Good afternoon Lads,
When I bought my Colly Master many moons ago, it came with a Pratt Burnard N52 7-1/2", 3 jaw chuck with an integral L0 backplate.
Over the intervening years, I've dismantled it several times, but not really taken much notice of its construction.
However I bought a bit larger Griptru a while back, that was cheapish considering, but it was in need of a lot of persuading to actually move anything.
Quite a lot of thought had to go into dismantling something I had absolutely no knowledge of.
To cut a tiresome story shorter, I sorted it, but it did leave an impression, that I'd seen that type of construction in my original chuck.
So, I stripped the original chuck, cleaned it, then measured everything, to put to cad.
I managed to come up with a workable Griptru conversion(I actually emailed a 600 Group technician, for advice on the adjusting screw size, but was told in no uncertain terms, no information could be offered due to copyright).
Anyway I had to make things fit the already manufactured article, so there was little or no leeway.
I'm now coming to the purpose of this topic, having to set up several datum's, to drill through the chord of the chuck body, so that a tapered adjusting screw will accurately impinge on the bosses of the backplate body.
I found that the length of the slotdrill I was using(long series 9/16" diam), was less rigid than I liked, but I'd gone down nearly to the measurement I intended.
I now had to change to a shorter one and grind the Autolock collet nut to clear the curvature of the chuck, now where on earth do I continue from.....
Tadah...the piccys tells all....
If any further explanations are preferred, then just ask,
