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Thread: CNC advice

  1. CNC advice

    Hey everyone, I just ordered everything I need to do a CNC conversion on a mini milling machine, and looking to get up to speed on the process.

    I know a few here CNC, so I wanted to see if I could pick your brains a bit.

    I plan on using Mach3 as my controller.

    I am looking for advice on how to create the toolpaths or Gcode.

    I have looked into Cut2d which looks pretty cool. It has some very basic vectors you can make, or you can also import 2D files elsewhere and turn the imported vectors into toolpaths.

    I am wondering what software you guys are using to create your 2D drawings, and also if you are using Cut2D or an alternative, if you can give me a feel for whether or not you like it.

    I know a lot of people use corel draw or photoshop to draw their 2D, but both of those are very expensive. Cut2d is expensive as well, although not nearly as much and seems to be very feature rich.

    Any advice would be appreciated.

  2. #2
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    Re: CNC advice

    Mach3 Sucks. Go with LiunxCNC. LinuxCNC is Free and has allot more to offer than Mach3 ever had. As for CAM programs, CamBam is really nice. Easy to learn and does 2.5D and some 3D too. For CAD, just about anything that can make a DXF will work. I personally use Inventor.. Corel Draw and Photoshop would primarily be used for Laser Printers I'm thinking. Not very common in the CAD/CAM world.

  3. Re: CNC advice

    Thanks for the advice! Can I run LinuxCNC on my Mac? Or do I need to setup an Ubuntu VM to run it?

  4. #4
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    Re: CNC advice

    It has it's own ISO you can download (Ubuntu 10.04lts). You really can't use it on a VM of any kind.. (Can't with Mach3 either) They both require a Real Time Kernel. I would recommend get a Cheap ATOM based Computer and using it for a dedicated CNC controller. The Intel D525MW Mini ITX Motherboard was a nice board to use, but, has been discontinued You might look around for an equivalent board on newegg or something.

  5. #5

    Re: CNC advice

    I plan on using Mach3 as my controller.
    I use Mach 3, as adapted by Tormach for their mill (very mild adaptation AFAICT.) I like it just fine. It reads G-code, and drives the mill, with toolpath preview and calibration features, which is really all I need it for.

    I am looking for advice on how to create the toolpaths or Gcode.
    Writing your own is a reasonable option for simpler toolpaths. Especially if you want movements in 3D that aren't easily described in all "2.5D" packages.
    I use Cut3D to prepare toolpaths when I just want a program that works with a nice GUI and preview. It's not perfect, but it's easier to work with than the cobbled-together free options. Whether that's important to you depends on your budget.
    For high-end work, you'd want something like toolpath tools integrated into your cad/design packages, like Inventor.

  6. #6

    Re: CNC advice

    Quote Originally Posted by AVRnj View Post
    I am wondering what software you guys are using to create your 2D drawings, and also if you are using Cut2D or an alternative, if you can give me a feel for whether or not you like it.

    I know a lot of people use corel draw or photoshop to draw their 2D, but both of those are very expensive. Cut2d is expensive as well, although not nearly as much and seems to be very feature rich.
    Try to look at http://inkscape.org/ This is free opensource vector graphic editor. It has CNC plugin - http://wiki.inkscape.org/wiki/index....ry#Gcode_tools .



    It is opensource and written in Python, you can change it or create your own on it's base.
    Last edited by Dan_2013; 08-28-2013 at 07:07 PM.

  7. #7

    Re: CNC advice

    Quote Originally Posted by Connor View Post
    Mach3 Sucks. Go with LiunxCNC. LinuxCNC is Free and has allot more to offer than Mach3 ever had. As for CAM programs, CamBam is really nice. Easy to learn and does 2.5D and some 3D too. For CAD, just about anything that can make a DXF will work. I personally use Inventor.. Corel Draw and Photoshop would primarily be used for Laser Printers I'm thinking. Not very common in the CAD/CAM world.
    Please tell me more how Mach3 sucks, I must have missed it when I was making all of the cool parts I make... http://teamnarprojects.blogspot.com
    Does it have limitations and shortcomings? Absolutely. So do the HAAS and Hurco mills that cost a lot more money (I use these every day professionally).
    To the OP, good CAM software costs. I personally use Alibre/Geomagic CAM by MECsoft. They do a standalone product called visual mill, as well as plugins for various CAD packages like the one I use in Geomagic. FWIW I use Mastercam at work, and although it's super well featured, for what I do at home I've found the 2D and 3D (and 4th axis) in the MECsoft product to be able to do just about as much.
    Let me know if you need help configuring Mach3, it can be a little daunting. Got links to the machine, steppers and drivers you chose? Ballscrew or lead?

  8. Re: CNC advice

    Everyone, thanks very much for the feedback, I really appreciate it.

    Connor, I have an older Windows XP machine lying around doing nothing as I hate Windows, so I could use that to get up and running with Mach3 only buying the Mach3 license fee as a start. If I find it does not work, I will definitely look into buying a new box and running Ubuntu or something else, I did not know that either of these could not work on a VM, so I appreciate the insight.

