Re: Gauge blocks

On 6/27/2024 4:56 PM, Bob La Londe wrote:

On 6/27/2024 12:35 PM, Snag wrote:

   Am I really going to need to allow for millionths of an inch ? I'm looking at an 81 piece set from Shars , a grade B with the deviation table for under a hundred bucks . Looks like the biggest variance is .000034" , or about a third of a ten thousandth . I can't see any project that I might get needing that kind of precision ...
   I'm considering buying the set just because I've kinda wanted some and I think they'll get me closer to perfect in my upcoming depth mike project . Since they can trace back to a national standard I can also use them to check all my other micrometers , none of which have been calibrated for at least 40 years , and in some cases longer than that .
>

 You will probably be fine.  I hardly even use my gage blocks.  I just CNC machine an angle plate with a stop.  I have a cheap B grade set, and I miced them (I have Starret standards), and they are as good as I can measure except the 4 inch which for some reason is almost exactly 4.001
 I have a set of gage pins too.  Most of the time I just use my set of drill blanks because its faster and most holes I'm checking are nominal standard sizes anyway.  If they aren't I measure them with an inside mic.
    

I'll probably only use them for calibration checks . And only because one of these days something I make is going to have to be a pretty precise fit for something somebody else makes . Gauge pins are on my wish list too . I got a set of thread wires a while back . Haven't used them yet but then I haven't needed a precise thread fit . I have a couple of projects in mind that will require a fairly precise thread ...
   OBTW , I did order that set of Shars blocks . Under 110 bucks , and there's no doubt that if I waited I'd be paying more .
--
Snag
  It's great to be straight !