Taking it up a step---

PS

terryd said:

Hi,
I have several cheapo 150 mm digital calipers a couple of them have what seem to be everlasting batteries as when switched off they really are off. The other two remember the previous setting when 'off' and use battery power to remember that setting causing it to run down. However they are not really that accurate and I prefer my Moore and Wright vernier calipers which are accurate (at 20°C) and easily read if you know what you're doing.

When serving my Engineering Apprenticeship back in the deep mists of time an old instructor who must have served his apprenticeship around the early 1920s taught me how to use ordinary spring calipers, both internal and external and once you learn how to 'feel' their use it is surprising how accurate such simple and relatively expensive devices can be especially when using them as comparators. They are shown in the (I seem to recall) 1935 Southbend instruction book on the lathe.

In the Museum of Science and Technology in London UK there are several examples of early 19th century machines such as Maudslay's early screwcutting lathes and the finish of the mating surfaces - all hand scraped - and accuracy have to be seen to be believed. All done without verniers, dials or elecronics just using spring calipers for comparing standards, those people were craftsmen of the highest leve. Of course Maudslay and Marc Brunel also designed and built the first mass production line installed and running by 1807.

Happy and prosperous New Year to all
TerryD

Click to expand...

P.S.
I forgot to mention that somewhere on YouTube a guy showed how modified his digital caliper by adding a sort of thin plastic slider which isolated the battery after use, an idea perhaps useful for those who have problems with battery rundown.

regards
TerryD

ajoeiam said:

An 8" digital vernier was my first measuring tool.
Found that I could influence the measurements far too much. (Could change the measurement by an easy 0.002"!)
Measuring with the tool not totally square to the bore (ID measurement) was also far too easy.
Also got bit real good making a bearing fit shaft one day and that taught me the crucial effect of temperature on measurements.

I have collected a few measuring tools - - - but it always feels like 'never enough' - - - LOL.

Wish I would have exposed to good instruction at the beginning of my learning machining rather than well into it.
Likely would have made a bunch of things much easier!! (And likely more accurate too - - - grin!)

Making to fit is not a bad way to work but not very useful when you start dealing with stuff that weighs enough or is not easily movable or doesn't fit onto the lathe - - - then you absolutely must be able to measure well!

Click to expand...

An old fashioned internal spring caliper is great for measuring most internal diameters over about 20mm. aafter setting tem in the bore, they can be moved side to side with one leg static to ensure that you are on the exact diameter then, again with one leg staticswing the other leg back and forth in the bore until you just feel that leg gently touching the bore.
You then have at least a couple of possible actions, i.e. use a micrometer to measure across the legs of the caliper ('feel' is crucial here) or, set a pair of external calipers to the legs of the internal one - again practice makes perfect - and use the external caliper to compare to your work, especially useful when turning but also in other types of work and you will be amazed at the speed and accuracy you can achieve using this method. As I said it takes practice, I was taught the process almost 60 years ago during my engineering apprenticeship by a real craftsman who served his apprenticeship in the early 1920s. It's a method worth trying and perfecting for it's speed of use.

Here's a scan from S.B. 1935 "How To Run a Lathe"



Happy and prosperous New Year

TerryD

terryd said:

An old fashioned internal spring caliper is great for measuring most internal diameters over about 20mm. aafter setting tem in the bore, they can be moved side to side with one leg static to ensure that you are on the exact diameter then, again with one leg staticswing the other leg back and forth in the bore until you just feel that leg gently touching the bore.
You then have at least a couple of possible actions, i.e. use a micrometer to measure across the legs of the caliper ('feel' is crucial here) or, set a pair of external calipers to the legs of the internal one - again practice makes perfect - and use the external caliper to compare to your work, especially useful when turning but also in other types of work and you will be amazed at the speed and accuracy you can achieve using this method. As I said it takes practice, I was taught the process almost 60 years ago during my engineering apprenticeship by a real craftsman who served his apprenticeship in the early 1920s. It's a method worth trying and perfecting for it's speed of use.

