Ok this is going to take a while … So don’t expect me to cover everything in the first post …
I am no EXPERT !
I don’t claim to be an EXPERT
And I do not have the facilities to verify tools for ABSOLUTE accuracy … ( And I in no shape or form claim such )
What I do have is a few calipers , and I have owned them for a while ( 30 years give or take )
I have also worked in engineering environments , with lathes / mills and grinders .
I have also occasionally taken the odd measurement . ( With calipers and micrometers and even rulers ) The company that issued us with rulers ( Run by Rabbits ) …
Anyhow !
The most important rule about calipers , is that they produce repeatable results …
What I mean by that is , you measure something 20 times and every time the resulting measurement is the same ( That’s repeat ability )
This is not acceptable if you manufacture to blue prints , as you would require certified / tested measuring that may need to be conducted under certain conditions especially if manufacturing parts for say the space shuttle . Or possibly a satellite or missile of some sort .
But we joe six packs don’t require such accuracy . do we ? ( This is a flashlight forum after all and I would be amazed if anyone could maintain + or - one thou in a manufacturing environment or would need to ) .
Back to calipers …
There are 3 types of vernier caliper …
The old line type ( etched markings like on a ruler )
These can be surprisingly accurate , + or - one thou in experienced hands is not un heard off .
Then you have your dial calipers - These are a mechanical device so suffer from all related issues … And with a lot of use they will suffer from wear and tear .
Treat these poorly and they will screw you …
Digital calipers - I like these as they dont suffer from wear and tear like mechanical calipers do ( dial ) … Though you may run into other issues ( electrical etc )
I really like the digital calipers , they are so easy to use and more importantly , easy to read ! .
You can buy calipers from $5 to , how much do you want to spend ?
Now here is something to store on the old memory card .
Calipers are not the last word on measuring , they are a accurate / fast / simple way of getting a ball park measurement … ( Ball Park )
There are so many variables that can effect the result of measuring something …
The most simple and blatant being the skill of the operator … If you don’t know how ! then the induced variable could be large ( induced by the user )
Common mistakes are torquing the tool ( sideways pressure ) not correctly lining up the object to be measured …
Using too little or too much pressure …
Another variable being the cleanliness of the object being measured and the working surface of the caliper jaws .
Another variable is heat / or cold . Cold tends to shrink things and heat tends to expand them , same goes with the calipers ( Heat can induce variance )
Also the materials the calipers are made from , different steels expand and contract at different rates …
And lastly you could be buying calipers that are simply faulty to start with ( I have a set of those ) .
Accuracy of the calipers ? : ( Just how much do you need )
Here things get interesting .
Calipers generally come in an accuracy scale of one tenth or one hundredth off a mm … Metric … And one hundredth or one thousandth off an inch . ( imperial )
These days that has improved to half a thou …
With dial calipers , you have a visual reference you can work from … So if the needle points between two marks you can guesstimate 1/3 . 1/4 or 1/2 … ( Depending on just how much accuracy you need )
With digital calipers you have no such visual reference . What you have is rounding to the nearest whole number .
So if you have calipers that are accurate to one tenth of a mm , then the caliper will round to the nearest tenth .
Hence the accuracy is regarde as + or - 0.1mm because the measurement will fall to the nearest tenth . And so it goes with hundreds and thousands .
The digital calipers will round to the nearest measurement the caliper offers .
Again , calipers are not the be all super duper measuring tool … They are generally considered to be ball park measuring tools in engineering circles … ( Depending on the tolerances you are working too )
Continued :
Problems to watch out for …
Lets start with dial calipers …
My first pair were Mitutoyo , I got them through a Engineering company that got the trade rate for its employees …
At the time I was a storeman , the guy that handed out the tools to the guys on the shop floor .
I remember talking to one of the foremen about calipers and he gave me the speel on looking after them …
Your calipers come in a case , keep them in the case . ( Don’t leave them lying about on dirty surfaces )
Before you use your calipers , clean your hands , clean the work , and clean the jaws .
Never open the jaws too quickly , this induces stress and can cause the gears to strip or jump and increases wear and tear …
( You see people ripping open calipers like it was a speed test and then closing them like they were trying to crush a beer can = Completely unnecessary )
Get dirt in your calipers and they will suffer for it , wear faster and that all important repeat ability can be affected .
