Drilling and Tapping

[DohNut]

Drilling and Tapping

 

I have an M3 bolt

and an M3 tap

I think the pitch matches

 

What diameter hole should I drill 🤔 I guess it must be Just less than the "thinnest" bit of the thread , but does an M3 bolt have a 3mm shaft that the threads stick out from or if the outermost part of the thread 3mm?

 

So should the hole be 3mm 🤔 2.5mm 🤔 2mm ❗

 

Nick

[DohNut]

PS

Is anyone good with sketchup?

I want to rotate a section about an axis to create a solid - like an eggcup shape

 

Nick

[elie boone]

A general rule = Bolt dia. minus the pitch = drill dia.

[Tony C]

Have a look here for tapping an M3 female thread. An M3 bolt has a nominal (outside) diameter of 3mm.

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

[David Brown]

Unless it's a thread rolling tap.

 

David

 

[Beelzebub]

From my Zeus Precision book.

 

For an an M3 tap the tapping drill is 2.5 mm. In old money it's 3/32

 

D.

[Foxy Smith]

Re sketchup, you can create solids round an axis, I think you use the "follow me" control. It's described in the first tutorial.

 

Re tapping drill , size depends on material used, class of fit required and most important of all, what drills you have. Generally 2.5mill will be fine and dandy.

[Sheds Moderator]

Not too critical with M3 because (a) the amount of material removed and (b) the likely loading is so small that a bit either side won't matter. There are tables on t'internet that will give you the precise figures, whether you then *own* a 7.3mm drill for your M8 tap is questionable. It's at this point that the rest of us start measuring the imperial drills with a mike to get something "close enough". 😬

[DohNut]

 

Cheers all

 

Will try to find a sharp drill around 2.5mm metric or otherwise.

 

Thx Foxy will have another go at the first tutorial

 

Nick