[dkaustin]

I recently noticed that just turning on the Main Disconnect started the machine without me pushing the green "Start" button. Odd, I thought, but things seemed otherwise normal.

Today, though, I discover that the E-stop does NOTHING!! Axis motion continues, the spindle keeps running. Had to hit the Main Disconnect, by which time the job was well and truly buggered.

Has anyone else seen this problem? Any suggestions as to where the problem lies?

I have to say I'm losing my enthusiasm for the PCNC1100. In the slightly more than one year since I bought the machine, it's been out of commission more time than it's been up. Most of the spindle drive components have been replaced at least once, but the machine is still erratic, and new problems continue to crop up.

In fairness to Tormach, I will say that they've responded quickly to every new problem. Now that the machine is out of warranty, however, I'm about ready to drag it to the curb and write it off as an expensive mistake.

Am I the only one with this kind of experience? Thanks for letting me vent.

[dkaustin]

But wait! There's more!

Am part way thru a job, machine head goes up to safe level and pauses for a tool change. As I'm reaching to open the spindle motor cover, the head rapids down about two inches and stops with a loud "THUNK". After that, any attempt to move the head back up only moves it further DOWN. Shuttle input Z+ or Z- both move the head down. Keyboard input PageUp or PageDown both move the head down. Attempt to reference the Z axis moves the head down.

Finally had to shut the machine down, restart, re-reference, reset my zeroes. Restarted the same program, and this time it ran normally.

What is going on? Software glitch? Electrical noise? Ideas please.

[StephanWenger]

When a stepper axle exposed to a torque moves in the direction of the torque regardless of the programmed direction, then usually one stepper phase is not working. This could be a result of a loose stepper cable, a burned stepper, or a burned stepper drive.
I would measure the resistance of the stepper coils of the Z-axis by right at the drive unit, after disconnecting one phase at a time. If you get indefinite resistance, it's time to check the cables. If the cables are fine, the stepper phase is shot. If, however, both phases have a reasonable resistance (a couple of ohms---don't have my datasheet handy here) then your problem may be the drive. If you get zero ohms resistence or something very close, it's again cables or stepper and the phase is short-cut. In his case, it's possible that the drive is shot as well.
If you get a couple of ohms, I would connect that stepper to the X-axis drive, and see whether things work when jogging the X-axis.
This whole exercise should not take longer than half an hour.
Stephan

[keen]

Hi dkaustin. Sorry to hear of your run of back luck with your pcnc. Its a nightmare when a cnc faults on a job - you get really rattled.

I think most pcnc's are reliable though - you have just been unlucky. I hope your machine settles down soon.

I had a few hiccups when I first got mine - I have another xp computer set up beside the current one, all ready to run -I keep them both current. I have a spare /keyboard/controller and full set of boards etc . That speeds up fault finding. But for the last 18months all is well - touch wood!

[R.DesJardin]

I understand your frustration, I have had my Tormach since Dec. 2008 and I am very pleased with it in all regards. Maybe this is of no consolation but a freind of mine just bought a new Haas and has had the spindle replaced twice along with several other items. Keep the Tormach. Even when I get ready to upgrade I'll be keeping the Tormach for prototyping.

[MichaelHenry]

Am part way thru a job, machine head goes up to safe level and pauses for a tool change. As I'm reaching to open the spindle motor cover, the head rapids down about two inches and stops with a loud "THUNK". After that, any attempt to move the head back up only moves it further DOWN. Shuttle input Z+ or Z- both move the head down. Keyboard input PageUp or PageDown both move the head down. Attempt to reference the Z axis moves the head down.

I had something similar happen on my X-axis and fixed it by replacing the X-axis drive unit.

Mine is old enough that it didn't have the cooling fan in the control cabinet and I suspect that heat may have killed the drive since I was leaving the mill powered up 24/7 at the time. I've since installed a cooling fan. If yours is 2 years old or more you might want to consider doing the same, especially if your mill is in a garage and you are in Austin, TX <g>.

