Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: grofone on November 26, 2017, 06:04:45 PM
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hi
i have mach3 with akz250 control card, i need to configure closed loop pwm vfd spindle.
on mach3 i set:
"use spindle feedback in sync mode" on
"closed loop spindle control" on
but the closed loop not work, when the spindle forces the rpm go down.
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Hi,
Mach3 is not a closed loop controller.
"use spindle feedback in sync mode"
refers to Mach reading the index pulse used particularly for lathe threading.
closed loop spindle control"
if relying on the index pulse (once per revolution) even if Mach could close the loop its going to be that slow
to respond that it would still be unusable for lathe threading.
An external motion controller with feedback capability (rare and expensive) or alternately an AC servo and matching
driver (which are closed loop by design) is indicated.
Craig
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if relying on the index pulse (once per revolution) even if Mach could close the loop its going to be that slow
to respond that it would still be unusable for lathe threading.
Sorry Craig but not quite true - there are many lathe users threading this way.
Tweakie.
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hi
ok "closed loop spindle control" is for only lathe?
br
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Hi,
AFAIK it works with any spindle.
Craig
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I think it depends on the motion controller. Some motion controls can do rigid tapping, which requires a closed loop spindle, while other can not.
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Hi,
yes, some motion controllers have closed loop operation, some of them pretty damn good at it too, they tend to be rare
and expensive.
If you really want a closed loop spindle an AC servo and matching drive are hard to beat. The loop is closed by the drive.
The manufacturer has both the servo and drive to design and play with and usually do a very good job; that you and I
would struggle to match even with a really great (expensive) motion controller.
As tweakie has pointed out many have used lesser performing control loop strategies and achieved good results at a lesser
price. I bought a second hand Allen Bradley servo (1.8kW 6 Nm 3500 rpm) and drive, I luv it.
Craig