DIY CNC Mill

Discussion in 'Shiny Things' started by RonS, Apr 15, 2012.

  1. RonS

    RonS Out there...

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    Lookding for advice. I’ve got this Rong Fu RF-40 knock off mill and a 6 inch rotary table that I’m thinking about converting to a 4 axis CNC. Looks like, at a minimum, I’ll need the following:

    4 stepper or servo motors of various sizes.

    4 stepper or servo motor drivers.

    Encoders if using servo motors.

    Motor couplers.

    Perhaps ball screws for X and Y precision.

    Motor power supply.

    Board power supply.

    Breakout board to drive the driver, process E-stop, interface to hand held pendent and interface to PC.

    Enclosure and various connectors

    PC w/Mach3 CNC software. Also used for software to tune stepper/servo motors.

    The other option to modifying the existing mill is pick up a mill like a Grizzly G0704 and start from scratch with a bit smaller mill that can be driven with smaller motors and cheaper drivers. Cost would probably come out the same. Planning on using Lazy CAD with Mach3 initially.

    Has anyone done this? Any words of wisdom or recommendations on which way to go?
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  2. a$$hole

    a$$hole Long timer

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  3. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Before you do another thing:

    How will you program it? Assume somebody GAVE you the machine you're dreaming of, how will you generate the code that runs it? Not the controller software but, the thing that turns a design into G-code the machine will use to make parts.

    Then: what do you want kind of parts do you want to make? Is the basic machine capable (mechanically) of doing the things you want? Spindle speed, HP, rigidity--all play into this.

    What I'm getting at is: will it meet your needs or dreams? Or will you sink $1K into making an interesting toy that won't really do what you want?
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  4. JamesG

    JamesG Rabid Poster

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    Most CAD/CAM software has the functionality to turn drawings into the machining operation and can spit out the G code instructions. I like CAM Bam the best.

    The real tedious part and potential to frustrate a DIY project to failure is tuning the controller (in this case Mach3) to get the mill to behave properly. Even a "plug and play" machine can be a PITA at first.

    @RonS- Have you ever set up and operated a CNC machine before?
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  5. jdiaz

    jdiaz .

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    If the mods only cost $1k, it would be the least expensive hobby Ron has had in the last 25 years. :lol3
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  6. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Although you already have a potential donor, you might want to keep an eye out for someones abandoned project. There was one on St Louis craigslist recently - Grizzly mill, Mach3/computer, some tooling, and a bunch of stock for $550. I almost bought it, but I have a Grizzly lathe at work and it is such cheap junk I didn't want to spend that much on something I'd be immediately looking to replace. Spindle run-out/rigidity is my main concern.

    I did acquire someones already-assembled DIY desktop CNC wood "mill" (just strap a Dremel to it) for ~$200 recently. I drive it with EMC2 software. I'm not sure if it's a real CAM program (generating g-code) as the little time I've spent with it so far, I've just manually written all my moves. I have to manually write tons of lines at work, so I'm used to the punishment.
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  7. RonS

    RonS Out there...

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    Solidworks for CAD, haven't decided on a CAM software yet and Mach3 for the control software. So basically don't know at this point. Probably start with writing my own G-code just to get to know it well enough to debug the CAM output when I need to. Will it meet my needs. Somewhat but I'm certain that what I really need is a 5 axis machine. In my dreams that is.
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  8. dorkpunch

    dorkpunch Oops...

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    Check instructables.com, seems like there were a few guys that had succesfully done this. Might be some good info over there.
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  9. RonS

    RonS Out there...

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    I'll look at CAM Bam. No, never setup or operated one. On top of that I'm not a machinist by any stretch of the imagination. I've worked with wood for 35+ years but metal is a different animal. I've had this mill for a couple of years and thanks to Smartflix I've watched enough instructional videos and butchered enough metal to have a basic understanding. Still, as an embeded software engineer I've done enough signaling (DIO, AIO), PID loop and stepper work that wiring the components together does not bother me. The tuning software for the servo's actully looks pretty interesting. It's the things I don't know that concern me. There'll be a good learning curve here. Maybe it'll keep my brain from rotting but most think it's already rotted to the core :lol3
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  10. RonS

    RonS Out there...

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    True :lol3

    It looks like a lot of work and a hell of a learning curve but it's something I wanted to understand for a while now. The biggest problem is that there appears to be a lot of domain knowledge that I'd rather not learn the hard way. It could turn into one of the more expensive hobby's depending on the volume "learning opportunities" (fuckups that is).
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  11. RonS

    RonS Out there...

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    Yeah, all these import mills (and lathes) need work. I've already replaced the spindle bearings and races with Timken's on mine. The thing is that they let you learn a lot with out spending big bucks and they do work (for some definitions of work).
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  12. dorkpunch

    dorkpunch Oops...

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    Another option would be to look into a community college or tech college. They will sometimes offer introductory courses that can teach you all of the basics PLUS you get access to some pretty sweet equipment. Then youll know if its something you really want to try...
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  13. RonS

    RonS Out there...

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    I might at some point but Smartflix offers full machinist courses and a lot of other metal working kind of courses. I've found them to be pretty good so far. When I feel like I need some additional training I can usually find someone to come out for a couple of hours (for cash of course) and provide personal instruction. Did that with Tig welding and didn't learn much that I didn't already know from other sources but it was a great help seeing someone who knew what they were doing and having them help hone my technique. Still needs a lot of honing though:)
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  14. JamesG

    JamesG Rabid Poster

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    Then you are better off than from coming the other way, a manual machinist trying to learn those infernal electric machines. Machining operations follow basic logic and common sense. The part that requires the skill and expertise is the actual cutting, and this is what the CNC automates.
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  15. SimpleSimon

    SimpleSimon Aspiring advrider

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    I have a similar model. I think you are better off just selling the round column and buying a BF-20, X3 or RF45 square column. There are turn-key conversions for the square column mills that are considerably less and the square column mills can be bought for what you can sell that round column for.

    My 2 cents.
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  16. Tman66

    Tman66 Shawn's bro

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  17. RonS

    RonS Out there...

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    Yes, I've come to the same conclusion. I'm going to pick up a BF-20 for conversion and keep the RF-40 for manual until I sell myself on a bridgeport.
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  18. GSWayne

    GSWayne Old Guy nOOb

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  19. RonS

    RonS Out there...

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    I'm currently looking at the CNC4PC servo cnc kit. 4 motors, drivers, breakout card, power supplies all in a prefab box for 1800. You can go cheaper by picking seperate components but this package is so easy. The 300+ inch/amp motors should drive that mill just fine
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  20. SimpleSimon

    SimpleSimon Aspiring advrider

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