Here's a scan from S.B. 1935 "How To Run a Lathe"
snip

TerryD

Click to expand...

I found learning the 'feel' for measurements was critical when using telescopic gauges.

Using the spring calipers - - - - likely almost a lost art.
Then if your machining using very rigid high powered machines - - - - well you turn off 0.150 to 0.300 the dia per cut and you final cuts are 2 - 50 or 60 thou cuts - - - comparative measurement isn't too useful.
(Now if your doing small cuts - - - - much more useful.)

Brian Rupnow said:

Digital vernier needs batteries and a read out. Analog verniers have a rack and pinion driven dial.

Click to expand...

Hi Brian,

With all due respect digital and dial calipers are not 'Verniers' they are simply 'calipers'. A 'Vernier' device uses two sliding scales which can be used, rather like a traditional slide rule, to establish accurate measurements (the capital V'' is to respect M. Pierre Vernier who devised the system (in 1631)). In fact a manual, non dial micrometer can have a secondary scale on the mic body above the linear scale to measure to within 0.0001".

My old Moore & Wright vernier caliper is accurate to within 0.001" or 0.02mm (0.0004") as it has dual scales - meaning that I don't have to press a button to change units nor change batteries. I only use my digital calipers for depth or small bore internal (greater than 0.635mm - 1/4") measurements. In the picture below, the secondary slider on the right can be clamped and accurate movement controlled by the lower captive nut and screw system, the ends of the jaws can be used for internal measureament above 0.625mm (the outer edges of those are rounded to a diameter of less than that). In the picure it is reading 9.06mm


Regards

TerryD

ajoeiam said:

I found learning the 'feel' for measurements was critical when using telescopic gauges.

Using the spring calipers - - - - likely almost a lost art.
Then if your machining using very rigid high powered machines - - - - well you turn off 0.150 to 0.300 the dia per cut and you final cuts are 2 - 50 or 60 thou cuts - - - comparative measurement isn't too useful.
(Now if your doing small cuts - - - - much more useful.)

Click to expand...

Hi,
You'd be surprised just how accurate it can be using spring calipers, in fact with a lot of practice I would say that they are accurate enough for 95% of my modelling work (mostly small live steam locomotives).

As an aside I'm sure that you know it is possible to turn to within 0.02mm (0.0008") by setting the top compound slide to 84.25° (84 is close enough). That setting gives a 1/10th reduction in cross movement if the compound is used to advance the tool. In imperial terms 0.001 will advance the tool by 0.0001" which on my lathe decreases diameter by 0.0002" - of course gib keys have to be well adjusted and spindle bearings need to be in good condition and adjusted (precision taper bearings on my old Boxford BUD)

Regards and best wishes of the Yuletide season,
TerryD

Richard Hed said:

OK, whatever

Click to expand...

Hi Richard,
It's not £whatever" The 10/11 ratio just doesnt work on a Vernier scale.

Regards and best wishes of the Yuletide festival,
TerryD

terryd said:

Hi Richard,
It's not £whatever" The 10/11 ratio just doesnt work on a Vernier scale.

Regards and best wishes of the Yuletide festival,
TerryD

Click to expand...

I understand, it was the concept that I was doing. 9-10 apparently is how Mssr. Vernier did it. I believe, any system could work such as 17-18 or 29-30, in which the larger the numbers, the more accuracy achieved, however, it would also be a very inconvenient system if not close to 10, 50 or 100, i mean, how would you like to try to add parts of fraction using a 17/18ths system to a decimal system--NAUGHT.

BTW, if you actually COUNT the marks, it depends how you do your counting. In the real number system (and for instance making gears with a dividing head), how many numbers between 0 and 10? Include the ends when counting. This will give you 11 numbers. If you count NOT including the ends, it gives you 9 numbers. So with the Vernier scale, if you start at the first mark or "zero", and count to the last mark, "10", you have 11 marks altogether. ON the other side of the slide, that will be 10 marks. I understand what you'all mean and you are correct, it's just that I am MORE correct in the way I count the marks. You get different results if you count the SPACES between marks.

