[hayes]

So after getting everything back together on my NM 200 Series 1 machine I've found that the X axis stepper is randomly losing steps. I really want to get this thing up and running 100%, and after reading all the good about the Torus Pro with servos, I'm considering upgrading all three steppers on my series 1 machine to hybrid steppers with something like these - NEMA34 Closed Loop Stepper Motor System- Hybrid Servo Kit-32 bit DSP Based , 1128 oz-in | Automation Technology Inc. The thought process is $1200 is a lot more palatable and affordable than $4500 for the full servo upgrade.

Am I heading down the right or wrong path? Thoughts, suggestions?

[TiagoSantos]

You might have a mechanical issue causing the lost steps, so the cheapest solution would be to figure that out first.. But if you are set on spending $1200 on motors, I'd take a good look at the DMM servos! Maybe the closed loop steppers are fine, but I haven't seen them used yet - although to be fair, it's not like I've been paying much attention

[SCzEngrgGroup]

Swapping parts without first establishing the root cause of the problem is a recipe for disaster. You stand an excellent chance of spending a lot of time and money, and ending up with a machine that works worse than what you have now. There is not a reason in the world the machine should not work perfectly with the existing motors, unless either a motor or drive is defective. In that case the fix is to simply replace the defective part, at a tiny fraction of the cost of replacing the entire drive system.

"Closed loop steppers" are the solution to a problem that really does not exist. By definition, they CANNOT prevent lost steps, they can only tell you when it happens. Stepper motors ALWAYS operate at maximum torque. Lost steps are the result of asking the motors to produce more torque than they are capable of producing. There is NOTHING the driver can do to make them produce more torque. If a stepper motor is operated within it's torque limits, it will NEVER lose steps. This has been adequately proven by many millions of perfectly performing stepper-driven machines over many decades. Ask yourself - If closed loop steppers are so wonderful, why is there NO CNC machines on the market that uses them? My Novakon machine worked absolutely flawlessly for the last year with steppers, running at over 200 IPM, and doing lots of heavy machining.

Regards,
Ray L.

[hayes]

Tiago & Ray,
Thank you both for the feedback, that's exactly why I posted and seek the knowledge you guys are willing to share. You guys have much more experience and wisdom with this equipment. I'm a noob rebuilding a used machine...

I'm soaking up all the info I can get and learning quickly!

[LeeWay]

I would first try to see if the motor operates okay without being connected to the screw. If it does, then I would next check the oil system. If that seems to work correctly, then check the gib adjustment. One screw too tight there by just a hair will cause big issues.

[hayes]

Thank you for the suggestion LeeWay. I've removed the motors from the screws and what I get on rapids, and to a lesser extent on slow moves as well, is not a steady motor turning at speed but it will turn and then miss a step or hit a clunk and then keep turning, and then again klunk.

Sounds like this: brrzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,clunk,b rzzzzzzzzzzzzzzzzzzzzzzzzz,clunk, brrrzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzclunk. .. until the movement is complete. It does this on all three axis on rapids and slow movements.

Any ideas on what to isolate and test next?

[SCzEngrgGroup]

That sounds like a PC software problem. Something is preventing the PP driver from delivering a clean stream of step pulses.

Regards,
Ray L.

[t300]

My pc that runs my nm145 has double duty, for example surfing the web so I have an antivirus program on it (I know, I know). I have to turn off the antivirus before using the mill otherwise I get the same thing. Actually have another pc I'm building now so I can keep things separate. Is your pc isolated to only your mill or are their other apps running on it?

[LeeWay]

I agree. It does sound like timing. Have you ran a Driver Test in Mach 3 yet?

[hayes]

So, I disabled almost every service possible in Win XP while still allowing the OS to run. Removed the antivirus and uninstalled all the junk on the machine (remember it's used). Rebooted, ran the Driver Test for Mach 3 and it gives me a green bar with "System Excellent" under Pulse Rating. I'm still getting the same behavior of the lost steps or clunking.

I purchased a new SSD to put in place of the old drive and will install a new clean WinXP build and then a clean Mach 3 install. If on the chance that doesn't fix the issue (I'll let you guys know) what is the next thing I should be looking at to isolate and test?

[neilw20]

Is the acceleration set too high? Keep halving it and see what happens. Do one axis at a time.

Golden rule. One thing at a time.
Some PCs will always have a problem. Try another OLD PC.

[sagreen]

So, I disabled almost every service possible in Win XP while still allowing the OS to run. Removed the antivirus and uninstalled all the junk on the machine (remember it's used). Rebooted, ran the Driver Test for Mach 3 and it gives me a green bar with "System Excellent" under Pulse Rating. I'm still getting the same behavior of the lost steps or clunking.

I purchased a new SSD to put in place of the old drive and will install a new clean WinXP build and then a clean Mach 3 install. If on the chance that doesn't fix the issue (I'll let you guys know) what is the next thing I should be looking at to isolate and test?

Hayes,

I noticed you posted the following in an earlier post. Did you ever resolve this prob?

A friend of mine recently gave me a Novakon NM 200. Some how, the X axis ballscrew was toasted some time ago. So I ordered a new one and new bearings from Novakon and installed them over the weekend. What I'm concerned about is that while turning by hand (using the knurled end) it feels like there is some amount of binding and I don't want to waste a new screw & nut. I've pulled everything back off for the time being.

Scott...

[hayes]

Scott,
Yes, I resolved the ballscrew issue. The ball nut was very slightly canted in it's mount and is now running smoothly. There is a remaining .0015" TIR at the bearing mount end where the ball screw couples to the motor. I currently have the motors off the X and Y axis while I'm trouble shooting the missed step issue.

I've installed a clean version of Win7 and clean install of Mach 3, issue remains. I've installed a clean version of WinXP and Mach 3, issue still remains. Running DriverTest show "System Excellent" each time.

I'm in need of guidance here. The machine and it's controller are 2008 vintage. If I need to start replacing hardware, I'm ok with that. I just want to get this thing running!

[neilw20]

1988 is vintage. 2008 still has some life left yet!

[hayes]

Well, I've tested the system with a spare PC and the missed step and clunking issue is vastly improved, if not nearly eliminated. That leads me to believe the PC in the controller is faulty somewhere. I'll replace that and drive on at this point, however, since it's a series 1 machine, would it be worth upgrading to the newer more powerful steppers of the current Torus Pro stepper model?

Thoughts?

[neilw20]

The PC is doing something in the background., if you are getting clunking. Try to select 25KHz. You probably don't need any faster.
Sometimes a CDROM can cause problems, even when not in use.
Makes sure hard disk is not slave, and unplug CDROM.
As I previously said, some PCs just clunk, and can't be made to work properly.

Make sure active high (or low) for step signal is correct. Try temporary swap and see if clunks get worse.
Reason: Step signal should not change when direction signal changes (as far as the driver sees).