Will grbl run a beefier machine okay?

Discussion about the arduino based g-code interpreter, grbl
Joe Pineapples
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Will grbl run a beefier machine okay?

Post by Joe Pineapples » Sun Apr 17, 2016 7:45 am

I haven't even built a Shapeoko yet, still in the planning stage. What I intend to do is build a basic Shapeoko as a test, then also convert a heavier duty bench mill to CNC. If that works, possibly go on to make a large, heavy duty Shapeoko :)
Obviously, bigger machines need bigger stepper drivers, would grbl running straight from an arduino have any problem with this? Would a mega2560 be better than an Uno (I already have a mega)?
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CastIrony
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Re: Will grbl run a beefier machine okay?

Post by CastIrony » Sun Apr 17, 2016 8:10 am

The arduino is just sending some relatively low current signals to your stepper drivers, which are what actually powers the stepper motor coils.

So there's not really any relationship between the size of the motor and the specs of the arduino.
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Joe Pineapples
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Re: Will grbl run a beefier machine okay?

Post by Joe Pineapples » Sun Apr 17, 2016 8:58 am

I was looking at the grbl wiki about connecting, here. https://github.com/grbl/grbl/wiki/Connecting-Grbl
and method one didn't show any external power source to the drivers. Now, I don't know anything about arduino, drivers or any of the other electronics/software involved in CNC, which is why I've been using the Shapeoko forum before I begin buying parts.

If I were to use an arduino to run bigger drivers, would they have their own power source or do they need to have some kind of interface board between them and the arduino?
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WillAdams
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Re: Will grbl run a beefier machine okay?

Post by WillAdams » Sun Apr 17, 2016 10:16 am

Yes, there’s usually a board, typically called a shield in-between the Arduino and the machine which the stepper drivers are mounted on.

There is a new all-in-one board which I’ve been trying to find time to experiment w/ and document, Panucatt’s Gradus M1 Pro which has the option of supporting two different size stepper drivers:

http://www.panucatt.com/product_p/gm1pro.htm

Check the specs for the stepper drivers which it supports?
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chamnit
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Re: Will grbl run a beefier machine okay?

Post by chamnit » Sun Apr 17, 2016 1:48 pm

It should. I've seen users run Tormach sized machines with Grbl, directly converting away from their old LinuxCNC setups. It all depends on the size and capability of the stepper drivers. Grbl is just the real-time signal generator that tells the steppers and their drivers to move without exceeding their physical limitations. For example, LinuxCNC does the same thing, but has to do it on a specialized version of Linux that allows for real-time, uninterrupted signals that are sent out of a parallel port. Grbl just takes that part of CNC control and puts it in a micro controller, which are designed to do real-time tasks very well.

Here's an example of a user that created a simple parallel port adapter to convert their LinuxCNC machine with an Arduino and Grbl installed on it. (https://github.com/grbl/grbl/issues/663)

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Re: Will grbl run a beefier machine okay?

Post by bharbour » Sun Apr 17, 2016 3:16 pm

I'm building a new large machine of MDF construction with 270oz NEMA23's and I plan on using GRBL...Windows10-->Arduino Uno-->TB6560Driver (probably)-->New Machine.
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Re: Will grbl run a beefier machine okay?

Post by picengravertoo » Sun Apr 17, 2016 6:34 pm

There is a DB25 Arduino UNO Shield available. This could drive a more robust stepper drivers like Gecko Drives with an UNO & grbl through a DB25 breakout board.

http://cnc4pc.com/motion-control/breako ... duino.html
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Re: Will grbl run a beefier machine okay?

Post by cvoinescu » Mon Apr 18, 2016 9:16 pm

The DB25 shield is valuable if your driver already has a DB25 input, such as many three-driver and four-driver TB6560 boards out there. If you're using separate drivers, though, there's very little point in gathering the Arduino signals into a DB25 connector only to break them out again. Just wire the Arduino straight into the separate drivers, maybe using a "screw shield" for convenience.
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Joe Pineapples
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Re: Will grbl run a beefier machine okay?

Post by Joe Pineapples » Tue Apr 19, 2016 9:18 am

cvoinescu wrote:The DB25 shield is valuable if your driver already has a DB25 input, such as many three-driver and four-driver TB6560 boards out there. If you're using separate drivers, though, there's very little point in gathering the Arduino signals into a DB25 connector only to break them out again. Just wire the Arduino straight into the separate drivers, maybe using a "screw shield" for convenience.
After much searching and eventually finding several guides/diagrams/video clips, this is the conclusion I came to also. If a shield is merely an interface for push-fit, smaller drivers, then it's not much good to me.

Can you allocate pin numbers in GRBL (through Arduino IDE) or do you have to connect the drivers to specific pins?
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Re: Will grbl run a beefier machine okay?

Post by cvoinescu » Tue Apr 19, 2016 9:35 am

You can configure the pins to a certain extent by editing GRBL source code, but there are restrictions. It's much easier to just go with the defaults (D2-D4 are X, Y, Z STEP, D5-D7 are X, Y, Z DIR, and D8 is ~ENABLE for all three axes). See https://github.com/grbl/grbl/wiki/Connecting-Grbl (I'd use the second image).

If you need help connecting a specific driver to the Arduino, I can probably help (especially if you have some documentation for the driver).
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