Need help on Threading

[bosipipes]

Hello all!

Its been a few years since I have been in the shop.
I have been searching the fourms looking for a answer, and I cant seam to find it.

What is the rule of thumb when tapping a 10x 1 thread? is it that I subtract one MM. for the the hole to be drilled ? (9mm)

Also for using a Die? Do I add 1mm? thus turning the diam. to 11mm.

Thanks for all the great Info.

Kirk Bosi

 

[bosipipes]

Well I found a answer for the taps and thought I would share.

To determine the proper drill size for a metric tap, subtract the tap's pitch from the tap's diameter. For example: a 42mm x 1.5 tap needs a 40.5mm drill (42 - 1.5 = 40.5)

 

[jjudge]

The rules for METRIC I've seen are this:

Tap: subtract the thread from the main diameter (e.g., M10x1 = 9mm drill).
However, most folks take another .0 off that, for easier threading/fit (e.g., M10x1 = 8.8mm drill)

Die: Main diameter is the diameter. (e.g., M10x1 = 10mm tenon)

If you read the machinery handbook (machinist's bible), there is a section on various tapping, threading, etc. My take-away was that a certain percent of the threads really have to engage (e.g., 65%) for it to all work well.

This explains the blanket "subtract 0.2" adage I've seen.

 

[Rich L]

You can easily find a tapping and threading or tap/drill chart chart on line. Here's one of many TAPPING DRILL CHART

Here's a handy calculator Tap Drill Sizes

For dies, you want your tenon slightly undersized

As Joe says, It all depends on how much thread you want engaged - 50% 65% 75% ...

It's basically the same rules for most 60º threads - there are slight differences but none that would factor into this kind of work. Check wikipedia for the theory.

Cheers,
Rich

 

[bosipipes]

Thanks Guys!!!!