Once dirt gets in , there is no getting it out .
I remember starting at one place and being issued a new set of calipers ( Mitutoyo ) … And the guys in the shop trying to steal them from me and replacing them with their worn out crap …
I always got them back and after a while just kept them on me all the time … ( You were issued a caliper and if you stuffed it you replaced it out of your own pocket )
It never ceases to amaze me how poorly people treated their calipers .
Problems :
Dirt , can cause increased wear and tear … Cause the dial to jump affecting repeat ability .
Make the calipers rough ( not smooth ) …
The dial cover can get dirty from the inside making reading the caliper hard if not near impossible …
Leave the calipers in sunlight can cause yellowing of the cover ( lens if you will )
And as mentioned , mechanical devices wear out with use …
I have seen people use calipers that are so worn , they are easily 10 thou out …
Or calipers where the needle jumps when opened at anything more than crawling speed
And calipers the feel like they have half a beach inside them .
Look after your dial calipers , treat them with care , keep them clean , and they may last a life time .
Treat them like crap and they may give you the same in return .
Digital Calipers …
I never encountered these in the work place …
But for personal use , I have had a few .
And quite a few of them have been NQR ( Not quite right )
Here are some issues I have encountered …
Battery - It works it does not work …
Turns on and off on its own , while you are measuring something
The measurement jumps , ( much like a dial indicator can jump ) … and the caliper is out say half an inch for arguments sake ( I had a pair like this = went in the rubbish bin )
Or my current ( cheap calipers ) where they simply lie to me … Yep … the measurement is a lie , a repeatable lie , but a lie never the less …
It took me a while to catch onto this , Im just glad I never measured anything important with that caliper … As I had another digital caliper that I verified against my Mitutoyo calipers .
So one day I had both calipers out measuring something , and the cheap calipers were giving me completely different results … ( Repeatable results - but way out )
So after a quick check against the Mitutoyo calipers the cheap nasty ones had the battery removed and actually hit the inside of a rubbish bag … But then I thought - What if I ever write about calipers , I might need an example of something that’s NQR … ( So I still have them )
Something that effects all calipers is build quality …
There are so many things that can be NQR that I can’t possibly cover them all …
Some of the more common issues
- How flat / true are the working surfaces of the jaws
- Inside measuring jaws - How true are they ?
- Depth measuring - again how true ?
- slop / tolerance of the working parts … Too much slop can introduce variance
- Do the calipers LIE … ( Not give a reasonably true reading )
Cheap VS more expensive …
This is Budgetlightforums of course , we do love cheap right !
And one thing is for sure ( almost a given ) , when you buy cheap you are increasing the odds of getting something NQR
I have thrown away my share of cheap things , be they Dash cameras , micro cameras ( spy cams to some ) , and calipers .
But I have never been dissuaded from buying cheap ( Because I find cheap to be fun - Ok - disappointing at times - but often a barrel full of fun )
If it wasn’t fun , i would not do it … ( Fun is important - never discount the fun factor )
But here is the interesting thing , most if not all my calipers ( except the Mitutoyo ) are cheap calipers … ( In comparison )
And they do a sterling job ( they meet my needs ) …
I currently have two grades of calipers …
Those that measure 0.1mm and those that measure 0.01mm ( 0.01 inch or 0.0005 inch )
When I need a quick and dirty measurement I reach for a $5 digital caliper ( 0.1 mm / 0.01 inch )
And I have verified the accuracy to its resolution ( accuracy scale ) … Measuring OD … I have not tested ID as yet ( these are about a week old )
Before these I used an old imperial MTI caliper accurate to 10 thousands ( OD ) but ID was some what out …
The old MTI calipers are almost as old as my Mitutoyo , and I got them for ball park measurements when I used to turn stuff at home …
( I used the MTI till I got within 20 thou , then switched to the Mitutoyo till I got within 2 thou and then switched to the digital ( Mitutoyo ) Micrometer for getting where I needed to be .
Next I will talk about the calipers I own , and compare them to the Mitutoyo …
As well as do some accuracy testing …
Remembering - these will be ball park figures as
I am no expert
and I dont have the facilities or equipment to verify ABSOLUTE accuracy
So its a comparison ….
