From: none@none.com99   
      
   On 9/20/2024 12:48 AM, Richard Smith wrote:   
   > Hello all   
   >   
   > Thanks for all help.   
   > Volunteering at local museum and hobby mines, benefitting from advice   
   > on things here, and hopefully starting work again as a welder   
   > imminently.   
   >   
   > Grinding flat surface on granite samples to make visually well   
   > presented samples of geological features - eg. the "contact" between   
   > different types of rock...   
   >   
   > Find is true a diamond-plate like for eg. sharpening plane-blades when   
   > on-site produces a beautiful find shiny smooth grind on the rock   
   > samples.   
   >   
   > Problem - the removal rate is tiny - need a flat sample to start with   
   > if going to do that.   
   >   
   > Advice here is glide tools over the surface and go through finer and   
   > finer grits getting a surface which is polished though not necessarily   
   > machine-flat.  Comments   
   > * this is the voice of experience   
   > * is there really the need for the sample to be machine-flat?   
   >   
   > Anyway, I was thinking how it might be possible to produce a flat   
   > surface.   
   >   
   > In the steelworks labs. there was the "swing-grinder" which had a   
   > vertical spindle and you swung it back and forth over a sample in the   
   > chuck, lowering it a bit per pass to produce a flat surface to start   
   > going through the finer and finer emery grits with until you could   
   > diamond-polish it to mirror finish.   
   >   
   > I thought of base and column of a bench-drill, clamp a collar on the   
   > pillar at height of finishing plane, and have angle-grinder on an arm   
   > you swing back and forth.  Letting the grinder ride-up for light   
   > "cuts", but eventually stopping at the plane dictated by the collar   
   > locked to the pillar (column).   
   >   
   > Anyone got a better idea / know how it should actually be done - if at   
   > all?   
   >   
   > Regards,   
   > Rich S   
      
      
   Making flat surfaces from rubbing surfaces together IS a slow process.   
   I can't imagine doing it.  The way I understand it is that it can be   
   done to near laboratory or at least machine shop tolerances, but it   
   takes three surfaces with swap of mates and orientation.  If I were to   
   get into it I'd look at some of Robin Renzeti's (spelling?) videos on   
   YouTube for the basic process.  He really goes down the rabbit hole on   
   the subject I think.  There is also a dentist who got into precision   
   grinding as a side business, but I don't recall his name or if he even   
   has a YouTube channel.  Abom79 on YouTube (Adam Booth) worked with the   
   guy on some stuff.  Might have just been making precision bench stones.   
   I don't recall.  While they are not necessarily anywhere close to what   
   you want to do, they may give you insight into how to do what you want.   
      
   That being said, the one thing you seem to catch my attention about was   
   time and material removal rate.  I am always sensitive to time, and I   
   don't know how you could improve that except by employing mechanical   
   means to assist in at least the rough/coarse part of the process.  The   
   problem I see with mechanizing the fine finish is you might need fairly   
   fine mechanical bits.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
      
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