I'm quite a heavy dipper I can dip with 4 to 5 plates hanging off my waiste
I find machine dips a waste of time ackward never work for me
Strong Dipper my Nugga! You probably have Phil Heath's 1st DVD where he does machine dips, from the front, then turns and does them from the back. He also does tri-sets on the pull down machine. He starts off with a weight, and usually each set is 10 pounds heavier than the first, but he starts off with the last weight done.
I also saw this done by a guy who I think was 2nd or third at the USAs this yr (Superheavy weight). He has one of the close grip Row handles ( you know the one that Ronnie likes to use for the T-bar rows), and he does tricep pulldowns with them. What happens is that it keeps you in a inverted position (knuckles pointed inward, due to gripping the close grip Row handle bars), and you have a constant stretch)---it's a like doing three point pushups (knuckles facing one another). Hopefully I explained this well.