Just from keeping up  on threadng, seems ver 033 is still the one to use for threading and you want to use spindle index as that is reading true rpm of the spindle.
now from memory .......
- there was a problem with some pc bus speeds which could cause problems and that was fixed with a later version ....but it realy didn't fix it  when an update was posted....

- i recently glanced through a posting on variable speed drives on the Yahoo site and ART made a whole bunch of comments about them...what i remember is that the VFD speed control could be fighting the program threading control ( based on rpm ) and the feed rate gets screwy for lack of better words. It was posted in the last week

So i am thinking that you want to set the spindle speed, that you want for threading, let the rpm vary if that is the case with you motor, and let the threading cylce do it's job varying the feed rate when it sees in a fluctuating spindle speed. 

Sorry i sound wishy wash and could be all goofed up on this, as i don't have a VFD or spindle speed control on mine. Maybe someone can chime in to give you more experience on the motor control side as it relates to threading.

RICH

Rich,
Thanks a lot for your reaction!

But there are two different problems: 1 threading goes wrong at about the sixth pass
                                                     2 the spindle motor is not controlled by mach at all, it only runs full speed

The treading is done without the VFD controlled by mach,,, it was controlled by a simple trim-pot. I did it this way to keep things simple and clear.
I never succeeded in mach controlling the spindle speed,, so I was (and still am) wondering if it was mend the be controlled by mach in the manual mode.

The last version of mach is probably better in threading.
Perhaps I will test mach with a very old computer to see if it works better.

gr jaja

jaja,
- What rpm do you have the spindle set at? When you use the threading wizard for your code, did you click the "Calc the number of passes" button? When it clcs, it will tell if your axis settings have the capability to thread at the inputed rpm. If you get a warning then you need to lower the rpm or increase the accel and velocity of the axis.

- How stable is your rpm? The more stable the better.ie; one or two rpm varying ok
- Don't thread, but do the tests i talk about in the manual.If you can't scribe a single line then no use trying to actualy cut a thread. Just saves you time.
- make sure all configurations is correct

What went wrong on the sixth pass?
RICH

I am thiking your running at 1750 rpm and that is fast for threading ......

 

Rich,

The spindle speed was set at different values,, and none gave a good thread,, they all did not follow the previous path, but cut on the place where the top of the thread should be.
When i was threading the VFD was not connected to the PWM signal of mach! The spindle speed was set by hand by a trim-pot. The last attempts were done at a spindle speed of 200, and this number stayed stable!

Do you think it is something in the program? Or is it the variable frequentie of the cpu in the computer?

Where is the manual you mentioned before?
"If you can't scribe a single line then no use trying to actually cut a thread."  I don't know what you mean with this. I use the wizard in mach. Scribe a line???
I sometimes connect some wizzards into one single action, but I do not scirbe them myself

gr jaja

Here is the link to the manual.
http://www.machsupport.com/forum/index.php/topic,13017.0.html

I don't know what you mean with this

See section 3.6 in the write up. What you do is just have very shallow depth of cuts ( .0002" ), and instead of cutting the thread, the tool  will just scribe a lines around the piece.

Make sure your config is correct see figure 7.1.2

RICH

Rich,, thanks again,

scribe a line,,, hahahahaha lol  that's what you get when using a strange language,,, sorry for this.

I'll print the manual and read it on every spare minute I have and then I'll charge the lathe again.

Thanks a lot, your help is much appreciated.

gr jaja