Tormach PCNC 1100 Spindle Question #3 (VFD Settings???)

[CNC-Dude]

Hi Tormacheers,

With the help from many of you, I have been able to beat the darned challenge which is to service a spindle. I am having a hard time believing it myself! But it appears to be working fine, so I am practically set!

Except that before I can hang that apron I have noticed an intriguing reality. This machine's spindle operates at 2X the speed. In other words, if I command to go to 250 RPM, I measure 500 RPM.

I know the belt is positioned on the correct pulley setting and MACH 3 is configured accordingly.

It is my impression that whoever owned this machine before must have modified the VFD parameters so they could run the spindle at a higher rate (2X in this case). In fact, it makes sense the spindle was all messed up because I don't think something that has been designed to operate at 5000 RPM would behave equally well at 2X of that!

Anyway, here is my Question #3 video in case you want to watch it, but the question is quite simple: How do I revert the VFD to the original settings? Has anybody played with this before? I downloaded the VFD manual but that thing is over 100 pages long and it is going to be a while before I can magically decipher such a mess.

Thanks for any advice on this matter!




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[SCzEngrgGroup]

VFD speed is normally controlled by passing an analog voltage from the breakout board to the VFD, which defines the desired spindle speed as a function of maximum speed. This is typically a 5V or 10V signal. Assuming it's a 5V signal, 5V would be 5000 RPM 2.5V would be 2500 RPM, etc. There are configuration settings in the VFD that determine how that voltage is interpreted - what the min and max allowable voltages are, and what speeds they correspond to. You'll need the VFD manual, which defines the configuration settings, and how to access them through the front panel, to check whether the parameters are properly set.

The other method, less common, but perhaps used here, is an RS485 or Modbus connection between the PC and the VFD. A quick look at the VFD wiring should tell you which way the Tormach is controlled.

Regards,
Ray L.

[Hirudin]

Do both of your machines have the same VFD? If so, could you just compare the settings of your old machine to the settings on the new machine? Even if the two VFDs are the same model by appearance, I imagine they might have different firmware or something. So, if there are tons of different settings it probably wouldn't be wise to change every one. But if you go through and there's only one difference, and that difference is that one is set to 10,200 and the other is set to 5,100, I think you can be pretty sure you've found something you should change.

If it were my machine I might just go through the settings and see if there's only one set to anything like 10,000. If there's only one, I'd change it to 5,000 and see what happens. This might be a little more nonchalant than some people would like to be though.

...
Regarding the possibilities of different firmwares...
There will probably be a "setting" in there somewhere that will display the firmware version. This "setting" will, obviously, not be user-adjustable - that might be a good way to identify it.

...
I looked for the VFD manual on the Tormach site, but I couldn't find it. Since you have it though you could use it for reference. For instance, if you find something that's set to 10,000, you could look up that specific setting in the manual. If that setting is named something like "spindle max RPM", you've probably found the right one to change. If it's named something like "LCD contrast" you should probably move along.

...
One last thing... When I mess with things like this, things where I don't really know what I'm doing, I'll video-tape myself going through all the settings. This way, I can reference the recording if I need to put a setting back to the original value.

[CNC-Dude]

Hi Hirudin,

Thanks for your input! I have documented the "intriguing-ness" on this blog post: The CNC Dude I also placed a temporary copy of the SK Commander VFD manual for those interested in taking a look. I imagine I will have to erase this at some point in time.

Anyway, I did a comparison and that helped even less because the values make little sense. There is a parameter called the Scaling Factor where I was expecting to see a 2.0 on the second machine. However, they both have a 1.0. WEIRD!!!

Then there is only one value which is different, but not by a factor of 2. The manual says it is a User Configurable Parameter, so that doesn't help me to know what it does.

I am going to have to take a break on this one until I talk to Tormach. Maybe there is an easy way to bring the VFD to defaults. Luckily today is Monday! Odd that anybody would consider a Monday a lucky endeavor... heh heh heh

[kstrauss]

I seem to recall that the load meter kit (32096) comes with a USB stick to reprogram the spindle VFD. Perhaps the stick can be purchased as a spare part from Tormach?

I wouldn't expect to find a value such as 5100 or 10000 in the VFD settings that relates to spindle RPM. Consider that the VFD merely outputs 3-phase power at the appropriate *frequency* (combined with pulley ratios) to give the desired RPM. I don't believe that the VFD knows anything about the resultant RPM.

