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Explain Thread Micrometers to Me

M

munruh

Hot Rolled
Joined
Jan 3, 2011
Location
Kansas
I have no experience with those shars mics but you need anvils, and on these the standard is also important (the standard is not like a normal mic standard) you'll need a couple different sets of anvils to cover the range of pitches, same if you want to do Whitworth.

I think you can check it on one set of anvils and then safely swap out (to Whitworth for instance) but I'm not totally sure
 
As you may know, a single set of Mitutoyo anvils will work in all of their frames. Unlike the cheapies, they're nicely made. The anvils stay properly seated while still being free to rotate, the adjustments are precise, and so on.

Once you get beyond 0-1" be sure each mic comes with the thread standard.

You DO need to have the proper pair of anvils to cover the thread range being measured. Even then, the anvils on all these types are an approximation of the perfect thread form. Good enough for most work. Maybe not precise enough for some specs.

What sizes do you need? I may have some extras in Mitutoyo or Brown & Sharpe etc.
 
I actually was wanting to purchase 0-1, 1-2, and 2-3 thread micrometers. Let me know if you have anything you would like to sell.
 
I have a 0 to 6" set from Shar's. They have never let me down. Oh and a 6 to 7" Insize. If you buy used, make sure you get the complete anvil set and a standard. Most anvils cover a range of pitches. Choose the correct one and install them in the mic. Doesn't matter which way. Zero the mic with the standard placed between the anvils. You have to unlock the movable anvil holder and push it tight to the anvil when at zero. You'll get used to it soon enough. You are now ready to use them in the same way you'd use a regular mic. Keep the mic as close to parallel as possible. Check it by going one thread out both ways with just one anvil. The smallest reading is the one you want.
 
I just bought a 0-1" Mitutoyo PANA mic (116-105), which as I understand it is the same as the thread mic but with a non rotating spindle. An advantage to the non rotating spindle is a variety of anvils can be used in addition to the thread measuring anvils. On ebay. My initial motivator is that I want to do some close measuring of some M3x0.5 threads. These can use the standard anvils from the thread micrometer or anvils that are not a point but more like a thread wire. I figured this would be a lot easier for the real small threads. The mic also came with a set of the standard anvils for measuring 24-14tpi threads. This was sort-of a wind fall because I thought I was buying a mic with no anvils. I wasn't sure if the standard thread anvils worked in the PANA mic but as I have found they do.

I am in the middle of a job making some parts with 7/16-20 threads, single point on a cnc lathe, and have been using go-nogo gages. Man it is nice to be able to see where I am in the range. Thread wires are really great but I guess I am just not coordinated enough to use them efficiently. I am very impressed with the quality of this stuff.

PETEM I think it was some of your posts that I was reading on the subject prior to taking the leap. Great stuff thanks! I don't think I would settle for the Chinese ones.
 
plastikdreams said:
This is in general not metrology, he can pound salt.
Click to expand...

That's a piss poor attitude mister :codger:

I have a moo goo gi pan one with interchangeable anvils. I was under $100. I do a fair amount of fairly fussy threading. I calibrate to known standards. Sometimes I make standards. I would trust a cheap thread mic with good standards over a fancy mic and a bolt.
 
Hardplates said:
That's a piss poor attitude mister :codger:

I have a moo goo gi pan one with interchangeable anvils. I was under $100. I do a fair amount of fairly fussy threading. I calibrate to known standards. Sometimes I make standards. I would trust a cheap thread mic with good standards over a fancy mic and a bolt.
Click to expand...

Hah do I get strike 2?
 
munruh said:
I actually was wanting to purchase 0-1, 1-2, and 2-3 thread micrometers. Let me know if you have anything you would like to sell.
Click to expand...

Munruh, Looks like what I have left are Swiss-made B&S/Tesa 0-1" and 1-2" with a complete set of US spec anvils (7 pair). Can send pix if you'd like. They're near mint condition and complete including the 1" thread standard. Closest Ebay comparable I could find (the 1-2" only, in fair and paint-marked condition) is this: NICE ! BROWN SHARPE SCREW THREAD MICROMETER 1 - 2 " .001 " | eBay

One advantage of these is that the anvils are interchangeable with Mitutoyo. I suspect Tesa established the standard, and Mitutoyo followed.

