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Messages - sungyeolyang

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1
Hi,
g76 is the standard lathe single point threading cycle.

It does not require a position capable lathe spindle but does require a very stable spindle speed. For instance if you 'dial' up 500rpm for lathe threading, it does
not matter particularly if its 450 rpm or 550rpm, but whatever it is it should stay there. So lets say you spindle is doing 525rpm and then it starts cutting a thread.
The Z axis will advance exactly 1mm per rotation or 8.75mm/sec  for a 1mm pitch thread....so the spindle must rotate at its assumed speed irrespective of the cutting load.
If the spindle slows down to 490 rpm as a result of the load then the Z axis must also slow down to 8.166mm/sec to maintain the same pitch.

All g76 capable spindles are fitted with at least an index pulse (that is one pulse per revolution), and some controllers will accept an index pulse and/or an encoder pulses of many pulse
per revolution. Mach uses the index pulse to calculate exactly how fast the spindle is going and when to start the Z axis travel so that multiple passes are synchronised on top of each other.
Mach will adjust itself to small variations in spindle speed.....but not by much. If you want to have good and accurate pitch control you NEED a spindle with a very stable rpm under load.

Note that this technique is a very common lathe operation and many tens of thousands of users make nicely accurate threads every day....but does have that requirement...ie stable spindle speed.

The technique that Katz has proposed is to have a POSITION controlled spindle, ie Step/Dir, and then you can program a rotational move, ie the spindle with a linear move, ie the Z axis.
This is how I do rigid tapping with my vertical mill. My tapping spindle is a servo motor and is position controlled, and so I can program a Gcode move of:

g1 z-10 c 3600 f14400
g1 z0 c 0 f14400

and the machine will rotate 10 revolutions (3600 degrees) while the z axis descends 10mm for a pitch of 1mm per revolution in about 15secs, whereon it will back out out the hole
by 10 revolutions and the Z axis rise by 10mm, again in 15 secs.

You can see that I do not require a g76 move, I'm relying on Mach being able to calculate a coordinated trajectory between a rotating axis and a linear axis.

This technique works fine....but note that it requires a powerful spindle, otherwise the lag of the spindle will screw up the synchronisation with the linear axis. In fact BOTH
threading techniques require a superbly powerful and stable spindle or the result will be crap.

This is the take-away that 'threading requires a very stable spindle speed......if you are trying to do lathe threading with a sub-standard spindle you will come a cropper bigtime!'

Craig


Thanks for the advice.

Here is my question.

I used an AC servo motor with good power of 3 kilowatts.
I thought it would allow for more precise control.

Installing an encoder in a general motor and

Controls expensive high-end AC servo motors and receives precise positioning pulses from the motor
to feed the motion board

I thought it would be better to use a high-end Ac servo motor.
It's a pretty expensive motor, and the output is quite high.

How can I fix this now?

My dream is to make great tap machining with my machine.

one more

Actually, I'm trying to make a lathe as a hobby.
There are no plans to machine steel or aluminum.

My goal is to process mostly acetal plastics.
So the spindle speed is steel. It won't be as slow as aluminum machining.

Since my goal is plastic processing, the power and capability of my 3 kilowatt AC servo spindle will be sufficient.

The problem is that it doesn't work.
I want to solve this problem.

Any ideas?

2
Hi,
g76 is the standard lathe single point threading cycle.

It does not require a position capable lathe spindle but does require a very stable spindle speed. For instance if you 'dial' up 500rpm for lathe threading, it does
not matter particularly if its 450 rpm or 550rpm, but whatever it is it should stay there. So lets say you spindle is doing 525rpm and then it starts cutting a thread.
The Z axis will advance exactly 1mm per rotation or 8.75mm/sec  for a 1mm pitch thread....so the spindle must rotate at its assumed speed irrespective of the cutting load.
If the spindle slows down to 490 rpm as a result of the load then the Z axis must also slow down to 8.166mm/sec to maintain the same pitch.

All g76 capable spindles are fitted with at least an index pulse (that is one pulse per revolution), and some controllers will accept an index pulse and/or an encoder pulses of many pulse
per revolution. Mach uses the index pulse to calculate exactly how fast the spindle is going and when to start the Z axis travel so that multiple passes are synchronised on top of each other.
Mach will adjust itself to small variations in spindle speed.....but not by much. If you want to have good and accurate pitch control you NEED a spindle with a very stable rpm under load.

Note that this technique is a very common lathe operation and many tens of thousands of users make nicely accurate threads every day....but does have that requirement...ie stable spindle speed.

The technique that Katz has proposed is to have a POSITION controlled spindle, ie Step/Dir, and then you can program a rotational move, ie the spindle with a linear move, ie the Z axis.
This is how I do rigid tapping with my vertical mill. My tapping spindle is a servo motor and is position controlled, and so I can program a Gcode move of:

g1 z-10 c 3600 f14400
g1 z0 c 0 f14400

and the machine will rotate 10 revolutions (3600 degrees) while the z axis descends 10mm for a pitch of 1mm per revolution in about 15secs, whereon it will back out out the hole
by 10 revolutions and the Z axis rise by 10mm, again in 15 secs.

You can see that I do not require a g76 move, I'm relying on Mach being able to calculate a coordinated trajectory between a rotating axis and a linear axis.