Guys
Several of you have mentioned that when turned off the Vernier remembers the last reading and this is a battery drain. Although it is very difficult to check, the battery drain should be very small (nanoA) and is no issue. However cheaper verniers are not well designed and have a larger drain. If you can afford to, stay with Mitutoyo.
Mike

Hi Richard, I understand. You are counting fence posts (marks, including zero), everyone else is counting fence panels (intervals).
I suspect we all agree now.
* Verniers are scales used on many measuring devices.
* Callipers are comparators, but if fitted with a scale (dial, vernier or electronic detection with digital display)
* Those without the skills of "old" techniques are happy with new technology.
* Those with "old" and traditional skills and training enjoy practicing those skills - and achieving the results of their skills.

- This site allows us to share in part some of those skills, and the methodology behind them, so maybe some of the un-initiated can learn and carry on the "old" technology, because history was made using it, and some of it teaches us fundamentals that are not otherwise appreciated with "modern" technology. - E.G. the use of callipers as comparators, and "feel" when using them.
How may use slip gauges, join them together using atmospheric pressure to hold them in stacks (the reason they are called slip gauges?), and use the comparators (of whatever form) to check against the accuracy of the slip gauges?
- Also, how many actually know what I am talking about? (I wonder if I do?).
Would any of the "modern technological" guys want to own my grandfather's vernier calliper with "20ths" of a mm on the scale? (19 scale divisions versus 20 vernier divisions - or 20 marks versus 21 - giving about 0.002" divisions for those in Imperial lands.) - I doubt it. But I get some weird thrill from making things as he did, with my hands on the same tools that made the same decisions as him. It's not genetics, it is "taught skill", that he taught me, and is more important than the batteries going flat of the modern technological device that is "more accurate". I just don't get the same thrill from using a digital device. It is just a tool...
Ultimately It is my hands and use of them that provides the accuracy and consistency of measurement. Combined with the knowledge and expertise of "how" good measurements are made... That is a real part of the "why" some of us make these little engines, etc. And this site helps expand my knowledge, from the experts who write about the "hows" and techniques. (Thankyou).
So: Please continue to share ideas, and respect the "why" we use the tools we have and ENJOY using. - It is not about "what is best" - but about sharing ideas within the technology.
(Sorry if I got a bit carried-away with my diatribe. Here-endeth the lesson!).
K2

I use a trad vernier at work. It's a PT job in a university machine shop, and none of the students will nick my callipers as they can't read them. Might not stop them borrowing them to open a paint tin, or perhaps mistaking them for a small old-style adjustable spanner, of course.

(Did I tell the one on here about the prospective technician who was asked to use a 0-1 mic to measure the dia of a bar? She found the point where it touched and then did it up another turn just in case (and put it out, permanently). They employed her.)

MRA: Ever had to measure a 12" micrometer? Teaches you to handle with care!
K2

There are some big-uns at the museum where I volunteer, though I think the largest journal I have encountered so far is about 10" dia. I am glad I get to play down there as compared to models, the tolerances are...generous.

(ETA - there's a Doxford from your part of the world whose mains might be 16". But I haven't done any measuring yet on that huge rusty pile!).

MRA said:

There are some big-uns at the museum where I volunteer, though I think the largest journal I have encountered so far is about 10" dia. I am glad I get to play down there as compared to models, the tolerances are...generous.

(ETA - there's a Doxford from your part of the world whose mains might be 16". But I haven't done any measuring yet on that huge rusty pile!).

Click to expand...

Rusty pile? Can you show a photo of the rusty pile? or many photos?

Hi MRA, Does the museum have a name or website? - They all need publicity and there may be a reader near "your neck of the woods" who wants to visit, or support?

