Tape measure accuracy

[RobinBHM]

I never rely on measuring from end of tape if I require accuracy

Yep, I generally start from the 100mm mark to avoid the inaccuracy of the slidey bit. If it comes out at 900mm (for example), I know its 800mm. Trouble is, it's in my head that I've got to take 100mm off, so end up cutting a piece at 700mm. Done that so many times. :roll:

It's so much fun discovering one has cut a piece exactly 100mm short. If I ever mark off the hundred mm mark, before cutting I roughly check the size marked using the tape with the end hooked, to try and avoid it happening. Same thing with marking a middle line exactly -roughly measure from each end just in case the maths is wrong!

It's surprising how many people don't realise the end of the tape is not just loose, its a precise measurement. I suppose it's not necessarily obvious.

I always seem doomed with new tape measures -all lovely and accurate for a day, until I knock it off the bench and it always lands on the hook!

 

[blackrodd]

I never rely on measuring from end of tape if I require accuracy

Yep, I generally start from the 100mm mark to avoid the inaccuracy of the slidey bit. If it comes out at 900mm (for example), I know its 800mm. Trouble is, it's in my head that I've got to take 100mm off, so end up cutting a piece at 700mm. Done that so many times. :roll:

It's so much fun discovering one has cut a piece exactly 100mm short. If I ever mark off the hundred mm mark, before cutting I roughly check the size marked using the tape with the end hooked, to try and avoid it happening. Same thing with marking a middle line exactly -roughly measure from each end just in case the maths is wrong!

It's surprising how many people don't realise the end of the tape is not just loose, its a precise measurement. I suppose it's not necessarily obvious.

I always seem doomed with new tape measures -all lovely and accurate for a day, until I knock it off the bench and it always lands on the hook!

As you say, the tape always seems to end up landing on the tape's end and bending it.
A bit like the jam lid seems to end up, the "wrong" way up, sod's law!
Regards Rodders

 

[BRYAN]

What annoys me is when I carefully measure and cut a timber twice and its still too short.

 

[beaver]

I agree with deema reply, always use the same tape and your measurements should be consistent.

 

[zb1]

Tape measures have a Roman numeral printed near the hook. This is officially how accurate they are. All Stanley tapes are Class II stamped giving an accuracy of +/-2mm over an 8m tape. A Class I stamped tape would give +/-1mm over 8m.

 

[blackrodd]

I've always bought stanley tapes as often as possible and lufkin and bahco, as second choice.
But, as the man said, just stick to the same tape per job.
Never seen the roman numerals, on a tape, not even sure they got as far as Sunny Devon!
Regards Rodders

 

[Phil Pascoe]

If I thought that accuracy demanded I used the same measure, I wouldn't be using a tape anyway.

 

[Eric The Viking]

I like the window idea on that BMI tape, but it looks expensive!

You can't trust steel rules either.

I have two Draper 600mm stainless ones. Neither were cheap (currently around 20 quid), and I bought the second one only recently when I thought I'd lost my original one, which is bout 30 years old. I've kept the new one because, although I found the old one, it's got a couple of dings in the edge, so I have one very straight edge and a backup.

I checked them the other day - they don't quite agree, by about 1/2mm. It's an offset - the newer one's scale doesn't align with the end correctly (the inch side is fine).

As has been said, as long as you use the same rule consistently it doesn't usually matter, but it's still annoying. Nowadays it shouldn't be hard to make rules to a very high quality cheaply, but like engineering squares, what's claimed and what's actual often doesn't agree.

I have one German square, BS-stamped, which is bang-on (as well as I can establish), but a set of Soba ones, ALL of which are off slightly. They're good enough for most things, such as setting up saws and the drill press table, but for setting out I've only got the one that I trust.

 

[xy mosian]

The bendy slidy hooky thing can be adjusted.
From a sharp edge measure from the 100mm mark say 300mm, and mark.
Measure the same distance with the hook over the edge. Should be 200mm.
Bend, or straighten, the hook to correct any error.
This will not work on thin stock, but 15mm melamine covered chipboard is generally fine.
These days I can get within 0.25mm, with the right glasses, if I can find them. I used to be able to do the same without
xy

 

[8squared]

Thanks for clearing that up, makes perfect sense... now I can sound clever when I tell someone who asks the same question.

 

[rafezetter]

How many of use really know when we measure 10mm we really do measure 10mm ? One of my rulers says something about it's accuracy at certain temperatures I believe, but the tapes don't, and so long as it's not too cold for me I use them anyway. To be honest I haven't even checked to see if all measurers that I use believe 10mm is the same distance.

They arn't. 10mm on one tape isn't 10mm on another tape. About the only thing you can rely on is that 10mm on your tape is approximately 10mm and why you should always use THE SAME TAPE, or other measuring device for every single measurement on a single build.

This is one of the reasons why "engineering" type squares / rules and distance incremented apparatus cost that much more than a tape measure from a DIY shed for £1.50.

I would say your ruler with accuracy at a certain temperature would be about as accurate as it's possible to get - unless it's a cheap knock off of course.

The point about measuring with a tape using the sliding tip - I don't. I measure from 100mm in, removing the tip from the equation. If I'm measuring something long and need to use the tip, it's likely that margin of error isn't going to cause an issue.

 

[Steve Maskery]

I didn't know about the Roman Numeral thing. Mine has II stamped on it. I love learning. Thank you.

 

[Harbo]

My Lufkin 5m has a 1 - I never knew that - thanks
I once was on a job where the setting out engineer forgot to add the Im back - had to demolish a newly constructed concrete bridge pier - expensive mistake!!

Rod

 

[Indie Shed]

Tape measures have a Roman numeral printed near the hook. This is officially how accurate they are. All Stanley tapes are Class II stamped giving an accuracy of +/-2mm over an 8m tape. A Class I stamped tape would give +/-1mm over 8m.

Well worth knowing, thanks for the tip.

My pet hate with tape measures is badly designed lock buttons, they always seem to be really brittle and protrude too much and as I result I have very few with it intact. Stanley FatMax lasted a day, Stabila (an awful tape to read) lasted a week.

The best tape I had was a metal cased Stanley 5M tape, lovely thing. But as with most sparkly things it attracted the magpies, and it got nicked. Lock button intact. :roll: