Messages

771

FAQs / Re: Losing steps or something?

« on: November 04, 2010, 03:43:52 AM »

I would like to note that it is not as easy as it may look trying to capture the timing between the step and direction signals using a plain scope. Thing is there is also the motor acceleration factor and the step pulse stream is not going to be constant frequency. One could probably try a very slow speed and VERY small acceleration and even then it's not going to be easy.

May be you could try in Incremental Jog mode, defining ONE motor step there...? But don't know if your scope can capture a single pulse.

Dan

772

FAQs / Re: Losing steps or something?

« on: November 03, 2010, 03:30:44 AM »

Hi Roger,

The Step Pulse parameter is how many micro-seconds are added to the base step pulse width (don't remember what it is). I think the label is wrong and it would accept values 0-15.

Dan

773

FAQs / Re: Losing steps or something?

« on: November 02, 2010, 11:22:17 AM »

Hi Roger,

I was talking about the Dir setting under Motor Tuning. The value there is how many micro-seconds before the first step in the opposite direction, the Dir pulse changes state. You are correct about the direction line that its Hi or Low state essentially defines the direction of the motor rotation. But the timing is critical here. Change it too soon and you lose one step in the current direction, too late you gain one.

Yes, the SS and the BOB were screwing the timing. It was an abnormal condition that was fixed with a new plugin for the SS. The opto-isolators on the BOB also were changing the timing slightly, but the change was so small that with the perfect timing of the fixed SS plugin it had no effect on the operation, but with the (rather "not perfect") timing of the PP it was adding up to a more substantial change that was affecting the operation.

Dan

774

FAQs / Re: Losing steps or something?

« on: November 02, 2010, 04:48:46 AM »

I have had exactly the same problem of losing steps on reversals, but I was able to isolate it to a combination of the BOB and SS plugin I was using.

Details, please! What was going wrong, and how did you fix it? The info may help here.

 

It was what you mentioned before. The drive was expecting the direction pulse to appear on the falling edge of the step pulse but the BOB/Smooth Stepper combination was outputting it on the rising edge (or vice versa). I was first trying to eliminate possible factors from the equation to find the ONE that was causing it. First take the BOB out of the equation - no change. Then take the SS out of the sequence and hook the PP directly to the BOB - no change. The switch between different cables. It was only after I accidentally removed both the SS and the BOB from the sequence that I found the problem was gone. A new SS plugin cured the problem. But the BOB was still no use without the SS - only worked with the SS new plugin.

One thing I seem to remember that was causing the problem with the PP was the Dir pulse setting was set too high. Setting it to 0 cured it. But I think Don has tried it.

Hope it helps.

Dan

775

FAQs / Re: Losing steps or something?

« on: November 02, 2010, 03:02:58 AM »

Hey Roger,

The reason I doubt it is Mach, is that there are many machines running Mach3 on daily basis producing thousands of precision parts. These people would have easily noted a problem like this if it existed.

Software bug or hardware issue or a combination of both, I think it is something unique to Don's setup that exposes the problem. Just can't see what might it be.

I have had exactly the same problem of losing steps on reversals, but I was able to isolate it to a combination of the BOB and SS plugin I was using. The test I was running was set to incremental jog mode and the finest increment I could read with a DTI (0.01mm), then use the keyboard to step jog one direction and the other repeatedly. I could actually see the DTI needle moving gradually to one side. After the problem was resolved, the DTI was spot on after hundreds of iterations. So no such problem here, but I am using the Smooth Stepper, so can't speak for the PP.

Don, the stuttering you're seeing is not something normal. Have you tried following the optimization procedure?

Dan

776

FAQs / Re: Losing steps or something?

« on: November 01, 2010, 03:29:27 PM »

Hi Don,

Seeing the same problem after switching over to a servo system is weird indeed! But then, as Roger noted, I am curious if you were merely bench testing with the servo or it was really driving the machine. But my curiosity has other reasons, and I am afraid I have to disagree with Roger. While an unloaded servo will act absolutely differently and  will need careful tuning, there is absolutely no reason for it to move to other locations from those commanded by its driver.

I am very doubtful it's a software bug thought, since you have abstracted it to merely:

PC -> Mach3 -> Parallel Port -> Gecko(/Viper) -> Stepper(/servo)

Thousands of people are using exactly the same setup and no one has reported this. So either they don't have this problem or they just never discovered it. I think its the first option.

After you eliminated a possible wring issue, and considering the above said, the only two links in the above sequence that can be the problem are PC and Parallel Port card. You have switched between two absolutely different PCs with no change. Can you try setting the PP to different mode? This usually has no effect, but who knows... I remember Brian or Art once had a recommendation for the particular setting, but can't seem to recall what it was, so you'd have to try them all and see if it makes any difference. I know your findings show that a break out board looks to be having no effect on the problem, but I wouldn't recommend putting it back into the above sequence - not until you find the most abstracted sequence that works and then start adding things to it and see when the problem appears back again. This is again, just to eliminate any possibility of a combination of things.

So see if you can play with the above sequence, trying out every possible combination of PC and PP (card and settings). Another way would be if you could put your hands on some external motion controller, like the Smooth Stepper.

Dan

777

FAQs / Re: Losing steps or something?

« on: November 01, 2010, 03:10:59 AM »

Hi Don,

You've been getting very strange results... The exact stop test that Roger suggests is interesting. Following the nature of the problem (its consistency and inconsistency) it looks to me that it is a combination of several things which causes it. Like both the particular mechanics and Gecko's/Mach3...

Dan

778

SmoothStepper USB / Re: Smooth Stepper Lathe Conversion

« on: October 25, 2010, 03:27:17 PM »

Hi Paul,

Mach3 can handle all you're asking for. Smooth Stepper being no obstacle. I have retrofitted an Emco Compact 5 and it works with the SS just fine.

To control the turret I put a disk with 6 slots on the turret shaft at the opposite end of the turret plate and fitted an optical sensor to count then. Then a simple macro handles the tool change by reversing the voltage to the ATC DC motor through a relay.

To read the spindle speed for threading you will only need ONE slot on the disk. Expand a bit the outer slot and you should be fine. Then again, it is easier to use a new photo interrupter (like the C3 combo from CNC4PC) rather than trying to figure the pinout of the original one.

You are correct about the flood coolant.

Basically, the 5 phase steppers are better than the common 2 phase ones. They usually run smoother. Problem is finding proper drivers for them. Anyway, not sure servos are the correct choice for this machine - especially for the X axis, having merely 50mm of travel. Steppers are much cheaper and can handle it no problem.

Mine came with a DC motor and I was able to control it with the C6 board.

Dan

779

SmoothStepper USB / Re: Smoothstepper problem when spindle is on

« on: October 24, 2010, 03:19:48 AM »

Hi David,

Very interesting findings! Thanks for the post.

I am curious what's the explanation though.

Dan

780

FAQs / Re: Losing steps or something?

« on: October 23, 2010, 02:25:05 AM »

Hi Don,

Can you now use your special shielded cable directly from the PP to the Geckos to bypass the breakout board?

Are the signal cables to the Geckos (step and direction) shielded and grounded at the breakout board end? Looks so on the picture, but hard to tell exactly

Dan