servo recomendation WHN 11

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26 Jul 2018 11:41 #114870 by Pawel77
Replied by Pawel77 on topic servo recomendation WHN 11

OT-CNC wrote:

what do you think about it, do you see limitations for that?


I think it will be impossible to to do pockets /circular/helical interpolation outside of the center of rotation on your rotary table.
Does this type of mill have manual handwheels that attach to the end of each axis to move the table in neutral? If so, can you mount your servo motors there?


It is actually drilling-milling mill, so not so huge need to have full CNC.
There is a good access to each of the axis screws at the front of it, you can see the gear box and right to it the motor. But I do not feel comfortable to remove or change that much.
At the moment I plan do a few tests with locking indexer and if it works out I will start looking on relays that switch each axis inside that box in front.
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26 Jul 2018 12:48 - 26 Jul 2018 12:48 #114875 by OT-CNC
Replied by OT-CNC on topic servo recomendation WHN 11
Okay, its a horizontal boring mill. Disregard my comment on pocketing in the center of the table.
That is a good size machine!
Last edit: 26 Jul 2018 12:48 by OT-CNC.

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28 Jul 2018 04:44 #115001 by Pawel77
Replied by Pawel77 on topic servo recomendation WHN 11

vre wrote: @Pawel77
I have also a knee milling machine with trapezoidal screws that has 1 motor that moves all axis XYZ each axis has a linear encoder scale installed.
The coupling to each axis is done mechanically with an actuator so only one axis can be moved each time.
This machine has heindenhain tnc 135 controller(not working) but i think to change it to linuxcnc.
Can linuxcnc control a machine like this ?


vre,
it looks like locking indexer mentioned by andy is available only for rotary axes, there is probably a way around but more complicated. I give up doing that with single motor.

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28 Jul 2018 12:46 - 30 Jul 2018 12:42 #115008 by andypugh
Replied by andypugh on topic servo recomendation WHN 11

Pawel77 wrote: it looks like locking indexer mentioned by andy is available only for rotary axes, .


I did wonder about that, but such a limitation wasn't mentioned in the documentation.

I just tried is in a simulator, and I was initially optimistic. I set up joints 0 1 and 2 to be locking indexer joints for axes X, Y and Z and during the homing phase everything acted like I hoped. No axes moved until their joint.N.0.is-unlocked pin was driven true and then no other axis was allowed to move until that pin was set to false. This is all exactly like you would wish.

But then, once everything was homed, it was possible to move all the linear axes independently.

This doesn't seem like the way it should be, so I will make enquiries on the developers mailing list.
Last edit: 30 Jul 2018 12:42 by andypugh.

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29 Jul 2018 01:03 #115038 by andypugh
Replied by andypugh on topic servo recomendation WHN 11
There are two other ways to do this that could work.

1) A HAL component that sets feed-override to zero and then watches for axis move requests. When it sees an axis trying to move it engages the clutches for that axis and then sets the feed-override back to normal until the move completes.
But what does it do if the G-code requests more than one axis to move?

2) A filter file that re-parses the G-code, wrapping each move with engage / disengage commands. This can split G-code with 2-axis moves into two single-axis moves.

I think that 2) would be the most reliable in practice.

It is a shame that here is no way to re-map the G1 and G0 codes, that would be the easy way.

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30 Jul 2018 21:49 - 30 Jul 2018 21:56 #115182 by vre
Replied by vre on topic servo recomendation WHN 11

LOCKING_INDEXER = 1 - When this is set to 1, a G0 move for this axis will initiate an unlock with axis.N.unlock pin then wait for the axis.N.is-unlocked pin then move the axis at the rapid rate for that axis. After the move, the axis.N.unlock will be false and motion will wait for axis.N.is-unlocked to go false. Moving with other axes is not allowed when moving a locked rotary axis. If motion is disabled (estop for instance), while the axis.N.unlock pin is set, the axis.N.unlock pin is reset to false.


Mine milling machine has 3 actuators 1 per axis and 1 motor for all axis movement
and engage the axis that will move with the motor with the actuators.
so only one axis can move at one time no arcs no movement of >=2 axis the same time.
All axis have linear scales installed for position feedback.

How can i make this to work (LOCKING_INDEXER) in my case ?

2) A filter file that re-parses the G-code, wrapping each move with engage / disengage commands. This can split G-code with 2-axis moves into two single-axis moves.


Can i make this to cam software post processor ?
So the generated code will be fixed ?
Last edit: 30 Jul 2018 21:56 by vre.

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31 Jul 2018 12:39 #115220 by andypugh
Replied by andypugh on topic servo recomendation WHN 11

vre wrote:

2) A filter file that re-parses the G-code, wrapping each move with engage / disengage commands. This can split G-code with 2-axis moves into two single-axis moves.


Can i make this to cam software post processor ?
So the generated code will be fixed ?


LinuxCNC can be configured to run input files through a script before executing them.

linuxcnc.org/docs/2.7/html/config/ini-co...html#_filter_section

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01 Aug 2018 21:54 - 01 Aug 2018 21:55 #115348 by vre
Replied by vre on topic servo recomendation WHN 11
ok with this i can write a java app that makes the conversion.
The problem i have not solved until now is how to read the analog linear scales.
Also where to find a driver that can drive 100V 26A DC brushed motor with pwm.
Last edit: 01 Aug 2018 21:55 by vre.

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01 Aug 2018 23:16 - 01 Aug 2018 23:21 #115356 by andypugh
Replied by andypugh on topic servo recomendation WHN 11

vre wrote: Also where to find a driver that can drive 100V 26A DC brushed motor with pwm.


Maybe the UHU

www.uhu-servo.de

60V / 20A rated, but the web site says that by swapping to other TO220 parts it can go higher on both.
[edit] The web site says 120V 35A for alternative parts

It takes step-dir but that's not terrible. I helped set one up in Stuttgart a couple of weeks ago and it seemed to work well with LinuxCNC.
Last edit: 01 Aug 2018 23:21 by andypugh.

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02 Aug 2018 09:31 #115387 by andypugh
Replied by andypugh on topic servo recomendation WHN 11

andypugh wrote:

vre wrote: Also where to find a driver that can drive 100V 26A DC brushed motor with pwm.


Maybe the UHU
www.uhu-servo.de


I talked to Uli and he didn't seem to think that his drive was suitable.

Mesa have a 160V / 22.5A drive but it is fairly expensive (it is a dual drive, for two motors) store.mesanet.com/index.php?route=produc...83_90&product_id=141 .
Pico have a 160V 20A one which is rather cheaper: pico-systems.com/osc2.5/catalog/product_...ath=3&products_id=10


When you say "drive with PWM" do you mean that you want to control it via a PWM input or that you want it to control the motor with a PWM output?

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