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IndustryArena Forum > Community Club House > General Off Topic Discussions > Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.
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  1. #1
    Join Date
    Jun 2016
    Posts
    2

    Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Hi
    I'm DIY CNC Lathe use BOB Mach3 Parrarel port

    I connect Proximity and config to index mach3

    I test run put parameter spindle 300 rpm, and Strue show about 303 - 307 rpm

    I try use wizards threading in mach3 turn, and export gcode this below

    G0 G40 G18 G80 G50 G90
    G00 X11
    G00 Z0
    G00 X10
    M03 S300
    G76 X8.5 Z-18 Q0 P1.5 J0.3 L0 H0.1 I0 C1 B0.025 T0
    M9
    M5
    M30


    Spindle 300 RPM
    Thread 1.5

    but when result part thread is about 2.0

    I try run code again I see in monitor I found number of mm per REV = 2.06

    how to fix it's for same gcode P1.5
    Sorry i'm newbie.

  2. #2
    Join Date
    Jun 2010
    Posts
    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Are you working in inches or millimetres?
    What metal are you cutting?

    Cheers
    Roger

  3. #3
    Join Date
    Jun 2016
    Posts
    2

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Hi mr.Roger
    I'm use in mm.
    I use matt is ss400


    Sent from my SM-G955F using Tapatalk

  4. #4
    Join Date
    Jun 2010
    Posts
    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    OK, known problem.
    When the tool hits the metal, the spindle is slowing down because of the load. On a geared lathe this does not matter, but on a small CNC lathe without gears and the spindle synchronising only on one pulse per rev, it does matter - hugely.
    You can try to use the PID controls in Mach3 if you are using a parallel port, but with only one pulse per rev ... no great joy.
    You could try making much smaller cuts so the spindle is not loaded as badly, but with SS, I have some doubts.
    Or you could use a geared lathe or a die.
    Sorry, but that's how it is.

    Cheers
    Roger

  5. #5
    Join Date
    Aug 2004
    Posts
    780

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    I don´t think the issue has anything to do with slowing down as rcaffin suggested.

    The thread looks fine, consistent, and thus the pitch is wrong.

    Does g1 move x and z accurately.
    E.
    Move 30 mm, and measure with calipers.

    Can you thread *anything* accurately in pitch ?

    A scratch test with 0.02 mm deep contact, one pass, should show if the tracking is wrong in pitch, or if spindle load affects it.
    A 0.02 mm deep cut has == zero spindle load.

    Your spindle rpm might be misread or "float" with rpm.
    This is common.
    Index pulse sensors are often soft and fuzzy in the signal.
    Thus they can report different rpms and varying lag delays at different rpms, or warm/cold lathe, or heavy chuck vs light chuck, etc.

    Single index pulses, when testing with custom microkernel and 533 Mhz tracking speed, proved to track a thread within 0.01 mm, even from 530 rpm one day to 450 rpm next morning with a cold lathe running slow due to cold oil.

  6. #6
    Join Date
    Jun 2010
    Posts
    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Yes, do a 'scratch' test with a tiny cut.

    Cheers
    Roger

  7. #7
    Join Date
    Feb 2018
    Posts
    2

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Hi.
    I'm trying to use a threading wizard in mach3 but i have a weird problem.
    no Mather what pitch i try to run, the g code run a different Z speed cutting the thread but the rights speed when the Z axis is retracting to the start position.
    Example:
    Spindle speed 300 RPM
    Thread 1.0 Z Axis is moving at 0.87 but retracting z speed = 1.0
    Thread 1.5 Z Axis is moving at 1.20 but retracting z speed = 1.5
    and i tried all i can find in internet about mach 3 wizard but nothing like this problem.
    i really appreciate if some buddy can help me i also can provide a video about this it.
    thanks

  8. #8
    Join Date
    Jun 2010
    Posts
    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Hi Pala

    Very simple: Mach3 SPIN controls the Z axis feed while threading. You can NOT control it. (Think about it.)
    The retract speed may be controlled by a prior setting.

