gear hobbing maschine-electronic gearing ?
30 Sep 2016 21:02 #81120
by viski
gear hobbing maschine-electronic gearing ? was created by viski
Hello!
I am thinking to upgrade existing mascine from mehanical gearing to electrical but , would be linux CNC able to do that?
How machine works :
Maschine Diferential is 12 . So , if i want to make 18 teeth i have to calculate gears a, b, c, d or a and d. a is master and d is slave.
soo.. 12/18 is 0,666666666667 . That i will get 18 teeth gear a(master) is 40 teeth and gear d ( slave) is 60 teeth .
If master gear rotate at speed 557 rpm , slave must rotate at speed 371,33333333333333333333333333333 rpm .
Could linux cnc controll at this speed and how ?
Maybe mesa card + analog drive +/-10 vdc or pluto p + hbridge + encoder feedback ?
What would you sugest me?
With best regards,
I am thinking to upgrade existing mascine from mehanical gearing to electrical but , would be linux CNC able to do that?
How machine works :
Maschine Diferential is 12 . So , if i want to make 18 teeth i have to calculate gears a, b, c, d or a and d. a is master and d is slave.
soo.. 12/18 is 0,666666666667 . That i will get 18 teeth gear a(master) is 40 teeth and gear d ( slave) is 60 teeth .
If master gear rotate at speed 557 rpm , slave must rotate at speed 371,33333333333333333333333333333 rpm .
Could linux cnc controll at this speed and how ?
Maybe mesa card + analog drive +/-10 vdc or pluto p + hbridge + encoder feedback ?
What would you sugest me?
With best regards,
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02 Oct 2016 16:40 #81150
by andypugh
Yes, LinuxCNC can do this very easily. LinuxCNC can do this very easily.
Replied by andypugh on topic gear hobbing maschine-electronic gearing ?
I am thinking to upgrade existing mascine from mehanical gearing to electrical but , would be linux CNC able to do that?
Yes, LinuxCNC can do this very easily. LinuxCNC can do this very easily.
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02 Oct 2016 16:44 #81151
by andypugh
Replied by andypugh on topic gear hobbing maschine-electronic gearing ?
This machine of mine is closer to what you are talking about
There is an encoder on the hob spindle and then the work axis is synchronised to that by a servo motor and its encoder. You can do it with any LinuxCNC-supported hardware, it really is a very simple bit of HAL setup.
There is an encoder on the hob spindle and then the work axis is synchronised to that by a servo motor and its encoder. You can do it with any LinuxCNC-supported hardware, it really is a very simple bit of HAL setup.
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04 Oct 2016 09:57 #81208
by gaston48
Replied by gaston48 on topic gear hobbing maschine-electronic gearing ?
Hello,
Also possible to machine a helical gear, with an encoder
coupled to the axis X
Also possible to machine a helical gear, with an encoder
coupled to the axis X
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04 Oct 2016 10:11 #81209
by andypugh
Yes, my hobbing setup for the mill allows me to cut helical gears too.
I have a GladeVCP screen that does basic gear calculations and cuts the gears:
Replied by andypugh on topic gear hobbing maschine-electronic gearing ?
Hello,
Also possible to machine a helical gear, with an encoder
coupled to the axis X
Yes, my hobbing setup for the mill allows me to cut helical gears too.
I have a GladeVCP screen that does basic gear calculations and cuts the gears:
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11 Oct 2016 20:40 #81563
by opw
Replied by opw on topic gear hobbing maschine-electronic gearing ?
Hi Andy,
Every since seeing your electronic hobbing video I have wanted to setup something similar. As I am exploring Linuxcnc I discovered encoder_ratio component.
On the Linuxcnc wiki you have documented your setup. I was wondering why you did not use the encoder_ratio component for gearing. Is this not suitable for the hobbing setup and realizing an 'electronic gear'?
Every since seeing your electronic hobbing video I have wanted to setup something similar. As I am exploring Linuxcnc I discovered encoder_ratio component.
On the Linuxcnc wiki you have documented your setup. I was wondering why you did not use the encoder_ratio component for gearing. Is this not suitable for the hobbing setup and realizing an 'electronic gear'?
