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Author Topic: EMC2.4/AXIS over USB w/Arduino and a call to the crowd.  (Read 13823 times)
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Thank you Jeff,

It sounds like you have been going over every bump in the road that I did. smiley Only difference is I started with the controller and worked my way outwards to the mechanical bits. I also knew from past projects that once I learn to make something ( like EMC2Arduino ) I end up learning some new things along the way.

I wrote EMC2Arduino as a pilot project to learn how to make a working DIY CNC.

These days as I get time, I'm working on writing HAL2Arduino to make it even better, to refine what I have learned and distill those ideas into less complicated easier to use / easier to understand project.

When I'm done I intend to make a customized live linuxCNC CD that will have all the tricky bits in place so people won't have to worry about it. That way all they'll have to do it play with is the Arduino.
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sound like a good plan an a lot of work...

i could spare a few hours today to tried it out and it did not work, which is not really surprising for me since i am not really new to linux but i have to learn a lot of things  so i probably did something wrong.
i could offer you to document everything in a latex file hoping that in the end it will work for me and there will be a more user friendly installation guide ( no offence, but if you dont know anything about linux its pretty much chineese).

Im gonna start over and post the problems

i would love to contribute but my skills arent anywhere in your range so i guess this is my way

jeff
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Luxemburg
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hi again,
hope you did'nt get me wrong in my last post...?

since 10 minutes ago i'm ready to go... i got my steppers to work -all 3 of them :-)
woohoo
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Sweet! Now the fun begins. smiley
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Hi :
Great project bro !
1-Can someone use servo instead of stepper motors in your project ???
I guess, cuz Arduino mega has pwm output,  so that, it would be easier to contact with servo motors without any motor drivers !!
2-what should I do to replace servo as stepper in programming ????
3-what are disadvantages of this action ???

Thanks !
Wish you best !
« Last Edit: January 06, 2014, 03:50:57 pm by mamal_asimo » Logged

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Well, first lets make sure we're on the same page.

Servos come several varieties;
  • Most widely known are the R/C hobby servos found in toy cars/boats/planes/etc. These are not as of yet supported. Why? Lack of precision, sloppy coupling to linkages makes them NOT the best choice for CNC control. Will I be including them? Yes, but its low on my ToDo list.
  • Linear gear driven servos (aka Linear Actuators), used for load-lifting. (Think powered doors/hatches/jacks/etc.) Slow, powerful and when used with an encoder; are supported. But if you really need 500lbs of table force maybe you should re-compare the build costs vs. a used bridgeport/lathe/something else built for steelworking. smiley-wink
  • Pneumatic linear servos, these ulta-fast lightweight actuators are used in many CNC machines today; where speed is more important than strength, one such example would be 'pick and place' machines, used widely in the electronics and packaging industries. Some move faster than the human eye can see. Supported.
  • My favorite pick: Machine Servos (with quadrature feedback encoders) have been recently added to my latest version. (Version 0.5) These can even be obtained from the scrap-bin, old pen-based plotters commonly used in 80s/90s era engineering departments. They're quite common once you know to hunt for them. These type of servos work REALLY WELL for CNC machines and bigger units are still in industrial use today. These gems are often just tossed-out of dusty old company store rooms. If you find one, offer to buy it. Chances are they'll give it away for the hauling. smiley-wink

As far as plugging-in your own code. That should be pretty easy, just set your servo code to monitor the targetPos[] array variable.

Where targetPos[0] = X axis position.
There are 9 axis variables. So, targetPos[0] through targetPos[8] are useable.

A great place to put a call to your servo routine would be inside the doUrgentStuff() routine.
That way it will get called as frequently as possible.

The axis list by letter designation are:
  • The common: X (left/right), Y(near/far), Z(up/down).
  • Less common: A (axial rotation of X), B (axial rotation of Y), C (axial rotation of Z).
  • Robot "arms", all of the above plus: U (rotation perpendicular of A), V (rotation perpendicular of B), W (rotation perpendicular of C).
« Last Edit: January 10, 2014, 08:52:27 pm by dewy721 » Logged

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Hi dewy721,

I'm running an EMC2 based 3 Axis mill CNC with a "traditional" parallel port setup.

I'd like to know first if you think this approach would be good to add a 4th rotary axis with an arduino+stepper driver.

I have built the 4th axis with a NEMA23, Arduino UNO and 3A stepper driver that I had in my shop, and I would like to add it to my machine. I've already tested my setup with Grbl + GcodeSender and the new axis is doing great. Now is time to add it to my current build (off course my parallel port interface has only 3 axis hence the Arduino + Driver idea)

I have read your post and Git Hub instructions, but before disrupting my current setup, I'd like to know your ideas about this kind of setup.

Regards.

Crispy
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As long as you bare in mind that the Arduino controlled stepper is moving around in a "carrot on a stick" fashion. With that said, yes it can do it, but that axis will catch-up a split second later than the LPT driven ones.

So you can either strategically insert some dwell codes where you need that axis to considered "finished moving", or slow simply your feedrate down a bit and wait.

Otherwise, like a horse chasing the carrot; go too fast and the horse will turn every corner into a radius.
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