CNC Sewing machine question

ahmetbm wrote:

I designed the needle as an axis which made it easy to manage the sewing steps. However when it comes to moving backward or forward, it rotates the needle. So i am confused to change back the needle to spindle.

Yes, I think this is the wrong approach. You could configure the sewing machine as a "spindle", with a spindle on/off
and a speed setting. And, you'd need to come up with a way to "index" the sewing motor to the needle-up position.
So, when the program does M03, the sewing motor starts. When the program does M05, the motor slows to a lower
speed and then stops when a sensor detects needle up. Every M05 would be followed by a wait command (dwell G04 Pnnn) to allow for the needle to come to a stop. During sewing, the X-Y feedrates would be slow enough that the moves would be accomodated by material stretch. Only after the M05 and dwell would the X-Y axes move faster to move
to a new part of the embroidery pattern. I'm pretty sure a number of people have done this before.


Jon

Is this part of the conversation about "sewing" a consistent stitch length such as making clothing, or a variable stitch length such as for embroidery?

The Rugbot needs consistent stitch length so I run the needle in velocity mode, without any gcode instructions, and it works flawlessly. This would not work for variable length embroidery type of stitches.

I have seen Rugbot, however my configuration has a difference. I have two motors(yaskawa) that run sewing machine's needle and hook seperately. With step control mode i was able to run the motors synchronously with no problem. When i faced going back problem, i searched and found two solution, one is to use spindle mode, other is to manage coordinates through linuxcnc. Since i am new on linuxcnc, i asked to yaskawa tech service, if it is possible to run two motors in velocity control mode synchronously. They did not give a clear yes, i think i will have to test it my self, if i can not find an easier way through linuxcnc.

Is this part of the conversation about "sewing" a consistent stitch length such as making clothing, or a variable stitch length such as for embroidery?

Stitch length is about 2.5mm and in some places between 1-2mm for tightening, it is not embroidery machine, it will sew only gloves.

I can lift up the needle part about 100mm, so it is not necessary to stop needle at the top position, but it would be better if i can. Because i don't waste time for the needle part to come to upper position.

andypugh wrote:

(For testing it will be fine to use the difference between the two floating-point position, but if long run-times are anticipated it might be better to scale the difference between the encoder counts. Encoder counts are stored internally as 64 bit numbers so will never overflow.
Floating point positions will, after a long time, start to be large, and subtracting one large number from another to return a difference close to zero will eventually become imprecise. This is because floating-point only has 52 bits of precision, but 52 bits is still a very long run-time for most machines.)

I need about 10K revolution and then the proces will start over. Can this be considered as long run?

I am using general mechatronics pci 6 control card.

andypugh wrote:

Can you attach a pin listing of all the General Mechatronics pins?

Here is parameters list. i will try to use one driver slave and other as master.

Master encoder will run in velocity control mode, and slave will run in step control mode, i am preparing test setup.