Messages

41

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 08:18:38 PM »

I do NOT think 4.5 V is acceptable.

I am a long way away and I do not know, but I suspect you might have a bad or loose connection in the power supply chain. I have seen loose screws, broken wires, and even the terminal block screw bearing down on the insulation rather than the copper in one case.

In the power supply lead to a power tool I found a completely broken conductor - deep inside the cable. Gave me hell for a while.

Cheers
Roger

Let's table that thought for a second. I only say this because

I FOUND A NEW SYMPTOM!!

Sorry, but I got a little excited.

When jogging with the ctrl key I thought I was doing something odd like not waiting enough time between steps so when it missed a step I didn't think much about it.

But there's a pattern there.

Using the X-axis alone, I discovered the pattern for the skips is as follows (1 being a step, 0 being a missed step)

011010110101101

That's a pattern of FIVE in a dual coil system.
My brain says it should only be 4 or 8 in a pattern, not FIVE.

So, once I figure out why it has a FIVE step pattern, I think I will be on to the solution.

I did test this over and over and came with the same pattern. This will explain the missing and jumping steps.

Any ideas?

42

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 07:27:05 PM »

X isn't working right now when isolated. There goes THAT test.

It's odd because when I jog the stepper I can see that the direction will switch back and forth when jogging without me touching the other direction. For instance, I jog clockwise a few times and it might make three jumps clockwise and one jump counterclockwise. ONLY when I jog it though. If I hold down the key to move it it will sometimes jog backwards for about 5 steps (7 degrees) and then go forward.

The Y axis and Z axis displayed the same symptoms.

As part of the above test, I switched around the coils and rain on just a single set of A/B. It didn't change the symptoms
I also flipped the polarity of one coil to see if it changed anything and it didn't.

There's something weird here.

43

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 06:56:34 PM »

Common Ground - DEFINITELY! I would never run on a common positive, ever. Huge room for disaster there.

Getting a good solid 0/+5.0 supply: YES.  Hard-wire - YES.

Now, a thought. The X axis now runs fine by itself, yes? Can you get the Y axis running properly *by itself*? If so, same for Z axis - *by itself*. If so, then the odds of there being a PS problem rocket.

Btw, if you are checking the PS voltage, check it at the PS output AND at the BoB PCB AND at the the driver PCB as well. Do not assume the wired connections are perfect. Advice for the day.

Cheers
Roger

Good thoughts. I will go there next.

I just swapped out to a common ground and flipped the standard in the port setup.
I also hard wired to the Computer power supply.
I checked voltages and now I get +4.5v at the driver (direction pin and enable pin) when it's engaged. That should be more than enough to ensure a "good" signal.

Same results, if not a little worse.

During all the different tests, I get weird voltages all over. At one point I found 2.2v 

I think it's time I mapped this out.

I will isolate the X then Y then Z to see if one of the steppers is giving a weird feedback. 

44

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 05:37:44 PM »

Hi Inferno

Oh, things are not that bad. There is usually more than one bug, and you have dealt with the first one.

Zip tie - hilarious! Gowachin Law: first exonerate the judge. Ah well.

likely that the problem is that the computer can't communicate properly with that many steps at the same time.
No, I do not think that will be the solution, not at all. That is not how Mach works. I think you should assume that the right pulses are coming out the PP. From memory, EPP is the right setting. Also remember that when you exercise the X axis only, it works perfectly.

These are all steppers? If so we can discount encoder noise.

I see two main possibilities: pulses are being lost going through the Bob, or the drivers are missing some pulses. But the loss is most likely due to the extra load when you go multi-axis. Something is causing the X axis drive chain to go wonky.

Power supplies are where I would be looking. Without a CRO this gets a bit tricky. Set up your system with that spiral test program (a good idea, btw) and monitor the various power supplies on the BoB and on the drivers as it runs.
Btw, that 4.25 V - that sounds wrong. Either 3.3 V or 5.0 V would be OK, but not 4.25 V. You may need to try an external PS on the BoB.

Cheers
Roger

I was mistaken about the 4.25
It's actually 4.45
That's splitting hairs.

I checked the USB on the BoB and it's reporting the 4.45 so that's where the drivers are getting their voltage.
I checked the power supply on the computer and I can get 12.08 or 5.1v if I hard wire into the power supply.

I'm leaning that direction now. Hard wire.

I'm also wondering if I should switch the drivers from a common positive to a common ground and then set the Mach3 for that in the port settings. I suppose it can't hurt.

I'm really leaning to the USB not being able to supply enough power for the drivers all at once. Especially considering it's 4.45v. Theoretically, if all lugs are going at the same time I could be drawing current on 12 devices. 4 drivers with 3 "devices" each.