    Threading is a bit strange anyhow, especially under Mach3. I suspect it was a late addition to what was originally intended for machining guitar bodies. But then, it was a bit strange in the NIST definitions, because they came from a committee of rival vendors.

    There are some docs on the Artsoft website about threading.

    Cheers
    Roger

  9. #9
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    Jun 2010
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    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    You do not have this problem with a manual lathe because there is a geared connection between the spindle and the Z axis. End of story.

    Are you using an ESS? Do you have an encoder on the spindle motor, or just a single 'tooth' for the Index signal?

    Cheers

  10. #10
    Join Date
    Feb 2018
    Posts
    2

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Quote Originally Posted by RCaffin View Post
    You do not have this problem with a manual lathe because there is a geared connection between the spindle and the Z axis. End of story.

    Are you using an ESS? Do you have an encoder on the spindle motor, or just a single 'tooth' for the Index signal?

    Cheers
    (Mach3 thread wizard)

    I'm using a infrared sensor for index signal.
    I also compare the rpm read by mach3 vs a mechanical rpm tester and both are the same +- 2 rpm in (300)

    my average rpm over (300 rpm) don't chance more than 3 rpm.
    the thread always start in the same place no problem.
    but the pitch never match whit the DRO indicator.
    look like the thread wizard has a bug

  11. #11
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    Jun 2010
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    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Read the docs on the Artsoft web site about threading. Do a single-pass scratch test and measure that.

    If what you have is a small lathe with a small motor, you cannot get a steel thread anywhere near spec without an ESS AND the latest ESS driver AND an encoder on the spindle. As soon as the tool tip touches the steel it will slow the motor down, changing the pitch. This is by now quite well-known and expected.

    Cheers
    Roger

  12. #12
    Join Date
    Jan 2005
    Posts
    15362

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Quote Originally Posted by RCaffin View Post
    Read the docs on the Artsoft web site about threading. Do a single-pass scratch test and measure that.

    If what you have is a small lathe with a small motor, you cannot get a steel thread anywhere near spec without an ESS AND the latest ESS driver AND an encoder on the spindle. As soon as the tool tip touches the steel it will slow the motor down, changing the pitch. This is by now quite well-known and expected.

    Cheers
    Roger
    That is not correct, there are lots of users that have been using Mach3 Lathe for threading for years without any problems

    If the spindle slows down so does the Z axes to match the set pitch, you can even move the chuck by hand and the Z axis will follow

    I would say they don't have something setup correctly, the steps per have to be correct, that would be a good starting point

    They should also try with the Mach3 Thread wizard

    https://www.youtube.com/watch?v=MaH_Nlh4sxk&t=3s

    https://www.youtube.com/watch?v=B0aoQ4iJzf0
    Mactec54

  13. #13
    Join Date
    Jan 2005
    Posts
    15362

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Quote Originally Posted by abdulasis View Post
    Hi
    I'm DIY CNC Lathe use BOB Mach3 Parrarel port

    I connect Proximity and config to index mach3

    I test run put parameter spindle 300 rpm, and Strue show about 303 - 307 rpm

    I try use wizards threading in mach3 turn, and export gcode this below

    G0 G40 G18 G80 G50 G90
    G00 X11
    G00 Z0
    G00 X10
    M03 S300
    G76 X8.5 Z-18 Q0 P1.5 J0.3 L0 H0.1 I0 C1 B0.025 T0
    M9
    M5
    M30


    Spindle 300 RPM
    Thread 1.5

    but when result part thread is about 2.0

    I try run code again I see in monitor I found number of mm per REV = 2.06

    how to fix it's for same gcode P1.5
    Sorry i'm newbie.
    Your G76 is incorrect
    Mactec54

