10 Foot Micrometer????

One of the many tools that I have....and have no use for, is a 100 to 120 inch Micrometer with the standard made by the Swiss company PAV .

I bought this, as I did many tools, because I had never seen one that big before.

Does anyone know what industry would use something like this? I realize that it is old and outdated but someone had to have had a use for it back in the day. Just wondering who and if anyone has ever used one before.

Thanks in advance for all the sharing of knowledge. I don't post often at all, but really enjoy the passing on of knowledge that goes on here.

Pics please!!!

Probably to measure a shaft that's approximately Ø110" +/- 9.9"

Derek Smalls said:

Pics please!!!

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I second this

RetiredRay said:

One of the many tools that I have....and have no use for, is a 100 to 120 inch Micrometer with the standard made by the Swiss company PAV .

I bought this, as I did many tools, because I had never seen one that big before.

Does anyone know what industry would use something like this? I realize that it is old and outdated but someone had to have had a use for it back in the day. Just wondering who and if anyone has ever used one before.

Thanks in advance for all the sharing of knowledge. I don't post often at all, but really enjoy the passing on of knowledge that goes on here.

Click to expand...

I wouldn't say exactly that micrometers that big are outdated. Just a couple of years ago I used mic's that approached 6 feet when I worked in a gear shop that made massive bull gears for the energy industry. During hobbing and before finish grinding, they had to be measured, over pins no less. Each time the mic was checked out, it had to calibrated to a rod. So, people still use them as there are simply very few ways to check parts otherwise.

Paul
I

RetiredRay said:

One of the many tools that I have....and have no use for, is a 100 to 120 inch Micrometer with the standard made by the Swiss company PAV .

I bought this, as I did many tools, because I had never seen one that big before.

Does anyone know what industry would use something like this? I realize that it is old and outdated but someone had to have had a use for it back in the day. Just wondering who and if anyone has ever used one before.

Thanks in advance for all the sharing of knowledge. I don't post often at all, but really enjoy the passing on of knowledge that goes on here.

Click to expand...

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many cnc can probe a part to measure part then adjust tool comp using gcode to take a finish cut so part is desired size. i have run programs that do this quite often. normally works ok but if there is tool deflection probe might have problems with tool deflection or need math formula altered to compensate for tool deflection changing from a heavy cut to a light finish cut
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for more critical dimensions, probe runs a calibration mode probing a known size round part attached to fixture. if attached round part is 1.0000 and probe measures .9990 it adjusts a macro variable and probes again so it measures 1.0000
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ideally a 10 foot part needs probe to calibrate to a 10 foot gage block. big parts change size with temperature. normal to get 0.0010" different reading from a dry part to a part covered in coolant. might have to compensate for different thermal expansion amounts of the gage block and the part being measured if different metals. it gets complicated
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120" with a 2F temp change iron and steel changes length about
.0014".......just saying big part difficult to get less than .001"
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i see every day where a big part that coolant only touches one end that end of the part goes down or not as high off the table .0005" different. obviously if aligning part to .0002" there are times it is best to not use coolant or to compensate for its effects. i can set that part end high .0005" cause when coolant is used only on one end of big part, it always goes down .0003 to .0006", basically compensating for a predictable temperature change effect
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i use a 2000 gallon temperature controlled to +/-1F coolant system. even then there is cooling action from coolant spray evaporating in the air. this often makes boring bars get smaller during a long bore causing a bore taper

That's a white elephant tool. Very expensive to buy but once its need has passed you'll be lucky to sell it on for a small fraction of the purchase price. Offer to it to a heavy machine shop, one with vertical boring mills in that table size or larger.

Remember that pi tapes are handier for VBM work so you may have a hard sell. Point out that a pi tape will not detect even order out of round like squish on hollow parts from face plate jaws.

A note on temperature: most open shop measuring tools measure to 4 significant figures with a little care. 0-1 mike reads to 0.0001" with relative ease. A 9-10 mike 0.001 and so-on proportionate with scale. If you carefully track temperature and have a comparison standard immediately available you can measure to 5 significant figures with some confidence. 100" micrometers have to be handled with excruciating care to prevent the heat of handling affecting the reading.

Whenever I had to mike parts in the ten foot range, I recruited a competent co-worker to verify my reading. Our 100" range OD mikes had tubular frames whose section measured 7" or 8" at the center of the "C". Even then confirming readings to 0.001" were a matter of time, care, and some controversy.

they sell caliper extender bars to mount 6" digital caliper on a bar that you zero to a gage block and measure what you are setting. usually when tolerance is +.-.005"
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i often used on printing press equipment when i needed coating equipment set to a certain width and i needed something better than a tape measure

I did some work in Starrett years ago, across the aisle where I was working was the area where a couple of guys built the large micrometers. In the conversations I had with them they said they were used in hydro- electric plants for measuring various components. You needed a crane to lift the mic.! Not so much because of the weight but to get it in position to do the measuring. Martin

A micrometer head is one of the very versatile fundamental measuring technologies, which is why you see them everywhere.

OP's device may very well been made for a single part/contract/family of parts, rather than an industry. Just like there are large special machine tools that only make some particular family of parts.

That size sounds like power generation (see @secetal's post), large marine (Forrest's time in ship yards), etc.

Note that some large structures have gone away (turret mounts for battleships) while others have appeared (high power modern windmills)

By the way "white elephant tool" isn't quite right, it's more "specific purpose tool all but impossible to repurpose". (In my mind white elephant would apply to very expensive tools that seem appealing, but don't actually work. Large micrometers, handled well, do work. It's just you only need them when you actually need them.)