This technique works fine....but note that it requires a powerful spindle, otherwise the lag of the spindle will screw up the synchronisation with the linear axis. In fact BOTH
threading techniques require a superbly powerful and stable spindle or the result will be crap.

This is the take-away that 'threading requires a very stable spindle speed......if you are trying to do lathe threading with a sub-standard spindle you will come a cropper bigtime!'

Craig


Thanks for the advice.

Here is my question.

I used an AC servo motor with good power of 3 kilowatts.
I thought it would allow for more precise control.

Installing an encoder in a general motor and

Controls expensive high-end AC servo motors and receives precise positioning pulses from the motor
to feed the motion board

I thought it would be better to use a high-end Ac servo motor.
It's a pretty expensive motor, and the output is quite high.

How can I fix this now?

My dream is to make great tap machining with my machine.

3
So I bet you are using step and direction to control you spindle motor . The documentation for the smooth stepper says you can but it also states that there could be issues with threading .

Right. I'm using a step, direction control spindle


Does anyone have any experience?
Successful tap machining in smooth stepper?

4
This is a lathe machine question using Mach 4 and smooth stepper.
Using the G76 command, there is a problem with the tapping operation.
The same is true for working with the job wizard.



The spindle starts rotating fine, but soon, it barely rotates, and neither the X-axis nor the Z-axis moves.

The spindle uses an AC servo spindle, and if you check the Smooth Stepper Diagnosis, the RPM is reported correctly.
The screen also displays the RPM correctly.

I currently set it to output 500 pulses per rotation.


Commands like M3 S1000 etc also work very well and have no issues at all.
There are no problems with other machining, but   tapping operations is problems.

We have prepared a YouTube video below.
What am I missing?

--G76 operation problem video--
https://youtu.be/VjyVQ6coxfQ
https://youtu.be/EnKnQ2SQlc0
------------------------------------

--Automatic turret tool change head test video--
https://youtu.be/wspTNS7x5Ns

5
Mach4 General Discussion / Spindle setting on lathe machine
« on: September 12, 2022, 07:16:39 AM »
My system looks like this:

Controller: Smooth Stepper

BOB board: CNC4PC

Spindle motor: AC servo spindle (Panasonic)

Spindle control method: Step and Dir control method (step motor control method)

Problem: Working with Threads





My spindle amplifier outputs 2500 pulses per revolution.

Input 2500 to Encoder Prescaler and 3 to Effective PPR to use.

(Smooth stepper spindle setting)

With this setting, the actual RPM will appear exactly on the screen of Mach 4.
( True Rpm )

Create a new job in machMotion Threding Cycle and enter basic values

Xi = 20 , Zi =0

Zf =-20

With this setup and start up, the spindle RPM's are almost low, and they don't appear to move at all.

(It's running, something is moving very slowly, but it doesn't seem to work at all)

What am I missing?

Normal machining is working without problems.
Threading is a problem



6
Mach4 General Discussion / A question about lathe machines.
« on: September 05, 2022, 08:57:02 AM »
I suddenly made a lathe machine one day.
Make it easy, connect the electrical wiring, and ask questions while preparing for operation


I'm confused about not being able to initialize the x-axis to zero.

If I was going to process a 20mm round bar and installed a 30mm material, would I need an input of 30mm somewhere?


I entered the tool offset for the tool.

If so, is the offset automatically determined according to the tool when the tool is used?

For example, if the tool is 10mm from the center,
When I command G00 X30, in the case of tool 0, it automatically moves to 20mm and
will proceed with the work?

Sorry. I'm new to lathe machine, so I want to understand the concept.

7
hello

I found a new problem while processing probing
Change tool manually, do G31 probing each time.

  If the length of the tool is adjusted to the long case, it does not take much time to reach the touch plate.


If I'm using a short tool, if I feed it low with g31 code up to the touchplate, it takes a long time.

As usual, move the touch plate quickly to touch and
Move back again, slowly touch the touch plate and
I want to complete probing

Any ideas?

8
Can I see a picture of the ATC in action with this script?

I'm curious to see a picture of the device that works with this script

Sorry, it has been a while.  But here is the m6 from the mill I have been working on.

9
thank you ^^

Thanks again for your kindness.
It will be of great help.

Sorry, it has been a while.  But here is the m6 from the mill I have been working on.

10
Thanks for the advice.

Is there any link or data I can refer to? (anything)
Can you share your M6 script?

My mail is ysy9999@gmail.com.
Thank you again.

when i start with pokeys  (about 4 years ago) we have many issues with noise ,more with there plugin for the realys cards
at beginning it was real big head ace for us(output was turn on without any command) and they blame...noise.. etc,..
but when they understand we not play games ,they take the problem in there hands improve plug in ,and after several software updates
i can tell you ,about 2-3 years many many cards "0" problems
no noise ,nothing
so this stable issue its real not point for me
about write the plc , i think that if you have some experience ( not much)with write code ,its very easy and much powerful then some patterns that some one build for you(like ladder) but this my opinion maybe some one else think something else
one more point very important for us its  remote control ,with windows software its very easy control and debug far customer
if you want i can send you link to see our ATC ( we have all typs,linear ,linear under gantry, carousel by toth wheel and carousel by servo)
also drill block with many drill inside
yaakov

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