[Hirudin]

I've downloaded the manual; thanks for that.

Quick question: Is it a perfect 2x scale factor? You mentioned 250 and 500 RPM. Did you only mention those speeds to convey the message quickly, or do those happen to be the only ones you tried? What actual speed do you get when you put S2500 into Mach3 on the new (to you) machine?

If #65 is essentially the only setting with different values between the two VFDs, I'd try changing it on the new machine, at least a little, to see what happens. If 14.3 is what it's at now, what does it do when you set it to 14.2?

Sorry, if I had a Tormach I'd probably be willing to go change that value myself, but since I don't I can only speculate... perhaps that's more of a hindrance than it is help.

[CNC-Dude]

Hi Hirudin,

The 2X factor is present on all the speeds that I tried and it seems pretty perfect. At S2500 I get 5000 RPM by measuring with the tachometer. It is pretty evident there is a 2X factor across the border. The speeds I tried were 250, 500 and 2500 and I got 500, 1000 and 5000.

I have been told that address 65 specifies how many hours and minutes the motor has operated. This explains why the numbers are different but not a factor of 2. In that case, changing this number (if at all possible) will not change anything.

I am going to have to get a little bit more critical in comparing the two machines. Maybe there is a weird wiring going on? Anything is possible, I guess...

[tmarks11]

Well if you were getting unusual vibrations at a displayed value of 5000 rpm, but you were actually at 10000 rpm, I guess you just discovered the source of the vibrations.

Check out the following:
Parameter 1. Max motor freq. Should be 170 Hz.
Parameter 7. Motor speed. Should be 1715.

If the Max motor frequency was set to 340 Hz, than commanding 2500 rpm would actually get you 5000 rpm (which you saw).
I am not sure if parameter 7 could be related with the mismatch between commanded speed and actual speed.

The Commander has 18 layers of menus, but it is set up to only easily access the first layer (menu 0) from the keys on the VFD panel.

To get to the higher menu levels, you have to edit Parameter #10, Good luck, let me know how that goes. Have you checked these out?

Menu #1 has a frequency reference value
Menu #3 has a "frequency reference scaling"
Menu #7 has "analog input scaling" which changes how the 0-10V analog signal form the BOB is treated, which could mess with commanded speed.
Menu #21 is "alternate motor mapping"

It is very probable that Tormach has stuff set up there that is causing you problems. They don't seem keen on helping diy set up vfd's, probably because it is anything but intuitive.

Maybe the original owner upgraded the VFD to Series III by buying it from eBay rather than from Tormach, and you are left with what he messed with rather than the official setup?

One last thing: have you tried using the same PC on you "new" Tormach (that you are trying to fix) as on your old one? I was just wondering if there is any mach settings that could be causing a problem? Such as the settings for pulley diameters (low speed vs high speed mode).

VFD speed is normally controlled by passing an analog voltage from the breakout board to the VFD, which defines the desired spindle speed as a function of maximum speed. This is typically a 5V or 10V signal. ...The other method, less common, but perhaps used here, is an RS485 or Modbus connection between the PC and the VFD.

Tormach BOB provides a 0-10V analog signal on the VFD T2 terminal, which controls the speed.

[CNC-Dude]

Well guys, allow me to start by thanking you all for taking the time to try and help me with this intriguing occurrence, but I am going to have to plead utter moronicity on this one.

As it turns out, Tormach has a procedure which needs to be performed in order to tune the VFD with the computer. Had I done this step? HECK YEAH!!! Except that I was missing one dinky little detail...

As detailed by both the documentation and the Windows App, you are supposed to run the Spindle at S500 and read the VFD number being displayed inside of the cabinet. This number you will then enter within the PCNC CONFIG 4.4 app to modify the machine profile.

I had done this to the point of exhaustion and every single time I omitted the important detail which is that this test must be performed with the system configured in the slow gear. ERRRRRR!!!!! Biggest blunder ever!

Sure enough, as soon as I ran the CONFIG as intended, WHAMMO! Problem solved!

Moral of the story? Just because you have read the instructions many times before does not exonerate you from reading them again ;-)

Thanks to all for putting up with my blunder!

[tmarks11]

Sometimes it is the simple things that gets you. When I installed the PDB, somehow during the process, I allowed the belt to slip onto the slow speed pulleys. I started everything up, and the motor was turning so s l o w l y. I scratched my head, and spent a lot of time looking at the manual and the computer and the vfd... before the obvious hit me...