Z axis conversion

I tend to agree with your "intrinsically crappy situation" statment.
I keep going around in circles trying to figure out how to power the
Z axis. All methodes seem to be bad. People that have seen the
front quill methode of conversion tell me that the attachment screw
to the quill always comes loose. I would not mind modifing my J head
if i could come up with a good solution. And i still wonder if
moving the knee is a good idea or not, in terms of wear. And or
replacing the acme knee screw with a ball screw.


Wally K.




Marcus & Eva wrote:

> Hi Wally:
> All of the commercial conversions I have seen, mount a small Z

axis

> ballscrew to the quill.
> This is probably the least offensive way out of an intrinsically

crappy

> situation.
> The basic physics you are up against, is that an extended quill

flops around

> in X and Y, because it is cantilevered out so far.
> This makes heavy cutting impossible, and accuracy a hit or miss

affair,

> depending on how far out the quill happens to be sticking.
> Connecting the Z axis servo to the quill downfeed mechanism adds a
> horrendous and variable amount of backlash to the equation.
> I can't guarantee it, but I'm pretty sure you will be disappointed

if you go

> to all the trouble to make the mount, and then find you can't

machine

> anything to closer than boilermaker's tolerances.
>
> Cheers
>
> Marcus
> -----Original Message-----
> From: Wally K <cnc4me@u...>
> To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
> Date: Monday, November 27, 2000 6:06 AM
> Subject: [CAD_CAM_EDM_DRO] Re: wrong guy, but have servo question.
>
>
> >Jon Elso wrote:
> >
> >> I used 200 Lbs force for the quill, as that is what the

Bridgeport

> >J-head's
> >> overload clutch is set to on the power feed. I punched the wrong
> >jog button
> >> and brought a boring head down on my hand once, and it sure FELT
> >like
> >> 200+ Lbs!
> >>
> >> Jon
> >
> >
> >Wally K. replys:
> >
> >Do you think the feed mechanism could be used for the Z axis on

CNC.

> >I think the little hand wheel on the side of the J head can be
> >switched in to be manually turned to lower the quill. It would not
> >be to hard to put a motor in place of the handwheel.
> >
> >Is this mechanism made for this kind of duty cycly.
> >
> >And how much backlash does it have.
> >