    Jwatte, thanks for the info. When you say writing your own, I assume you mean writing your own Gcode? Do you find that to be a pain, or is it easy enough? I assume you use Mach3 to simulate the Gcode to see what you are going to get first?

    Dan_2013, thanks, I will definitely check that out. I always like opensource when it's a viable option.

    escott76, Understanding that on the CAM software costs, makes sense. I am used to 3d printing where everything is pretty much free, and good since its opensource. I will check out the packages you mention. As for the machine, I am going with the LittleMachineShop version of the SXL2, here is the link: https://www.littlemachineshop.com/pr...ory=1387807683

    I am using CNCfusion's conversion kit specifically for this machine, uses ball screws. Here is the link: Kit 5 http://www.cncfusion.com/minimill1.html

    For the motors and the drivers, I am using this: http://www.cncrouterparts.com/3-axis...-kit-p-74.html

    G540, 3 Nema23's for now. I would eventually like to upgrade to a 4th axis, but to get started 3 should be fine.


    Thanks again everyone. Spent some time last night playing with Cut2D as they give you a free trial version, and I found that I can easily create DXF files in openSCAD which is my preferred SCAD for 3d modeling, and import them into Cut2D and create the toolpaths rather easily and preview it. Cant wait to get this thing up and running!

  9. #9

    Re: CNC advice

    Similar to what I run, although my mechanics are all custom. Everything else looks good. If you do chose to run EMC2 it comes with an optimized and set up version of Ubuntu with all of the mods needed done to it.
    One thing no one has mentioned yet is pulse generation. Sometimes you can get away with parallel port pulse generation, sometimes not. This depends on the specific computer in question, specific parallel port hardware and a number of other odd factors. Timing is EVERYTHING when running one of these systems. I personally use a Smooth Stepper, which has done pretty well for me although I did have some issues with earlier versions of the driver code. It is Windows/Mach3 only, and uses a USB connection to get only trajectory data from the host PC. It uses an onboard FPGA dedicated to generating pulses, offloading it from the host. There are other add on PCI cards that will do the same and work with either Mach3 or EMC, they tend to be more expensive than the Smooth Stepper. If you are going to start with Mach3, take a look at the SS or the other options available. Will most likely save you some hair pulling down the line. When I have to do it all again I'll most likely just drop the coin on a Siemens 840 (I think thats the number) which is a regular CNC control.
    I started writing G code to run a HAAS TM1, and no it's not that hard. To the contrary you will learn a ton, and help yourself greatly when making the transition to CAM. In fact, if you can get experience with manual machining first I would recommend that you do that. I have had a number of kids work in my shop who had "been to school for CNC" but simply did not know the first thing about taking a cut with a machine, or how to use their senses to know when the machine was cutting well or not. CNC removes the manual "feel" that you get when cranking handles and the resistance that workpiece and cutter throw your way.
    You can use the graphics window in Mach3 or EMC to verify, you can also set your Z a few inches above the part and cut air. For extra safety turn your feed overrides down. If you are going to learn to write code manually, take some time to learn and understand cutter compensation (usually G41/G42). When you use this, you program the geometry of the part you want to cut, and the machine figures out how to run the tool diameter that you are using around it. Say you want to cut an outside 2"x4" rectangle. Instead of figuring out where the coordinates would work out using a .375" end mill you program the path of the 2"x4" rectangle with simple linear moves, starting and ending slightly (anything over half the cutter diameter off the part). The controller figures the rest. Very hand when you want to re-run an old program and don't have the cutter handy, or you are making a part to close tolerance and your .375" end mill is not .375" (far more often than you might think).

  10. #10

    Re: CNC advice

    When you say writing your own, I assume you mean writing your own Gcode? Do you find that to be a pain, or is it easy enough? I assume you use Mach3 to simulate the Gcode to see what you are going to get first?
    Custom Gcode is great for parts with simple lines, and cases where you need an arc to run in the XZ plane or similar, which Cut3D cannot do for you. It's also great for specific manufacturing, like drill patterns with successive offset or whatnot.
    There are a number of previewers available for the code; I get by with just seeing the toolpath for the simpler cases where I hand-code the Gcode. When you get into complex splines, the solid preview of Cut3D is very nice. I typically take vectors from Inventor, Illustrator, or Inkscape into Cut3D to prepare them when it's complex or organic shapes.

    Regarding the open source Inkscape toolpath option -- I tried to get that to work, and it just wouldn't work for me. This was on Arch Linux, which may or may not have anything to do with it. In general, the project seemed not nearly as mature as the real tools -- even freeware (not open source) on Windows worked a lot better. Cobbling together a bunch of crappy open source tools to make a working solution can be done and might be the best option if you are severely cash constrained. But time is the most limited resource for any human being, and I don't have the patience for doing that :-)

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