onset is the opposite of offset. so while offset helps to get the ball up and straight easier, onset requires precision when striking the ball and there is very little room for error. at impact the hand position is almost square while for onset irons, the hands position are ahead of the clubface for offset clubheads.
most of the time if you strength the loft on an iron and you bend the irons at middle part of the hosel, you will get closer to a onset.
i remember World Cup Mission Hill 2008. Rory Sabbatini came with his R9 TP irons and they were forged (not the retail B) and very bendable. somehow, someone has bend his irons before and it had a 1/8 inch onset on his 9 iron and PW, looks wired really. he wanted it square and with the same loft. we had to bend it 2 ways (one at the end of the hosel nearer to the club head and another in opposite direction nearer to the shaft). the best part was he wanted to bend it himself cos he enjoy doing so but we had to set it for him and prompt him to bend and yell again for him to stop. it took 10 mintues to bend 2 pieces of irons.
we have a regular who is so particular about the offset on his clubs that it has to be precise. from driver to wedge, the offset have to be the same and if its out by just 1/16, he can tell. i am sure we will have a lot of fun when his yonex arrives.
DGman
Subject: Onset Irons 
Wed Feb 09, 2011 1:30 am
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