Accuracy of old Stanley folding rules

[chris carter]

I’m thinking about picking up a Stanly 36-1/2 folding rule/caliper. My most used rule is my steel 6”, followed by my 12”, and lastly my tape measure. I also have a brass caliper that I whip out occasionally. I feel like the 36-1/2 would kill a lot of birds with one stone (all but the tape measure), and it would be fun at the same time.

BUT…. How accurate are these old Stanley folding rules? I’ve never used one before. I assume the markings are perfectly accurate, but I wonder about the thickness of the rule playing a role in accurately placing a knife or pencil as you sight over the edge. Most of the time I just need a ballpark measurement, but sometimes I need things to be pretty accurate.

[Mel Fulks]

I worked in a place that made window sash. They wanted everyone to use those rules….it was a rule. Like snowflakes no two were ever the
same. But some are made of box wood, and they are fun. The steel folding rules are accurate. You are right about the thickness of wood
rules being a problem….but they probably sell small plumb bobs to drop for better accuracy!

[Kevin Jenness]

I keep a 6' Lufkin folding rule with a brass slide insert in my toolbox for inside measurements only. Way slower than a tape. When I was a youngster my dad worked with an old-timer who used one regularly. It was painful to watch that thing get unfurled and refurled every time. Mine agrees with my tapes, but parallax is an issue and the painted gradations are rather coarse. For precise marking out an engraved rule is far better.

[Jack Frederick]

Having come out of the pipe trades, the first day of my apprenticeship in ‘70 I was told to report the following morning with a pair of Channelocks, a torpedo level and a 6’ folding rule. The rule is a Lufkin 46X’s with the slide and hook. In the shop if I grab a folder it is the inside White Lufkin. Much better to work with as it lays flat on the table. Some work I will use it some I won’t.

[Tom M King]

The ones I use always read the same thing every time.

If I'm up high, calling measurements to a saw man down below, we compared measuring devices to start with.

[Jim Koepke]

The rule of tapes and rulers is to use the same one for all of your measurements.

My woodworking became a lot better by no longer trying to mark and cut everything down to 1/32 of an inch.

My most used folding rule:

466711

It has had its markings redrawn with an extra fine point Sharpie™. Not ANSI accurate, but the lines don't change from measurement to measurement.

If the line is too far away from the work, tilt it up on its edge.

For me it works fine with a try square underneath the rule to set it where a line has to be knifed or drawn with a pencil.

My tape measure is always in my pocket and is my most used tape measure. It is the Stanley SW Hart 175 year anniversary edition.

jtk

[Luke Dupont]

I keep a 6' Lufkin folding rule with a brass slide insert in my toolbox for inside measurements only. Way slower than a tape. When I was a youngster my dad worked with an old-timer who used one regularly. It was painful to watch that thing get unfurled and refurled every time. Mine agrees with my tapes, but parallax is an issue and the painted gradations are rather coarse. For precise marking out an engraved rule is far better.


Interesting. I just recently bought a folding ruler (granted, made of plastic and not tape) because I've always been so darned annoyed at tape measures.
They're fast and great for carpentry work I'm sure, and maybe I just suck at using them, but they're so unstable that it's difficult to do detailed work and get an accurate measurement. You have to keep one side hooked to the end of the work using tension, and you have to hold the tape measure up right, and it always wants to come unhooked or fall over or whatever. A plain, straight ruler that you can just lay down on your work is *so* much nicer, but takes up a ton of space to store. Enter the folding ruler! Stable and compact. Just lay it down on your work and then you have both hands free to mark and you're not playing this delicate balancing act in which your measure will come crashing down at any moment.

Again, maybe I just suck at using tapes, but flat, non flexible, stable ruler is much easier for me to use.

[Jim Koepke]

Again, maybe I just suck at using tapes, but flat, non flexible, stable ruler is much easier for me to use.

One of my favorite things about my folding rule is the hinges have been oiled with silicon oil and it can be picked up and folded from the center and the two legs fold via gravity. It is a quick one handed movement from fully extended to folded into my pocket or set aside on the bench. It can also be opened just as easily.

jtk

[Kevin Jenness]

The rule of tapes and rulers is to use the same one for all of your measurements.

My woodworking became a lot better by no longer trying to mark and cut everything down to 1/32 of an inch.

My most used folding rule:

466711

It has had its markings redrawn with an extra fine point Sharpie™. Not ANSI accurate, but the lines don't change from measurement to measurement.

If the line is too far away from the work, tilt it up on its edge.

For me it works fine with a try square underneath the rule to set it where a line has to be knifed or drawn with a pencil.

My tape measure is always in my pocket and is my most used tape measure. It is the Stanley SW Hart 175 year anniversary edition.

jtk

Jim, that's a nice rule, quite a different design than the Lufkin I have in that it will lay flat on the bench. I can see why you like it. The 6" extension on the Lufkin is what makes it useful to me for inside measuring.

I often need to pull relatively large measurements so I always have a 3/4" x 16' Stanley tape at hand. For layout I often will use a spring clamp to secure the extended tape to the workpiece or story pole, referencing off the 10" mark so I don't have to tension the hook (referencing off the 1" mark has been the cause of many an error). A Fastcap flat tape is also handy. For more precise gauging I may use trammel points on a beam or a bar gauge. For relatively short measurements I have 6", 12" and 24" rigid rules and a nice 1 meter flexible rule with metric and imperial gradations.