Put that on your HDD … Comparison !
continued :
Some interesting results :
I measured 3 items
A steel security bolt
A hex driver ( shaft )
And a piston cylinder assembly ( K&B Conquest - 2.5cc )
6) Mitutoyo .3135 for the bolt - .1375 for the hex driver - and .591 for the piston ( OD ) and .5905 for the cyl ( ID ) imperial
8) Sontax .3135 for the bolt - .1375 for the hex driver - and .591 for the piston ( OD ) and .5905 for the cyl ( ID ) imperial
Shahe Calipers ( Not Pictured ) .3135 for the bolt - .1375 for the hex driver - and .591 to .5915 for the piston ( OD ) and .5905 for the cyl ( ID ) Kept switching on the piston from .591 to .5915 imperial
7) SWT Dial metric 7.97mm for the bolt - 3.50mm for the hex driver - 15.02mm for the piston ( OD ) and 14.99mm for the cyl ( ID )
For comparison I used the No8 Sontax in metric mode … 7.97mm for the bolt - 3.50mm for the hex driver - 15.01/15.02mm for the piston ( OD ) and 15.00 for the cyl ( ID )
3) MTI Dial imperial .32 for the bolt - .14 for the hex driver - .59 for the piston ( OD ) and .597 for the cyl ( ID )
2) Ebay plastic Dial 8mm for the bolt - 3.5mm for the hex driver - 15mm for the piston ( OD ) and 14.85mm for the cyl ( ID )
5) Ebay plastic Digital 7.9mm ( .31inch ) for the bolt - 3.4mm ( .13inch ) for the hex driver - 15mm ( .59inch ) for the piston ( OD ) and 14.6mm ( .57inch ) for the cyl ( ID )
1) Plastic Sontax 7.8mm ( .3inch ) for the bolt - 3.4mm ( .13inch ) for the hex driver - 14.9mm ( .58inch ) for the piston ( OD ) and 14.8mm ( .58inch ) for the cyl ( ID )
4) Bad Calipers 8.3mm ( .327inch ) for the bolt - 3.79mm ( .1495inch ) for the hex driver - 15mm ( .591inch ) for the piston and 14.97mm ( .5895inch ) for the cyl ( ID )
To be continued ( 1.25 AM ) time for bed …
9.23 AM ….
I consider myself rather lucky in the regard that my first calipers were the Mitutoyo …
As it gave me the opportunity to check any and all other calipers against it .
I can’t remember how many calipers I have thrown in the rubbish bin over the last two decades .
It could be 3 or 4 , I just don’t remember .
The first digital calipers not to be binned were the Sontax Steel Calipers (8) …
And I was very surprised to find that they gave me the exact same reading as the Mitutoyo calipers across a very broad measuring range …
Well I was hooked on cheap calipers … I don’t remember what I paid for them , but it was not more than $15 Ozzi Bananas . I may have paid a lot less ( Just don’t remember )
Anyhow ! This allowed me to put the Mitutoyo out to pasture so to speak and the Sontax became my go to caliper for when I needed that one thou reading . ( 0.0005 inch resolution )
I am not sure how long I have had the Sontax , could be around 10 years … I would buy another , but there is no Sontax out there on Ebay land …
There are the generic stainless steel calipers with the same body as the Sontax from about $18 …
I might see about playing with the cheap plastic Dial caliper (2) and see If I can’t get it tuned a little , especially measuring ID …
For $7 Ozzi bananas its a Cheese Burger with fries … But I like the potential it has for being decently ( Ball Park ) accurate …
So for you guys with only one caliper , ?
Again as long as its consistent - Repeatable measurements , Much like my (4) calipers that lie … As long as its the same lie …
Then its not the end of the world . ( For home use )
The results I posted are an eye opener …
Batteries , go online … Buy a Card of batteries for like $3 shipped to your door and make sure to check the USE BYE DATE !
I purchased a lot of button cells for my calipers like 10 years ago … Only to discover that from the 3 different sources they were all past there use bye date …
My latest purchase has a 2021 use by date … So hopefully the batteries will have a little juice …
Lots of cheap batteries on Ebay past there use bye date . ( Just something else to check )
