problem pitch theards lathe

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24 Feb 2013 00:54 #30484 by jlviloria
hi all,

I was doing tests on my lathe thread NPT. but I have a problem.

The machine makes my thread good. wastes no pitch.

I'm doing an NPT 1 1/2 having a step of 11.5 threads per inch. in millimeters 2.208mm.

but my machine makes a thread as 16 threads per inch, do not understand that if you have good step in the program,

anyone can guide me may be happening and how I can fix this.

thanks

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24 Feb 2013 03:28 - 24 Feb 2013 03:36 #30496 by cncbasher
can you post your code as an attachment are you using G33 ?
Last edit: 24 Feb 2013 03:36 by cncbasher.

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24 Feb 2013 09:51 #30509 by joekline9
I Assume your using G33.
If you post your Gcode I can test it.

Have you tried cutting other threads using G76? Is the pitch correct?
Check that your encoder puts out the correct pulses per rev of the spindle.
The following user(s) said Thank You: jlviloria

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25 Feb 2013 13:14 #30546 by jlviloria
Friends clear'm using g33.

I'm not using ngcgui, because even not very well mastered

my program for the thread is as follows:



g33 x43.5 z-28 k2.208
etc

Check that your encoder puts out the correct pulses per rev of the spindle. how I check this?

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25 Feb 2013 15:12 #30547 by emcPT
Replied by emcPT on topic problem pitch theards lathe
Although I do not exactly did myself I think that you can use the halmeter to see the pulses counter. In fact I am currently adapting an encoder in my spindle and then after I also most do this procedure to see if I am receiving the correct signals.
You must know your encoder pulses per revolution and see if they match the value that linuxcnc receives. I think that linuxcnc will receive that as x4 more, since they are processed by quadrature.
Your index pulse should count once per turn.

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25 Feb 2013 18:59 #30552 by emcPT
Replied by emcPT on topic problem pitch theards lathe
I am now doing the same thing as you, so I can help.

Goto:

HAL Configuration
Select the hm2_5i20 (if you are using this mesa board)
Select the 0 (if you have one 5i20)
Select encoder
Select the encoder slot where you have the encoder connected to
In there you can see the counts, and so on regarding the encoder feedback

Filipe

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25 Feb 2013 21:42 #30560 by andypugh

HAL Configuration
Select the hm2_5i20 (if you are using this mesa board)
Select the 0 (if you have one 5i20)
Select encoder
Select the encoder slot where you have the encoder connected to
In there you can see the counts, and so on regarding the encoder feedback


It is best to add the signals you are interested in to the "Watch" tab as that updates automatically. The values in the other window are not visible live.

Sometimes it is more convenient to set up a number of Halmeters (also in the "machine" menu) as those take up less space on screen.

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26 Feb 2013 11:54 #30593 by jlviloria
I tried to solve the problem but I could not set the thread pitch is with all the threads. G76 and G33 have the same problem.

to do anything one thread with 2.208 mm. I got to putting on 3.072 mm.

I know I have a problem with the spindle encoder that is not configured correctly, but not to do. anyone have any advice on how to correct this problem

thanks

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26 Feb 2013 14:44 #30596 by emcPT
Replied by emcPT on topic problem pitch theards lathe
If you have a problem with the encoder, this problem should be reflected in all the threads, expecially the ones with a large step. Can you confirm this?
Also what type of encoder do you have?
Did you managed to see the correct values in halconfiguration?

My opinion is that if the encoder is working properly then you have an incorrect ppr set up in the encoder (depending on the encoder used - if you only have an index then it can't the the ppr set up).
As I told you before I am also working on this, and yesterday I was able to see that mine encoder is outputting the correct spindle speed to linuxcnc. To see this I made a mark on the spindle and putted working slowly. I started to count the turns and the time passing, then you can see if the encoder feedback matches what you expect.
Hope I helped, and do not trust all my words as I am still learning.

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26 Feb 2013 17:31 #30605 by andypugh

to do anything one thread with 2.208 mm. I got to putting on 3.072 mm.
I know I have a problem with the spindle encoder that is not configured correctly, but not to do. anyone have any advice on how to correct this problem


Open a halmeter and look at the encoder counts value for the spindle encoder.
Move the spindle to a position that you can accurately return to. (maybe with a chuck jaw resting on a block or something)
Make a note of the encoder.N.counts and encoder.N.position values.
Rotate the spindle by hand exactly 1 revolution. Note encoder.N.counts and encoder.N.position values.
Rotate another turn, note the encoder.N.counts and encoder.N.position values.
(repeat a few times).
Now rotate the spindle backwards, noting encoder.N.counts and encoder.N.position values every rotation.

Tell us the numbers you see here.

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