FYI: Why Tape Measure Claws Move Around
By Chuck Cage
Today a friend asked me a question that the folks at Stanley tell me they hear all the time: why does the claw — you know, the little catch at the end of your short tape measure — move back and forth? Is it just poorly attached? The short answer: no, the loose claw is no accident of manufacture. It’s loose on purpose. The longer answer lies after the jump.
Actually, the claw moves back and forth slightly to allow you to measure both the length of an item inside the claw and an item outside the claw. To do this, the claw must slide back and forth by a small amount — exactly the same distance as the width of the claw. That way when you, for example, push the end of the measure against a wall, the claw slides in and renders an accurate measurement to the wall. When you catch the claw on the end of a stud and pull to measure a cut, the claw slides out and again you get an accurate measurement to the end of the board.
And if the claw is firmly attached and doesn’t move? Better check to see whether the tape’s calibrated inside or outside the claw before you measure or you could end up with an extra (or worse short a) 1/16″ or so.
June 26th, 2009 at 10:20 am
Makes perfect sense (now that I’ve read it!).
June 26th, 2009 at 10:25 am
Come on guys! you cant tell me you didnt know this. I found this out the first time i ever used a tape lol
June 26th, 2009 at 11:07 am
Duhhh…
June 26th, 2009 at 12:18 pm
i was just teaching that to someone working with me the other day, i was trying to teach them to understand what they were doing and not just hitting a nail or moving materials
June 26th, 2009 at 1:59 pm
I j-b welded mine in place. My whole house is crooked.
Actually, only one of those statements is true.
June 26th, 2009 at 3:13 pm
[...] via Toolmonger » Blog Archive » FYI: Why Tape Measure Claws Move Around. [...]
June 26th, 2009 at 4:41 pm
I was just teaching that to a fair number of people on site today. It’s one of those things that people don’t think about so they never know, like why framing hammers have a checkered face.
June 26th, 2009 at 5:32 pm
You have it all wrong. It’s much easier to get the claw stuck in some small crevice where it won’t come out without ruining the tape measure if it’s free to move about a little. That way they can sell more tape measures.
June 26th, 2009 at 7:33 pm
i thought it not made well, just because i found the claw with firmly attached. now, i learned.
June 26th, 2009 at 8:23 pm
for really critical stuff I use a lufkin folding rule. THe other guys on the crew make fun of me but my miter cuts never require any corrections.
June 27th, 2009 at 7:13 am
One more note–check the bend of the hook to make sure it does vary the right amount inside to outside, i.e., the inside and outside measurements match (and that the corners of the hook are square). Repeated catches in cracks, drops, etc. can throw it off (it would NEVER be wrong out of the box).
June 27th, 2009 at 11:22 pm
I think the claw test is a good way to judge if someone is an idiot or not
no offense to anyone who didn’t figure this out as a kid the first time they picked up a tape measure and noticed that it was loose.
June 28th, 2009 at 2:36 am
This post epitomizes what toolmonger is all about. Delving deep into the construction of a common tool.
June 28th, 2009 at 3:40 am
I’m not sure a lot of Far Eastern tapes measure designers realise this - I’ve got some cheap measures from the pound shop that move about 5mm…
June 28th, 2009 at 12:55 pm
@ jeff says:
When I started working - over 40 years ago - I noticed that most journeyman carpenters carried folding rules . They came (still do) with extension bars at one end for taking inside measurements - no need to bend the tape and eyeball things.
Some plumbers carried their own version (also still made):
http://www.jimslimstools.com/Products/626-Lufkin—Red-End-6-ft-Plumbers-Rule__626.aspx
– and there were vesions for brick masons as well.
June 29th, 2009 at 6:01 am
I think this is a good test for people who like to “brag” about how “good” they are.
June 29th, 2009 at 8:19 am
Although it might not matter to you (depending on your level of precision) many tape measures are calibrated differently. Last fall while we were building my friend’s log cabins we (three carpenters, aged from 46 -53) noticed that all five of the tapes we had on site (2 new Stanleys, an older Stanley, a Tajima and a Fastcap) were giving vastly different readings. The largest difference was over 1/4″. We all usually worked alone, where a difference like this would never be a problem, you measure - you cut, but on a site where one person measures and another cuts it made for some sloppy fits that had to be re-cut.
We solved the problem by finding the three Tapes that measured closest and tweaking the claws so they were the same.
June 29th, 2009 at 8:37 am
you would think that there would be some standards.
did you notice variation between the new and old stanleys as well?