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vmax549

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Re: Really need help
« Reply #40 on: August 14, 2009, 07:40:15 PM »
I run 40,000 steps per unit  4 axis at a time for 8 hrs at a time from the LPT port and no lost steps.

Just throwing more hardware at the problem rarely fixes anything. YOU have to find the problem as to WHY it is loosing steps.

Most lost steps problems can be related to misengineered machines. motors/drives/powersupplies TOO small for the stated application.

Next on the list is bad connections

Then on to Bad BOBS(slow optos on super fast pulse rates)



IF this is a commercial machine making money do yourself a favor and bring in a machine TECH that understands the process.

COmmon myths tell you stepper are not as good as servos. BULL, if properly engineered steppers can be MORE accurate and last longer than servos in most low speed applications. AND are much easier to setup and maintain. GOOD steppers are almost indestructable.

(;-) TP



Offline simpson36

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Re: Really need help
« Reply #41 on: August 14, 2009, 09:23:36 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.

You have it backward. Ignorance is recommending something that you do not know works simply because you read a spec and *think* it will work.

SMART, is trusting the knowledgeable people on this forum who have may years of MACH specific experience and *know* what works.

Beating one's head against a walll for days on end with no result is usually the first step toward a CNC troubleshooting, but it would appear the OP has already accomplished that task and perhaps is ready to move on to step two; . . . making it actually work.


Lastly, the fellow with the problem has stated that this is for a business and not a hobby, and there is an objective here to diagnose a NON working system and get the thing going. Wasting time dinking around with oddball unknown components from an old system that are NOT working with MACH for the sake of saving a company $70 is just foolish . . . in my humble opinion.

Your mileage may vary . . . .

Offline simpson36

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Re: Really need help
« Reply #42 on: August 14, 2009, 09:33:20 PM »
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?

If the relay is operating something now and the relay can be triggered with 5V, you should ne OK . . . . . unless it is RF isolated . . LOL! Be careful though that the relay doesn't draw more juice than the BOB can provide, or you can hurt the BOB. The chips are socketed, so it's easy to replace them (don't ask). Specs on the BOB are available on the site, you'd need to look up the specs on your relays.

You have some distance to go yet with this project and you are already getting plenty of opinions on this what-not and that doo-dad, so I am going to give you my best advice on the project menagement level. You stated that this is not a hobby project, so that changes the game. In my view, your decisions should boil down to how much your time is worth, and any losses associated with the machine not producing anything.These CNC parts are dirt cheap in comparison to what I might guess your wages are. You *might* be able to reuse an old piece and save $18, but if it takes you three hours and you need to buy or buld test equipment to figure that out, you have not saved anything for your company money AND, you still have an old part that nobody can give you advice on and now you also have a 'production' machine of unknown reliability. Would the relays shut down production if they fail?

As a matter of personal preference, I avoid 'multi function' stuff if possible. Problem is when one component goes bad, you need to replace the whole thing if you don't have room to add another board or if the failed feature can't be disabled, or if it took other stuff with it.

« Last Edit: August 14, 2009, 10:46:34 PM by simpson36 »

Offline simpson36

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Re: Really need help
« Reply #43 on: August 14, 2009, 10:03:11 PM »
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.


Great tip! Someone should collect all of these gems into a FAQ or tech tips document.

Just to add to the stew, my Jurassic dual P3 server died yesterday (finally) and I replaced it with my wife's old 1.8ghz Intel Pentium on a Gigabyte MB . . Windows XP home. Still really old machine, but plenty to run Mach.

Passes driver test at 60 and 65 with 'excellent' rating. Set Mach to 60, steppers get sbout 6" and lock up. Set to 45, all is well smooth as silk.

For $155 all of the PP issues can be sidestepped (yuck, yuck). Only hold up for me is swap axis. Once that is implimented  . . or . . . I find another method to replace it, I'm going to go with the SS.

Offline simpson36

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Re: Really need help
« Reply #44 on: August 14, 2009, 10:33:39 PM »
IF this is a commercial machine making money do yourself a favor and bring in a machine TECH that understands the process.
Exactly. While your solution is a bit on the extreme side, methinks there is not enough recognition that in a business environment, the priorities change and the costs are not the same as on a hobby level . . . possibly due to the large proportion of hobbyists on the forum . . . just a guess. Employees tend to think only in terms of purchases and don't consider thier wages to be a 'cost'.

COmmon myths tell you stepper are not as good as servos. BULL, if properly engineered steppers can be MORE accurate and last longer than servos in most low speed applications. AND are much easier to setup and maintain. GOOD steppers are almost indestructable.