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11 Oct 2016 21:08 #81564
by andypugh
The emcoder_ratio component needs a quadrature encoder on both axes. It counts the A/B pulses of both encoders in software.
My first setup used a Mesa card to count the spindle revs (so HAL never sees the A/B pulses) and a stepper on the work axes (so no slave pulses) and my current setup uses a resolver on the spindle (so no A/B pulses exist anywhere) though it does have an encoder on the slave.
I rather feel that encoder_ratio solves the problem the hard way, and only in a limited set of circumstances.
Replied by andypugh on topic gear hobbing maschine-electronic gearing ?
I was wondering why you did not use the encoder_ratio component for gearing. Is this not suitable for the hobbing setup and realizing an 'electronic gear'?
The emcoder_ratio component needs a quadrature encoder on both axes. It counts the A/B pulses of both encoders in software.
My first setup used a Mesa card to count the spindle revs (so HAL never sees the A/B pulses) and a stepper on the work axes (so no slave pulses) and my current setup uses a resolver on the spindle (so no A/B pulses exist anywhere) though it does have an encoder on the slave.
I rather feel that encoder_ratio solves the problem the hard way, and only in a limited set of circumstances.
The following user(s) said Thank You: opw
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03 Sep 2020 14:36 #180552
by jefsaro
hello andy,
I made this machine with your help, 10 years ago, it works perfectly in straight cutting, I would like to make the helicoidal, but I do not know how to do it, I attach my configuration.
thanks for the help
have a good day
jf
Replied by jefsaro on topic gear hobbing maschine-electronic gearing ?
hello andy,
I made this machine with your help, 10 years ago, it works perfectly in straight cutting, I would like to make the helicoidal, but I do not know how to do it, I attach my configuration.
thanks for the help
have a good day
jf
Attachments:
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03 Sep 2020 16:12 #180558
by andypugh
Replied by andypugh on topic gear hobbing maschine-electronic gearing ?
Helical _ought_ to be fairly easy. But I have not tried it yet.
I know that I claimed to have done so above, but I haven't hooked it up yet.
In theory you just need to add some proportion of the absolute X position to the workpiece angle.
I currently use this HAL component:
To cut a helical you would need to add:
Then in the calculation section:
Note that in this example the helix is defined as an angular lead / mm so that the HAL component does not need to know the gear diameter.
In practice I think that I woild have my GUI calculate that, based on helix angle and the gear parameters (because that _does_ know the pitch diameter.
I know that I claimed to have done so above, but I haven't hooked it up yet.
In theory you just need to add some proportion of the absolute X position to the workpiece angle.
I currently use this HAL component:
component hobbing "synchronise a rotary axis to the spindle";
pin in float teeth;
pin in float starts = 1;
pin in float spindle-pos;
pin in float spindle-vel;
pin in float A-pos-cmd;
pin in float gear-pos-fb;
pin out float gear-pos;
pin out float gear-vel;
pin out float A-pos-fb;
author "andypugh";
license "GPL v2+";
function _;
;;
FUNCTION(_){
static double pos_ref;
static double spindle_ref;
static int old_teeth;
if (old_teeth != teeth){
pos_ref = gear_pos_fb;
spindle_ref = spindle_pos;
old_teeth = teeth;
}
if (teeth != 0) {
gear_pos = pos_ref + 360*starts*(spindle_pos - spindle_ref)/teeth + A_pos_cmd;
gear_vel = spindle_vel / teeth;
A_pos_fb = gear_pos_fb - pos_ref - 360*starts*(spindle_pos - spindle_ref)/teeth;
} else {
gear_pos = pos_ref + A_pos_cmd;
gear_vel = 0;
A_pos_fb = gear_pos_fb - pos_ref;
}
}To cut a helical you would need to add:
pin in float y-pos
pin in float leadThen in the calculation section:
gear_pos = pos_ref + 360*starts*(spindle_pos - spindle_ref)/teeth + (lead * y_pos) + A_pos_cmd;Note that in this example the helix is defined as an angular lead / mm so that the HAL component does not need to know the gear diameter.
In practice I think that I woild have my GUI calculate that, based on helix angle and the gear parameters (because that _does_ know the pitch diameter.
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