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Thread: Mini Horizontal boring mill build

  1. #1
    Join Date
    Mar 2006
    Posts
    1,182

    Default Mini Horizontal boring mill build

    Time for a dedicated thread as the machine is becoming a reality now.
    Early threads with some discussion here- http://bbs.homeshopmachinist.net/sho...ghlight=gilman
    and here- http://bbs.homeshopmachinist.net/sho...lding+machines

    So basically I'm building a small horizontal boring mill/lathe.
    The bed and base is a high end Gilman box way slide. .ooo5" accuracy over 3 feet. Meehanite iron base with hardened and ground rails. Scraped bearing surfaces and anti friction coating on the gibs.
    The 2 columns are from a Sieg mini mill. The spindle is from a Sieg mini mill retrofitted with better bearings.
    The z-axis for the horizontal spindle is 16tpi acme with a delrin nut. A gas strut will be used for counterbalance.
    .2 pitch ball screws are used on the long and cross feed axis with dual preloaded nuts. 269oz steppers on each axis. The cross feed has been tested at a smooth reliable 200IPM and I have not yet fully tested the long axis as I just finished it today.
    The cross feed table is mounted to a doweled sub plate so it can be easily removed for parts that might need to be mounted directly to the table.
    The z axis is manual for now.
    The spindle will be indexed with a proximity sensor and this info sent to mach 3. This will enable the machine to cut any pitch thread.
    The spindle transmission is a 3 speed planetary drive with reductions of 72:1-40:1- and 13.5:1 and features a detent torque sensing clutch. A direct drive mode with slight reduction is also available by swapping the belts around.
    Spindle speeds of around 20-3000+. A dc 5000 rpm motor and a Minarik DC drive will be used.
    The boring bar in the pictures is there for scale. It is 1" diameter by 13" long.
    The end support column can either be stationary and locked to the bed or towed with a strap by the main table.
    The end column uses a rack and pinion for it's z-axis with fine feed. Heights will setup equally with a height gage.
    The end column still needs to be finished.
    A sliding support for the spindle will be built to give the headstock better rigidity.
    I plan on adding another stepper to allow indexing the spindle and a small grinding/milling head to be used on the cross feed table.
    Once finished I'll paint and pretty up the machine.
    Steve
    Main table-
    long axis ball screw with soft limit-

    Stepper mount-

    cross feed table-

  2. #2
    Join Date
    Mar 2006
    Posts
    1,182

    Default more pics

    another view of cross feed, it has 6.5" of travel so can be used for as a small gang slide in cnc lathe mode-





    Steve

  3. #3
    Join Date
    Jun 2008
    Location
    SF bay area, California, USA
    Posts
    1,054

    Default

    What happened to the bevel gear and crank drive?

  4. #4
    Join Date
    Mar 2006
    Posts
    1,182

    Default

    What happened to the bevel gear and crank drive?
    That setup went into the parts bin once I decided to cnc the machine with ballscrews. Originally this was to be a manual machine. But it just made sense to cnc it instead.

  5. #5
    Join Date
    Mar 2001
    Location
    Nottingham, England
    Posts
    15,195

    Default

    Steve,
    Very impressive, will there be any form of eccentric drive to the boring bar like the commercial ones or will it just be plain bar ?
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  6. #6
    Join Date
    Mar 2006
    Posts
    1,182

    Default

    Thanks John, Right now I'm thinking of just using plain bars. An auto facing head would be nice though. While many times I have wished for an easier way to line bore some of my projects I know that line boring is not something I'll be doing all that often. So it made sense to cnc this machine and also make it a cnc lathe. The adjustable spindle height axis (and once a stepper drive of some sort is added for position indexing with live tooling on the table), I think it should be pretty versatile.

    Open to any and all suggestions!
    Steve

  7. #7
    Join Date
    Mar 2001
    Location
    Nottingham, England
    Posts
    15,195

    Default

    Any chance of a close up of the spindle nose.
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  8. #8
    Join Date
    Jun 2007
    Location
    North of of the fudge tourists
    Posts
    655

    Default

    Keep posting please. Too damn cold to play with my machines so I'm having to watch the work of others.

    Nice work so far.

    Clutch

  9. #9
    Join Date
    Mar 2006
    Posts
    1,182

    Default

    John, the spindle is a mt3 tapered mini mill spindle. I have a ETM brand mt3 shank er32 collet chuck inserted in it which has excellent low run out.
    I also have a mini lathe spindle with the flange for bolt on chucks I could use. But I thought the mill spindle without the flange would be better suited for this machine as I don't intend to do much chucking work. But I do plan on a making a mt3 shanked 3" 4 jaw chuck for occasional use. I also have mt3 collets.

    What are your thoughts?





    I figured for this machines size and hp that any tooling I use would be adequately held by the er32 chuck. I quasi line bored my SB9 headstock using this milling head and hardly any belt speed reduction from the motor and had excellent results.



    Steve
    Last edited by S_J_H; 01-17-2009 at 06:50 PM.

  10. #10
    Join Date
    Aug 2004
    Location
    Central Queensland, Australia
    Posts
    2,187

    Default

    What spindle bearings does it use and how do you preload them....


    Great looking machine...I envy the skills of many on this board...

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