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The Survey of Antique Fractional Gage Blocks

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Ulma Doctor

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i was surfin' on the site that sounds alot like E-Pay....

i found a wonderfully handcrafted set of antique fractional gage blocks that spoke to me :grin big:
so i got them!

IMG_3414.jpgIMG_3415.jpg

not knowing the accuracy of the blocks,
i decided to clean and measure them and cross check with other mic's and calipers so i could assess their usefulness

IMG_3417.jpg

after cleaning the blocks with rubbing alcohol i started the survey.
for the first measurements, i used the trusted Mitutoyo .0001" digit micrometer,
and just for giggles i ran the blocks through the jaws of the Harbor Freight Digital Calipers to see the differences
i also cross checked with lower resolution mics to test the differences between the earlier findings

for those interested, here is the results of my less than laboratory test....{EDITED}

corrected survey.jpg
[Disclaimer- the testing was not performed under laboratory conditions, so take the readings with a grain of salt ;)
{the ambient shop temperature was below 70°F}
the mitutoyo digit mic was cross checked against 2 other 1" gage blocks as well as against the .401" gage blocks from 2 different sets ]

i was blown away as to the accuracy of the toolmaker who produced these fractional gage blocks
most were dead nuts to a +/-.0001" on 7 of the 17 blocks tested, 10 blocks were dead nuts no error at .0001" o_O

what was equally amazing to me,
was that the inexpensive Harbor Freight 8" digital calipers, read similar findings compared to the Mitutoyo digit micrometer.

all of the other cross checks had similar readings, to a lower resolution of .001'.
i didn't feel compelled to record the lower resolution cross checks.

Results:
my hat is off to this craftsman.
i ponder the skill and tenacity it must have taken to produce these nearly perfect gage blocks.

i feel great pride to introduce these tools into my home shop.
not for anything i did, but for having functional works of art to make other creations from.

as always,
thanks for reading :grin:
 
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FOMOGO

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Pretty impressive that they are that accurate. Nice score. Mike
 

Ulma Doctor

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The 11/16" block should be ,6875" so -.0004".
I mistakenly wrote the .6874” wrong and transposed the error to the ten thousandths when I recorded it :(
i edited the survey above to reflect the mistake on my part
 
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hman

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Functional works of art, indeed! Thanks for posting. You got yourself a winner, there ... too bad they didn't come with a history. That would have been fascinating.
 

RJSakowski

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At this point, you are within the range of error of the micrometer. It might be worthwhile to have them calibrated by a metrology lab.
 

C-Bag

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Good score Mike and thanks for sharing. You just never know what's going to show up. Any guess why somebody would want a fractional set of gage blocks? Precision woodwork? A decimaphobic? Inquiring minds wanna know :)
 

matthewsx

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Nice score.

I have that exact HF caliper and it has served me well for many years.

John
 

Stefants

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Encouraging result! I got a 12” HF caliper a while back figuring it would be less than perfect but likely good enough for my purposes...offers me a ray of hope ;)


Sent from my iPhone using Tapatalk
 

Ulma Doctor

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Good score Mike and thanks for sharing. You just never know what's going to show up. Any guess why somebody would want a fractional set of gage blocks? Precision woodwork? A decimaphobic? Inquiring minds wanna know :)
thanks C-Bag!
i got the blocks solely on the merits of being unusual
i had no idea that they were as well crafted as they are.

the only conclusion that makes any sense to me is that the old boy worked in fractions of an inch,
and he didn't want to stamp the decimal equivalents on his blocks.
but that is grabbing at straws
 

Ulma Doctor

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Encouraging result! I got a 12” HF caliper a while back figuring it would be less than perfect but likely good enough for my purposes...offers me a ray of hope ;)
i wouldn't go use the HF calipers without verifying their measurement, especially where life or limb could be concerned.
i'll use them to around .002" and then verify with more accurate methods beyond that
 

Bob Korves

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Nice score.

I have that exact HF caliper and it has served me well for many years.

John
I have 2 of them and after 7 or 8 years the first one is still working fine and is still accurate, on the original battery! I use that caliper just about every day for lots of measurements. They were ~$10 on sale, added the 25% off coupons, and then got a freebie as well. It does shut itself off if you let it sit idle for a few minutes, and it does not remember it's previous position when you turn it back on...

Edit: I recently started using the second one on a rolling tool cart I picked up. So far have only used the second one a few times due to habit of going for the other one... They are fine tools for almost all of what I do.
 
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westerner

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my hat is off to this craftsman.
i ponder the skill and tenacity it must have taken to produce these nearly perfect gage blocks.
Oh my goodness, yes! Picture the scene- a significant amount of time and talent to produce a product of great precision, in a discipline separate from the one the dimensions are useful for. I would love to have been there, when he said "Ya, good idea! I think I will!"
 

