Threading on a Boxford TCL lathe

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17 May 2021 10:34 #209209 by john11668
Thanks for the above Andy

Spindle index shows false once per rev as notch passes the sensor.

Spindle revs increases by 2 . for every rev ( whether clockwise or A/C)
So what do I need to do to correct this .

WRT the error message :-
I have an amendment in my postgui hal file which prompts manual tool changes. The error message seems to appear if I have forgotten to hash out the manual tool change instructions in the Hal file .

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17 May 2021 11:23 #209211 by andypugh
[quote="john11668" post=209209
Spindle revs increases by 2 . for every rev ( whether clockwise or A/C)
So what do I need to do to correct this .[/quote]

Change the encoder scale. This is probably pulled in to the HAL from the INI. Look in the HAL first, and see what number is assigned to encoder.0.scale. If it is a number, double it. If it is something like [SPINDLE_0]SCALE then look in the INI for the matching entry and double that.

I have forgotten if you have full A / B quadrature set up? If you do then the spindle pos should decrease in the reverse direction.
If you have full quadrature then make sure than encoder.0.counter-mode is set to zero. (this might require the scale to change again)


The error message seems to appear if I have forgotten to hash out the manual tool change instructions in the Hal file .

If you try to link something already linked then you will be informed of the difficulty.
You can add "unlink" commands in the later-executing HAL files to alter things that have already been made, if that is more convenient.
The following user(s) said Thank You: john11668

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18 May 2021 08:21 - 18 May 2021 08:23 #209314 by john11668
Increased Encoder scale number from 50 to 100 and it is now increasing by one on each completed rev
Still does not execute a G76 canned cycle though

Full A/B quadrature ?
I am only at this stage using two sensors ( Set for index and A)

"If you try to link something already linked then you will be informed of the difficulty.
You can add "unlink" commands in the later-executing HAL files to alter things that have already been made, if that is more convenient."

Can you spell out to me what I need to do please, in order to avoid the need to hash out these parts of the Hal file each time I make a change to my configuration
Last edit: 18 May 2021 08:23 by john11668.

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18 May 2021 10:12 #209324 by andypugh
I don't really understand why you keep having to change anything back.
Do you keep running the config wizard?
At some point it is time to stop using the wizard and start editing your HAL and INI directly.

The system runs the HAL files in sequence. You can "undo" something done in a previous HAL file in a later HAL file, if you want.
Though generally it is better just to not do the thing that you don't want in the first place.

"unlinkp" can be used to remove an individual pin from a net.
"delsig" can be used to delete a net and unlink all the pins in the net.

linuxcnc.org/docs/2.8/html/man/man1/halcmd.1.html
lists the commands that can be used in a HAL file (or in a live hal session)

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18 May 2021 10:50 - 18 May 2021 10:52 #209330 by john11668

I don't really understand why you keep having to change anything back.
Do you keep running the config wizard?
At some point it is time to stop using the wizard and start editing your HAL and INI directly.


The simple answer Andy is that I am a total novice taking my initial steps , having been encouraged into linuxcnc on another forum.
And whilst the stepconfig process is simple no-one has yet instructed me on the parameters in the hal files to edit and what to edit them to.
I am also having to learn a new language as the terminology and the words you guys use in Linux are often new to me, and the meanings of words employed in linux are seldom the same as plain English.

I am getting there albeit step by step.


So going back to the problem I now have a correct setting showing in Hal meter for my spindle revs , Can you possibly suggest where I should go next to get a threading canned cycle running.?

Thanks john
Last edit: 18 May 2021 10:52 by john11668.

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18 May 2021 10:57 #209333 by andypugh
It should now just work if you start the spindle and type a G76 command in the MDI window.

1) Make sure that the Z = 0 position is clear of the chuck
2) Do this without a workpiece first.
3) Jog to Z = 50, X = 7 (I am assuming a metric config)
4) Go to the MDI window and type

M3 S200
G76 P1 I-1 J0.25 K1 Z0

And let us know what, if anything, happens. It should machine an M6 air thread.

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18 May 2021 21:14 #209411 by john11668
Spindle starts! onscreen scale says 450. mechanical tacho says 400 (as near as I can read it
Change spindle command to S100 revs on both come down to 300

Tool Moves to X 5.75
And then just sits there No sign of any traverse in Z
I cant find a spindle speed which will permit the threading traverses to commence

Clearly there is a major discrepancy between spindle speeds called for . and speeds achieved .

There is a 2/1 speed switch on my DC motor controller
Tried both positions

In position 1 I call for 400 and I get 200
In position 2 I call for 400 and I get 650

Just cant find a speed at which cycle will start
looks like it takes the first step and reduces Diameter reading
Just wont make the first traverse in Z

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18 May 2021 22:24 #209419 by andypugh

And then just sits there No sign of any traverse in Z
I cant find a spindle speed which will permit the threading traverses to commence


Three things can cause this:

1) spindle.0.at-speed is not going true (check with halmeter)
2) spindle.0.revs is running backwards (should be increasing, halmeter again)
3) spindle.0.index-enable is not being reset by the index pulse (once again, halmeter)

There is another possibility, that the required traverse speed is too high for the Z axis, but that seems unlikely at mm pitch. Of course if it is 1 inch pitch because G20 is active?

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18 May 2021 22:26 - 18 May 2021 22:27 #209420 by andypugh

2) spindle.0.revs is running backwards (should be increasing, halmeter again)


Actually... Maybe not. The 160TCL is a back-toolpost lathe, isn't it? I don't actually know what the right setup is for back-toolpost. It probably depends on whether you choose an inverted tool or left-to-right threading.
Last edit: 18 May 2021 22:27 by andypugh.

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18 May 2021 23:22 #209422 by john11668
It is a slant bed but I am using the tool in front of the work and spindle is running counterclockwise . But hal meter is increasing (only using index and A in the config so increasing in both directions) . Traverse speed is fine unless as you say it is looking for 1 inch per rev. Will call up G21 to be sure

Will look at the Hal meter readings for 1,2,3

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