Could use some info on Taps

[Bret4207]

I buy a lot of stuff at Tractor Supply Company out of convenience sake. You learn quickly to check the contents of the bins carefully, even if it's the high dollar stuff in the little baggies. I swear there must be black market for metric set screws out there because every bag I look at that's supposed to have, say, 3 in it has 1 and it might not be the right size at that!

You might want to get a "screw checker" from Brownells or any of a number of other outlets. It's basically a flat steel plate with various sized holes in it, tapped out to different thread sizes. I have 3 of them, 2 from Brownells in standard American sizes and in metric and another that I picked up somewhere that does wire sizes, sheet metal gauge sizes and some other stuff I can't recall. Use them often. Real handy when one of the tiny screws in a chainsaw carb takes a leap onto my filthy shop floor and you need to determine what size you need to hunt for.

 

[KeithB]

I was given one of these as a gift and I like it very much:

https://www.mscdirect.com/product/details/74011073

Basically short pieces of steel round stock with male threads on one end and female on the other connected with a steel cable to keep them from getting lost. You can check any standard small nut or bolt very easily. The plate type Bret refers to are very handy also.

 

[Mike W1]

10-32 is fine thread (NF). 10-24 is the coarse thread size (NC).

Another place where our language kind of duplicates the obvious I guess. One would think 10:32 is a finer thread than 10:24 without hanging NC or NF on there when it's already described by the numbers. Think I'm finally straight and ordered a bottom type tap. See how that works out in case I do a mod or two on another couple molds and need bottom taps for those. Anyhow thanks for all the help on here.

 

[smokeywolf]

Mike, just conjecturing here but, I suspect that the perceived need to label NC and NF is that there is also NEF (National Extra Fine) and several different pitches of each thread that are labelled NS (National Special)

Keith, I've never seen your formula for tap drill sizes that you describe in Post #11. One of the best little machinist tips/tricks I've learned in a long time. I do love to keep learning. Like Ben, you may be a retired educator, but you'll never be finished teaching.