I hope you realize that some of that will depend on your level of proficiency. Running machine tools with precision requires some very careful steps, consistent clamping, consistent locking of devices. It gets down to almost everything making a difference. It's something you'll come to understand as you become familiar with your given machine----so do be a little patient at first. And please remember that it's easy to make chips, but not so easy to make good parts. It comes with experience.Bolsterman wrote:Indeed. I would be pleased if I could keep the machine itself square within .001 over 5" and would settle for .002. As far as projects are concerned, I'm hoping I can hold .003 on small items (think 5" or less) and would grudgingly settle for .005.
Judging from your comments, below, that may be part of your problem. You should not experience excessive movement when locking a slide. Depending on the nature of the lock (BP, for example, always moves a little), you shouldn't see more than a thou, and less is very desirable.I did not remove the Z gib for inspection.
That you misunderstood it isn't as important as the information you now understand, so you can see the significance of what I said.I think I understand your advice about method sequence now (I misunderstood it the first time you gave it!)
That's correct, but when you're running the head up and down, determining the attitude side to side, it will be wise to do the same with the indicator touching the face of your angle plate (square) while it's facing the column. There's no guarantee that your spindle housing is bored parallel to the ways. It would be useful to you to know if the column is proper in both directions. Once you have the column properly aligned, then the reading you get from your spindle will be indicative of the quill as it relates to the column. You have adjustment for side to side, so that's a non-issue. If you find you are out front to back when the column is erect, you're going to have to make some decisions about how much error you can live with. That's assuming that there is no mounting surface between the head and column ways. If there is, the surfaces can be altered to correct parallelism.but just to make sure: First you get the column square left/right by using the indicator running vertically against an angle plate. You use the Z-axis crank only (not the quill feed) to move the head up and down. THEN you perform the sweep method referencing against the table, and rotate the head as needed to get that as good as possible. When it comes to correcting front/back, if the chin is dripping, I'd need to place a little shim under the bottom two bolts holding the head to the column, right?
Definitely you should investigate the gib, and how tight it is. Make sure it is bearing full length. When properly adjusted, you should see little movement when tightening.
I've noticed that my head shifts position between .002 and .003 when tightened (with the "chin" coming up, obviously), and the amount you tighten it does make a difference! I've wondered how to deal with this when Z-axis movement is necessary to make the cut. With testing so far, it seems it'll cut up to .003 deeper if the head isn't locked. Well, you can't lock it when you need to plunge a cut, so...here's maybe an .003 I'll just have to live with.
Harold