  14. #14
    Join Date
    Jan 2005
    Posts
    15362

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Quote Originally Posted by abdulasis View Post
    Hi
    I'm DIY CNC Lathe use BOB Mach3 Parrarel port

    I connect Proximity and config to index mach3

    I test run put parameter spindle 300 rpm, and Strue show about 303 - 307 rpm

    I try use wizards threading in mach3 turn, and export gcode this below

    G0 G40 G18 G80 G50 G90
    G00 X11
    G00 Z0
    G00 X10
    M03 S300
    G76 X8.5 Z-18 Q0 P1.5 J0.3 L0 H0.1 I0 C1 B0.025 T0
    M9
    M5
    M30


    Spindle 300 RPM
    Thread 1.5

    but when result part thread is about 2.0

    I try run code again I see in monitor I found number of mm per REV = 2.06

    how to fix it's for same gcode P1.5
    Sorry i'm newbie.
    What is the diameter of your part
    Mactec54

  15. #15
    Join Date
    Jun 2010
    Posts
    4252

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    there are lots of users that have been using Mach3 Lathe for threading for years without any problems
    True I am sure. I had no problems with low diameter aluminium and plastic, as the motor and solid chuck had enough guts to handle them.
    It's when the diameter goes up or you switch to steel that the torque required starts to worry the motor.

    If the spindle slows down so does the Z axes to match the set pitch, you can even move the chuck by hand and the Z axis will follow
    Ah ... if the Z axis is actually geared to the spindle, yes to the second part. But with most CNC lathes this does not happen. After all, why should it?
    The first part can happen if you are running an ESS with the latest driver and an encoder on the spindle/motor. But this is a function NOT of Mach3 but of the ESS itself. That is, the sync is done entirely by the ESS as Mach3 does not know anything about it.

    In more detail: Mach3 does sense the Index pulse and get the RPM from that, but it can only update the spindle drive once per revolution. If it is doing speed averaging it may not be even that fast. So the spindle can slow right down for a long way before Mach3 even knows about it. This can also be seen by the loss of thread-profile: the machined gap between threads gets wider. There are a couple of Forum threads on this on the Warp9 web site, some of them between Andy of Warp9 and me.

    Cheers
    Roger

  16. #16
    Join Date
    Jan 2005
    Posts
    15362

    Re: Mach3 Function wizards Lathe threading REV 1.17 Problem . Help me please.

    Quote Originally Posted by RCaffin View Post
    there are lots of users that have been using Mach3 Lathe for threading for years without any problems
    True I am sure. I had no problems with low diameter aluminium and plastic, as the motor and solid chuck had enough guts to handle them.
    It's when the diameter goes up or you switch to steel that the torque required starts to worry the motor.

    If the spindle slows down so does the Z axes to match the set pitch, you can even move the chuck by hand and the Z axis will follow
    Ah ... if the Z axis is actually geared to the spindle, yes to the second part. But with most CNC lathes this does not happen. After all, why should it?
    The first part can happen if you are running an ESS with the latest driver and an encoder on the spindle/motor. But this is a function NOT of Mach3 but of the ESS itself. That is, the sync is done entirely by the ESS as Mach3 does not know anything about it.

    In more detail: Mach3 does sense the Index pulse and get the RPM from that, but it can only update the spindle drive once per revolution. If it is doing speed averaging it may not be even that fast. So the spindle can slow right down for a long way before Mach3 even knows about it. This can also be seen by the loss of thread-profile: the machined gap between threads gets wider. There are a couple of Forum threads on this on the Warp9 web site, some of them between Andy of Warp9 and me.

    Cheers
    Roger
    I used to do it without an ESS so this is not needed, you can not cut a thread unless the spindle and Z axis is electronically geared which is what happens, I even had it doing rigid tapping with my milling machine, Mach3 can use an Encoder for this also which I used 1024 and it reads it just fine

    Any way that is not what his problem is his G-Code is completely wrong so there is not way it can cut a 1.5mm Pitch thread like it is programed
    Mactec54

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