on Ajax. I was under the impression the Centroid/Ajax was pretty well debugged since they have been around quite a long time. However, they are a proprietary system, and the first order of business is keep their software locked up tight, and charge what the traffic will stand. That is pretty standard industry/corporate policy.
 
Regarding your questions about the Vital System, dspMC/IP controller, I have nothing but good things to say. The company is on top of any problems, and work with users to make things work. They are improving the software/firmware and make their updates available via the internet. There are no "special codes" to get things working.

There is no auto-tune, but the PID tuning is now done in a plug-in screen set with tabs for each axis, which is accessed from within the Mach3 program. No shut-down, restart. The tuning has a big graphic screen which shows visually the acceleration/decel curve vs time.  You can keep changing numbers, run an axis back and forth in real time, and play with settings until you get a best fit/feel/sound from the axis, then save your settings to the controller, and to the .XML file. There are more advanced settings on the tuning graphic that I have not used yet. My machine seems to really run fine and smooth with the basic settings that I found by experimentation, and the manual suggestions.

In my situation, the installation is a retrofit for an orphaned system that is now out of business. My motors are DC brushed, approx .7 KW, 100v Westamp amps, and the motors run smoother and faster now, than the original controller.

The controller has analog spindle control, and (3)MPG inputs directly to the I/O board. The higher end dspMC/IP controller has analog I/O, which is a nice option. I do not have that controller.

Quadrature encoder inputs, plus index via Z channel homing. All working a OK.   

There are two types of I/O boards. the 7535 is buffered and optoisolated, 12-30v dc I/O, and each board has 8 outputs, and 16 inputs. Using two boards in the J4,J5 position gives a total of 16 outputs, and 32 inputs. The corresponding Mach3 pin numbers are in a correspondence table, keeping everything pretty simple.

That pretty much sums up my experiences.

There are some very experienced, professional machine builders/users on this forum, who could give more detail regarding PID tuning.

John


 

14
Greetings Neyland:

The Mach3 program does act strangely when nothing is connected. Once you get the encoders connected, and the analog signal going to the servo amps, things will settle down. It is tempting to make something happen you can see visually, before all the various components are hooked up. I did the same thing.

Make sure your units are set correctly. Inches or millimeters. There are several places where this is referenced. Motor Tuning, Home Limits etc.

Set-up the encoder counts/rev in the Motor Tuning section of General Config…. , and then the parameters for the PID numbers are set in the screens when you click the plug-in section.  Config; Config Plugins; Config (Plugin name: M3dspMC-dspMC-Plugins-3.12-Vital-) Click the yellow box, and the Plug-in screen configuration will come up. Each axis will have it's own screen under a tab.  PID settings are saved to the dspmc, as well as to the Mach3 XML for that particular named setup.  This is where all the motor tuning happens.
 If an axis is not enabled under Ports and Pins, it will be dimmed out in the Motor Tuning.  Enable the axis motors in Ports and Pins, set to active LOW.  There are boxes for accel and such, but the only ones that matter are the encoder counts/unit, and the velocity  in/min to make things move.
 
May I suggest doing one axis at a time. Connect the power to only one axis, and get that one moving, start/stop under the plug-in screen for that axis.  Get all the tuning, encoder counts, and various  parameters OK. There are lots of little settings, but once one is working smoothly, you can copy the settings to the others one at a time.

Regarding you question about encoders, the dspmc can read (6) encoders, 3 channels each. Look at the Vital System manual regarding J6, J7 Pin Assignments. For J6; Channel 0 = X, Ch 1 = Y, Ch 2 = Z. For J7; Ch 3 = A, Ch 4 = B, Ch 5 = C.  The (6) encoder count does not include the inputs for MPG's, on J4, J5, which are a separate kind of device.

For example, on J6, The X axis is called Ch 0, and it has connections for A+, A-, B+, B-, Z+, Z-, 5v., and ground. A and B are the two counting channels, and Z is a once per rev index channel. There should be 5 wires per encoder. Use quality shielded wire for connecting the encoders, and analog signals, and keep the colors uniform for the channels.

 On my machine, which was a factory built 4-axis CNC which I am retrofitting with the dspmc, Channel A+ is green, channel B+ is red, channel Z+ is white, +5v is blue, and ground is black. They also had a separate ground wire for each axis, A-, B-, Z-, which was set up as a pair for each channel; A+ and A-(ground) twisted together, and was encased in it’s own foil wrap, etc.  At the business end, I connected all the grounds to 1 wire.  This might seem like overdoing things, but I never had a glitch due to noise. I am not sure you can even get wire of this quality anymore.  If a motor goes the opposite direction you want, it can be reversed in the Homing Limits tab. Don’t start switching A & B around.

You can make the axis motors move without completing the home /limit switches. However, once an axis is tuned, and moves good, work on the home switches, and Z channel index home feature working properly. 

It takes some patience and time, when starting to tune an axis. The starting PID numbers are a ballpark in the Vital Systems manual, but should get something moving. In the plug-in screen, you can move a specific distance, and see the encoder count, and the motor acceleration curve on the graphic screen. It is a really slick way to tune your motor settings. Once things begin to get moving, you will feel a lot more positive about the process.  It is all very logical and well defined, and a lot of engineering has gone into the dspmc controller.

