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Offline RICH

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Re: Really need help
« Reply #30 on: August 13, 2009, 11:46:13 PM »
TurnerTom,
Please excuse me Tom, as i am attempting to help you. Now take a breath...........................
After reviewing all of your all postings I sincerily and honestly don't know where you are coming from
and will have a hard time answering you questions appropriately, but will try.  
I have grouped your question's and remarks together . So please bear with me.

1A. Have problems with instability (losing steps) and am curious if anybody thinks adding a Smooth      
        Stepper card might help me?

   I would suggest you not spend a penny on anything until you review all the components of your
   system in light of how they relate to each other both, mechanically and electricaly, from the pc to the
   stepper.

   Yes, the SS can help if you have a PC with bad pulse stream out of the PP and have checked the    
   PC per all that has been recommned and know that it is the problem.
   You can't clean up a crap signal very easily if at all.

   No, the SS won't help if there are basic power supply, BOB, Driver or wiring problems.

1B.  - the stepper motors (particularly the Z-Axis) fail to return exactly to their starting points
       - tried numerous settings,A max speed of 300 mm/min  ( say 12 inches per min ) would be nice    
      to obtain.
       - the "Z" fell short by 25 steps,I tried slowing the motor's max speed settings down from 250 to      

    200. I don't like the way G0 sounds at 200 mm/Min and the end position never got better.
       - The problem seems to show up when curring curves and both motors are running simultaneously
          at varying rates...

Do you really realize how manny things can be a culprit for the above?
 - Poor Pulses from the PC
 - configuration - inproper steps / unit, backlash setting, pulse width etc.
 - Bad wiring of the steppers
 - power supply voltage and amperage
 - BOB board influences
 - Improper driver settings ( what kind of drivers are you using? Don't just say ******************, ,
   post specific info on them, please, and maybe folks will have a look, but don't expect them to
   to do the walking and looking for the information )

The sound of the steppers can tell a lot. If it sounds like your steppers have a bad bearing, being hit
with a little mallet in a reapeatble way, can 't get any speed, there are marbles rolling around in them,
then the PC really needs to be looked at.

2..Is there anything wrong with my choice of the Probotix RF isolator?
 
I don't know. Why do you need one?

3..We might be able to use a laptop at the lathe, we have a fairly new laptop running Windows Vista.
    Is it worth trying an SS on that machine?

I don't use don't use Vista. There is a thread on using Vista, so you may want to read throught it and
see what they all have to say.
Some laptops work fine, some not so. There is a thread about using Laptops.
I treid  the SS on three different laptops and all was fine with it.

4. If there is some glaring error in my present setup

I will assume your motor steps / unit are based on calculated values and you tested to see where they
started skipping and backed off from that point to leave some headroom. Even if it's 2 inches / min, but
here we circle back to the top of all the questions.

5.The motors are 3.5 volt so I assume the drive is outputting something close to 3.5VDC

Look at the power supply as whole to suite your drive and stepper requirements. Having info on the
motors helps.


6.This is all sort of new to me.

Walk before you run......you can't learn all this at once.
Read some on your owne, read the manuals, go to the gecko site and read for understanding.
Don't jump to conclusions and focus on one problem at a time. Ask for understanding.  

7.I fear we are straying from my original question.

I hope ths gets you back on track.

8. I wonder if both these motors are skipping pulses every time and the lost pulses in one direction
  compensate for the same number of lost pulses in the opposite direction. That way, in this situation
  with one motor running at a time can always return the hand-wheel to zero??

I think reply #6 addresses this.

9. Anybody know of a simple kit to build a TTL pulse-counter with about six digits of display?

I don't know of any.

10. This skipping steps issue is the only thing keeping us from doing production.
      I will tell my employer and suggest he consider springing for a smooth stepper.

Hmm .....But what will you say if the boss asks why?
« Last Edit: August 14, 2009, 12:03:42 AM by RICH »
Re: Really need help
« Reply #31 on: August 14, 2009, 08:04:38 AM »
I'm truly sorry if I have offended anybody. It was not my intention.

I think the best thing for me to do now, is to wait until the scope I ordered arrives.
Is it fair to assume the place to scope the pulse train is across the outputs on my Probotix RF Isolator?  That is what is going into the drives...

I think I also need to tell you all,  that this lathe was built and outfitted by a private individual.  It was operated by a DOS computer, and the interface electronics between the parallel port and the Slo-Syn drive was also scratch-built.  The profiles were written using Microsoft BASIC and are (for me) a nightmare to edit. We are hoping to move forward here, to use industry-standard software.  This interface is disconnected for the time being, but I can, and have, reconnected it and the lathe still works properly from the old DOS machine.