C-Bag

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I had 6" HF dial caliper for over 10yrs in the field doing fab and repair. Dropped it several times, took it jammed in a field toolbox on numerous air trips, no problem. Then dropped it at home and it hung up. Decided to get what I thought was a better digital caliper from LMS and it eats batteries rediculously fast, always dead. So got a me a new dial Mititoyou. Accurate, smooth made in Brazil. Had it a week and it fell off the bench and died. So much for shockproof. So I was in a scrape and tried the old HF, and it quit the hiccup and is a little stiff but still going and accurate according to my 1" and 2" gages I got with my old Starrett micrometers. Go figgur.
 

Latinrascalrg1

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"Wring"??? Could someone please explain to those of us whom are novice students what this is and why it is done? I tried to look it up but i cant frame a context to base a search on!

Nevemind, I found a video explaining it. That is pretty cool and very interesting.
 
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T Bredehoft

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Wringing. A stack of four of rive Jo blocks is awkward to handle.

If you wipe two jo block surfaces on the clean inside of your wrist (it's generally clean and dry) and put them together, then, holding one in each hand, swirl them together for a second or two. they'll bind. I can't explain it, something about molecular attraction. Do this to the whole stack, it becomes solid, won't fall apart when you pick it up.

They can be separated by sliding them apart.
 

C-Bag

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I'm still new to all the different aspects of machining, especially metrology. So Mike antique set of blocks made me dive the rabbit hole and when I searched "fractional gauge blocks" this came up: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654600/

Basically laying out how gauge blocks are old "zombie technology". Many things were mention including wringing. Although I'd heard it mentioned like when Mr.Pete put together a stack for making precision angles for a sine gauge it was taken for granted and I never looked further. In the zombie tech article it makes it pretty clear that the ability to wring is crucial to proper use of gage blocks which of course I didn't know. I also didn't know that wringing isn't completely understood as I just assumed it was like vacuum developing between two flat surfaces but it still works in a vacuum!

I've toyed several times with buying a set of blocks for checking and measuring but was always stuck between buying old name sets that were often in not that great of shape and missing blocks for 4x's what a new set from Shars would cost. But after that article I can see it would have been a blunder as corroded blocks won't wring.

This is not to demean your score Mike as it's useful art, it is sharing what your survey has led me to in further understanding.
 

RJSakowski

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I'm still new to all the different aspects of machining, especially metrology. So Mike antique set of blocks made me dive the rabbit hole and when I searched "fractional gauge blocks" this came up: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654600/

Basically laying out how gauge blocks are old "zombie technology". Many things were mention including wringing. Although I'd heard it mentioned like when Mr.Pete put together a stack for making precision angles for a sine gauge it was taken for granted and I never looked further. In the zombie tech article it makes it pretty clear that the ability to wring is crucial to proper use of gage blocks which of course I didn't know. I also didn't know that wringing isn't completely understood as I just assumed it was like vacuum developing between two flat surfaces but it still works in a vacuum!

I've toyed several times with buying a set of blocks for checking and measuring but was always stuck between buying old name sets that were often in not that great of shape and missing blocks for 4x's what a new set from Shars would cost. But after that article I can see it would have been a blunder as corroded blocks won't wring.

This is not to demean your score Mike as it's useful art, it is sharing what your survey has led me to in further understanding.
An interesting paper.
From a hobbyist or small shop standpoint, I don't believe that gage blocks are a dying technology. One of the issues with making accurate parts is that there is a method of verification of the accuracy of our metrology instrumentss. A common practice requires that a calibration standard have an order of ten times better accuracy than the device being calibrated. At the bare minimum, an order of three times better accuracy. The most accurate device that most of us has in the shop for measuring length is the micrometer, typically with a resolution of .0001". For internal verification and/or calibration of a micrometer, a gage block set makes a convenient and economical calibration standard.

Working for an ISO certified manufacturer requires that all instruments, the use of which affect manufacturing quality, be calibrated by methods traceable to NIST. This usually means sending the instruments to a certified metrology lab. This is typically not the case for the small shop or the hobbyist. We just need to calibrate our instruments to our own satisfaction. Calibration of a micrometer to .0001" allows it to be used to calibrate our calipers, DRO's, etc. with confidence.
 

C-Bag

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I agree RJ. I was as usual dragging on but came to the same conclusion. I still need a way to calibrate and gauge blocks are still useful to me. But like so many things in the thread it was surprising to find out that it was seen as zombie tech. I am still hesitant about exactly what to buy. Can I ask what you have?
 

Cadillac

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I had good luck at auctions. Gage blocks are one of those things a business would buy new so they’re left for the pickings cheap. I had gotten lucky at one and got five sets in one bid. Two do-all sets and two mitutoyo sets one blocks and one set is round with a tapped center hole then a large set of brown and sharpe. The two do-all’s looked like they were used in the shop missing one and three blocks. The B&S and the mitutoyo were mint either use in inspection or sat on the shelf. I might have paid a hundred bucks for them. I just remember it was the opening bid and no one else bid on them. I was happy I got way more than I’ll ever need for less than some junk now days. Name brand sets can definately ring up some Benjamin’s.
 
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