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Author Topic: Index pulse in Lathe  (Read 9453 times)

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Index pulse in Lathe
« on: April 18, 2011, 01:08:50 PM »
Hi all,

I am testing my lathe with threading.  My index pulse is generated by the machine original encoder.  The signal is fed to a bb board where it is supposed to be properly conditioned and then on to Mach.  The RPM reading seems to be accurate and stable.  But when I do threading the thread cut is not repeating its trayectory.  I have used both the G76 cycle and G32.  Any ideas what could be going on?

The fact that there is a an RPM reading makes me think the signal is o.k.  My threading is all within max feed limits.

Thanks,

Jorge
Re: Index pulse in Lathe
« Reply #1 on: April 18, 2011, 07:01:36 PM »
On the ports and pins under spindle have you check to use spindle sync?
Re: Index pulse in Lathe
« Reply #2 on: April 18, 2011, 08:56:21 PM »
Yes I did and still having trouble.  Could there any reason why the RPMs read o.k. and the thread trayectory is random?  The pitch seems to be o.k.

Thanks,
Re: Index pulse in Lathe
« Reply #3 on: April 18, 2011, 10:01:42 PM »
I agree, if the RPM reading good and steady you ought to have a good trigger.

What Mach version are you using? Par port or SS?. There have recently been a LOT of work and changes made to the driver code for threading- see mostly the Yahoo group for lots of detail. If you are runing anythng less than the latest version you are wasting your time.
Re: Index pulse in Lathe
« Reply #4 on: April 18, 2011, 10:13:29 PM »
Running Version 3.042.029

I am observing that the index pulse signal goes on and off with an unstable frequency.  I do not know if this has any meaning. How should it behave.  Should it be constantly on?

Thanks,

Offline RICH

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Re: Index pulse in Lathe
« Reply #5 on: April 18, 2011, 10:13:34 PM »
You should be using  Mach3 version 3.042.32 and above and if not upgrade.
I assume the encoder is only giving you 1 pulse per revolution....ie; same as if you were using a single slotted disc. Multi slotted
discs or encoders are not supported for threading and will not provide for greater accuracy even if they were.
Are you providing for 3 to 5 pitch lengths to allow the Z to accelerate to desired speed?
Do you have any backlash?
Is the rpm fluctuating or the spindle slowing down when cutting the thread?
You may want to have a look at the Threading on The Lathe write up located in Members Docs.
Do a scribe test.
RICH

Offline RICH

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Re: Index pulse in Lathe
« Reply #6 on: April 18, 2011, 10:15:15 PM »
Upgrade your Mach Version and the problem should go away. 
Let us know how things go.
RICH
Re: Index pulse in Lathe
« Reply #7 on: April 19, 2011, 12:52:11 AM »
Rich, I got a very rigid and accurate machine.  The control is on an Emco CNC lathe that is in very good mechanical condition. It has a repeatibility of 0.005mm or less. From this post and other posts on the subject it seems as the problem is clearly related to the Mach version I am using.

Questions. 

1. If I upgrade (meaning I install a new version).  Which is the best way to configure the new version.  I have spent a lot of time configuring the existing version (including modbus communication) motor tunning etc.. Are there configurations files I can save and then transfer on to the new version?

2. If my existing version is licensed, how do I make the new version licensed.  The downloads which I find are demo versions.

3. Will any upgrade above 3.042.32 work? The latest one seems to be 3.043.022.  Is this the one I should download?

Thanks,


Jorge

Offline Chaoticone

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Re: Index pulse in Lathe
« Reply #8 on: April 19, 2011, 04:55:52 AM »
Jorge, It is allways  good idea to save a copy of your XML, and any of these you may have that are custom: Macros, Brains, PlugIns Screen sets and related bitmaps.  I also save a copy of my *****Lic.dat (licenses)files. All of these can be found in your Mach3 folder.

When you update Mach will recognize your licenses.

In the downloads link above, Mach and Lazycam, under the lockdown version you will see the development version.

Bret
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline RICH

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Re: Index pulse in Lathe
« Reply #9 on: April 19, 2011, 06:13:08 AM »
I have not tested every version above 3.042.32 but have not seen any reports of threading problems above 3.042.33.
So anything above them should work.
RICH