CNC Machine With Adafruit Motor Shield

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electronics man
 
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CNC Machine With Adafruit Motor Shield

Post by electronics man »

I want to use the Adafruit Motor shield to make a desktop CNC Machine but I also want to be able to use a common CNC software such as MACH3 but I am not sure how to convert the information to the Motor Shield, then to the CNC machine. I would also like to be able to use a simple 3D design software such as Goolge Sketchup but I am not sure if any of these programs are compatible with one-another. I also need to find a good program to convert my info to the "G code". All suggestions of different softwares or design programs are greatly appreciated!!! I am also concerned about the fact that I can only use 2 stepper motors. A CNC machine will require 3, but I thought I might be able to use a servo for the Z Axis. PLEASE help!!!

Mashurst
 
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Re: CNC Machine With Adafruit Motor Shield

Post by Mashurst »

I program a CNC mill for a living. I can tell you that you need to find a CAM tool to help you. You could (and should) do some basic stuff "hand programing" in G code so you learn how it works but to get more complex stuff done you will want a CAM tool. I don't know of any that are free (though I haven't looked) but http://www.alibrecam.com/ It is affordable for a hobbyists and is worth a look. I have never used it but I hear its good. It will also serve as your CAD tool if you want. Its probably more capable than sketch up perhaps at the cost of being a bit harder to learn.
You will want to be sure whatever you get has a post processor (Post) that works with your CNC driver/controller. The Post is just a file that the CAM uses to convert the graphical tool path on the screen to the G-code your controller wants. G-code is not exactly the same for all machines. The basic are all there but some controllers support more macros or interpret them slightly differently.
What kind of material are you going to be cutting?
Let me know if you have any more questions.

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mauricio.imbe
 
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Re: CNC Machine With Adafruit Motor Shield

Post by mauricio.imbe »

Hi Mashurst and Electronics Man,

I started a project using Arduino + motorshield = 2 steppers and 1 servo.

Questions:

1- What code I must to put on Arduino?
2- What software can handle Gcode PC to Arduino?
3- How can I do all of this?
4- Do you know any project like this?

Thanks for any help,

BANNED.

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jasonwebb
 
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Re: CNC Machine With Adafruit Motor Shield

Post by jasonwebb »

I also am planning to create my first CNC router next semester, but do not have any experience in the area (CNC professionals, you may cringe now :)). I plan to draw on the work and information figured out by the MakerBot, RepRap and hobby CNC communities.

Answers to your questions (as best I can):
1. I am not exactly sure, but I am willing to bet there are several options out there. Try to dig into the MakerBot and RepRap communities to see how they utilize Arduinos. I believe RepRap has their own interpreter (see http://reprap.org/wiki/Darwin/Arduino_GCode_Interpreter), and don't forget your best friend, Google: https://www.google.com/search?sourceid= ... rduino+cnc

2. ReplicatorG is quite popular, I think.

3. Start small, add small changes and read everything you can get your hands on. Start by first just learning how to use the Arduino to interface with steppers. Then try to connect leadcrews to the motor shafts, then add gantries; fixing, tweaking, learning and testing until you understand.

4. Yes, many. As I said, MakerBot and RepRap are two very popular 3D printers that are essentially DIY CNC machines (specifically, CNC 3D printers). Remove the vertical axis (or lessen it) and replace the extruder with a rotary tool and you have a CNC router.

Get involved in both of these communities and you can probably find some hobby CNC machinists who can help you out.

Also, check out the following sites (I'm sure there are many more, just keep searching):
- http://buildyourcnc.com/default.aspx
- http://www.cnczone.com/

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cstratton
 
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Re: CNC Machine With Adafruit Motor Shield

Post by cstratton »

Keep in mind a CNC machine which experiences cutting forces will likely need much larger stepper motors than a 3d printer with only an extrude head. Low impedance (relatively low nameplate voltage) 150 oz/in NEMA 23's are about the smallest I'd consider spending money on acquiring new to use with a sherline-sized machine, though lower rated or higher impedance freebie NEMA23's could be worth playing with at low speeds during early stages if they are available, since you could bolt on better replacements if and when you decide that the other parts of the machine work well enough to justify the investment.

Also, that direct belt drive on the X axis is pretty much out - you want lead screws on all axis, and either anti-friction nuts or those that can be adjusted as they wear to keep backlash minimal.

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philba
 
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Re: CNC Machine With Adafruit Motor Shield

Post by philba »

I think you are going about this project completely backwards.

Start with what you want to use a CNC machine for. Cutting metal? Wood? Plastic? Foam? Then think about the size of the things you want to make. This will give you a sense of how powerful motors you will need. That will, in turn, tell you what kind of motor controllers you need. check out cnczone.com - there you will find tons of cnc machine plans, ideas, ...

Frankly, I think considering using an Arduino falls into the "when all you have is a hammer, everything looks like a nail" category. Even if you could find a use for it, I would never put a motor controller on a shield. At least one capable of driving the kind of stepper you would need even for a very small CNC machine.

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