Homebrew PCBs

derekhawkins wrote:
>>For lead screw applications I'd keep the encoder on
>>the screw. Doing so allows the screw to be driven
>>indirectly and velocity/torque/rotational-precision
>>to be scaled via simple friction coupling without
>>introducing slippage error.
> 
> 
> A DC gearhead motor is best for lead screw applications as it allows 
> the screw to be driven "directly" without any complications provided 
> speed and torque requirements are met. It doesn't get much simpler 
> than this;
> 
> http://www.pbase.com/eldata/image/45200286
> 
> http://www.pbase.com/eldata/image/45200509

Depends upon what one is trying to accomplish.
A direct coupled gear head approach is certainly
straightforward if somewhat of an expensive option.

Then again there is the backlash in the gear train
which needs to be factored-in when making fine
adjustments via changing direction to minimize
over travel.  There is also the need to align both
axises within a given tolerance to minimize bearing
wear.  These tend to be non-issues with frictional
coupling.

BTW what type of rotational velocity are you
getting out of this setup?  Actually the linear
velocity is of more interest.  Hard to gauge from
the jpg but the lead screw appears to be ~10TPI?

-- 
uhmgawa@...        www.gnu.org