Big Mic's

Ox · Apr 29, 2019

I am new to this design.
Has anyone used them?

TESA 36"- 40' OUTSIDE MICROMETER IN WOODEN CASE WITH STANDARDS | eBay

Are they more thermally stable from hand/heat transfer?
I'd guess no as the less material there is - the quicker it would be to warm up?

Maybe they are s'posed to be more rigid/pound to aid in handling/accuracies?

I see that SPI (MSC) has copied that basic design on their new ones.

SPI Electronic Interchangeable Anvil Micrometer 36”-40”/1000mm Range 13-498-1 | eBay

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Then there is this:

Scherr Tumico Micrometer 36"-42" inches | eBay

This has an interesting head unit on it.
That could be a good plan on these big (heavy) units, allowing two hands (with gloves) to handle the weight and manipulate the unit to get a consistant apex reading.

Has anyone used this design, and what is your experience?

I am quoting a 38" part and I only have mic's to 36", but I doo have a vern calipers that could possibly work.

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Think Snow Eh!
Ox

Delw · Apr 29, 2019

we had starett mics up to 40" if I recall where I used to work long ago. but we got better and more accurate readings with out muller bar set-ups. getting a mic that big ,anything over 30" to seat right was always a pain in the ass.

our shop was climate controled and we alwasy layed the mics and muller bars on the surface plate to keep it same temp.
when we had to check parts in machine, we usually ran a Test part checked it on machine then took it out layer it in inspection on the plate for a while and checked it.
a few times mainly on titanium we had to make the cut run the run the spindle at a few rpms with coolant on to make sure the part wasnt to hot to check.

Ox · Apr 29, 2019

Delw said:
muller bar set-ups.

Google come up with things that have "& Grill" after it.

Not hip on the term.

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Think Snow Eh!
Ox

Milland · Apr 29, 2019

High Quality Precision Dimensional Inspection Gages

From your first post, isn't the third link a gauge, not a micrometer, as it doesn't have a screw thread mechanism? But I agree it's likely more usable than a mic at that size, as long as you've got the calibration rods to suit it.

guest · Apr 29, 2019

Ox said:
...Then there is this:

Scherr Tumico Micrometer 36"-42" inches | eBay

This has an interesting head unit on it.
That could be a good plan on these big (heavy) units, allowing two hands (with gloves) to handle the weight and manipulate the unit to get a consistant apex reading.

Has anyone used this design, and what is your experience?

I've never had to use mics that big- but of the 3, the S-T would be my pick. I think getting a good reading on the indicator would be much easier than trying to manipulate a normal mic anvil with my arms fully extended...

More like a big snap gage, and you can swap out the indicator if you want a digital.

Delw · Apr 29, 2019

Ox said:
Google come up with things that have "& Grill" after it.

Not hip on the term.

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Think Snow Eh!
Ox

Sorry
mueller gage company look at series 2900

High Quality Precision Dimensional Inspection Gages

they work both i.d. and o.d.

What was nice is that you can get one gage and use i for a huge range of measurements.

Ox · Apr 29, 2019

Delw said:
Sorry
mueller gage company look at series 2900

High Quality Precision Dimensional Inspection Gages

they work both i.d. and o.d.

What was nice is that you can get one gage and use i for a huge range of measurements.

Looks like these would be more akin to a calipers then?
Not going to read more than a cpl inches in from the end?

While that may work for the parts that I quoted, I don't see it replacing a C frame mic.

???

Milland:

"Gauge" / "Mic"

6 of one.

Either way - it's measuring the D, and my experience in mics of this size is that it takes a long time to feel your way to a spongy reading, so the dial indicator may be way better.

A digi head would only make that set-up all Janc'ied....

I wouldn't want that at all! :ack2:

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Think Snow Eh!
Ox

PeteM · Apr 29, 2019

The big Tesa mics would have the advantage of being lighter. No easy task to position a big ass cast frame micrometer with one hand and "feel" the thimble with the other. Doubt those would be any better on dimensional changes due to temperature. Heat up inner, outer, or both chords and they'll move.

I've owned one of the Scherr Tumico interchangeable mics in a 24" size. Tumico = TUbular MIcrometer COmpany -- the original company name. The tubular frame was a decent concept for a big micrometer. Much lighter than cast but still rigid. George Scherr Co. and Tumico merged years back, continuing the tubular design for many decades. Later it became S-T Industries.

Most of the ones I've seen had a regular mic head instead of a dial gage. One problem with a dial indicator is that the gearing inside is likely to get pretty beat up trying to measure things like big rolls on a lathe. What might be gained in not needing "feel" could soon be lost in worn rack gearing inside.

Actually will be selling a Mueller gage one of these days -- it's pretty versatile for a repeat gaging operation. Mine's just a baby, though, maybe as much as 8" range for the arms.

Depending on the accuracy you need and what features you have to measure, a Pi tape might be the ticket for a 38" round dimension??

Delw · Apr 29, 2019

Ox said:
Looks like these would be more akin to a calipers then?
Not going to read more than a cpl inches in from the end?

While that may work for the parts that I quoted, I don't see it replacing a C frame mic.

???

Milland:

"Guage" / "Mic"

6 of one.

Either way - it's measuring the D, and my experience in mics of this size is that it takes a long time to feel your way to a spongy reading, so the dial indicator may be way better.

A digi head would only make that set-up all Janc'ied....
I wouldn't want that at all!

----------------

Think Snow Eh!
Ox

No these are far better than calipers and just as good if not more accurate than A mic of equal size. they read in tenths .0000 , Extremely rigid.

