Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 18, 2014 03:52PM |
Registered: 13 years ago Posts: 106 |
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 18, 2014 07:03PM |
Admin Registered: 11 years ago Posts: 1,063 |
Quote
mung
I am no expert in motion control or Reprap so not totally sure about this and no one seems to want to explain.
I was saying that a controller I designed was limited to 10kHz as that covered 90% of the possible use cases for stepper motors, but one of the site admin seemed to infer that 100kHz was needed ( [forums.reprap.org] ). Unfortunately I have not received any reply to my queries as to what Reprap requirements needed 100kHz step rates.
I thought maybe I misunderstood what was needed for a Reprap printer so I should ask the rest of the forum users if there was any help available showing what speed a motor needed to turn and what resolution and force would be required by motors.
Anyone have any knowledge about such things?
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 08:37AM |
Registered: 13 years ago Posts: 106 |
Quote
thejollygrimreaper
Quote
mung
I am no expert in motion control or Reprap so not totally sure about this and no one seems to want to explain.
I was saying that a controller I designed was limited to 10kHz as that covered 90% of the possible use cases for stepper motors, but one of the site admin seemed to infer that 100kHz was needed ( [forums.reprap.org] ). Unfortunately I have not received any reply to my queries as to what Reprap requirements needed 100kHz step rates.
I thought maybe I misunderstood what was needed for a Reprap printer so I should ask the rest of the forum users if there was any help available showing what speed a motor needed to turn and what resolution and force would be required by motors.
Anyone have any knowledge about such things?
i pointed out that we already have faster firmware,
assuming the use of gt2 pulleys and 16x microstepping the maximum x y axis speeds you'll get are:
16toothgt2 : 100steps/mm : 100mm/sec max
20toothgt2 : 80steps/mm : 125mm/sec max
these are reasonable x y axis speeds however looking at the extruder axis, if you are running a direct drive extruder you're probably fine as most direct drive extruders will be 90 to 110 steps/mm which means retraction is limited to between 111mm/sec and 90mm/sec however if you are running a geared extruder like a wades extruder or a bulldog extruder where the steps/mm are up in the high 300 to 500 then your dealing with a maximum retraction speed 33mm/sec to 20mm/sec which is a bit of a serious problem, unless you lower the microstepping however the trade off will be extrusion resolution, common retraction speeds people run are between 60mm/sec right up to 160mm/sec
and if you run 32x microstepping you can half all the above speed figures.
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 09:26AM |
Admin Registered: 11 years ago Posts: 1,063 |
Quote
mung
Quote
thejollygrimreaper
Quote
mung
I am no expert in motion control or Reprap so not totally sure about this and no one seems to want to explain.
I was saying that a controller I designed was limited to 10kHz as that covered 90% of the possible use cases for stepper motors, but one of the site admin seemed to infer that 100kHz was needed ( [forums.reprap.org] ). Unfortunately I have not received any reply to my queries as to what Reprap requirements needed 100kHz step rates.
I thought maybe I misunderstood what was needed for a Reprap printer so I should ask the rest of the forum users if there was any help available showing what speed a motor needed to turn and what resolution and force would be required by motors.
Anyone have any knowledge about such things?
i pointed out that we already have faster firmware,
assuming the use of gt2 pulleys and 16x microstepping the maximum x y axis speeds you'll get are:
16toothgt2 : 100steps/mm : 100mm/sec max
20toothgt2 : 80steps/mm : 125mm/sec max
these are reasonable x y axis speeds however looking at the extruder axis, if you are running a direct drive extruder you're probably fine as most direct drive extruders will be 90 to 110 steps/mm which means retraction is limited to between 111mm/sec and 90mm/sec however if you are running a geared extruder like a wades extruder or a bulldog extruder where the steps/mm are up in the high 300 to 500 then your dealing with a maximum retraction speed 33mm/sec to 20mm/sec which is a bit of a serious problem, unless you lower the microstepping however the trade off will be extrusion resolution, common retraction speeds people run are between 60mm/sec right up to 160mm/sec
and if you run 32x microstepping you can half all the above speed figures.
