Re: Re: Re: Rack and pinion

>Message: 23
> Date: Fri, 5 Dec 2003 01:36:26 -0000
> From: "Dave Fisher" <dave@...>
>Subject: Re: Re: Rack and pinion
>
>All interesting stuff about the pros & cons of rack & pinion drive, I can
>indeed
>vouch for the accuracy and speed of the big Bystronic laser machines - and
>seeing them run
>is unreal !! However, could one of the many learned members of the group
>either
>point me to a site or in simple terms explain the concept of 'Preloaded'
>with respect to
>rack & pinions - I see this term in many posts and am not fully aware of
>what it means ?
>

Dave, One of the least complicated implementations of preload of a rack and pinion
drive has the drive pinion motor mounted on a hinge that lets the gear and motor rotate into
and out of the rack teeth. This device is then preloaded with a strong spring that holds
the gear tightly against the rack, thus eliminating backlash. If you can get a close
up shot of a Shopbottools.com, (the X axis assembly), their full size CNC router
uses this principle. It allows for dust and crud buildup that will stop other drive systems
dead in their tracks and still holds close enough tolerances for woodworking.

Fred Smith - IMService