No movement on one axis

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15 Mar 2011 16:33 #7859 by piasdom
Replied by piasdom on topic Re:No movement on one axis
Thanks,
well i guess i'll leave it as is. the stepper can only go 20imp anyway.
Thanks for all ya'll help.

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24 Mar 2011 19:04 - 24 Mar 2011 19:28 #8054 by piasdom
Replied by piasdom on topic Re:No movement on one axis
i ran the axis on all three axis and they all moved exactly .5"
so i ran a program(hour long-no stock or end mill) and i keep losing
steps or something. i had the max_acc and stepgen at about 30/45.
i'm down to 12/18 for xy and 20/30 for z. if i widen the time(guessing what is widening)
will this give the axis more time to change direction ? and i do have backlash enabled.
i think the sherline mill started at 10/12
Thanks

or in the axis test, i can make it move farther. change .5" to 1" or 2" inches ?
Last edit: 24 Mar 2011 19:28 by piasdom.

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24 Mar 2011 19:29 #8055 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Are you loosing steps on all axis or just one?

To allow more time for a direction change you would increase the direction setup and/or direction time.

What stepper drives do you have?

The MAX_ACCELERATION is how fast the stepper accelerates not how much time is allowed for the stepper driver to change directions.

Is there any possibility that friction is causing your lost steps?

John

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24 Mar 2011 21:10 #8056 by piasdom
Replied by piasdom on topic Re:No movement on one axis
Are you loosing steps on all axis or just one?
was testing x and y, didn't have time for z yet

To allow more time for a direction change you would increase the direction setup and/or direction time.
in the ini ?

What stepper drives do you have?
sherline steppers, can answer better when i get to work monday

The MAX_ACCELERATION is how fast the stepper accelerates not how much time is allowed for the stepper driver to change directions.
what DO the two numbers do to each other.

Is there any possibility that friction is causing your lost steps?
i was running the test(program) without cutting anything.
same as i did with the axis test. i even oiled the ways before both test.
was trying to keep everything the same. would increasing the distant
to 1 to 2 inches instead of 1/2" in axis test change anything ?

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25 Mar 2011 11:36 #8065 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Increasing the distance would not make any difference as long as you are moving far enough to reach the maximum speed for the axis.

Even if you oiled the ways they can be binding up if they are too tight and I'm not sure how the Sherline ways are made.

Just looking at the stepper wizard the step and direction times for a Sherline are 22000ns for step time and step space and 100000ns for direction hold and direction setup. These numbers are the time the stepper drive needs between steps and direction changes. For each step pulse for the Sherline the step pin must be on for 22000ns and then off for 22000ns. For a direction change the direction pin must be on for 100000ns prior to the change and stay on (or off depends on the direction) for an additional 1000000ns.

The acceleration numbers are how fast you accelerate from 0 to maximum speed and how fast you decelerate from maximum to 0. If your acceleration numbers are higher than possible I assume EMC never tries to go that fast but goes as fast as the step time and step space allows. To see the effect of the MAX_ACCELERATION keep reducing the number in until you can see that it takes some time to go from 0 to maximum. Comment out your backlash for the axis until you get the lost steps sorted out and ignore STEPGEN_MAXACCEL for the time being.

John

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28 Mar 2011 09:57 - 28 Mar 2011 10:00 #8185 by piasdom
Replied by piasdom on topic Re:No movement on one axis
BigJohnT wrote:

Even if you oiled the ways they can be binding up if they are too tight and I'm not sure how the Sherline ways are made.
sherline has dovetail and gibs


Just looking at the stepper wizard the step and direction times for a Sherline are 22000ns for step time and step space and 100000ns for direction hold and direction setup. These numbers are the time the stepper drive needs between steps and direction changes. For each step pulse for the Sherline the step pin must be on for 22000ns and then off for 22000ns. For a direction change the direction pin must be on for 100000ns prior to the change and stay on (or off depends on the direction) for an additional 1000000ns.

where to i change the step time/space and direction hold without running stepconf wiz? don't want o start all over :)

The acceleration numbers are how fast you accelerate from 0 to maximum speed and how fast you decelerate from maximum to 0. If your acceleration numbers are higher than possible I assume EMC never tries to go that fast but goes as fast as the step time and step space allows. To see the effect of the MAX_ACCELERATION keep reducing the number in until you can see that it takes some time to go from 0 to maximum. Comment out your backlash for the axis until you get the lost steps sorted out and ignore STEPGEN_MAXACCEL for the time being.

