[str8tjaket]

Hey guys hope you can point me in the right direction for adjusting the run out on the z axis, if I turn a 3" dia x 5" long down to 2.75" dia i Get about a ..005" to .006" fluctuation on the diameter at the point which I end face it is 2.745 but near the chuck it is a true 2.75 so its cutting on a taper... not sure how to go about alignment on this machine.
thanks

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much appreciated

[md63825]

First, what machine?

Next, you'll need to determine if the taper is due to wear on the ways or if the head is out of alignment. Older machines get a lot of wear over time on the ways close to the headstock. As the carriage dips down into this worn area, the tool center falls below the part centerline and produces a taper measuring smaller to larger as you get closer to the headstock. Not much you can do about that except to have the ways ground or scraped. If the headstock is in fact out of alignment, the taper will show up along the full length of the bed. If this is the case, then yes the head can be aligned. This is normally performed by loosening the bolts that attach the headstock to the bed. Behind the machine shield under the headstock, there are jack screws that move the front of the headstock similar to the adjusting screws on the tailstock. You will have to mount a gage bar in the chuck, indicate it in and traverse the carriage along this bar with an indicator to get it running parallel to the bed. Not necessarily an easy task.

[str8tjaket]

the machine is an ez path 2, I will look into this, but how do i determine if its the ways or the jack screws....should I indicate first and see if the taper is through out the entire travel of the machine? also is there a manual of some sort that i can download so I can have a visual??
thanks for your help

[md63825]

You can determine this a few ways (no pun intended). One way would be to take a precision round bar (Turned, Ground, and Polished (TG&P) will work) about 20" or so long and indicate it in at a location as close as you can get to the chuck and at the other end close the the end of the bar so your total indicated runout (TIR) is less than 0.0005" at each location. Mark these locations for reference. With this, you will know that the bar is parallel to the theoretical centerline Z-axis through the headstock. Do not support it with the tailstock. It should be held only by the chuck. Once it is solid and true, place an indicator on the carriage and position the needle on top of the bar and move the x-axis in and out until you find top dead center (TDC) at one of the reference marks where you indicated the bar. Record the X-axis position on the screen. Note the needle location on the indicator and traverse the carriage to the opposite end. Watch the needle movement. Once you are at the other reference mark on the other end, again move the x-axis in and out to find TDC. If TDC location on your needle is the same and the x-axis location on the screen is different, that is a good indication that the headstock is out of alignment. If TDC is different and x-axis location is the same, then that would tend to indicate that the headstock is aligned properly but you have wear in the ways. This is a method that I have used many times in my 20+ years as a machinist but I am sure there are other methods that will work the same.

I have attached a copied section from my manual on the issue of alignment. I do not have a digital version but you can find them on ebay sometimes.