Re: [CAD_CAM_EDM_DRO] help with Y axis on bridgeport

Wally K wrote:

> I am trying to design the mounts for a bridgeport retrofit to CNC.
> my machine is assembled and i cannnot see how the internal end of the
> Y axis is mounted. Does anyone have pictures or drawings of this.
> Or any words of advice.

By the 'internal end' do you mean the Y nut? The X and Y nuts (on a
manual Bridgeport Series I) are keyed bronze sleeve-nuts that slide
into holes bored in the 'Yoke'. The yoke bolts over (and through)
a rectangular opening in the heart of the saddle. 4 Socket head
cap screws bolt straight down through a flange on the yoke into the
saddle. The X screw passes through the top of the yoke (and over
the top of the saddle). The Y screw passes through the bottom of
the yoke (and underneath the saddle). There is no rear support
for the Y screw - it is fairly short.

If you want to see the assembly, remove the left end bracket on the
X screw, and remove the nut, handle and dial on the right side.
You should now be able to screw the X screw loose from the
right side bracket. When it is free, slide the table to the right.
Be careful, it is at least theoretically possible to make it sail
right off the machine, although it will usually bind a bit at the
extreme end of travel. When it gets farther to the right than
possible with the left bracket installed, you will expose the
yoke, and can look down somewhat into the knee.
The table cannot be removed to the left, as the casting is much
heavier at the right end to accomodate the weight of the power
feed. (The original gearbox-style power feed weighed 88 Lbs!)

To remove the Y axis screw, remove 4 socket head cap screws
on the plate around the Y dial, and simply unscrew the screw
out of the nut, while gently supporting the weight of the outer
end. You can clean and relube it before reinstalling.
This gives the best access to the knee interior for cleaning out
swarf (Gasp! How did all that &$#& get in there!!!), checking
the condition of things, etc.

In both cases, there are pairs of bearings (at the Y mount, and
the LEFT X axis bracket) that constrain axial play in the leadscrew.
A quick and dirty CNC conversion can be done by just belt-driving
the ends of the screws with a stepper motor. The ends of the screws
have keyway slots fot the handles. You could get toothed belt
pulleys, bore to compatible size and install matching keyways.

Jon