Hole size for threads

[Scribus]

I'm wanting to fit a couple of grease nipples to the end of a shaft but wondered about the diameter of the hole. The nipples are 10mm diameter across the thread but I presume the hole needs to be smaller to allow for the tap to bite into some metal, but how much smnaller, 9mm or even 8?

 

[Sharpy]

I'm wanting to fit a couple of grease nipples to the end of a shaft but wondered about the diameter of the hole. The nipples are 10mm diameter across the thread but I presume the hole needs to be smaller to allow for the tap to bite into some metal, but how much smnaller, 9mm or even 8?

Measure the bottom of the threads. Or be rough and weld a nut on.

 

[Scribus]

Measure the bottom of the threads. Or be rough and weld a nut on.

But that's some dainty welding at that size.

 

[Sharpy]

But that's some dainty welding at that size.

That should be a 17mm nut for m10, easy with a mig , bit slower with the stick as letting it cool a couple of times.

 

[Ploughteringindubs]

Bolt diameter minus thread pitch.

 

[Lincs Lass]

Try this

 

[anzani]

www.ebay.co.uk/itm/Zeus-Precision-Engineers-Metric-Data-Book-Chart-Charts-Reference-Sizes-Tables-/272728872114

 

[Boohoo]

It'll be printed on the tap how much smaller you need to drill the hole. For example an M10 tap might say M10x1.5 so you drill the hole 8.5mm

 

[A1an]

Bolt diameter minus thread pitch.

Every day is a skool day. ??

 

[Pennine Ploughing]

That should be a 17mm nut for m10, easy with a mig , bit slower with the stick as letting it cool a couple of times.

A 10 mm grease nipples usually has a 10 mm head, not like bold at all

 

[Pennine Ploughing]

Grease nipples have a tapered thread, so no need to tap right through the steel if it's a thick walled bit,

 

[Sharpy]

A 10 mm grease nipples usually has a 10 mm head, not like bold at all

I have done the nut trick, think it was an 8mm nut I used. Have a rake through a selection box and its surprising what you can find.

 

[Lincsman]

I have one of those charts, but have yet to see some of those drill sizes, usually manage with the .5mm steps.

 

[Mur Huwcun]

M10 needs to be 8.6, in an ideal world you need tapping drills which are usually more precise but an M10 will easily get away with 8.5. I always advice students to drill an offcut of 6mm steel first and test the tap in the hole, just in case.

 

[tinman]

Mur is right enough with the 8.5mm hole for a tap of M10x1.5 but the threads pitch of the nipples is now important, it ill either be M10x1 or M10x1.5, normally but could be M10x1.25 either altho not as common.

M10x1 has a tapping hole of 9.1mm
x1.25 is a 8.9mm drill
x1.5 is a 8.4mm drill.
9,9 and 8.5 will let you away on those numbers tho.