MadModder
Gallery, Projects and General => How do I?? => Topic started by: DavidA on January 03, 2016, 03:37:22 PM
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When cutting BSF threads there is a formula that allows one to derive the thread root diameter. This is very useful as it means you can turn a bit at the end of the tread to know when you are down to full depth.
It is Root Diameter = OD - (1.28066/TPI)
Where OD = Outside Diameter
and TPI = Threads Per Inch.
My question is , is there a similar formula to carry out the same operation on ISO Metric threads ?
My specific need being to know the root diameter of an 2 MM pitch thread on a 22 MM bar.
Dave.
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Dave,
The depth of thread is independent of the diameter of the bar you are threading, so just look up the depth of thread for any 2 mm pitch then subtract it from your bar size. Or use the factor of 0.614
2 mm pitch has a thread depth of 0.614 x 2.0 = 1.228
http://www.newmantools.com/tech/threadm.htm
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Andrew,
Thanks, that was exactly what I wanted to know.
Dave. :thumbup:
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David
I just deduct the pitch from the dia
Ok for tapping drill and single point
See ref in above link for 12 mm 2mm pitch yes that's a standard one but in your case the root dia is 20mm
Stuart