So what effect does microstepping have on torque?
Why does the extruder need to be retracted with microstepping?
surely extrusion speed and resolution will be proportional to speed of movement of the extruder?
To try and make the simplest possible description,
step speed required = the speed of movement required/ the resolution of each step.
If you want 100mm/s at a resolution of 0.01mm ....... 100/0.01 = 10,000
10kHz should be sufficient for most uses.
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 10:54AM |
Registered: 9 years ago Posts: 269 |
Quote
mung
Quote
thejollygrimreaper
Quote
mung
I am no expert in motion control or Reprap so not totally sure about this and no one seems to want to explain.
I was saying that a controller I designed was limited to 10kHz as that covered 90% of the possible use cases for stepper motors, but one of the site admin seemed to infer that 100kHz was needed ( [forums.reprap.org] ). Unfortunately I have not received any reply to my queries as to what Reprap requirements needed 100kHz step rates.
I thought maybe I misunderstood what was needed for a Reprap printer so I should ask the rest of the forum users if there was any help available showing what speed a motor needed to turn and what resolution and force would be required by motors.
Anyone have any knowledge about such things?
i pointed out that we already have faster firmware,
assuming the use of gt2 pulleys and 16x microstepping the maximum x y axis speeds you'll get are:
16toothgt2 : 100steps/mm : 100mm/sec max
20toothgt2 : 80steps/mm : 125mm/sec max
these are reasonable x y axis speeds however looking at the extruder axis, if you are running a direct drive extruder you're probably fine as most direct drive extruders will be 90 to 110 steps/mm which means retraction is limited to between 111mm/sec and 90mm/sec however if you are running a geared extruder like a wades extruder or a bulldog extruder where the steps/mm are up in the high 300 to 500 then your dealing with a maximum retraction speed 33mm/sec to 20mm/sec which is a bit of a serious problem, unless you lower the microstepping however the trade off will be extrusion resolution, common retraction speeds people run are between 60mm/sec right up to 160mm/sec
and if you run 32x microstepping you can half all the above speed figures.
So what effect does microstepping have on torque?
Why does the extruder need to be retracted with microstepping?
surely extrusion speed and resolution will be proportional to speed of movement of the extruder?
To try and make the simplest possible description,
step speed required = the speed of movement required/ the resolution of each step.
If you want 100mm/s at a resolution of 0.01mm ....... 100/0.01 = 10,000
10kHz should be sufficient for most uses.
Quote
pololu
Six different step resolutions: full-step, half-step, 1/4-step, 1/8-step, 1/16-step, and 1/32-step
and also
For instance, driving a motor in quarter-step mode will give the 200-step-per-revolution motor 800 micro-steps per revolution by using four different current levels.
Quote
as you increase the number of micro-steps per full step the INCREMENTAL torque per micro-step drops off drastically. Resolution increases but accuracy will actually suffer.
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 11:49AM |
Registered: 13 years ago Posts: 106 |
Quote
pushthatbolder
and this - [www.micromo.com]
the last one is important to you
'micro-stepping myths and realities'
Quote
as you increase the number of micro-steps per full step the INCREMENTAL torque per micro-step drops off drastically. Resolution increases but accuracy will actually suffer.
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 12:38PM |
Registered: 10 years ago Posts: 564 |
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 19, 2014 02:24PM |
Registered: 9 years ago Posts: 269 |
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 20, 2014 08:04AM |
Registered: 13 years ago Posts: 7,616 |
Generation 7 Electronics | Teacup Firmware | RepRap DIY |
Re: Is it extremely important for Reprap controllers to have higher step rates than 10kHz? October 20, 2014 08:31AM |
Registered: 13 years ago Posts: 1,611 |