Mike

[bevinp]

DK,
I suffered something similar about 18mths ago. The cause was the printer cable shielding allowing ambient high frequency noise to interfere with the signals on the cable resulting in various intermmittent faults. Consequently Tormach did some testing and confirmed the some printer cables are susceptible to noise in a frequency range that can interfere with the Tormach control signals. Tormach designed a ferrite ring "choke" that is place at the computer end of the cable. Check if your printer cable has the ferrite ring. If not let Tormach know and they will ship one to you.

The main symptom I was experiencing was intermittent uncommanded "External E-Stop requested". At one stage in the subsequent investigation I had the X axis always moving away from the home position, whatever key I pressed. The controller thought the X limit switch was tripped and was trying to move the table off it. (The specific cause of this was a bent pin in the printer cable, and that is another story).

If your printer cable does have the ferrite ring then your problem is unlikely to be the cable. I suggest you follow the steps in the User Manual trouble shooting, record the results, then send a detailed but concise email to [email protected]. I suspect you are already in dialogue with Tormach support.

I am sorry that you are having problems, but one of the reasons I sing the praises of Tormach is the high level of support they provide. I recently had a problem with my Machine Control Board tripping the GFI, the diagnoses of which was made difficult because I don't have access to non-GFI power but was made easier because Greg always answered my emails the next day, even over the weekend.

Good luck,
Bevin

[dkaustin]

Bevin,

I think I am seeing the same electrical interference problems. I will ask Tormach for a ferrite choke.

I also think that Tormach support suspects there is a short circuit in my main control board. Mine also causes tripping when I plug into a GFCI outlet. What was the final diagnosis of your control board problem?

Agreed that Tormach customer support is without equal. They've walked me through my many problems and supplied many replacement components at no cost while the machine was under warranty. The machine is a treat to use when it's working right. I just wish mine worked right more of the time

Dennis

[bevinp]

Dennis,
The uncommanded External E-Stops were fixed with fitting a new printer cable and then subsequently, after Tormach did their research into noise susceptibility, they announced the ferrite choke so I installed that just to make sure of noise protection.
My recent GFI problem would occur whenever I commanded the spindle to start either manually or via MDI. After much emailing and testing (following the manual and Greg's suggestions), we all agreed that there was a short in the MCB.
I decided to upgrade to the new spindle drive which comes with a new MCB and I just received the parcel today. I hope the new MCB cures the problem.

In regard to your MCB tripping the GFI, Greg told me that the manufacturer of the Variable Frequency Drive recommends not using GFI-ed mains supply because it can cause some GFIs to trip. Greg was talking about the original VFD, and I assume the same applies with the new VFD. Greg added that the tripping should not cause any damage to the mill electronics.

The User Manual for the original 1100 does not include this recommendation, but Greg was very clear. So that may be the problem with yours, hopefully.

I will let you know if the new MCB cures my problem, and I would like to hear how yours is resolved.

Bevin

[dkaustin]

After some discussion of the problem, Tormach support decided that the current problem was caused by a short in the MCB. VERY much to my surprise, they said they would send me a replacement board at no cost even though my machine is out of warranty! Shorted MCB's must be a common problem. I should receive the replacement board today. I'm keeping my fingers crossed that this will be the final fix.

If I had been forced to buy the replacement MCB, I think I would have gone with the spindle upgrade.

As frustrated as I have been with the machine, I have nothing but good to say about the people at Tormach. The level of support they provide beats anything I have ever seen. I would still recommend the PCNC for that reason alone.

[dkaustin]

Received and installed the replacement MCB. Now the machine does not power up at all. Diagnostics screen in Mach indicates "E-stop on M/C."

Have sent email to Tormach. We'll see where it goes from here.

[dkaustin]

Well, the problem appears to have been resolved. Replaced a blown fuse (FU3, 0.6A), and the machine is running normally. I have no idea how the machine with the old MCB continued to run with the blown fuse. Maybe someone with some electronic know-how can explain it.

Given my history with this machine, I'm not crowing just yet, but things look good.