I'd sell the pair (0-1 and 1-2") for $425, plus whatever shipping and insurance you'd want. Same as the Ebay recently "sold" price for just one mic in lesser condition. Problem is, I don't have a 2-3". Also have a Mahr 0-1", beautiful thread mic, but only with two pairs of fine thread anvils and not as easy to find additions (but others may fit, see below). Somewhere I might have a 0-25mm Mahr with more anvils that can be used, but it seems to be hiding.
 
I have Mits 0-1 and 1-2 thread mics with most anvils. One thing I noticed with the 0-1 mic is that, if I zero the mic with the anvils touching and then measure a certified 1"-8 thread gauge, the reading is a few tenths off of the standard pitch diameter stated with the gauge. If I do the opposite, and set the mic to the gauge's marked PD, then they don't quite zero when closed. I suppose thread mics are a slight approximation compared to thread wires and comparators, but they are plenty good enough for any male thread turning or milling I do.
 
For what it's worth, years ago I compiled a list of thread mic anvil sizes; measuring those I had on hand. Turns out many follow the original Swiss pattern with anvil diameters to fit a 3.5mm hole. Others tend to use a 4mm fitting. The cheap Chinese ones tend to use a 5mm fitting:

Anvil sizes

B&S / Tesa
3.48-3.49

China / Shars (straight cylinder)
5-
Feinmess – Suhl, DDR
3.94
3.94
Fowler (by?)


Mahr
3.48
Split end, marked in scallop
Mauser bench mic, mech digital
4-
Mauser (0-25 & 25-50mm hand)
3.48
Length 13.5mm; Mitutoyo, Tesa too long – need ground
Mitutoyo & Pana-mike, panamike
3.485-3.492

NSK 50-75mm old set
3.52
Too large, marked on flats Nippon Seiko Kabushik Kaisha
Nippon Seisoku
4
Old mic I had -- listed in COFES Micrometers
PAV Liechtenstein (Swiss Economic Territory)
3.49
Perfect swap for Mitutoyo
Toolmex (since distcontinued)
3.497
Fits Mitutoyo; grind in length to fit Mahr
USSR 0-25mm
3.48
.137 & fit loosely in Mitutoyo
VIS Poland
3.49 or so









 
munruh said:
I'm looking at buying some thread micrometers as we have a whole bunch of threading to do. How do these work? I notice the Mitutoyo don't include anvils. There isn't much else to choose from except SPI and some cheap stuff on Ebay. Here is one

SPECIAL NEW 0-1", 1-2" & 2-3"SCREW THREAD MICROMETER | eBay

SHARS 1-2" Screw Thread Micrometer .0001" Graduation Anvil NEW | eBay

Would you trust something like this? I need the anvils correct?
Click to expand...

Hold out and get a well know brand, shars and shitty products inc. (spi) are bottom of the barrel brands. It's worth it in the end.



Or you can just use some chinese digital calipers with cheesey attachments and a hokey pressure device on it...ahem
 
As long as the anvils used will come in contact with the thread at the pitch diameter, I see no reason why the zero would differ other than an inaccurate standard.

Can anyone explain how that can happen? Dirty standard? Uneven wear on the anvils? What?
 
EPAIII said:
. . . Can anyone explain how that can happen? Dirty standard? Uneven wear on the anvils? What?
Click to expand...

One reason is that each anvil pair typically covers a range of threads. For Rich's 8tpi standard, the anvil might cover a range from 7 to 10 tpi. A perfect thread form has to be right at both the flank and the root. It's pretty easy over a range of, say, 7-10 tpi to see some differences in real world threads (and thread standards for that matter).

All that said, thread mics are a terrific tool for most real world uses and unlike, say, thread wires (which should get the flank of a perfect 60 degree thread right) thread mics can be easily used with a part still in the lathe.
 
PeteM said:
... unlike, say, thread wires (which should get the flank of a perfect 60 degree thread right) thread mics can be easily used with a part still in the lathe.
Click to expand...
Umm, what ? I use thread wires in a lathe all the time. Big bubbles no troubles.

I won't say I prefer thread wires but they work perfectly and cost a lot less.

Do your Tesas have those slant lines ? I hate those. Otherwise Tesa is almost as nice as Etalon ...
 
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