Tapping sizes for M0.6 and M0.8 threads

[92220]

Hi Folks.

I don't know if anyone has used the tiny M0.6 and M0.8 hex head screws sold by Knupfer in Germany, and would be interested in the tapping sizes for these threads. I have just bought some, having been steered towards them by Roger. I have just got the tapping sizes from Knupfer. If you want taps and dies, they are available in HSS from AliExpress in China, at very reasonable prices. The taps come in packs of 10.......probably because they expect breakages!!

Tapping sizes:-

M 0,6 = 0,45 - 0,5 mm 
M 0,8 = 0,6 mm


Bob.

[andyhigham]

Subtract the pitch from the diameter to get the tapping drill size

[simplyloco]

Jul 22, 2019 8:58:38 GMT andyhigham said:

Subtract the pitch from the diameter to get the tapping drill size

Plus a little bit!
John

[David]

Plus a little bit for sure! Every time I've tapped a metric thread with the 'dia - pitch' sized hole it's felt like the tap will break.

[Deleted]

For threads this small I drill as large a hole as I think I can get away with. For our hobby this small is only going to be used for cosmetics hence why I'm not too concerned with the strength of the thread. I have 1.6 mm sizes for my steam valves which Paul did for me, these of course do need to be drilled to spec. Nice to know though what the correct sizes should be for these little threads, thanks for sharing Bob.

Pete

[44767]

As Andy says, taking the pitch away from the thread OD gives the drilling size for tapping a metric thread. This already leaves about 75% thread engagement (i.e. the minor diameter of the female thread is truncated per the standard even though the tap is full form.

The chart I use states that the minor diameter of a M0.6 female thread has a max of 0.504mm and also that the pitch diameter has a min and max of 0.503-0.523 so I would take care using a larger drill for tapping!

Knupfer has taps for these which come in a set of three. They are a series of progressively larger pitch diameters the third one being the correct size while the first two, used in order, rough out the thread. It is very unlikely you would break a tap using this method.

[92220]

Hi Mike.

Thanks for that info. I didn't see them on the Knupfer website. That is why I went to AliExpress. I must look again at their site.

Bob.

[44767]

Hi Bob,
Here's the link to the page:  Knupfer Taps

Cheers, Mike

[44767]

I may have put this up here before but this is a spreadsheet I did for choosing the scale metric bolt to use to represent an imperial bolt in 5" gauge:



You can choose whether you want the across flats dimension to be closer or the diameter, depending on what looks better.

[timo]

If you want to see some really tiny work go to Stefan Gotteswinter's youtube site which is quite fascinating. Go to

www.youtube.com/watch?v=E8vmgBa6qhk

This is Archives 3 and you want 12:50 - Machining Torx headed screws

I would probably break the cutters just putting them in the chuck and drop the screws on the floor!

Tim

[92220]

Hi Mike.

Thanks for posting that chart. I hadn't seen it before this. VERY handy!!

Bob.