Because this can still be made to work, I feel reasonaby confident that there is nothing wrong with the drive, the stepper motors or the wiring (at least from the output of the drive)...
« Last Edit: August 14, 2009, 08:08:51 AM by TunerTom »

Offline simpson36

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Re: Really need help
« Reply #32 on: August 14, 2009, 12:24:20 PM »
Can't speak for others but I am not offendable in this venue. I'm like Seargent Friday on Dragnet . "Just the facts, maam".  Personalities are pretty much irrelevant on a CNC forum. You might have a bunch of unpopular people buried under your house . . but that's not a CNC topic.

This stuff is really not complicated. Think of it like the old Vaudeville joke where the patient says "Doc, it hurts when I do this",  Doc answers: "then don't do that !"
So, what is an RF isolator? . . answer; something you probably don't need. If nobody here knows what it is . . . .  likely you aren't going to need it.

So here's the plan . . very simple: You need to connect the parallel port to a Break Out Board with an everyday all-pins-connected straight thru parallel cable, preferably short and shielded.  That protects your computer and provides nice convenient pins to connect to. You then connect the breakout board pins to the step and dir pins on your stepper drives. Light gage solid wire is ideal for this. Use nice bright insulation colors, otherwise it won't work right . .  nobody knows why  ;)    Your stepper drives should already be correctly connected to the motors, so that's a gimme.

How do you sculpt an elephant? Start with a big rock and chip off everything that does not look like an elephant. Anything you have left over that is not mentioned in the above plan . .  chip off.

This is similar to one of my breakout boards. Note the LEDs on every pin. No guesswork here. The lights tell you what the port is 'saying' and on which pin. http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=47

You are going to need a BOB no matter what, so it is not going to be wasted $$$ regardless of what your problem turns out to be. And my guess is that the problem may go away when you get rid of the strange leftover junk from the DOS setup. You are just digging yourself a deeper hole dinking around with a scope. All it is going to tell you is to get rid of something that you need to get rid of anyway.

If all of the above fails, then just put the whole thing in a box and send it to Hood. He'll fix it for ya  :P
Re: Really need help
« Reply #33 on: August 14, 2009, 01:21:45 PM »
OK Simpson36, let's try this...

I will order the C1 - Parallel Port Interface Card as soon as I hear from you about the following relay board
I have a relay board that I bought with the RF Isolator. It has screw-terminal inputs & outputs. Any reason you think I should replace it with your C15 - Dual Relay Board?

The DOS machine and its interface is disconnected for now.  I don't plan to reconnect that unless I can't get the Mach-3 system working.


Thanks for your advice...

« Last Edit: August 14, 2009, 01:25:33 PM by TunerTom »

Offline Jeff_Birt

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Re: Really need help
« Reply #34 on: August 14, 2009, 01:33:53 PM »

Quote
So, what is an RF isolator? . . answer; something you probably don't need. If nobody here knows what it is . . . .  likely you aren't going to need it.


That is kind of an odd attitude. Ignorance on your or other folks part should never be a determining factor.  ::)

Tom - The RF isolation BOB you have looks interesting. I went and looked up the types of isolation IC's it uses and they seem like it would work well, it is just a newer style of isolation. It accomplishes the same things as an optically isolated BOB but used Radio Frequencies instead of light.
Happy machining , Jeff Birt
 
Re: Really need help
« Reply #35 on: August 14, 2009, 02:22:12 PM »
Jeff,

I'm the first person to admit, I am ignorant.

I'm an organbuilder, not a machinist, and I have no experience with CNC.  I do have some programming skills  and I have an X/Y plotter. The plotter was built by the guy who did the lathe.  I have an older laptop that uses Windows-98SE and it has a parallel port.  I can run the original BASIC programs in a DOS wiindow, and the plotter will trace the actual toolpaths on paper. The plotter is fitted with a digital counter that counts up or down. revealing the X/Y position in terms of the number of pulses sent.

I inserted break points at the end of each line or arc and ran the BASIC profiles. From that I wrote all the values displayed on the X & Y counters and put them into an Excel spread sheet. I was able to extract radiuses for the curves from the BASIC source. I then worked these spreadsheets to generate simple G-Gode scripts, which I saved as text files.

I also have my main PC... just loaded with software running XP. It too, still has a parallel port.

