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View Full Version : How to properly adjust gibs on IH Mill?



kumaichi
08-01-2007, 11:50 AM
HI All,

I was wondering if there was anything written on how to properly adjust the gibs on my IH Mill? I've never done it and I think it might be time to do some maintanance on the mill.

Any insight, techniques or suggestions would be greatly appreciated.

Have a great day,

Craig

IHCNC
08-02-2007, 12:58 AM
Adjusting a gib is not rocket science, but more of a feel. Easy to do if done in the right sequence. First loosen the slide locks, (chrome and black handles on the X-Y and Z Slides). They are used to lock the table and column slide, not tighten the gibs. OK lets do the X gib first. This is where the feel thing starts. Turn the handle by hand both ways X-, X+. Get the feel of the pressure needed to move the table. Second loosen the gib lock bolt on the left side of the slide. 2 or 3 turns is enough. Third, tighten the right gib bolt until the table gets a little harder to move. Use the right handle and turn only clockwise to get this feel. 4th, Back off the right gib bolt 1/2 turn then lock the left gib bolt and try moving the table back and forth and see if is to tight(to hard to turn by hand). If it feels good leave it, if not begin the sequence again till your happy. Remember when tightening the gib only test it to the left until you tighten the lock on the other side otherwise you will get a false feel. The Y and Z are done the same way. The Y would be tightened by the front bolt and tested clockwise. The Z would be tightened by the top bolt and turned clockwise. Be careful on the Z, it might feel good going down, but be a bear to lift up. Find a happy medium. Be patient and don't leave out any steps or take shortcuts and you will be happy with your results.

kumaichi
08-02-2007, 11:39 AM
Thanks for the detailed steps, that will help a lot. One thing I forgot to mention was that the machine is converted to CNC :-(. Is there a way to duplicate the feel part?

Thanks again for your help and all that you do,

Craig

Andre' B
08-02-2007, 01:50 PM
With servos you can put a meter in the circuit and watch the motor current, with steppers I think you are out of luck.

IHCNC
08-02-2007, 04:28 PM
Adjusting the gibs on an IH CNC Mill is still a matter of feel, but it is also a matter of measurement. Move the table to the center of the mill, both X and Y. SHUT OFF ALL THE POWER!!! Again lets do the X gib first. Turn the X axis knob moving the table back and forth about an inch either way. Get a feel of how hard it is to turn. Practice a little to really get the sense of pressure needed to move the table. Now comes the measurement part. A good test indicator is needed to do this part because you will be measuring in tenths of a thousandth. Lock the Y axis with the lock handles so there is no Y movement. Put the test indicator on the Y dovetail and the tester tip on the table side. Grab the table and try moving it front to back and read the movement on the Gage. We set a new CNC Mill at 1 to 2 tenths of a thousandth pulling hard on the table end. Adjusting the gib as on the regular mill. Make sure that when you are done the table still moves at the same pressure as before. On a broken in mill you should be able to get this movement to 1/2 a tenth or less and still have a good feel. To do the Y axis just lock the X axis and do the same procedure. Just move the test indicator down to the slide just below where you tested the X axis. You should get the same results as with the X axis. When setting up your test indicator have the touch probe at about a 15 degree angle to your work to get the best results. The Z axis is done the same way. Get the feel, check your play, get rid of the play and most important check the feel as not to overwork your servos. With Zero play on your X and Y ballscrews and zero or almost zero on your table you should be able to CNC in the low tenths of a thousandth without using any backlash settings in Mach, which we never do.(not needed) Again be patient and careful and have fun.