1205mm vs. 0.492"

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qquake

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I've been looking at the Nouveau Sceptre kits. The description calls for a 12.5mm drill bit. But the instructions call for a 0.492" bit. I looked it up, and 12.5mm is 0.4921". Does 0.0001" really make a difference? I already have a 12.5mm bit, I'd hate to have to buy an expensive 0.492" bit.


 
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Mach4

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I routinely drill blanks where the pen kit calls for a .375 drill with a .394 drill. And have even done some at .394 where the kit calls for .360. That’s .020 to .030 oversized with no ill effects. I’m not recommending this, but just using it as an illustration that .0001 is not relevant (and with wood, likely not even measurable). Normally you need a precision reamer to get a hole within .001.
 

More4dan

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I believe the 0.492 is just the conversion of the 12.5mm dimension to inches. Your inch options are either 31/64” or 1/2” with the former too small and later too big. The 12.5mm is the “Goldilocks” one that is just right.


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Edgar

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I believe the 0.492 is just the conversion of the 12.5mm dimension to inches. Your inch options are either 31/64” or 1/2” with the former too small and later too big. The 12.5mm is the “Goldilocks” one that is just right.


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0.492 bits are available though. I bought one for this size kit before I finally bought a set of metric bits. Now I use either the .492 or the 12.5, whichever is closer at hand at the time.
 

budnder

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In this video, there's a comment that runout measured on a drill press of .001 or .002 is "pretty good"... meaning it's often worse. That implies a hole made by a bit marked .492 may vary between .490 and .494 anyway...


But you probably can't see that extra couple thou from the road :)
 

ed4copies

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IF your bit is truly .492", your hole will be a MINIMUM of .492. Wobble may INCREASE a hole, it will never decrease the size of the hole.
 

qquake

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0.492 bits are available though. I bought one for this size kit before I finally bought a set of metric bits. Now I use either the .492 or the 12.5, whichever is closer at hand at the time.
Yes, PSI has them listed, but they're out of stock. Like I said, I already have 12.5 and 10.5 bits, I'll use those.

 

frank123

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A tenth (of a thousandth) precision is beyond the capability of any woodworking and most metal working tools. Also beyond the ability of most of their operators to achieve even when the tools can.
 
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