RetiredRay said:

One of the many tools that I have....and have no use for, is a 100 to 120 inch Micrometer with the standard made by the Swiss company PAV .

I bought this, as I did many tools, because I had never seen one that big before.

Does anyone know what industry would use something like this? I realize that it is old and outdated but someone had to have had a use for it back in the day. Just wondering who and if anyone has ever used one before.

Thanks in advance for all the sharing of knowledge. I don't post often at all, but really enjoy the passing on of knowledge that goes on here.

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Most likely power generator rotors, hydro or steam. They can get quite large.

I would like to see a pic of it too, with a person standing next to it for a sense of scale. I would love to have it, but shipping would most likely be the deal killer, it would make fabulous wall art, which might be its greatest value today.

They're used all the time in large machine shops. No other way to measure a large diameter in the middle of a workpiece in the lathe or VBM with any real accuracy otherwise. Also often used on the big floor traveling horizontal mills. We had both regular tubular micrometers and what were called "rail" micrometers - which were basically aluminum I-beam with micrometer head and anvil mounted on arms that clamped to the I-beam. The arms could slide and clamp down to be set at whatever length you needed to measure. Final setting was checked with a standard and we'd just write a little note like -.003" to remember that the mic was .003" off to the standard. Being aluminum I-beam it was important to keep insulated grips to prevent thermal expansion. Always checked to the standard in the same position that the tool would be held and utilized as well, because they definitely do flex when they're that big. Also had inside mics up to around 10 feet. I remember making one for a very large job once - that was a 12 footer I think.

eKretz said:

They're used all the time in large machine shops. No other way to measure a large diameter in the middle of a workpiece in the lathe or VBM with any real accuracy otherwise. Also often used on the big floor traveling horizontal mills. We had both regular tubular micrometers and what were called "rail" micrometers - which were basically aluminum I-beam with micrometer head and anvil mounted on arms that clamped to the I-beam. The arms could slide and clamp down to be set at whatever length you needed to measure. Final setting was checked with a standard and we'd just write a little note like -.003" to remember that the mic was .003" off to the standard. Being aluminum I-beam it was important to keep insulated grips to prevent thermal expansion. Always checked to the standard in the same position that the tool would be held and utilized as well, because they definitely do flex when they're that big. Also had inside mics up to around 10 feet. I remember making one for a very large job once - that was a 12 footer I think.

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We do some big stuff, huge Mics are really awkward, 2-3 man job, and not super accurate .001" is pretty damn good.

Pi tape is much better, with less mass.

R

I’ve used loads, we had them bigger even in the roll shop, we used to dangle them off the auxiliary hoist of the 85 ton crane, they aren’t one man tools, very difficult to use, cosine error is a real risk, off perpendicular to the axis amounts to a lot, you don’t want to mess up a 100” workpiece, thousands or tens of thousands gone in a single cut, not so bad in a roll shop as we welded them up with a welding lathe (electro slag or mig), on a cold roll you might even have to throw some burners under to warm it.
Mark

litlerob1 said:

We do some big stuff, huge Mics are really awkward, 2-3 man job, and not super accurate .001" is pretty damn good.

Pi tape is much better, with less mass.

R

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Pi tapes are good too, but they won't show or measure roundness error. They are also prone to misalignment.

eKretz said:

Pi tapes are good too, but they won't show or measure roundness error. They are also prone to misalignment.

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They hurt my thumbs pulling the damn things tight, trying to get a reading
on the ^%$#@@! vernier lines.

digger doug said:

They hurt my thumbs pulling the damn things tight, trying to get a reading
on the ^%$#@@! vernier lines.

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Wanna bitch, try 3 guys holding an 80lb. Micrometer hoping that at least a third of you are competent, and the other 2/3 have steady hands, and understand why parrallel is even a thing.

R

I almost forgot the best part, the guy running the Thimble is on a step ladder, extended out on a scissor lift, suspended from a crane in a Man cage (very steady now) or the best; remember 20,000 times we've all heard don't leave the key in the chuck? Right after that lesson is the 'don't sit down on top of a giant part, while it's in the Chuck' lesson. Or, try to run the part on the VTL, and holding that POS Mic gets even better.

litlerob1 said:

Wanna bitch, try 3 guys holding an 80lb. Micrometer hoping that at least a third of you are competent, and the other 2/3 have steady hands, and understand why parrallel is even a thing.

R

I almost forgot the best part, the guy running the Thimble is on a step ladder, extended out on a scissor lift, suspended from a crane in a Man cage (very steady now) or the best; remember 20,000 times we've all heard don't leave the key in the chuck? Right after that lesson is the 'don't sit down on top of a giant part, while it's in the Chuck' lesson. Or, try to run the part on the VTL, and holding that POS Mic gets even better.

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Never had those problems. "Smooth Forrest" was my nikename in my career shop. Could have been "Infallible Forrest." Maybe it was something else. There was a lot said behind my back. Chances are it was complimentary but said in a low tone so as not to embarrass me.

Forrest Addy said:

Never had those problems. "Smooth Forrest" was my nikename in my career shop. Could have been "Infallible Forrest." Maybe it was something else. There was a lot said behind my back. Chances are it was complimentary but said in a low tone so as not to embarrass me.

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Obviously you weren't doing it right then If it were just me, it would have been fine, I'm positive.

Forrest, you let me know when I can start comparing myself to you, I think I have a long ways to go before that happens. Not sure you are going to be around buddy.

Robert