Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jaja on January 09, 2010, 04:44:48 PM
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Can't get proper true spindle reading,,, the DRO shows chaotic numbers
Situation:
Optical sensor (reflection type), two slots, wide enough
On input signals: Should I use index and timing????
Do they use the same pin?
On outputsignals: should i use Enable 1, or Output 1??????
I think this causes other problems like not being able to set the control ratio from the pulleys (the seem to live a life of there own).
Have been messing around for days and days now,,, I'm missing the basic vision behind this.
And without a good true spindle reading its not possible to do threading.
On all the other functions Mach is really fantastic and works great.
gr jaja
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I am not 100% sure but I think the Timing was done away with in later revisions of Mach due to the threading changes. It may be just for using whilst threading though so take that with a pinch of salt.
I am not sure what you mean by Optical sensor (reflection type), two slots, wide enough
as if using multiple slots there is meant to be one that is wider than the rest. Best thing to do is just have one slot and set it up as the Index input and it should be fine.
I have never set up a spindle with VFD (I use servos) but I would think the control ratio would be set on the Spindle Pulleys page (from Config menu) and that box you have shown above will just be to inform you what the ratio is rather than setting it.
Hood
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Ah Hood, nice of you to react, and so quickly again.
The optical sensor is one that sends light that reflects on a surface and than receives it again.
The settings done on the Spindle Pulleys page aren't remembered by the Calibrate Spindle page.
I don't know why.
I'm busy reading the 73 pages on the topic "Problems threading on the lathe", and tried to figure out if this can help me,, but,,, no success at this moment (page 37).
So I use the Index input,, but I do not use it as an index, more like a timer, I thought. And should it be on Emulated?
And which output should I choose? Enable 1, or 2 or 3? Or should I use Output 1 or 2,,,,,?
If I stop the spindle, the S true DRO still gives a number like 127, or 378.
Can't figure out how mach can see 378 revolutions when there is no signal from the optical sensor.
And as long as this is not oke, threading can't be done, I think.
gr jaja
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Ok first make sure you just have one reflective strip or one black part if the rest is reflective.
Next set that input up as the Index input, dont need emulated chosen as that is just for testing purposes so you can set a keyboard key up to emulate it.
You should then have good readings for your RPM, if you dont what Rev of Mach are you using?
Hood
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I'm using mach 3.042.033, but is just saw a later version on the Artsoft site.
Tomorrow morning i will configure it the way you explained.
thanks
jaja
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There have been a lot of issues lately with the most recent versions of Mach driver and some computers, most work fine but some dont. 035 is the best to try and if that doesnt help try going back to before 030 and see if that helps.
Art is working on trying to solve things for these problem computers so there may well be new updates in the following days/weeks so keep an eye out if you are still having problems.
Hood
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Hood,
It seems that the modern CPU's have variable frequenties (read it on the forum), that causes a lot of problems.
Perhaps this can be locked down on the motherboard-settings of my lathe computer, which has one of the latest CPU's.
gr jaja
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Could well be the problem but I am sure Art will get the driver sorted out :)
But give it a go anyway and see how you get on, your computer may be one of the ones its ok with.
Hood
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All of the 73 pages of info from that posting are rather summarised in the Threading on The Lathe writeup in Members Docs.
Timing is currently no longer functional. You only use index with single index slot,so disable the timing. The turn diagnostics is now outdated as of Rev 32 and 33. Do not enable the plug in until its fixed in the future. And don't use some of the other experimental plug ins you will find posted. Timing for threading is based on readng spindle rpm and
although haven't even tried 034 or 035, don't think the threading plug was fixed . Go to the last two or three pages of the Problems Threading on the Lathe thread as there may be info relative to you.
RICH
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When in manual mode, you give a S-DRO of 200, the spindle must turn at about this speed???
Seems a stupid question, but I can not get the spindle on another then maximum speed.
I think I'm the one who makes a stupid fault, but Ive been searching for it and cannot find it.
gr jaja
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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
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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
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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 ......
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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
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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
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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