45

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 04:57:49 PM »

Went into the BIOS on the computer. It was selected as a PS/2 port. I changed it to EPP and measured the voltage. Still about 3.3
Tried to run code. No change in the performance. Still drops steps.

I checked the voltage at the drivers, coming from the BoB and it measured 4.25v so the BoB is allowing the USB power from the puter to switch based on the signal from the PP. Basically there's USB power coming through to the drivers.

I'm considering hard wiring directly from the computer power supply to the BoB. It would allow more amperage to be supplied to the BoB than the USB can supply.


Good point on the timing belt on the ballscrew. I had considered that the single step on the stepper on a 5:1 ballscrew allows for a .001 precision which would be plenty for my needs. Having a gear reduction and microstepping on the motor could make that smaller (not needed) but also a lot quieter.

46

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 12:41:38 PM »

I THOUGHT I HAD IT!!!

I had made a lot of different configuration changes. Finally I found one where the X-axis (working with only one axis til I found something that worked) was working flawlessly.
I had it set to single step mode and ran a test G-code file and after three times running the file I checked and the X-axis hadn't lost a single step.

Also, during this configuration searching I realized I wasn't dropping as many steps as I had thought. My rotational indicator (a zip tie on the shaft of the motor) was slipping as it went around the table side of the arc.

Anyhow, after the test, verifying that the X-axis hadn't missed a step, I hooked up the other 3 motors with the same configuration. Then I ran the test file again.

The test file is just a spiral design. Nothing fancy.

After a single run of the test file I found that all three active axis had dropped a LOT of steps. As many as 60, based on the angle of the indicators.

So, I am thinking that it's very likely that the problem is that the computer can't communicate properly with that many steps at the same time. Possibly the 3.3v on the parallel port issue.

Without an oscilloscope I won't be able to "properly" diagnose this. It's going to be some trial and error.

The other possibility is that the power supply can't handle 3 motors but my better judgment tells me this power supply ran (checked again) SEVEN of these motors in their original machine so it should be able to handle three of them.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On the other side of things, I do believe I will stick with a NEMA 23 setup. There are a lot more options available in the 23 and even the dual shaft that I'd like to have for the X-axis.  Plus they are a lot less expensive than the 34's.
If I need more torque I can always gear them up/down a little.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm not ignoring the advice on the timing belts. It made it into the noggin. I've been toying with belt timing, lead screws, gear drive or ballscrews. My mill will definitely have ballscrews (bought two axis of them already) but the CNC router will probably be run on timing belts or gear rails.



Now I'm going to see about increasing the parallel output to 5v if there's any possibility. I can't help but wonder if a PCI card would deliver 5v.

I'm also going to try running the file again with the network controller unplugged (it's a USB type).

47

General Mach Discussion / Re: Low voltage on stepper port issues

« on: April 01, 2018, 02:46:22 AM »

Check the pins at the computer first. If OK at the computer, check at the end of the cable.
I just went through the same thing and discovered it was a bad cable.

48

General Mach Discussion / Re: Only X-axis motor is working

« on: April 01, 2018, 01:45:49 AM »

Hi,
the parallel combination is better for performance. Provided it does not get too hot that's the way to go.

A four winding two phase stepper can be run flexilbly as unipolar or bipolar and therefore potential OEMs sales increase because of the flexibility of application.

Craig

When I had them in parallel they did get pretty warm. Maybe 110-120 degrees F

I've read unipolar and bipolar several times but still can't fully comprehend what that means.

49

General Mach Discussion / Re: Running 2 instances of Mach3 on same computer to control 2 machines

« on: April 01, 2018, 01:34:35 AM »

There goes that theory. LOL

50

General Mach Discussion / Re: Running 2 instances of Mach3 on same computer to control 2 machines

« on: April 01, 2018, 01:07:27 AM »

I'm not terribly familiar with Mach3 (learning) but I know a little bit about computers so I'm going to offer a potential way this could work.
I don't know about running over a network...

Let's assume you added a parallel port to a computer using an existing parallel port.
Now, let's assume you put a copy of Virtual Machine on your computer.

On the main computer you could address the main parallel port and in the virtual machine you could address the second parallel port.

You'd have to load Mach3 in two configurations, and possibly (likely) two different partitions on the hard drive to accomplish this.

There's also some monkeying you might have to do in the registry to separate the two "machines" but this could potentially, be done.

Now for the $64,000 question. What's the advantage of doing this? You could accomplish the same thing with an extra $200 PC and a KVM switch or remote computing.