Very large problem on the Z

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Thread: Very large problem on the Z

  1. #1
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    Default Very large problem on the Z

    So my first playing around I noticed some bad parallelism issues when 4 squaring a block. Figured it was me as I wasn't being very detailed just running the machine through some test paces.

    Then when I had a small issue I needed to correct on the facemill I faced with a 1/2 EM and had some ridges I could catch my fingernails on. So I just sat down and releveled the machine (start from basics). Its as close to perfect as I can get. I do not have a master level but I do have 2 different Starrett Bench levels and they're within 1/4 of the vial indicators which means we should be around .001 in all directions. Tested in a few different spots.

    After that we do a test face and faced off a the 2" block with fingernail size ridges using my 3.15" facemill. Put the indicator on the spindle and indicated a .014" taper moving in the Y direction. Indicator tip starting on the edge closest to the column and moving Y towards the column the indicator falls .014. Moving X its perfect just a little wiggle from the movement.

    Reset the indicator on a mag stand setup on the vise. Indicate each tooth of the face mill and we are within .001 if I include the oddball tooth I need to look at. Everything else is within .0005.

    I zero on a tooth closest to me and again move the Y towards the column and there is an air gap between the indicator and the teeth.

    The Z is leaning very heavily towards the operator. This is a pretty big uh oh......

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    Default Re: Very large problem on the Z

    Hi Yugami. 2 things to try.
    1. with the indicator in place, push up on the head and see how much it moves. If it moves a lot you may have some bad rail blocks.
    2. level the machine, screw the 2 outside cent legs up. level with the 4 corners. put one level along the X and one along the Y. once it is level. put a indicator on a mag base and attach it to the spindle, bring the Z down and with the indicator facing you zero the indicator, set the indicator to sweep a 10" circle. sweep the table and note what the indicator is at all 4 quadrants. This is called TRAM. It is possible to "level to tram" and make the column move quite a bit.

    sportybob



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    Default Re: Very large problem on the Z

    I can definitely move it over .005 lifting the head up probably closer to 7 or 8

    How hard are those to replace?



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    Default Re: Very large problem on the Z

    Hi Y It is a Project.
    run an indicator all the table front to rear, is it flat?
    Try the level to tram and see what happens.

    sportybob



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    Default Re: Very large problem on the Z

    I'll have to try that next week. Currently have the tool changing air cylinder taken apart and the 3" face mill installed The indicator arm doesn't like to reach around that one. Once the cylinder is put back together I'll get on this.



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    Default Re: Very large problem on the Z

    I'm not 100% happy with the metrology of my setup but I have pretty consistent results.

    In order to span the nose to table gap I had to use a magnetic indicator base on the nose. A few attempts got the small base pretty secure without sitting on any bumps and supported so it doesn't wobble.

    Zeroing out 1" in from the table edge and ignoring fluctuation due to minor defects in the table the indicator falls off fairly consistently in both directions. Moving the Y axis at any point the needle stays pretty consistent. So I'm pretty sure its not table defects that cause my issue.

    Measuring an approximately 10" arc. Zeroing the indicator in the front (high point) the Z needs to be moved .052" down to rezero at 180 degrees.

    I have the mill low in the back and level from left to right. The level is bottomed out bubble disappearing and having to lift the tail end up significantly to get it to reappear. The .052 is down from .058 but thats not much of an improvement.

    Just pushing hard on the belt casting I can move the indicator almost .005 so when I was lifting I bet I was moving it way more and just couldn't see how far it moved.

    Bob, may need a run down of that replacement project. I'm guessing you have to crane the head off.



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    Default Re: Very large problem on the Z

    So after talking with Bob I found some surplus new rails and bearings which arrived much faster than I was expecting.

    Whats the key to getting these little caps off the rail screws?



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    Default Re: Very large problem on the Z

    small screw driver and hammer, pop a hole in it and pry it out. They will need to be replaced

    sportybob



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Very large problem on the Z

Very large problem on the Z