Re: help with Y axis on bridgeport

Jon, i read your post and all the other peoples posts that responded,
3 times. I thank all of you for responding.

I was dumbfounded to learn the end of the Y axis screw is unsuported
inside the milling machine after it passes thru the nut.

So if i understand this correctly when i do the acme to ballscrew
conversion the ballnut in the machine is the only support for the Y
axis free end.


Wally K.

--- In CAD_CAM_EDM_DRO@egroups.com, Jon Elson <jmelson@a...> wrote:
>
>
> 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