Don't confuse some of the references in the Mach3 manual, and the dspmc manual.  It takes several readings of it all to make sense, and sink in. The dspmc manual makes clear the specific Mach3 input pin numbers relative to the dspmc I/O boards.

One last warning. Be careful with the I/O boards.  The 7535 is fully opto-isolated, and can take up to 30v dc., but the 7711 is not. I accidently put over 5v to the wrong terminal on a 7711 board, and damaged my dspmc when first wiring things up.   

Hope this is of some help.
Regards, John

15
The dspmc controller does not "convert step/dir" to analogue. The motor/servo setup does not rely upon the clock cycle of Mach3 step pulses.

John

16
The short answer is Yes.

However, you will need a controller that can communicate with them, and output the +/- 10v signal, as well as read the motor encoders. I personally like the dspmc controller by Vital Systems. It is a very capable, state-of-the-Art CNC controller, and there is a specific forum section for it. Just scroll down the topics to get there.

John
 

17
General Mach Discussion / Re: tool force compensation
« on: December 03, 2010, 03:49:08 PM »
Trying to compensate for tool deflection is a very large variable, influenced by;
(1) Weight/rigidity/design of the machine itself.
(2) Type of cutting tool, roughing mill cutter/finish mill cutter type.
(3) Sharpness of the cutting tool.
(4) Cutter design, cutters for aluminum have more chip clearance than general cutters.
(5) Type and alloy being cut; aluminum, mild steel, tool steel, high-carbon, stainless etc.
(6) Material hardness.
(7) Speed the cutter is being pushed through the work.
(8) Depth of cut.
(9) Direction of cut; climb cutting v.s. conventional cutting.
(10) Type of coolant, if any?
(11) Solid carbide tool v.s. High speed steel cutter.
(12) Length v.s. diameter of cutter.
(13) Spindle precision.
(14) Tool holder/collett quality.

and, probably a few more I have not thought of here.

Climb cutting gives a better finish, but must be used carefully, as machne backlash may allow the table to let the tool dig in unexpectedly.
For consistent production type machining, use a roughing cutter leaving the part oversize (approx .010/.015") and finish off with a finish style cutter
using a climb cut. This will permit the lightest possible tool load for the finish dimension, and the variation of the roughing deflection will not enter into
finish dimension equation.

Also, the finish cutter will see less material to (less cubic inches of material to plow through) to dull it's new sharpness.
If the finish cutter is a high quality carbide, it will be even better, as carbide will retain it's edge longer than H.S.S. 

All tools deflect to some degree or another. It depends on how close and how smooth your finished part has to be. It is all a trade-off, and how much
time and money can be expended per part.

Regards,

John

18
General Mach Discussion / Re: Tube/pipe coping or notching
« on: October 30, 2010, 02:31:26 AM »
Sorry about that. I missed the "input 5 values" part, but did read the "or relatively simple method to program in various tube / pipe fitting cuts. "
part.
Regarding the "Tubefit" site, and equation #9, they mention plotting templates, and using templates for the best fit. etc.
That equation #9 could be put into Excell, but de-bugging and testing could be quite a task.
Waiting for non-existant, or hugely expensive software could be a bummer.  Regarding a macro, Mach3 doesn't even have a reliable probing macro! This problem is orders of magnitude more difficult.
This tube intersect problem is a good one!  Good luck on finding a viable solution that meets your needs.

John

19
General Mach Discussion / Re: Tube/pipe coping or notching
« on: October 29, 2010, 11:14:22 PM »
How about a paper template marking fixture, using a "laser pointer" to simulate tube #1, and a mandrel the same diameter as tube#2, with a paper wrapped around?

The laser "tube" can mimick any diameter, and be rotated by hand. The paper holding mandrel is on a pivot, to duplicate the required angle of intersect; both "tubes" centerlines intersect. Make as many pencil marks on the paper as you think necessary for the precision of the plasma cut. Also, the paper holding mandrel must be able to be rotated 180 degrees, to get the opposite side of the cut, depending on the type of intersect.

Use "teach mode", and a pointer in the spindle, to follow the paper template on the real tube, using the rotary table, and you get the real program, without math, or CAD programs. In addition, if desired, you could draw an "offset" line from the laser marked path, to account for plasma cut width. No math; no CAD programs; no file manipulation; no "Big Bucks!"

John

20
General Mach Discussion / Re: Tube/pipe coping or notching
« on: October 29, 2010, 06:19:56 PM »
Hello All:
This is an intriguing problem. I believe it may lend itself to a simpler solution, but not as visual as a CAM program. If you slice a tube at a given angle, the line at the tube surface is a path in X, (the long axis of the tube) and angle A, the corresponding point as the tube rotates. This is assuming that the tool/spindle centerline, or the plasma torch remains over the tube centerline, Y, as the tube rotates. Therefore, a series of point pairs, X,A will drive the machine along this path. Furthermore, each 90 degrees of rotation is a mirror image of the previous 90 degrees. This path can be calculated in Excell. I can expound on this further, if interested.

Regards,
John

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