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drill size
5K views 28 replies 9 participants last post by  gn7 
#1 · (Edited)
What size drill bit is need for a 18mm 1.5 tap (02 senor).
 
#11 ·
Easy enough formula is to subtract the thread pitch from the thread dia. and that's a good drill size. 18mm wiith a thread pitch of 1.5mm...18 -1.5 would be 16.5mm drill. (16.5mm=.6496...closer to the 75% than 16.8mm which = .6614):p
 
#14 ·
You crazy kids all argueing about a tap drill size.
 
#18 · (Edited)
Steel, do you like your metric thread info in metric units or in Imperial (inches)? lol

More then you ever want to know. Note the there is no 4H for this size. only 6 and 5H. kinda interesting I thought. Machinery's handbook doesn't have the 5H data listed either. Hummm


note there is no 4H6H spec for intrenal threads. But you are correct on the 4g6g for external except you got yer g and h mixed up. hehe




 
#20 · (Edited)
Steel, do you like your metric thread info in metric units or in Imperial (inches)? lol

More then you ever want to know. Note the there is no 4H for this size. only 6 and 5H. kinda interesting I thought. Machinery's handbook doesn't have the 5H data listed either. Hummm


note there is no 4H6H spec for internal threads. But you are correct on the 4g6g for external except you got yer g and h mixed up. hehe




I got this right out of the Machinery's Handbook. 27th edition, p. 1783:
"Application comparison with inch threads...Tubular data are also provided for a tighter tolerance fit external thread of class 4g6g which is approximately equivalent to the inch class 3A but with allowances applied. It may be noted that a 4H5H/4h6h fit is approximately equivalent to class 3A/3B fit in the inch system"
H tolerance position = no deviation allowances.
Interestingly enough, machinery's Handbook lists the 18X1.5 as a "sparkplug" thread.
 
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