Re: Backlash Fixes

YM,

Here's a few new pictures of the device and little article about
how it works:

http://www.dakeng.com/backlash.htm

The force on the slide is 15-20 lbs depending on position (spring
rate is 120 lb/in IIRC). Why that particular size force? Well,
that's how much the 1 gallon paint cans weighed that I had on
before. Scientific, eh? :)

A little "egghead" work in Excel on available envelope and forces
produced the best lever length and spring characteristics.

Actually, most of the force goes to overcoming the friction of the
gibs, in order to guarantee the postion of the slide.

Dave Kowalczyk
Seattle WA

--- In CAD_CAM_EDM_DRO@y..., ym_wong@p... wrote:
> --- In CAD_CAM_EDM_DRO@y..., dkowalcz@d... wrote:
>
> > It's a small aluminum lever with its fulcrum mounted on an "L"
> > shaped bracket on the carriage. One side is pulled by a strong
> > tension spring.
> >
> > The other side is attached to the cross-slide by a short cable.
> >
> > Why so complicated? Well, regular tension springs don't
deliver
> > constant force over their span. Instead of using 3" of travel on
> the
> > spring this gadget makes it 1/2" through the lever, so the force
on
> > the slide is more consistent.
> >
> > If you need a better picture, I can take one when I get home as
> my
> > lathe is apart right now for maintenance.
> >
> > Dave Kowalczyk
> > Seattle WA
>
> Yes, a picture or two would be great. May be one showing it in
> relation to the carriage & cross-slide, i.e. perhaps a bit further
> away so I can see the "bigger picture". A closeup of the assembly
> would also be nice as well, however.
>
> How much force is the spring applying to the cross-slide, do you
have
> a guess? I assume it must be greater than what the cross-slide
> experiences during cutting. I wonder how much that would be?
Perhaps
> a better question is how did you pick your spring?
>
> Thanks.
>
> ym