RE: [CAD_CAM_EDM_DRO] Re: ball screw preferences

Really I would think the two are only to stop backlash, on a mill a ball
screw without backlash adjustment is normally within about 0.5 thou of
backlash, mine measure at about 0.2 including the endfloat on the main screw
which isn't bad.

On a router though at least the wood ones, you aren't looking for that kind
of accuracy. I would try using one and measuring the backlash. Make sure
there is some sort of wiper on the end to keep the dirt out. Mine don't have
seal wipers between.

If you building a small router for something like PCB work, then backlash
might be more critical.

Since one normally pushes against the other with a set preload, I would have
thought they may well be a lot more efficient (free) with only one ball nut.



Regs Mark



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of wjstape
Sent: 09 March 2007 17:54
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: ball screw preferences



Hi Mark. I am building a CNC router using some parts I scrounged
from a friend. The x-axis ball screw assembly I am using has a
double nut arrangement similar to the one you described. This
arrangement is designed to eliminate backlash but at the expense of
full travel. My question is can I take of one of the nuts
without "screwing" things up? I need the extra travel. WJS

--- In CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com, "Mark Vaughan" <mark@...>
wrote:

>
> Curious you picking two ball screws.
>
> I've just stripped the ball screw on my big mill. Those I have

stripped in

> the past were always one track with a bit of pipe to return the

balls from

> one end to the other.
>
> Now I have it apart, my machine uses two ball nuts, each runs the

balls in

> one turn with a junction to drop the balls one turn. They do this

five times

> in each ball nut. But the ball nuts come together with a taper face

and a

> sprung steel ring with tapered faces between on a clamp, tightened

to zero

> the back lash.
>
>
>

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