My use of the large mic was turning castings into cross-heads for large Broom-Wade compressors, and turning engine flywheels to take new ring-gears for starter motors. (replacements were not always the same bore as the original ring gears).
K2

Yes, I've mentioned it here once or twice - the Anson Engine Museum, Poynton Cheshire (near Stockport, and very near Hazel Grove where a lot of the older guys used to work at Mirrlees). The website is not very 'updated', but there is quite a lot going on. Currently working on Mirrlees single and 4-cyl diesels (like this one, which is a 5 cyl ) - the larger one we have used to pump water back up a set of ship canal locks at times of lower flow - and also a Crossley diesel single, which is about 144l capacity (18.1/2" bore, 28" stroke) - just a massively scaled-up sideshaft engine, with a 13 ton flywheel. It's a lot of fun. We open between Easter and about October, and 'steaming weekends' are the most fun of all.

Here's us on a recent-ish visit to Mode Wheel Locks on the ship canal to get some spares for our engine (from another set of locks) when this engine was about to be scrapped



...and here's a video from long ago when Mirrlees apprentices removed our engine from its own engine house, on its way to the museum where it only now starts to come together



One of the volunteers posts on youtube as 'Tanisla2'. If you search there you'll find loads of clips of things we have been doing.

cheers
Mark

Found a couple more.

Getting a cylinder liner out of a spare pedestal, to replace the one in our single which was shattered



...and putting a large-ish crank in, in the snow. There's now a building erected over this bit, which is where I'm off to now!



I hope that's whetted folks' appetite to come and have a look, if you're in the area.

Using Stilsons and extension tube to remove stubborn nuts should be a no no for any real engineer. Long handled large spanners are used at every heritage railwayworkshop and I'm sure they would have loaned you one, with a bit of foresight.

Mike Ginn said:

Guys
Several of you have mentioned that when turned off the Vernier remembers the last reading and this is a battery drain. Although it is very difficult to check, the battery drain should be very small (nanoA) and is no issue. However cheaper verniers are not well designed and have a larger drain. If you can afford to, stay with Mitutoyo.
Mike

Click to expand...

Hi mike,

I have 2 almost identical inexpensive digital calipers which I purchased at more or less the same time. One retains it's reading, the other switches off completely. One uses a battery in around 6-8 weeks, the other's battery lasts for years (I just had to change but can't remember when I did so previously). I'll leave you to guess which is which. It's not a simple matter of expensive vs inexpensive.

As far as cost is concened, I can buy one of my cheap caliers for around £10 while the cheapest Mitutoyo costs £100 or so the CR032 batteries cost less than 5p each from Amazon, so for my £90 saving I can buy more than 1800 batteries and I always keep a supply handy as they have a shelf life of several years. I can also afford to buy several inexpensive digital micrometers, one for each machine, and also modify them for other uses, I certainly couldn't do that with Mitutoyo et al.

Best regards
TerryD

Though if an existing nut is already damaged it can make more sense to use Stilsons as they will tend to grip the nut better than an open ended spanner which could slip off a worn nut. The Engineers at Anson also do a good job of making new nuts and even make them to original works drawings





There are a lot more photos of these and other engines being worked on on Anson Museum's facebook Page for those that want the full picture

Also worth bearing in mind that when these engines become available it is often at short notice and time to remove them can be very limited as the demo guys will be chomping at the bit. So the volunteers often don't get a chance to find out what spanners are needed for each and every nut so the 1 size fits many Stilsons are a practical choice

That's one of 8 nuts (well, we had seven - doh! - we are bound to find #8 one day now we don't need it) which helps hold the two-part flywheel together at the hub for the big Crossley whose crank is going in, in the pictures above. It's got to be right, as the rotational inertia will be considerable! It was cast in one, and then broken at 0 and 180 deg at the rim (elsewhere the casting was all split in the mould), so the two halves fit very nicely.

Those were Mirrlees apprentices taking the engine out (knowing the Ship Canal Company / Peel Holidings - under time pressure) in 1993. I imagine no spanner was available, or the training manager (who appears in the video, is still very much with us, and is a stickler) was looking the other way!

OK, I'll not mess up this thread any more. Perhaps I ought to start one with video links 'recently at the Anson Museum' in case folks would like to see what is going on.