How did they do that- accurate measuring

[David R. Pennington]

I enjoy trying to use original methods and tools as much as possible but one "modern" tool in my shop I might find it hard to do without is my dial caliper. How did the old smiths measure and layout accurately. I find my dial caliper usful in many stages of the work, particularly when acurately dividing distances to find centers etc. Any thoughts on tools or methods they might have used in the old days?

[The other DWS]

Just a WAG, but I've always assumed that they used proportioning dividers a lot to transfer sizes and proportions from a try-piece, or a shop reference sample, to the work in progress.  I also suspect that a shop would have a collection of reference parts and matching individual measuring pieces cut for each part.

[Swampwalker]

While I agree the country smith probably didn't have calipers, I'm willing to bet he had dividers, and may have had proportional dividers which make finding center really easy.  Also, I bet they relied on there eyes for finding centers a lot of the time.  With practice, the eye gets really good at this.  It's also obvious that they weren't as hung up on it as we are - plenty of slightly off-center mountings and screw holes in period work.

[Dave Faletti]

Simpler calipers existed sometime back.  Look at wikipedia for some examples. Dividers, compass, string, rulers, gauge blocks were around.  A lot of techniques from hand drafting apply.  A piece of thread works for a long straight edge or finding a midpoint.  Easy enough to double up a thread into sections to divide a large distance.  Regular dividers for short. 

[bgf]

Marking centers with dividers, eyeballing and relative measurements.  You don't NEED to know how long the barrel is, just put on the stock and cut off the wood somewhere near the muzzle.  You don't have to center the TG precisely to the angstrom for it to work, just put it on so that it looks symmetrical about the centerline.  I think precision measurement taken too far shows up in contemporaries as that cold, machine-made look that some cherish and others don't, whereas the margin of error on many originals seems to have been "looks good [enough]", which varied by the skill of the maker .

[54ball]

 I know this is talking cars but I do feel that it is related.  When my brother was learning to paint, he began to measure while laying out the hood stripes on his 70 Chevelle.  The teacher stopped him.  He said that you cannot layout hood stipes that way.  They must be done by eye, if not, it won't look right.
  I think laying out a patchbox is much the same way.  There are many tricks to the eye with these old rifles.  I quess that's where the Art and Mystery come into play, knowing when to be presice vs when to eyeball.

[T*O*F]

As far as eyeballing goes, the human eye can detect differences up to 1/32 of an inch and the hand can feel differences in the .00 range.

[boman]

 

I think precision measurement taken too far shows up in contemporaries

I don't post much but this topic caught my eye.  i verified a few years back that I can hand file within .003 when I'm "on my game".  I was hand building a Rifle shop lock form castings and fittinf a frizzen to the pan.  Took it over to a friends and we verified the fit with a cncd knee mill.  I also know that beginning engineers in some foreign countries(India) used to have to hand file a cube form a random shape as part of an exercise. This may still be a requirement in some places.  I constantly am amazed what the good old MKI eyeball and sense of touch is capable of.

Steve

[Dphariss]

I enjoy trying to use original methods and tools as much as possible but one "modern" tool in my shop I might find it hard to do without is my dial caliper. How did the old smiths measure and layout accurately. I find my dial caliper usful in many stages of the work, particularly when acurately dividing distances to find centers etc. Any thoughts on tools or methods they might have used in the old days?

They did not have precision measuring devices in general use until well into the 19th Century.  This was why Nelson King changing the gauges and such was such a disaster from Sharps.  The modern micrometer was in its infancy in the 1870s. They used gauges and did not measure as is done today so parts were made with nobody being the wiser, for awhile...  Today parts are machined and measured to a dimension on a print etc.
So Nelson King's actions were as if he had redrawn the prints so the parts would not fit. The bores too large, the chambers off etc.
This was in a major gun factory the 1870s. Things in a 18th century gun shop would have been even less precise.
See
http://en.wikipedia.org/wiki/Micrometer
For what its worth.
Dan

[Dphariss]

I think precision measurement taken too far shows up in contemporaries

I don't post much but this topic caught my eye.  i verified a few years back that I can hand file within .003 when I'm "on my game".  I was hand building a Rifle shop lock form castings and fittinf a frizzen to the pan.  Took it over to a friends and we verified the fit with a cncd knee mill.  I also know that beginning engineers in some foreign countries(India) used to have to hand file a cube form a random shape as part of an exercise. This may still be a requirement in some places.  I constantly am amazed what the good old MKI eyeball and sense of touch is capable of.

Steve

They had precision measuring devices when a friend of mine apprenticed in Nazi Germany in WW-II. He told of having to make a cube with a file. He said some of the cubes got pretty small before they passed inspection . THEN they had to make a square hole through the center of the cube. He did not mention not being able to measure. It would have been impossible to make a cube by eye.
I don't think it was possible to proceed in the industry until the cube was finished.

Dan

[James Wilson Everett]

Guys,

 I believe that the Vernier (as in vernier calipers) is a rather ancient invention.  If my faulty memory serves - 17h century.  But I do not know when the vernier was actually applied to a caliper like device as we use today.  The John Wyke clockmakers tool catalog from the mid-18th c shows no such measuring devices.  It would be an interesting research to find out the real answer to this question.  Unfortunately, there is an almost complete lack of any published research on any metalworking tooling or techniques from this time period.  Maybe someday a book will be published, but not yet.  I have never seen any such precision measuring devices in any on the gunsmithing tools that I have found.  I guess the closest is the precision go-nogo gauges used to manufacture military arms parts in the 19th c.  Some of these are on display in the museum at Harpers Ferry N.H.S., Harpers Ferry West Virginia.  This place is very well worth a visit.

Jim

[Dphariss]

This might be of interest

www.practicalmachinist.com/vb/antique-machinery-history/very-rare-1816-vernier-caliper-now-my-collection-231792/

But the fact remains that they were apparently not in common use until well into the Industrial Revolution and the current form of Vernier seems to have appeared in the 1930s. As near as I can tell this one is calibrated to .010". But .010" of which inch was in use I could not say.

The vernier scale apparently dates to ancient China.
The Vernier Caliper is named after Pierre Vernier who worked in the 17th century.
I think the rub here is standards. If the verniers were all made in the samel shop using the same scale it would be one thing but I somehow think that standardization was not all that good so a Vernier from one location might not give the same measurement as one from someplace else.
They would allow comparing a part to a master or gauge I suppose but writing a letter to someone 200 miles away with a vernier made in another country and thinking he could produce a part with .001 or .0005 of what was specified in the letter is pretty unlikely.

These threads are always learning experiences. I knew that precision measuring was not generally done and I assumed that the equipment was not available. I think that the rarity might be linked to cost or lack of standards. Since the technology was apparently known for maybe 200 years before they became very common and I suspect that they were not that precise until the late 19th century or even into the 20th.

Dan

[Dave Faletti]

I suspect that any manufacturer doing precision work would have made or procured their own set of standards.  They may or not have closely  matched whatever the government had but their tooling and products would be consistant.  Precision weight standards are easier and were done much sooner than dimensional ones.  Wikipedia mentions the US started a standards office mid 1800's.  Somewhere I read when Englands Tower of London created their different standards and the troubles they had making stable references. Wish I could remember where I read it.  Like Dan mentioned it can make a mess if a standard gets changed.

[The other DWS]

The whole concept of "standards" in weights and measurements has a fascinating and long history.  The ability to produce relatively uniform storage, shipping, and marketing containers for food products goes very very far back in antiquity.  calipers and measuring sticks have been used by potters for many thousands of years and wood turners for nearly as long.
 Even as early as the "100-Years War" era the English government established standards and even circulated "official samples" via the guilds to create a reasonably consistent production of arrowheads, arrow shafts, bow staves and bow strings. Having a reasonably standardized arrow was critical for the mass "arrow storm" that created the English victories at Crecy, Poitiers, and Agincourt and many other engagements.   I suspect that much of the "Art and Mystery" of the technical guilds was centered on creating, perpetuating, and disseminating standards in their craft and trade.

 When we think of "precision" most of our thought/practice was formed in the "industrial era" and most of it was done using identical gauges and jigs and it was pretty much an in-shop or in-factory degree of standardization.  Small parts made in sub-contract shops and cottage industries had to be made to standards if they were to be assembled at a different location with minimal hand fitting.  On a truly industrial scale I suspect that it may have had its beginnings in the need for interchangeable parts at our national armories at Springfield, Harpers Ferry etc and the contract arms producers of the American civil war

[dannybb55]

Don't forget that the standard measure of an inch, foot and yard or pulgada, pie, and vara in Spain varied widely, even in Spain and the UK and they varied much more in the Americas. SAE did not exist. Even in the 20 th century quite a bit of hand fitting was required on weapons. The plans that the U S received in WW2 for the Swedish Bofors 40 mm had notations for large components to be hand fit, The Supermarine Spitfire Mk 22 had NP------X part number stamped that indicated no plans were ever drawn. the whole aft deck was built by eye. British trucks and tanks had very little interchangeability which is why our trucks were so admired. There are good examples of hand fitting on British jets from the fifties. Lapping, filing and trying have been the standard for most work for most of the time. The big jumps in the US came with WW 1 and WW2 mass production using mainly unskilled labor and the Space program. These days there is more handwork. If what you are using was made in China then there is a good chance that it was assembled with cheap child labor, tiny devices require tiny fingers.
 For my two bits on the original question: Patterns and experience.

[Bob Roller]

This is within my automobile history interests and out of topic but it goes to precise measurement.
In the late 1930's when it became apparent to the Brits that Hitler would sooner or later start another war,they started looking for a manufacturer capable of building aircraft engines based on a Rolls-Royce design,a liquid cooled V12. After a while,they came to the "Master Motor Builders" of the Packard Motor Car Company in Detroit,Mich. and showed their plans to Col.Jesse G.Vincent,known throughout the industry as "Mr.V12" who introduced a V12 or Twin Six in 1915 in a Packard automobile. This was in a time when other engineers were still debating over a 4 or 6 cylinder engine for automobiles.
Col.Vincent did by means of precision manufacture took the Rolls Royce design and made it into a marvel of engineering and power that was the envy of the industry that with a demand type supercharger goosed 2500HP out of a design that was to top out at about 850HP.
Combined with Henry Leland's precision measuring ideas from years earlier at the Lincoln Car Company and developing machinery and technical skills,the Packard/Merlin engines helped rid the skies over Europe of the FW 190's and Me 109's and are still in use today for sport aviation.
To me,as a machinist,precision measurement is a joy and sometimes a challenge but still an enjoyable thing.

Bob Roller

[westbj2]

Some interesting insights to accurate measurement C. 1840.  This was "space-age" technology to most American gunmakers and probably took several decades to find its place here.  None the less, Sir Joseph Whitworth's Truth Machine and development of a "Plane Surface" in large part,  bring us to where we are today.
http://www.archive.org/stream/whitworthmeasur00whitgoog/whitworthmeasur00whitgoog_djvu.txt
Jim Westberg

[flehto]

As an apprenticed tool and die maker w/ a few yrs on the bench, I've used all the precision measuring instruments  and used them to the nth degree...but, when making LRs, mainly use "eyeball" measurements. If it looks good , it is good. Not complicated at all. Vernier calipers are used by me in lieu of a micrometer becaue it's faster and is mainly used for measuring dias of screws and bolts to make sure they're the right ones. After a centerline is penciled in for the wrist, the  calipers are used for width , but the centering is by "eyeball". The height of a wrist is also measured w/ calipers. Very few dims on a LR  have to be actually measured....again the "eyeball" determines if it's too big or too small and if it looks good, go w/ it....Fred

[B.Habermehl]

Dividers and the Mark I eyeball can center up a pin punch mark in a tang etc within .005 or less. Especially when the surfaces that need to be compared are relatively close together. Most of the more skilled hobbiests in this craft are working with inlet fits with less than .005 clearence. All this my carefull hand fitting. God gave us two hands, and two eyes, its up to us to train them.

[Dphariss]

Dividers and the Mark I eyeball can center up a pin punch mark in a tang etc within .005 or less. Especially when the surfaces that need to be compared are relatively close together. Most of the more skilled hobbiests in this craft are working with inlet fits with less than .005 clearence. All this my carefull hand fitting. God gave us two hands, and two eyes, its up to us to train them.

When my wife was fitting stocks for Shiloh Rifle she worked to .001, the term for .005 is "a gap in the inletting".
But you cannot "eyeball" .001 when making a lock or measuring an unmarked drill shank.
I don't measure anything when inletting. What it measures is irrelevant.
My wife working on precarves used a .001 feeler to make sure the gaps were small then would set it back as needed, the Sharps design allows this. In doing the custom guns I just fit to "0". This is the goal with all my inletting.
It it interesting to note that the original stocks of the 1860s were machined much closer and require less fitting than the pantographed stocks of today.

Dan

[JBlk]

When you consider that the average human hair is approximately .0155 the measurements that the pioneer gunsmiths made were remarkable.I suspect that you could conduct test on the old tools that you have collected from the trade and find that the tolerance would exceed that in the hinge pins.Even with the ability to use a set of mikes on the same object different reading will result because of the feel by the operator.I sure don't know how they did it, but I sure admire the end result.

[rich pierce]

For barrel bores for standardized armory muskets, guages that were "go" and "no go" were commonly used.  Same for round balls for muskets, and probably for common trade guns as well.  Not an adjustable precision measuring tool, but quite easily made and used for a standardized weapon.