From: none@none.com99   
      
   On 9/21/2024 12:06 PM, Snag wrote:   
   > On 9/20/2024 5:51 PM, Snag wrote:   
   >>    I got the back plate finished for the 3 inch chuck and I'm a bit   
   >> disappointed at my initial testing results . I've measured .015 runout   
   >> on a piece of 1/2 inch stock that I'm pretty sure is straight . Might   
   >> be the jaws since the chuck body indicates about .004 near the face .   
   >> These are the inside step jaws and the clamping surface is not very   
   >> long so that may be part of it . I'll be installing the outside step   
   >> jaws tomorrow and checking them - it came with 2 sets of those , one   
   >> which matches the chuck s/n and one that doesn't . The inside step set   
   >> I have installed do not match numbers ... aaahhh , what should I   
   >> expect for a $10 yard sale purchase !   
   >>    Actually , it may be as simple as regrinding the mismatched jaw   
   >> sets to match this chuck . I have a little time to play with it , got   
   >> no "other people's projects" in the shop right now .   
   >   
   >    Further testing having been completed the chuck has runout with all 3   
   > sets of jaws of around .007" . Chuck body is more like .002-.003 . A   
   > known straight 1/2" rod is not pointing  straight with the ways ...   
   > looks like it's time to set up the toolpost grinder .   
   >    So it looks like maybe a cheap chuck , though well made . Fit and   
   > finish are good , everything fits as it should and the scroll moves   
   > smoothly with all 3 pinions . Which brings me to a question - since   
   > there's more than one pinion is it going to make any difference which   
   > one I use ? Do I need to give 'em all 3 a twist when I mount a piece of   
   > stock ?   
      
   Does a known straight rod point straight and parallel if is directly in   
   a collet that fits in the native spindle bore?  If not then level   
   (untwist) your lathe before doing anything else.   
      
   Which pinion to use?  I have no idea.  Whenever I use a scroll chuck I   
   try to do all operations that are important to be concentric in a single   
   setup so runout is not a big deal.  If I can't and close is good enough   
   sometimes I wing it or carefully clock the part, but if it must be dead   
   nuts I either dial in the set tru for that size or use the 4 jaw.   
      
   I expect when I get the turret/collet lathe finished I'll do most of the   
   close enough repetitive work in it.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
      
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