re:Re: Re: Is this too nuts to consider ?

Alan,

How about using the 'screwless' leadscrew idea mentioned a short
while ago? Three small bearings mounted through the outer tube at the
pitch angle, and spring loaded towards the inner tube? Your
application should be clean enough for this to work well!
Repeatability might suffer some, but I don't think this would be a
problem in the focuser app...


Whaddya think?

Ballendo

P.S. For this app, I'd definitely look at using a cable to pull the
saddle of the lathe.(Imentioned this earlier) Mount a die grinder
with a ball nose cutter on the toolpost, and turn the spindle by
hand, wrapping the cable, which pulls on the saddle... Like a taper
attachment, sort of... only working the saddle, instead of the
crossslide.

On 25 Jan, CAD_CAM_EDM_DRO@egroups.com wrote:
>
> Personally, I think it would be much simpler, quicker and lots
cheaper to
> simply use a differnt gear ratio on one of the compound gears
between the
> spindle and the gearbox.

It would be, if I could find suitable gears. Unfortunately, I can't.

The manufacturer sells a pair of gears that gets things down to 4TPI
with the stock leadscrew - with my fancy ballscrews, that means 8 TPI.

What I want is ONE TPI.

I'm making a focuser for a Newtonian telescope .. a tube inside a
tube, basically. I plan to cut the coarse thread on the outside of
the inner tube. The outer tube will have a single small diameter
ball
spring loaded, pressing into the thread.

Alan