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Milling around in circles again...

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  • Milling around in circles again...

    Been playing with several different ideas for a small mill - gave up on the idea of the old vertical mostly because of the weight...8*(

    Specifically, I'm thinking of an adaptation of a speare drill press I have in my shop for light-duty work. In replacing the bearings in the present quill, I find I'm going to be restricted to a shaft size of 3/4" or so without reboring the casting for a new quill - and that gets into the realm of not-worth-the-effort.

    My question is this - to take a reasonably sized collet (R8) I'm thinking of putting a larger-diameter spindle nose on a piece of 3/4 grund machinery tubing . Seems to me that I could shrink fit that on, then true it up as an assembly. Bore to proper size, then finish it up actually in the mill to ensure it's running true.

    Drawbar would then close collet from the back - that's pretty well a no-brainer.

    COmments on the concept of the spindle nose being an add-on? I don;t want to hog down a 1.5" bar to 3/4" for the shaft... WAY too much work.

    ajr

  • #2
    3/4 is too small for an R8 collet that has a .950 shank dia, Check here for collet dims.
    http://www.cox-internet.com/drspiff/...Collets.htm#ER
    and a drill press is a very poor substitute for a milling machine. Milling machines need rigidity from side to side, a drill press has none. There are a number of machines out there that weigh less that 8000 lbs. Many of them are bench top models and some come with a cabinet for storage of tooling.
    Check of MSCdirect.com for an idea of what to look for.

    ------------------
    Paul G.

    [This message has been edited by Paul Gauthier (edited 02-02-2005).]
    Paul G.

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    • #3
      By "finish it in the mill" I assume you mean the drill press converted into a mill? How do you plan to grind or bore the "spindle adapter" to the proper dimensions for an R-8 collet once it is installed to have it run true? Unless the castings and the drill press itself are heavy and rugged, ANY attempt at a conversion into a mill may not be worth the effort, regardless of how "light duty" you intend it to be, IMO. There are features on a mill that will be of benefit that you may not have on the drill press. Depth stops, quill lock, table locks, etc. Unless the drill press has one already, you will need an x/y axis table also. My opinion FWIW, if you need/want a mill, save your resources, persue obtaining one.


      [This message has been edited by ERBenoit (edited 02-02-2005).]
      Paying Attention Is Not That Expensive.

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      • #4
        TO be honest, this thing has most of the features in question already. It's sn ancient Atlas press - lots more CI in this thing than in any of the import mill drills.

        I misspoke using the R8 designation - there is a smaller collet size thart would suit but I don't have the designation of it offhand.

        Having seen an Edgar Westbury design for a light vertical mill that is much like what I'm imagining I think this would be worth the effort of at least thought experimenting it out.

        BTW, I'm not an idiot, of course I'm changing the quill bearings for something suitable...SKF makes a very nice dual-row angular contact ball bearing that is a good fit for this application.

        ajr

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        • #5
          mrchurchhill,
          This is a photo (poor quality) of the quill lock that I made for a small import drill press so that I could use it for light milling. I couldn't take more than a .010" cut (1/4" endmill) with it because the spindle shaft was so thin that it would flex. It may give you some ideas for the quill lock on your project. The drill press that you have will work if anything will. Hope this helps. Have fun with this project.

          To invent, you need a good imagination - and a pile of junk. Thomas A. Edison

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          • #6
            THanks, George!

            There's a quill lock already built into the castings - quite a beefy thing. Essentially it's two sliding bevels pinched by a pinch bolt which locks the quill in its bore.

            The change this is going to need is a method to raise and lower the head on the column - I'm eliminating the sliding table completely because that simply wouldn't be rigid enough.

            I'm going to end up milling the casting for a rack and pinion drive and a pair of gibs - this will prevent rotation of the head to the column and give me gross vertical adjustment, with fine adjustment to be from a worm gear setup on the quill pinion.

            This ought to be entertaining...8*)

            ajr

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