I'm on the lookout for outside jaws for a 6" (imperial) Pratt- Burnerd
3-jaw (actually a Griptru but that doesn't make any difference to the jaws) also for a 200mm Metric P-B 3-jaw.
Looking on the Thame workholding site
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for dimensionstheir part nos are EOG and EG20.
Buying a new chuck would be cheaper, though :-(
I've got a 6" 3-jaw, anonymous and needs a good clean but looks in half-decent order, with outside jaws only. Sadly they don't fit a Pratt :-( Might be handy for someone for a rotary table. I'd gladly swap it for the jaws I need, or for a bit of beer money. (Warrington area)
Tim