winding yer own transformers, somewhat OT.

[R.G. Keen]

>In the factory we added or removed steel cores to alter the voltage to 
>specifications. We tapped them with a small hammer to adjust the voltage. 
>
>The type of core influences the magnetic flux linkage, as does the thickness and
>type of core. In fact the core has voltages induced in it which can effect the 
>voltage positively or negatively in the secondary. 

You were clearly working on Ferroresonant (voltage regulating) transformers. Normal power
transformers don't use shunts, and you can't adjust the voltage by changing the stack or
by changing the leakage by tapping the winding. 

You CAN change the leakage current and primary inductance losses in normal power and output
transformers this way, though; just not the voltage ratios.

But yes, everything affects the transformer's performance a bit.