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A bunch of beginner CNC router questions

Discussion in 'General Talk' started by Jason Kraft, Jan 15, 2016.

  1. Jason Kraft

    Jason Kraft Well-Known
    Builder

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    I'm working on designing and building my first CNC router. As I am not a mechanical engineer nor have I much experience with building (apart from K'nex and Legos from my childhood), I have virtually no clue what I'm doing. That said, I do know how to use a CAD program, so I've been working over the past two weeks to make what I think will be a working design.

    Now that I have completed a first draft of my CAD model, I have a number of questions:
    1. I plan on using 3/16" thick 3003 grade aluminum for my gantry supports since that was a cheap affordable option from my local supplier. I've never worked with 3003 aluminum before. Do you know if it will hold up to the strain of a CNC?
    2. My machine uses 3 Nema 23 stepper motors (2 for the Y-axis and 1 for the X-axis along the gantry). Would this be considered overkill for my system, and could I get away with a Nema 17? The X and Y motors are each turning a 500mm lead screw.
    3. Since I don't have a CNC to help make my gantry supports, I plan on borrowing a drill press to make all the holes and couterbores. Since my X-axis uses a lead screw that must be kept straight and I'm essentially making the supports by hand, how can I keep my tolerances as narrow as possible while drilling?
    4. Furthermore (from question 3), what would be considered acceptable tolerances for such a design?
    5. Lastly, do you have any suggestions on how I could improve my current design?

    Here's my progress so far:

    TRIMETRIC VIEW
    FRONT VIEW
    RIGHT VIEW
    TOP VIEW
    I know that was a lot of questions thrown at you, so if you'd prefer, I could separate these questions into individual posts (I'm not sure what is considered the proper etiquette on this forum).
     
  2. ChadRat6458

    ChadRat6458 Journeyman
    Builder

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    I would stack the plates on top of each other. I would use some double sided carpet tape to hold them together. You can get it at home depot. I would use a fence on the drill press table to make sure everything lines up. You might be better off buying the plates. In the future, you will be able to make your own.
     
  3. Joe Santarsiero

    Joe Santarsiero OB addict
    Staff Member Moderator Builder

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    Hey there Jay,
    Using 3003 to start with is fine. Machinining it may be the difficult part. It is soft and likes to plug tooling. It's a little easier with the hardened variety. If you can find it in a hardened condition it'll be a little more workable for you.
    Regarding drilling the plate holes yourself on a drill press, you should be okay. Other members have done the same with decent results.
    Remember to square up the table as best as you can . As Chad mentioned, drill the plates together as one. Good center punch location and pilot holes will help with alignment as will a fence. Once you get the machine dialed in and trued up you can make another set of you're not happy.
    It is best to have them made by another piece of CNC equipment. Next best is on a manual mill. Worst case would be by hand drill (brace and bit.lol).
    Sticking with the 23's is a safer bet imo.

    Joe
     

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