Yet another Bridgeport question?

While trying to track down slop in the x axis, it came down to the new big headed screw that holds the nut in place was a bit too long and was
bottoming before it captured the nut and let it float .010". I have it down to <.0005" of slop. Is this as good as I can expect? My brand new Kirk is out a bit less than half a thou. also and I don't feel like chasing it. Half a thou. here and there is going to add up pretty soon. Son-of-a-bitch! Why can't things just be perfect!
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down
is
Son-of-a-bitch!
Turn your vice so that the .0005 error cancels the one found in your table. :)
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Good thought but the table moves on the x half a thou and the vise bed is off parallel to the table half a thou over 6".
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Are you talking about backlash? You should be able to do good work on a machine with .005" or .05" backlash.
In fact, if you're using a proper technique, backlash should be entirely unimportant (although certainly annoying, of course). It is not appropriate to reverse any axis feed without accounting for backlash (even the knee). You must always account for backlash by moving back and beyond your next position, and then approaching it from the same direction as the previous position. While this may sound like a lot of work, it is a requirement for fine work, and will become second nature quickly.
Also, any axis which is not in motion *must* be locked during cutting. Manual machines *will* move if not locked, regardless of backlash.
I apologize if I'm telling you things you already know and not actually answering your question.

While the work you're doing will dictate the required accuracy, I generally don't chase .0005" over 6". It's not trivial to truly hit that with a surface grinder reliably without serious attention to warpage and cleanliness of your fixturing/part.
I make it a habit of, after snugging the x-axis lock, giving the table a good push/pull a couple of times to see if the gibs are tight enough (with the DTI on the vice jaw). If you're seeing the needle on the DTI weaving back and forth as you crank the x-axis, your gibs are likely not adjusted correctly which will prevent you from squaring the vice correctly, and will cause chatter and a loss of accuracy.
Regards,
Robin
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wrote:

So far, everybody I asked said they would love only half thou here and there. It's just that the BP is new and my expectations are high. I guess it's a curse that the DRO has five digits to the right of the decimal point and I don't believe that the scales are .00001 precise. I think I'll cover those last two digits with some electrical tape.
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On Sat, 03 Feb 2007 06:30:50 GMT, "Tom Gardner"

My Accurite 3 had the ability to go 5 digits. I read the manual and changed the jumpers for 3 +1, cause it was confusing the shit out of me.
Gunner, Gorton MasterMill, which makes a BP look like Gumby
"Deep in her heart, every moslem woman yearns to show us her tits" John Griffin
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