On Sat, 19 Jan 2013 16:09:59 -0500, Steve Walker
wrote:

On 1/19/2013 12:17, PrecisionmachinisT wrote:
"Steve Walker" wrote in message
...
On 1/18/2013 22:56, PrecisionmachinisT wrote:
"Steve Walker" wrote in message
...

Got a new, oversize y axis gib for my bridgeport yesterday. Fitted it,
cut
the notch for the gib adjusting screw, drilled for oiling, and it's
working. Now working on cleaning the X axis scale, already did the Y.

Did you blue it up and scrape away material from the middle area so that
the
only surface in contact is an inch or two at each end ?





Damn. More work. I wondered why the one I replaced was worn only on the
ends. (the gib screw slot was broken)


Works well, just make sure you still have a good amount of contact area at
both extreme ends of travel if the gib is longer than other dovetail
(resulting in overhang)

While this does not affect accuracy at first, it allows for the gib to be
re-adjusted as it wears, due to the fact that most wear occurs at the ends;
once it's finally worn down to the point where there is full contact along
it's entire length, scrape away the middle area once more...if you do not,
then eventually what happens is you will only have contact in the middle
area, further tightening of the gib at this juncture, causing the mating
dovetail to undergo excessive wear at the mid-travel area.




Makes a lot of sense. Thank you.


Which is why those of us who either fix machines, or regularly have
them fixed..put the vise on the table in 3 locations. Right, Middle,
Left.

Using them for a year or s in each location tends to equalize the wear
across the full travel over time.

Gunner

The methodology of the left has always been:

1. Lie
2. Repeat the lie as many times as possible
3. Have as many people repeat the lie as often as possible
4. Eventually, the uninformed believe the lie
5. The lie will then be made into some form oflaw
6. Then everyone must conform to the lie