A similar common myth is that a dump truck is not as good as a Ferrarri. What are these people thinking  :P

OK seriously, how does one go about 'properly engineering a stepper'?  . . and  . .  how does one identify a 'GOOD stepper'. Cost? Brand name? I'm not going to use any more steppers, but I think it would be valuable info to share. 

Offline ger21

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Re: Really need help
« Reply #45 on: August 14, 2009, 10:47:31 PM »
I just skimmed through this, and it doesn't appear that anyone mentioned that resonance may be the culprit? Steppers are notorious for mid band resonance, especially when running in full steps. Does your drive have microstep settings, and have you tried them?

If not, a damper may help. It's helped a lot of people at CNC Zone double their speed and make their machines far more reliable.
http://www.cnczone.com/forums/showthread.php?p=256639#post256639
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline simpson36

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Re: Really need help
« Reply #46 on: August 15, 2009, 07:38:50 AM »
TurnerTom,

I noticed that you have the pulse width set to 5.     Just curious if you have tried setting it at 2.

Also noticed someone posted a description of your 'RF isolator.' Seems like a bad strategy to me. What keeps the RF from one pin from bleeding over to receivers in other pins? That would certainly be one potential explanation as to why you only have problems only while two axis run simultaneously.

I have had a bad time with RF problems. For example, if I plug in a wireless network adapter (USB), the steppers immediately start stalling. This behavior is completely repeatable. Unplug adapter, problem goes away. Plug in adapter . . immediate stalling. I has similar problem with wireless Xbox controller.

Others will chime in and say that they have had no such problems with this or that wireless device. 

This does not say that you will or will not have RF interference problems.  What it does say is that the question of whether RF can interfere with the CNC operation is NOT a debatable issue. It is a fact.

Based on my own experience, I would not voluntarily introduce any RF devices unless there was no alternative.



Offline simpson36

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Re: Really need help
« Reply #47 on: August 15, 2009, 08:05:35 AM »
I just skimmed through this, and it doesn't appear that anyone mentioned that resonance may be the culprit? Steppers are notorious for mid band resonance, especially when running in full steps. Does your drive have microstep settings, and have you tried them?

If not, a damper may help. It's helped a lot of people at CNC Zone double their speed and make their machines far more reliable.
http://www.cnczone.com/forums/showthread.php?p=256639#post256639

I've just discovered something to throw into this arena. I replaced a Gecko 203V with a used Centent 143 'anti resonance' stepper drive. This is an expensive commercial drive about three times the size of the Gecko, but available used for $45 to $100. There is also a 142 and a 146 model with sightly different specs.

Let me say that I love the Gecko203V for it's 'unkillableness' which saved my bacon more than once, and it does an excellent job with small(ish) steppers. But performance wise, the Centent drive is in a whole differnet category. There is NO resonance at ANY speed running a 900 oz-in NEMA 34 stepper parallel at 22x voltage. Although it never lost steps, this was my 'problem child' stepper on the Z axis from the standpoint of resonance. I've heard it said more that a few times that the commercial drives (stepper and servo) are in a different class altogether and that is certainly the case with this product.

Re: Really need help
« Reply #48 on: August 15, 2009, 08:21:44 AM »
My boss thinks he can borrow a scope from a friend of his and if so, it will be in the shop Monday or Tuesday.

If the scope is unavailable, I will all have to wait until the one I purchased for $55.00 arrives  (assuming it works)

When this lathe ran under DOS (and the BASIC programs were outputting the pulse train directly at the correct speed), the stepper motors followed faithfully. If the conputer had to be replaced, then the timing loops that controlled the rate of data flow, had to be adjusted to deal with the new processor speed. This has always been sort of a nusiance, but it did work.

As soon as I can get some wave forms, I will get the display synched and try to shoot some images using slow shutter speed.
I'll submit the images here, if they don't make sense to me.


From what all I have read so far, this seems to me to be my best next step...

Offline RICH

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Re: Really need help
« Reply #49 on: August 15, 2009, 08:25:01 AM »
Simpson,
" if properly engineered steppers "
" How does one go about 'properly engineering a stepper? "

I believe what VMAX  refers to, is the proper selection of a component to a system and not the actual design of a just the one component. Systems are "designed" at the professionsl level. True engineering of a system is beyond the understanding of most hobbiest's. In fact, the total engineering of a system requires the application of multiple engineering talents. In light of the above, one does not know how lacking they are until entering anothers discipline, or as Clint would say " a man needs to know his limitations".
 
With a defined basis of design, any level of engineering deisgn can be applied to support a selection. Good engineering judgment is always part of application of a component.

Discussions are great, but when entangled in replies to a thread, it goes off course real quick,
  
Rich