Hi .
I may have the answer to your Question . I was reading Scroll saw Fretwork Techniques & Projects by Patrick Spielman & James Reidle .
On page 56 it says Hegner introduced a " piercing pal " accessory . The PP is a blade-centering device that speeds up blade - threading operations when you are making internal cutouts as in fretwork. It goes on to say how you use it. On the following page it says , the piercing pal , when inserted behind the blade clamp, aids in properly centering the blade within the blade clamp.
Hope this helps . Cheers . Roger |