The one drawback like you mentioned is length. if I recall we had feet(what we called them) up to around 6" in length, we made some out of solid carbide so there was no flex.
the nice thing about them is you could rest the gage on a cut face of your part for example and get a reading with out the spongy feeling. like you would on a mic.

also you could set the pressure of the gage to read super thin parts so they dont deform the part so to speak when is was NOT being checked Restrained. we did a ton of APU/turboprop etc etc stuff for Garrett aka Allied signal we made very thin shrouds, seals and other parts. some of these parts we .050 or less thickness in 24" and above dias. so flex was an issue.

There great tools if you run big dia parts and they have advantages over mics.. I am suprizes more people havent hear of them, every shop I ever been into hear in AZ that did big parts for allied signal had a bunch of these in there inspection department in various sizes. we had the bars down to 6" long as well.

oh we used starrett 1" sqr blocks(ones with the holes in them for stacking) to set them with. and to set the height of the feet we used the blocks as well.

Gordon B. Clarke · Apr 30, 2019

Ox said:
I am new to this design.
Has anyone used them?

TESA 36"- 40' OUTSIDE MICROMETER IN WOODEN CASE WITH STANDARDS | eBay

Are they more thermally stable from hand/heat transfer?
I'd guess no as the less material there is - the quicker it would be to warm up?

Maybe they are s'posed to be more rigid/pound to aid in handling/accuracies?

I see that SPI (MSC) has copied that basic design on their new ones.

SPI Electronic Interchangeable Anvil Micrometer 36”-40”/1000mm Range 13-498-1 | eBay

--------------------

Then there is this:

Scherr Tumico Micrometer 36"-42" inches | eBay

This has an interesting head unit on it.
That could be a good plan on these big (heavy) units, allowing two hands (with gloves) to handle the weight and manipulate the unit to get a consistant apex reading.

Has anyone used this design, and what is your experience?

I am quoting a 38" part and I only have mic's to 36", but I doo have a vern calipers that could possibly work.

--------------------

Think Snow Eh!
Ox

First off not what you are looking for but this might be interesting to some. The largest I have seen measures from 8" to 12".

Ox you don't mention the tolerance capability you're looking for and mention vernier calipers. Maybe a circometer would do what you are looking for?

PeteM · Apr 30, 2019

Circometer = Pi tape

Ox · Apr 30, 2019

Gordon B. Clarke said:
First off not what you are looking for but this might be interesting to some. The largest I have seen measures from 8" to 12".

Ox you don't mention the tolerance capability you're looking for and mention vernier calipers. Maybe a circometer would do what you are looking for?

View attachment 255579 View attachment 255580

Well that sure is interesting!

I can see one distinct advantage - and that would be that you could hang it on the part while fiddle farting with the smart end.
WAY better than a mic!

But you would need a 38" round disk for the standard to set/check the zero. :eek:

And these would be huge units.

But interesting to say the least!

As far as tol, there was no tol block on last nights quote, so I'm guessing that was +/- .005, which I could likely git away with the vernier calipers. But if I was to buy something, I would expect something along the lines of a mic.

I routinely chase .001 on this stuff, not that I like it ....

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Think Snow Eh!
Ox

DDoug · Apr 30, 2019

PeteM said:
Circometer = Pi tape

Back when I ran Bullards (54")....we had Pi tapes....I absolutley HATE
Pi tapes.

Damn things kept sliding down on the back.

We had some gage system, you would take a copy of the print to the gage cal room,
circle the dim you wanted, and then in a short time you would get this gage.

They stacked up a set of jo-blocks (the ones with a screw holes thru them),
and on top of the stack was your gage, with the dial indicator reading zero.

a real erector set kind of system.
The mueler bar system might be it, hard to tell.

Gordon B. Clarke · Apr 30, 2019

Ox said:
I can see one distinct advantage - and that would be that you could hang it on the part while fiddle farting with the smart end.
WAY better than a mic!

Think Snow Eh!
Ox

There's no reason I can think of that a large micrometer can't be used upside down.

I can't see much else than a micrometer managing 0.001".

If you put some kind of stop in the chuck of a lathe and an indicator dial in the turret then, after you zero, use the lathe travel to measure the diameter of the part sitting on the lathe.

Nope, I've never tried it but why shouldn't it work? Apart from the fact you'd have to take the part out of your machine and probably put it back on.

Ox · Apr 30, 2019

Upside down mic.

I have used them that way before, but one thing that I have never checked - is to see if the added weight on the bar opens it up?
I bet it would.
I may check that some time....

Yes, they can be used upside down, but a 2 pt mic isn't going to just hang there like a 3 pt would.
It still takes a lot of user input, but it does help.

These parts don't come out of the machine and then go back in.
When that chuck opens, they need to be done.

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Think Snow Eh!
Ox

TDegenhart · Apr 30, 2019

One advantage of a indicator system could be to use an electronic head with a remote readout that could either be read directly or recorded by computer.

Tom

PeteM · Apr 30, 2019

digger doug said:
Back when I ran Bullards (54")....we had Pi tapes....I absolutley HATE
Pi tapes.

Damn things kept sliding down on the back. . ..

Assuming you're turning steel - a strong rare earth magnet to hold one end in place? Still clumsy, but not sure I'd rather wrestle with a 54" mic.

MCritchley · Apr 30, 2019

PeteM said:
Assuming you're turning steel - a strong rare earth magnet to hold one end in place? Still clumsy, but not sure I'd rather wrestle with a 54" mic.

I have used the magnet trick as well, or tape. I really like Pi tapes. I am always surprised how repeatable they are.

DDoug · Apr 30, 2019

PeteM said:
Assuming you're turning steel - a strong rare earth magnet to hold one end in place? Still clumsy, but not sure I'd rather wrestle with a 54" mic.

Which I didn't have 32 years ago.

kenton · Apr 30, 2019

digger doug said:
Which I didn't have 32 years ago.

Well stop being old.

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