Metric tap and die size

[Mike6158]

I know... 50 lashes for using the M word... I actually don't care what the units are, until I accidentally mix them.

I've been Googling around all morning trying to find a tap and die for a screw that goes in one of my Ham radios. It's a Yaesu FT-817ND for the Hams in the bunch. I'm pretty sure they install self destructing threads in these rigs because the screws never seem to survive the first time to remove them.

Anyway, it dawned on me that this would be the place to get the answer I need.

Yaesu specs the screws (and therefore the threaded holes) as M2.6x5B. Victor Machinery Exchange Inc comes the closest to having a tap this size but not quite. Their M2.6 taps stop at M2.6x4.5. At least they have an M2.6 tap though. I have a M2.5 tap and it did a decent job of chasing the threads.
Well... the screws went in... so I guess that's decent.

An metric experts here that can explain why M2.6 is so hard to find (if it really is) and what 5B means? Even better, where can I find a tap and die that size?

 

[mksj]

Metric taps usually come in increments of 0.5 in both fine and course thread. So a 2.6 is an oddball, from what I read it is a holdover from a German precision thread. This is also a very small screw/thread and seems to have very limited applications. I am assuming the 5B is either specific to the part or possibly some thread tolerance limit. The M2.6 has two thread pitches, the coarse thread is 0.45 and the fine thread is 0.35. I am assuming you are looking for a fine thread tap. There are several places that stock this in a tap and die, example below.
Fine thread
https://www.ebay.com/itm/M2-6-X-0-35-D5-HSS-BOTTOM-TAP-/302040584785
https://www.ebay.com/itm/HSS-M2-6-x-0-35-13-16-OD-Round-Adjustable-Die-Cutting-Tools/400992170234

Coarse thread
https://www.ebay.com/itm/2-6mm-x-0-...Tap-M2-6-x-0-45mm-Pitch-CAPT2011/382346161341
https://www.ebay.com/itm/2-6mm-x-0-...Die-M2-6-x-0-45mm-Pitch-CAPT2012/382313930984

 

[magicniner]

It's a "Proprietary Thread", you can make, or have made taps and dies but none of my suppliers, even the ones who usually have odd-ball stuff list M2.6 x 0.5

Metric taps usually come in increments of 0.5 in both fine and course thread.

0.35mm, 0.75mm and 1.25mm are common pitches in smaller standard metric threads ;-)

https://mdmetric.com/tech/tic1d.htm

.

 

[MrWhoopee]

Mr Whoopee here, recovering shop owner. Oddly enough, this thread was interesting enough to cause me to join and write my first post.

I believe what you have is an M2.6, 5mm long with a binding head. Something that I learned while translating Japanese part drawings is that there is only ONE standard pitch in metric. On drawings, they will simply be designated with an M and diameter (M4, M5, M6 etc.). In the standard pitch series M4=.7, M5=.8, M6=1.00, M8=1.25, M10=1.5, M12=1.75. There can be other pitch combinations, but these are the standards. All others will designate diameter and pitch, such as M10x1.00. This can be very confusing for those of us who are not familiar. The standard pitch for an M2.6 is .45, which explains why your M2.5 tap chased the threads without binding.
https://www.fullerfasteners.com/tech/basic-metric-thread-chart-m1-m100-2/

 

[mksj]

To clarify, above 2.5mm the metric diameter size is typically in increments of 0.5mm with the exception of the 2.6mm. Beyond M4 they are typically in increments of 1.0. Of course anything is possible. One reason why you would not see a 2.6mm in typical tap and die sets. There can also be numerous fine thread metric pitches with some shown in the attached chart, so you need to check the pitch carefully.

 

[magicniner]

No they're not, M8 & M12 standard pitches are on 0.25 increments ;-)

 

[MrWhoopee]

No they're not, M8 & M12 standard pitches are on 0.25 increments ;-)

I believe mksj was referring to diameter increments, not pitch.

 

[magicniner]

I believe mksj was referring to diameter increments, not pitch.

Yes, apologies mksj!
I missed that as the discussion is about a particular pitch being difficult to find and was centering on pitches ;-)

 

[Mike6158]

Mr Whoopee here, recovering shop owner. Oddly enough, this thread was interesting enough to cause me to join and write my first post.

I believe what you have is an M2.6, 5mm long with a binding head. Something that I learned while translating Japanese part drawings is that there is only ONE standard pitch in metric. On drawings, they will simply be designated with an M and diameter (M4, M5, M6 etc.). In the standard pitch series M4=.7, M5=.8, M6=1.00, M8=1.25, M10=1.5, M12=1.75. There can be other pitch combinations, but these are the standards. All others will designate diameter and pitch, such as M10x1.00. This can be very confusing for those of us who are not familiar. The standard pitch for an M2.6 is .45, which explains why your M2.5 tap chased the threads without binding.
https://www.fullerfasteners.com/tech/basic-metric-thread-chart-m1-m100-2/

Man... I'm late to my own post I guess I missed the post notices. Thanks to all that replied.

That's exactly what the description called them (binding head). If I'm following what you've written the M2.5 chased the threads because the pitch was correct but was 0.1mm short of the 2.6mm diameter. I can get the screws from Yaesu but they are pricey. I guess I can sort of chase the threads with my M2.5 tap...

PS- I told ya'll that ya'll would know