Re: Asian Import mills, EMCO, PRAZI, Myford, MOTORS

Cadman,

This is a tapered Gib. As the single screw moves it in and out it
DOES tighten and release the clearance on the axis. The sherline uses
a similar technique.

There are a couple of gotchas however:

1) The taper of the gib needs to match the machined taper of the
saddle for the gib to have equal pressure/adjustment along its'
full length.

2) The slot FOR the adjusting screw head is wider than the head of
the adjusting screw. This allows the gib to move when the axis
changes direction, which means it is either too tight or too loose
(depends how you look at it <g>) during one direction of travel.

For 1) You can lap the gib and axes to a better fit than the factory
provides. Be sure to use non-embedding lapping compound. It is
available at Mcmaster-Carr. It is also worthwhile, IMO, to dis-
assemble the xy table and do some de-burring of ALL these parts!

If you lap, keep in mind that you DON'T want a completely shiny flat
surface on the ways! This will make them stick, and is the reason
there is a pattern of "scratches" to let air/oil into the space
between and prevent this sticking on the machine as delivered.

For 2) Fit a shim in the slot or make a new adjusting screw to
eliminate the sloppy adjustment of the gib. This is probably the
single most important mod to do to a mill/drill. If you have a lathe,
you can turn a "step" in the outer part of the top of the adjusting
screw. Then turn a ring (same diameter as the screw head) to fit
tightly and glue/braze in place. This "extends" the screw head, while
still allowing the slot in the screw head to be used for adjustment.
Now face the added ring to the EXACT thickness of the slot in the
gib. a file or emery paper can be used for final fitting.

___ ___
| |_| |
|___ ___|
< >
< > orig. screw
< >
_ _
| | | | -- ring to extend head thickness
|_| |_|

_ _
_| |_| |_----- Turned recess in head fits ring above
|___ ___|
< >
< > modified screw
< >

Hope this helps.

Ballendo

P.S. I've always thought a Jib was a foresail on a boat :-)



<snip>What bothers me is the "Jib

>adjustment" They only give one screw to tighten the ways. It is
>located at the end of the jib (If you can believe that). I am not
>sure if it does anything at all. The only real jib tightning is
>done by the way clamps. You know the ones that you tighten to lock
>the way from moving.
>
> CADMAN