[steve_goldsmith]

Hi,
First off, I am not a machinist, I am a goldsmith. I bought a package deal 4-axis Taig milling machine with stepper motors off eBay that is giving me some trouble. The controller is a DriveMasterNC 4-Axis with WWW.MICRONC.ORG printed on the circuit board. I did a Google search for MicroNC and found nothing. The steppers are rated at 167 oz/inch. I am using Mach 3 software. Now for the problem. I have tried to tune the motors. When I settle on a velocity and acceleration and jog the axis, after a short time (roughly 15 to 45 seconds) the motor will start to "miss", then eventually the motor will freeze, accompanied with a drastic change of noise from the motor (the DRO's continue to move). This happens with a very large range of velocity's/accelerations (from 40 inch/minute to 10-12 inch/minute). Also, if I set the velocity, then jog at a lower percent (like 20 to 50 percent), it still misses. Does anyone have any idea as to what is wrong and how to fix this? I want to use my mill.
Thanking you in advance,
Steve

[ger21]

It sounds like it may be resonance. Does it do the same thing when running g-code? Or running code using MDI mode?

[steve_goldsmith]

Gerry, thanks for the quick reply. To answer your question, I do not know. I have not gotten to the point where I have run any g-code. I must confess, I do not know what MDI mode is. If it is resonance though, what is the fix? New controller and/or motor drives, or something less dramatic?
Steve

[ger21]

Click the MDI button next to the Program Run button at the top to get to the MDI screen. Once there, you can type in individual lines of g-code. For example to set the feedrate to 10ipm, clicl in the input bar, and type F10 and hit enter. To move the X axis 5 units, type G1 X5 and hit enter.


If it's resonance, and happens at a certain speed, try to avoid that speed, and maybe change the acceleration settings might also help to avoid problem speed zones.

[steve_goldsmith]

Gerry,
If it is resonance, I do not know how to avoid it. It happens at wildly different speeds (40 ipm to less than 15 ipm). I have also changed the acceleration settings with no impact.
Steve

[Torchhead]

Two quick questions

1. What kind (speed) computer running MACH
2. What does you interface look like between the computer and the controler?

If you are trying to run the controller directly off the PC parallel port you may be dealing with marginal step & dir signals. Also the polarity of the drive from a parallel port needs to be "Active Low" (green check in the Ports & Pins/Motor outputs. SInce you don't know what the insides of the control have for motor drives you might be dealing with something that takes more drive current than the PPort can provide.

[ger21]

Try at 5ipm. Does it still happen? Perhaps there is some binding in the machine. Does everything move freely?

[ger21]

Also try increasing the pulse width in the motor tuning.

[steve_goldsmith]

Thanks for all the information. The machine is at work and I am not. I'll give your suggestions a go on Monday and report back.
Steve

[Switcher]

I did a search and found what looks like maybe the company name was changed (not sure).

This seller had a listing similar.

Link:
http://cgi.ebay.com/TAIG-CNC-metal-l...03787447QQrdZ1


Now the seller has open listings.

Link:
http://cgi.ebay.com/Taig-Peatol-benc...QQcmdZViewItem

The open listings say.

Link:
http://www.stepmasternc.com/

I'm thinking the "DriveMasterNC" was changed to "StepMasternc", you might contact them, maybe it's a new owner ?

Anyway, does the drive look similar to this ?

Link:
http://www.stepmasternc.com/stepmasternc51606002004.jpg





Jerry

.

[posix]

are your steppers at first warm to the touch and get progressively hotter and hotter as you jog them around and after a few minutes become sizzling hot as the sound gets worse and worse? if it's so I would suspect that your drivers may be set at a higher current than your steppers are rated. just a stab in the dark really...

[steve_goldsmith]

Thanks again for all the responses.

Tourchhead, I am running a 3 gig P4 with 1 gig of RAM, Windows XP with all updates. I do have a long cable run between the parallel port of my computer and the controller (for cosmetics only). On Monday, I will reconfigure with a short cable and see if that makes any difference.

Posix, The steppers run very cool, not hot at all.

Switcher, I also found the StepMasterNC web page. They are two different products. From the looks of it the front of my controller has been printed with someones home computer, like a garage outfit not a manufacturer.

Ger21, I will try 5 ipm, and increasing the pulse width. Also, before I mounted the motors, the axis turned silky smooth, no binding that I could feel. I will remove one of the motors and recheck that.

Steve

[steve_goldsmith]

Ok, here is the update.
I eliminated all cable but 6 feet between the computer and the controller. No effect (motors still miss)
I changed the polarity of the drive, with all at "Active Low". No effect.
I ran the motors at 5 ipm. No effect.
I increased the pulse width from 1 to 2, then 3, then 4. No effect.
I removed one motor. Even at 5 ipm, I could feet the motor missing.
I rotated the axis by hand. It is smooth, no binding.
Thanks again for all the suggestions, but nothing yet seems to have any effect.
Steve

[steve_goldsmith]

One more thing.
Gerry, I used the MDI function to control the motors. I tried different jog speeds and the motors still missed.
Steve

[pminmo]

What is the power supply voltage? What is the vref set on for the motor/current settings?

[KTP]

Is the shield on your parallel port cable grounded? This sounds a bit like a noise issue.

[steve_goldsmith]

PMinMO, I do not have my voltage meter with me. I will check that tomorrow.
KTP, I would assume the cable to be grounded, it is a manufactured one. Maybe the person that made my controller box neglected to wire it correctly and ground the cable. Would I need to attach a ground from the parallel port to the ground from the wall outlet?
Thanks for the help,
Steve

[KTP]

Is the cable you are using shielded? I don't know what your motor driver system looks like. Does it have a DB25 port, bare terminals or something else?

When you mentioned you shortened your cable run, it made me think perhaps you were using some homemade parallel port cable that perhaps was not shielded, or you don't have the shield connected to ground.

Hard to debug this over the internet

[steve_goldsmith]

KTP
I have several DB25 parallel printer cables. All manufactured. For cosmetic purposes, I was originally running a longer cable (I think it was 20 to 25 feet). This morning, I replaced the longer cable with a 6 foot cable.
Steve

[juzwuz]

Out of curiosity, does your problem occur on all three axes or is it worse on one axis? If it occurs mainly on the z-axis, maybe you need stronger stepper motors? I was originally going to use 150 oz-in stepper motors on my Taig but I was told by Nick Carter (www.cartertools.com) that 200 oz-in or larger would be better. I eventually got 280 oz-in steppers off of ebay. I'm still working on the stepper motor wiring and control for my Taig mill so I haven't actually had it under computer control yet.

It sounds like you have to somehow verify that you are getting enough torque from your stepper motors so it could mean you need bigger stepper motors, or your stepper motor driver is not set correctly to give enough current to your motors, or there is a wiring issue.

Have you been able to get in contact with the seller to see if he will help you out?