Re: Ball screws

Allan:

Thanks for the help, the dwg files look great. I have to check the
dimensions of my mill to see if they are comparable with yours. The
screw sizes on your drawing show a screw with a 3/4" diameter. What
criteria made you come to select that size of screw?
On my machine I would like to use some form of feedback loop that is
relative to the table position and not the screw angel. I was
thinking that way I could lower the cost of the screws by purchasing
a rolled screw verses a ground screw. The only disadvantage that I
can see is that I would have to develop the preload set-up for the
nuts (two nuts with a spring or solid shim) to minimize the
backlash. I have seen and heard of some different methods for
encoding the table position, rack & pinion, cable & pulley, friction
wheel. Do think that using a simple method of encoding table
position like the ones above along with less expensive ball screws
and still be able to maintain good accuracy (0.001 tol. or better) is
practical?
If you are still looking screws for your machine, ball screw
manufacturers like Tompson, Nook, and BSA have online catalogue that
you can download. They all are similar and most have some drawings
that you can view (pdf format).

Trevor

--- In CAD_CAM_EDM_DRO@y..., allan_r9@h... wrote:
> Trevor,
>
> I uploaded the .SAT 2.0 file and .DWG Acad14 files as zipped files
to
> the files section. Look under Drill 2HP model folder. The 4 axis
> file is not mine - don't know how it got into the folder I just
> created.
> Before trusting my dimensions, check your machine before cutting
> parts. I used a tape measure for the larger parts during
modelling,
> so 1/16" accuracy. Also, these machines may vary slightly during
mfg.
>
> Allan
>
>
> --- In CAD_CAM_EDM_DRO@y..., tbrooking@s... wrote:
> > I am intersted in your modeling of the screw components. I am
> > currently using autocad r14 for my cad work, if you could e-mail
me
> > the files in a format supported by autocad r14 that would be
great.
> >
> > Thanks
> >
> > Trevor
> > --- In CAD_CAM_EDM_DRO@y..., allan_r9@h... wrote:
> > > Hello,
> > >
> > > I too am shopping for ball screws to convert my GEM500 to CNC,
so
> > I'm
> > > interested in the same answers you get. I did convert an Enco
> > > Mill/Drill (2HP version) to 3 axis CNC using Kerk Motion
Products
> > > zero backlash nuts and screws (not ball screws). I wish I had
> gone
> > > for the ball screws now. I have all the pertinent components
> > > modelled in 3D solids. If you would like the file, let me know
> what
> > > solids format you can use. The Mill/Drill started with Ah-ha
> > control
> > > and Gecko G201 drives with 3 Sanyo-Denki 720oz/in motors, then
I
> > > bought the BDI disk from Paul at the NAMES 2001 show, and got
the
> > EMC
> > > control working. It runs much smoother than the Ah-ha
control.
> > The
> > > EMC system will be used for the GEM500 conversion which will be
a
> 5
> > > axis machine. The 3d model for this machine with 5 axis
trunnion
> > > will be placed on the files list soon.
> > >
> > > Allan