CNC Sewing machine question

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08 Jan 2020 18:00 #154330 by ahmetbm
Replied by ahmetbm on topic CNC Sewing machine question
Hook is the lower part where needle makes the stitch, i attached a picture.
How can i make the rotary axis stop at specific position when suddenly pause is triggered? Thanks.
https://images.app.goo.gl/fYaaSgVXeAkSCTi89

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08 Jan 2020 18:40 #154335 by andypugh
So, you control the hook that loops the thread round the lower bobbin separately from the needle movement? That is unconventional, but I can see that it might actually be simpler than a mechanical linkage.

To only allow program-pause in a cerrtain range of needle travel I would use a wcomp component on needle position and an and2 logic element feeding in to the pause pin. You would also need a modulo component assuming that the needle axis rotates continuously. There isn't one in HAL but the "orient" component will do the job.
The following user(s) said Thank You: ahmetbm

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08 Jan 2020 18:59 #154336 by ahmetbm
Replied by ahmetbm on topic CNC Sewing machine question
We are developing a prototype machine on which three parallel sewing machines will run together on same continuous fabric feed. Currently there is one sewing machine on the prototype, i am trying to solve this problem, after this problem is solved we will attach 2 more sewing machines and i will send a fully operating video, for your opinions.

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09 Jan 2020 02:22 #154392 by jmelson
Replied by jmelson on topic CNC Sewing machine question
My own thoughts on how to do this are to have the sewing machine driven by a servo motor. When the CNC program calls for stitching, as in "spindle on" or M03, the
motor runs at some set speed. When the spindle command is turned off, (M05)
then the servo drive is commanded to a lower speed, and when the needle full up
sensor on the sewing machine detects it is there, the motor is stopped. If every
place in the G-code where the spindle is stopped has a short dwell for the needle(s)
to reach full up, then it will be safe to slew to the next part of the embroidery
pattern.

This scheme could be implemented in physical hardware, some simple analog circuits and a FF to trip the servo off when the sensor senses the needle up.

Or, it could all be done with a few HAL components. You couldl also have a
DAC that sets the normal speed and the needle up seek speeds, and use an
enable command to stop each motor at the right time.

Jon

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09 Jan 2020 07:32 #154412 by ahmetbm
Replied by ahmetbm on topic CNC Sewing machine question
I should give more detail of my system, since it is prototype i can make changes.
Attached you can find the config files and sample piece of g code.
We are using servo motors to control 4 axes.
Since needle is defined as an axis it has home sensor, but i could not find a way to pause motor when home sensor is triggered.

File Attachment:

File Name: 4-axis-stepper.hal
File Size:6 KB

File Attachment:

File Name: 4-axis-stepper.ini
File Size:7 KB

File Attachment:

File Name: 4.ngc
File Size:3 KB
Attachments:

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09 Jan 2020 11:22 #154426 by ahmetbm
Replied by ahmetbm on topic CNC Sewing machine question
Can we use and2 on pause signal and needle home signal for program-pause?

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09 Jan 2020 12:58 #154433 by andypugh

ahmetbm wrote: Can we use and2 on pause signal and needle home signal for program-pause?


That would rely on the needle-home signal lasting long enough to be detected during the thread cycle. But if that is the case, yes.

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12 Jan 2020 14:58 #154676 by ugurbircan
Hi,
linux cnc really efficient?

www.toprakcnc.com

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12 Jan 2020 17:26 #154695 by jmelson
Replied by jmelson on topic CNC Sewing machine question

ugurbircan wrote: Hi,
linux cnc really efficient?

www.toprakcnc.com


What does this even mean? Yes, LinuxCNC is efficient, it can run thousands of lines of G-code per second
on decent PC hardware, and control closed-loop to the PC servo systems at hundreds of IPM, tens of MPM
speeds.

Jon

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12 Jan 2020 17:29 #154697 by andypugh
I think that he might be a spammer. (ugurbircan that is, not the thread starter)

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