Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: ljd10 on July 12, 2012, 08:14:39 AM

Title: lathe threading
Post by: ljd10 on July 12, 2012, 08:14:39 AM

I have been reading posts on lathe threading. my question is has any body been able to "trouble free" cut threads consistently on the mach lathe setup?
I haven't been able to find a positive answer to that.
thankyou

Title: Re: lathe threading
Post by: Hood on July 12, 2012, 08:29:24 AM

Yes. thread all the time, anything from 10mm long to 900mm long. 3mm dia to 100mm dia. 0.5mm pitch to 4mm pitch
Hood

Title: Re: lathe threading
Post by: Hood on July 12, 2012, 11:08:31 AM

Some pics of threads I have done.

Title: Re: lathe threading
Post by: Hood on July 12, 2012, 11:14:47 AM

Some more

Title: Re: lathe threading
Post by: Hood on July 12, 2012, 11:18:31 AM

And another but have done loads more that I dont have pics for, or may have some place  ;).

Title: Re: lathe threading
Post by: RICH on July 12, 2012, 12:18:17 PM

Yep, threading works fine. CNC threading will spoil you...!
RICH

Title: Re: lathe threading
Post by: ljd10 on July 12, 2012, 04:31:59 PM

well thanks for the come back. the problems are all posted on here but it is nice to read positive stuff too.
I guess I will be trying threading on the lathe. 

Title: Re: lathe threading
Post by: RICH on July 12, 2012, 04:42:24 PM

You may want to brouse thourgh the Threading on The Lathe write up in members docs.
RICH

Title: Re: lathe threading
Post by: Rhonmac on October 21, 2012, 11:17:09 AM

Hood, you seem to have threading sorted. Can i ask you what spindle sensor setup you are using/
Thanks,Reg

Title: Re: lathe threading
Post by: Hood on October 21, 2012, 01:24:26 PM

I now use a SmoothStepper so can use the Index pulse of the encoder on my spindle motor. Previously when I used the parallel port I used an Optek OPB916B or 917B

Hood

Title: Re: lathe threading
Post by: Rhonmac on October 22, 2012, 04:23:45 AM

thanks Hood,
i just started building a controller using Smooth stepper and will use cnc4pc index pulse card and their C25 smooth stepper terminal board hope i can get results like you have. Just one more question, how many pulses/rev are you using from the spindle sensor?

Thanks,
Reg

Title: Re: lathe threading
Post by: Hood on October 22, 2012, 04:41:04 AM

You can only have one pulse per rev with Mach when using the parallel port, the Timing is no longer an option. As you are using the Smoothstepper I now believe that it can support multiple ppr but I have only ever used one.
Hood

Title: Re: lathe threading
Post by: tripleblack on October 22, 2012, 12:20:20 PM

Hood, did you have to modify the index pulse , as in a pulse stretcher with the smoothstepper?

Title: Re: lathe threading
Post by: Hood on October 22, 2012, 03:31:27 PM

No, the SmoothStepper can see the  short pulse from an encoders Index no problem.
Hood

Title: Re: lathe threading
Post by: Len-Tikular on April 01, 2015, 05:17:46 AM

Hood, I'm contemplating going down the Smooth Stepper route and may buy the USB version.
What other boards are available as Break out and Spindle control.
I see that CNC4PC have a terminal board that plugs directly onto the Smooth stepper.

George

Title: Re: lathe threading
Post by: Axle on April 01, 2015, 10:58:03 PM

 Thanks Ron Rich and Hood for the response I think I may have explained the threading problem wrong all works wonderful in NSF turn and all works well in threading for 3 to 4 passes then all of a sudden it stops thinks a minute and moves to a new location then starts cutting a new thread in the air it does match up with DRO where ever it stops I did notice today that the RPM fluctuates when it decides to do this I have checked pulse signal and it is working on the board and in mach diagnostics what can make it change its mind in the middle of a thread I read in forum someone edited the G76 macro changed the test False to True can someone explain how and where to do this I am up for any thing.I read Hood you were going to switch to USB is this because of the signal speed and do you think I should..       Thanks Everyone       Axle.

Title: Re: lathe threading
Post by: RICH on April 02, 2015, 05:55:18 AM

Axle,
See page 47 in Threading on The Lathe  write-up for how to change the M0176 macro. Just provides option to how the code is posted ie; G32 or G76.  Using the G32 will alow easier monitoring of the threading passes. Using g32 or g76
will not fix your problem.

Read the write-up as there are a number of things that account for having problems with threading.
- Mach Version
- Computer Pulse frequency
- Spindle slowdown / Inadequate motor power
- Exceeding axis velocity and acceleration settings for thread to be done
- etc , etc all in the write up

RICH

Title: Re: lathe threading
Post by: natefoerg on April 02, 2015, 03:45:03 PM

I had endless problems threading with a SS and mach 3 till I changed the debounce settings for my spindle index pulse input in the SS settings area.



Been cutting perfect threads ever since.

I would have it run several passes just fine then it would just screw up somewhere, and then attempt to reset itself and it was never right... adjusted the debounce, Voila! fixed.

Chased this problem intermitently for 2 years. drove me nuts.

Title: Re: lathe threading
Post by: Toymanf on April 04, 2015, 04:11:41 PM

Hello Natefoerg,
Can you possibly be more specific regarding the changes you made on debounce setting. Do you remember if you increased or decreased?
Perhaps you could share the current setting that works for you and type of spindle sensor.
Looking to try threading soon and would really like to avoid the "Chased this problem intermittently for 2 years. drove me nuts" part.
Thanks,
Frank