Re: unbalanced load

--- In CAD_CAM_EDM_DRO@y..., cadcamcenter@y... wrote:

> Hi,
>
> Table ___
> | || |
> | <-------)
> Drive nut solid coupler |___|| |____
> |
> | | |
> \/\/\/ |______| |
> /\/\/\/\/\/\/\/\/\/\/\/\___ __________|
> __| |__________ Stepper
> /\/\/\/\/\/\/\/\/\/\/\/\/ ______ | Motor
> /\/\/| | | |
> | | |
> ___ | ____
> | || |
> | <-------)
> | ||___|
> Table
>
> In the above arrangement, the stepper motor is fixed directly to
> the "table" and to the leadscrew via a solid coupler. The other end
> of the leadscrew is left free-standing and is only "supported by

the

> drive nut. In view of what has been mentioned about unbalanced/non-
> coaxial load leading to the rotor rubbing against the stator of the
> steppper motor leading to premature failure, is the above arrange
> likely to lead to such problems?
>

Peter,
Yes this arangement isn't suitable as it's missing some form of
thrust bearing. The end bearing in a stepper isn't designed for a
thrust load. If you substituted a back to back thrust arangement
between the stepper and the motor, idealy using the bearing housing
to mount the stepper then this idea would work fine.
To add a cheery to the cale would be to support the tail end of the
screw in an unflanged roller bearing. This will support it and allow
it some freedom from expansion and alignment problems. I've just got
out of the bath and it's raining so can't get over to the workshop,
so tomorrow I'll scan a typical ballscrew mounting in and put a link
up for it.