I added a second parallel input to the plotter and wired the output end to the appropriate points in the builder's interface with Mach3 requirements. The Point is, I can plug my laptop into the plotter and run plots of the profiles on paper... unplug the laptop and run my g-code profiles using the alternate socket on the plotter from my main PC through Mach-3, and trace right directly over the original BASIC plots, using my Win-XXP Desktop.  It took some tweaking of the g-cod, but it works!

Based on this, I was convinced that I could convert the lathe to use Mach-3.  I still believe this is possible, but I'm totally at a loss as to what to try next. I have to try something.  I'm paying out of pocket for my hardware mistakes. It isn't fair to ask my employer to do this...

So yes, I am ignorant.

We turn drawknobs for our consoles (see attachment)...
« Last Edit: August 14, 2009, 03:18:13 PM by TunerTom »

Offline Jeff_Birt

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Re: Really need help
« Reply #36 on: August 14, 2009, 02:38:37 PM »
Tom, first there is nothing wrong with being ignorant about something, we all started out at the same place in CNC. I was also not trying to be offensive to anyone. My comment about ignorance was directed to another persons comment (the quoted one) saying that if he or others didn't know what an 'RF isolator' was then you probably didn't need it. I was trying to say that the ignorance of others should not be a determining factor in your decisions. Get the facts, as you are trying to do, and make the best decisions you can.
« Last Edit: August 14, 2009, 03:21:30 PM by Jeff_Birt »
Happy machining , Jeff Birt
 

Offline RICH

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Re: Really need help
« Reply #37 on: August 14, 2009, 06:14:31 PM »
Tom,
What are the steps / unit that your are using for the pc that you will ultimately use for MACH?
Can you show us how they were calculated?

I would suggest that you first confirm the signal quality generated from that PC ( at the PP outlet / pins ).
If you can have a knowledgable friend take a look at the pulse with the right equipment that would be benifical.
Then look at the signal with the cable hooked up. Then look at the signal with the BOB hooked up.
So you are just checking the quality of the signal from the source and on down the line until it feeds the drive.
I would also suggest that you start off with the Z axis, as that is the one that seems to be off.

RICH



 

Offline Chris.Botha

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Re: Really need help
« Reply #38 on: August 14, 2009, 06:42:42 PM »

To my mind the driver test is there to weed out the really bad computers that have no chance of running Mach in their present state rather than saying it will definitely run Mach.

Hood

You may view it as a pass/fail, but it also 'grades the papers' so to speak, and provides what appears to be a benchmark useable as a guide to setting us Mach. The logical assumption, and the one that I myself made, is that a passing grade at XX khz is a green light to set up for that speed. This is where the problem lies. Another area where the 'sin of ommission' is committed by the Mach documentation. I discovered that the driver test is not neccessarily indicative of how fast Mach can run on a given computer only after much wasted time and frustration  :'(

Info worth sharing, methinks.




bit late to this game and very left of centre... but.. i did an install of a Minitech Mill with Mach3. SAme mill as mine, same software, and guess what... complete balls up.  the drives were hooking and jumping or stalling.

I went through the usual suspects.. driver test said ok. cabling was good, no other spurious signals coming from anywhere as far as i could tell.. I was at my wits end.

I happened to do another drivertest and it was fine.. left it running while i was lloking for a way to tell this customer i thought the controller was a duck. drivertest suddenly went to fail then jumped back. noticed it happened as customer moved the mouse. it would work fine until the mouse was moved then would go to fail mode. completely bizarre. further testing revealed that ANY other activity on the pc would cause this behaviour even at 24K rung up my mate in the US and his first question was "is it an AMD?", it was, then next question was "is it a newer one, multicore?"  yes again.

he suggested taking windows over to standard install from acpi, and lo and behold. worked perfect after that, even at 100K kernel.

soo.....   never overlook even the most bizarre bit of hardware that can be interfering with mach3 signal. subsequent reinstalls onto different machines at my place i have follwed the mach optimization rules document. never a headache since. install - plug - cut.

simple.


Re: Really need help
« Reply #39 on: August 14, 2009, 06:54:39 PM »
Tom,
What are the steps / unit that your are using for the pc that you will ultimately use for MACH?
Can you show us how they were calculated?


OK...
The lead screws are metric... 4mm/turn
The motors are 200 pulses/revolution.
The drives are set for full-step.
Therefore, 200 pulses per revolution = 4mm, and 1mm=50 pulses
I'm using metric measure in Mach-3 and the Diamener Mode.
The diameters I am turning match exaclty with the G-Code, once I have accurately set the "Zero" point for the X-Axis.
I'm using Sherline 1/2 pulse mode.

I will post screen-shots of my motor setups
« Last Edit: August 14, 2009, 06:56:15 PM by TunerTom »