The spec says shaft
misalignment should be under 0.01", which means that the individual
mounting holes need to be even more precisely placed, so as the
cumulative error will stay within spec.

Second question, I will need to tap #4-40 holes in same aluminum. How
risky is this as far as tap is concerned and should I use lubrication?

Not certain which US Digital encoders you are using but here are some
being installed directly to tiny motors (no plate). One way to achieve
accuracy with this encoder type is to use the centering tool with
double sided tape on the plastic plate then use the plate as a drill
template.

Hand tapping machine (Enco) and Tap Ease "crayon" was used for
tapping. Also, flat instead of pan head screws were used only for
neatness. The supplied pan heads work just fine. Pictures here;

http://www.pbase.com/eldata/motor_mod&page=1


On Jun 18, 3:40*pm, Ignoramus13320 ignoramus13...@NOSPAM.
13320.invalid wrote: