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Dear Industry: Maybe it's time to buy some calipers?

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I have been doing a bit of airgun smithing lately. I have 12 years experience smithing handguns (and 30 years experience designing airframe structures among other things), and I have been surprised by the relative complexity of spring driven airguns.
I've also been surprised by the lack of useful data provided by airgun manufacturers and aftermarket parts suppliers.
Basic stuff like velocity claims with pellet weight and atmospheric conditions, CRITICAL DIMENSIONS of things like springs, seals, and fasteners.

Just a moment ago I was looking at the website of a well known aftermarket parts supplier, and the part I was looking at had these dimensions reported:

.019 × .012 × .002 cm

Now, the part in question was, in reality, roughly by eye, 2.5 x 0.7 cm.

Another very popular supplier offers what would be considered engineering services in any other industry, apparently without the benefit of a qualified engineer. This is the definition of Tort Liability!

These examples (and plenty more) make me wonder about the general quality of engineering in this industry.

I could specifically mention some of the worst acts by the worst actors, but I'm not here to kill the Easter Bunny and take away everybody's fun, just here to get some decent data so I don't have to guess or seek questionable advice when I need to purchase a part.
 
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_pycnogonum_ said:
I have been doing a bit of airgun smithing lately. I have 12 years experience smithing handguns (and 30 years experience designing airframe structures among other things), and I have been surprised by the relative complexity of spring driven airguns.
I've also been surprised by the lack of useful data provided by airgun manufacturers and aftermarket parts suppliers.
Basic stuff like velocity claims with pellet weight and atmospheric conditions, CRITICAL DIMENSIONS of things like springs, seals, and fasteners.

Just a moment ago I was looking at the website of a well known aftermarket parts supplier, and the part I was looking at had these dimensions reported:

.019 × .012 × .002 cm

Now, the part in question was, in reality, roughly by eye, 2.5 x 0.7 cm.

Another very popular supplier offers what would be considered engineering services in any other industry, apparently without the benefit of a qualified engineer. This is the definition of Tort Liability!

These examples (and plenty more) make me wonder about the general quality of engineering in this industry.

I could specifically mention some of the worst acts by the worst actors, but I'm not here to kill the Easter Bunny and take away everybody's fun, just here to get some decent data so I don't have to guess or seek questionable advice when I need to purchase a part.
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If the reported dimensions are correct, you would need a microscope to see the part.
.019cm x .012cm x .002cm is a part that is about 2 human hairs (.0075") wide x 1 human hair (.0047") deep x 1/5 of a human hair (.00078") thick.
 
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_pycnogonum_ said:
Exactly. But even if they shooed a couple of those pesky fleas and ticks off of those numbers, they would still be wrong for the OD, ID, and Height of the part in question. Gets mighty hot and itchy under that shade tree this time of year.
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It sounds like you're criticizing their ability to measure correctly but if those are truly the published dimensions, it is obviously either a misprint or misinterpreted units of measure.
Your attempt at wit behind the keyboard leaves a great deal to be desired.
 
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So...about calipers..?😅
I have 2 sets.
1 "analog"? Idk regular? Lol
And 1 digital that reads...so so...
But they are both "cheap"...
Like the cheapest regularone i could find and the cheapest digital...
Both give me a ballpark and what not for my main purposes...
But....
what does everyone else use?🤔
I'd love more accurate measurements for this hobby🥴
 
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_pycnogonum_ said:
I have a cheap dual needle dial caliper with English and metric scales, and a Starrett 425 pocket that goes with me everywhere. 64ths divided by 2.5 are pretty close to mm.

I apologize for being witless behind the keyboard. I am kind of bitter after buying a few parts from a few places that were not as advertised.
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Probably chinengish conversation equations. A toss of metric, imperial, inch rounded off to the nearest 10th +/- .2
 
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Engineers tend not to like metric tools because the smallest graduation is typically 1/2 mm, whereas you can easily read 64ths on a scale, and 100ths if you have young eyes. We didn't resist metric for no good reason, as is sometimes implied. I do appreciate that going metric implies standardizing on a smaller assortment of screw sizes, which is generally a good thing.
 
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_pycnogonum_ said:
Engineers tend not to like metric tools because the smallest graduation is typically 1/2 mm, whereas you can easily read 64ths on a scale, and 100ths if you have young eyes. We didn't resist metric for no good reason, as is sometimes implied. I do appreciate that going metric implies standardizing on a smaller assortment of screw sizes, which is generally a good thing.
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Globalization to the new world order math = metric. Please just conform or be cancelled..lol

I like my fractional caliper
 
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Modern Mitutoyo over modern Starrett for fit, finish & durability but Starrett used to be the gold standard in a machine shop. I'm a dimensional inspector amongst other things at a 30,000 sqft machine/fab shop so I have an unfair advantage with measuring tools. The "regular" calipers are called "dial" calipers but if you ask an old timer like me, regular calipers are "Vernier" calipers with scales instead of a dial. I've got dial and digital calipers from 4" to 24" all Mitutoyo and then Starrett Vernier calipers up to 72".
Calipers are good for a reference or for anything +/- .005" so there is very little discrepancy between a $200 Mitutoyo & a $50 Chinese set of calipers as long as they're not damaged. I use a $50 12" dial caliper almost daily and it passes calibration every year. Digital beats dial or vernier, not just because they're faster but because you can zero them on a pin or screw to measure the depth of a hole. Or zero them on a hole and measure between hole centers. If you need accuracy, you need micrometers with .0001" scales. Some digital micrometers even go down to half of the 5th decimal place or .00005". I've got Mitutoyo micrometers from 0" - 72".
All my serious measuring is done on a Zeiss Contura scanning CMM, programmed off of CAD models.
 
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_pycnogonum_ said:
Engineers tend not to like metric tools because the smallest graduation is typically 1/2 mm, whereas you can easily read 64ths on a scale, and 100ths if you have young eyes. We didn't resist metric for no good reason, as is sometimes implied. I do appreciate that going metric implies standardizing on a smaller assortment of screw sizes, which is generally a good thing.
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With most tools in the industry being digital, you have the convenience of pushing a button and converting from metric to inch so most digital calipers have a resolution of 0.00 mm or 0.0000". All of the European drawings I've seen in 23 years of manufacturing are in metric and most American drawn parts are in inches. Even when a part uses all metric threads, the rest of the drawing is in inches usually. Some American companies that make things like computer monitor mounts and things draw in metric but most machinists in America convert everything to inch when making.
 
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Funny bit of conversation last weekend. We had a birthday party for my son ( 34 ) & had a few of his friends over. My son had recently purchased himself a nice hobby milling machine & was currently working on acquiring TOOLING. I had gathered up a bunch of duplicate tooling from my shop to give him ... WHEN a vintage Mitutoyo 0-1" thimble micrometer came into conversation 🤪
Now my son is a software engineer and a very smart fellow, his friends as well. When the rotate the barrel, look at the lines on body counting the numbers & exposed lines, figure whats not being shown, read the thimble 0-25-0 & add that to the line figure .... THEN IF wanting a .0000 figure as well read again a scale of lines on body to thimble finding which one lined up the closest to get the 4th decimal position BLEW THERE MIND !!! Wheres the DIGITAL easy to read version of a micrometer as they shook there heads 🤣 🤣🤣🤣

At that juncture I left the Vernier calibers out of the conversation .... Was a classic old man gets the upper hand conversation and GREAT laugh :D
 
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Motorhead said:
Funny bit of conversation last weekend. We had a birthday party for my son ( 34 ) & had a few of his friends over. My son had recently purchased himself a nice hobby milling machine & was currently working on acquiring TOOLING. I had gathered up a bunch of duplicate tooling from my shop to give him ... WHEN a vintage Mitutoyo 0-1" thimble micrometer came into conversation 🤪
Now my son is a software engineer and a very smart fellow, his friends as well. When the rotate the barrel, look at the lines on body counting the numbers & exposed lines, figure whats not being shown, read the thimble 0-25-0 & add that to the line figure .... THEN IF wanting a .0000 figure as well read again a scale of lines on body to thimble finding which one lined up the closest to get the 4th decimal position BLEW THERE MIND !!! Wheres the DIGITAL easy to read version of a micrometer as they shook there heads 🤣 🤣🤣🤣

At that juncture I left the Vernier calibers out of the conversation .... Was a classic old man gets the upper hand conversation and GREAT laugh :D
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That is funny. The Vernier's would have blown their minds lol. You ought to try measuring something with a 6 foot set of Vernier calipers, it ain't easy.
 
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