i did this and got down to 4 MAX_ACC and noticed the slow movement in direction change. but never got any following errors.
should i have ? i moved the MAX_ACC to 10 and testing now.

found this in axis.hal file, this step time/space and direction hold ?
setp stepgen.0.dirhold 150000
setp stepgen.0.dirsetup 150000



here's the rest:
setp stepgen.0.position-scale [AXIS_0]SCALE
setp stepgen.0.steplen 1
setp stepgen.0.stepspace 1
setp stepgen.0.dirhold 150000
setp stepgen.0.dirsetup 150000
setp stepgen.0.maxaccel [AXIS_0]STEPGEN_MAXACCEL
net xpos-cmd axis.0.motor-pos-cmd => stepgen.0.position-cmd
net xpos-fb stepgen.0.position-fb => axis.0.motor-pos-fb
net xstep <= stepgen.0.step
net xdir <= stepgen.0.dir
net xenable axis.0.amp-enable-out => stepgen.0.enable

setp stepgen.1.position-scale [AXIS_1]SCALE
setp stepgen.1.steplen 1
setp stepgen.1.stepspace 1
setp stepgen.1.dirhold 150000
setp stepgen.1.dirsetup 150000
setp stepgen.1.maxaccel [AXIS_1]STEPGEN_MAXACCEL
net ypos-cmd axis.1.motor-pos-cmd => stepgen.1.position-cmd
net ypos-fb stepgen.1.position-fb => axis.1.motor-pos-fb
net ystep <= stepgen.1.step
net ydir <= stepgen.1.dir
net yenable axis.1.amp-enable-out => stepgen.1.enable

setp stepgen.2.position-scale [AXIS_2]SCALE
setp stepgen.2.steplen 1
setp stepgen.2.stepspace 1
setp stepgen.2.dirhold 150000
setp stepgen.2.dirsetup 150000
setp stepgen.2.maxaccel [AXIS_2]STEPGEN_MAXACCEL
net zpos-cmd axis.2.motor-pos-cmd => stepgen.2.position-cmd
net zpos-fb stepgen.2.position-fb => axis.2.motor-pos-fb
net zstep <= stepgen.2.step
net zdir <= stepgen.2.dir
net zenable axis.2.amp-enable-out => stepgen.2.enable


John[/quote]
Last edit: 28 Mar 2011 10:00 by piasdom.

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28 Mar 2011 12:48 #8200 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Sorry I put one too many zeros in the direction setup and direction change...

Just looking at the sample Sherline 3 Axis config that comes with EMC the X , Y and Z axis have the following

MAX_VELOCITY = .36
MAX_ACCELERATION = 2
STEPGEN_MAXACCEL = 2.2

John

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28 Mar 2011 14:30 - 28 Mar 2011 16:36 #8202 by piasdom
Replied by piasdom on topic Re:No movement on one axis
i had looked at some of the other ini, but they all had different MAX_ACC and MAX_VEL. i don't have the samples
as i deleted them thinking i wouldn't use them. first is from 5 axis and the other to are from sim. when i got the mill(4 or 5 years)
it was 10 MAX_ACC and 12 MAX_VEL. i changed the the leadscrews(XYZ), and start with the trouble. i never thought it would go as low as 2 :)
from being here(forum) i never saw any ones' that low. doing as you suggested, i noticed it slow to change direction at 4. so i set MAX_ACC
at 10 and trying to cut a part. so far so good :) think i should get closer to 4 ? THANKS

MAX_VELOCITY = 200.0
MAX_ACCELERATION = 800.0

MAX_VELOCITY = 4
MAX_ACCELERATION = 100.0

MAX_VELOCITY = 1.2
MAX_ACCELERATION = 20.0
Last edit: 28 Mar 2011 16:36 by piasdom.

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31 Mar 2011 19:17 #8338 by piasdom
Replied by piasdom on topic Re:No movement on one axis
if emc2 updates/upgrades, does that change the MAX_ACC and MAX_VEL ?
or is it just the new friction from the new leadscrews?

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31 Mar 2011 19:24 #8339 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
An EMC update will not change anything in your configuration files.

John

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