[Robert Engel]

I took all my rulers and tapes out one day, lined them all up against the fence and compared the measurement to an 8" long piece of wood measured with my Starrett.

The results:

Two tapes out of 6 were dead on accurate: a Milwaukee 6' tape and a Komelon 12' tape. The Stanley's, Dewalt, and Lufkin were all off by up to 1/16".

All 3 Veritas hook rules were dead on as well as several stainless steel rulers.

None of the 24, 36, 48 and 60" aluminum rulers were within 1/16.

The Lufkin folding rulers were the worst.

[Edward Weber]

When doing any project, it's best to use the same rule or tape throughout the entire process to eliminate any variance between measuring tools. If you do this, accuracy is sort of moot.
Back when folding rules were the common method of measuring, people didn't usually have seven different tapes, rules, gauges and so on. One folding rule did pretty much everything.

[James Pallas]

I use a four fold or a 6’ 90%. I also use story sticks (poles). I believe a lot of it has to do with how you learned. Many times in the course of work there are multiples of the same piece. I measure and mark one and use that to mark the rest. The same piece used to mark the rest. Im only using the measuring device once. You have to remember to “take the line” or your parts will grow. Once you learn a few tricks you can set angles and some other things with a folding 6’.
Jim

[chris carter]

Thanks everyone; this is all great info.

I think I’ll try and get one. Whenever I use my tape measure it’s just for ballpark where the exact measurement doesn’t really matter. The more important measurements are when I’m using my 6” and 12” steel rules and the 36-1/2 will cover those so I could stick with the one measuring tool to keep things consistent if it’s a little off.

[Jim Koepke]

I also use story sticks (poles).
[edited]
Once you learn a few tricks you can set angles and some other things with a folding 6’.

+1 on story sticks. Some of mine use a gauge block that comes in handy when repeatedly marking the same size:

466775

One gauge block can be used on multiple sticks.

Some of those tricks can be done with a two foot folding rule:

466776

Usually it is handier to have a protractor in the kit.

jtk

[Jim Koepke]

Went out to the shop to test drive a Veritas Dovetail Saw. More on that in a different post.

Thought about my folding/wooden rules so took a photo:

466781

The oldest 36" folder is used the most. The new looking folder was purchased in a hardware store in Portland, OR.

The 12" folding rule has a caliper with one side in inches and the other side in metric.

My Lufkin zig-zag with the slider was given away since it was seldom used after making a sliding inside measuring device from some yard sticks:

466782

This is an old post about making it > https://sawmillcreek.org/showthread.php?151635

One day my plan is to make a couple smaller sliders.

jtk

[Charles Guest]

I’m thinking about picking up a Stanly 36-1/2 folding rule/caliper. My most used rule is my steel 6”, followed by my 12”, and lastly my tape measure. I also have a brass caliper that I whip out occasionally. I feel like the 36-1/2 would kill a lot of birds with one stone (all but the tape measure), and it would be fun at the same time.

BUT…. How accurate are these old Stanley folding rules? I’ve never used one before. I assume the markings are perfectly accurate, but I wonder about the thickness of the rule playing a role in accurately placing a knife or pencil as you sight over the edge. Most of the time I just need a ballpark measurement, but sometimes I need things to be pretty accurate.


If you use the same rule throughout the process then it doesn't have to be objectively accurate, just accurate enough to measure the proportions you've designed into the project. If you're making furniture, you rarely need to measure even to the sixteenth, much less anything smaller. It's cut to fit, plane to fit. If you swap between two or three things -- a tape, a bench rule, and a folding rule and you expect them to all be dead on by themselves and also in comparison to each other, then you have a fundamental misunderstanding of the process.

If you're working on a carpentry crew, there is a process to calibrate everybody's tape. This can be found on carpentry websites. It is not necessary for the individual bench woodworker making on-off pieces of furniture or even built-ins. If you're doing built-ins, you just make story sticks right off the room. The numerical measurements are almost meaningless when you get ready to cut wood.

[Jason Buresh]

I have a book in the basement from 1903 that explains this. These rules are thick, and the proper way is not to lay the rule flat on the board, but to stand it on edge and touch the knife to the mark. Probably one of those little tidbits of advice that got lost over time with the invention of thinner rules.
466903

[Andrew Seemann]

I always wanted to like folding rules, but I never could. They were just more clumsy and time consuming compared to tape measures.

I have never had a problem using multiple tape measures in a project (or combining rules and tapes). Normally I have around four in the shop that I use. Not sure where you all are getting yours, but I took a look at six I grabbed randomly from the shop and various tool boxes, and they were well within 1/16" over six feet. Not being able to use different measuring tools kind of defeats the entire purpose of standardization of measurements.

[Charles Guest]

I always wanted to like folding rules, but I never could. They were just more clumsy and time consuming compared to tape measures.

I have never had a problem using multiple tape measures in a project (or combining rules and tapes). Normally I have around four in the shop that I use. Not sure where you all are getting yours, but I took a look at six I grabbed randomly from the shop and various tool boxes, and they were well within 1/16" over six feet. Not being able to use different measuring tools kind of defeats the entire purpose of standardization of measurements.

It's far more useful to have a gaggle of marking gauges than it is a gaggle of rules and tapes. Marking gauges, story sticks, and marking identical workpieces from the first one you get out. Put away the tapes and rules and quit measuring everything to a number the entire duration of a project.

[Edward Weber]

It's far more useful to have a gaggle of marking gauges than it is a gaggle of rules and tapes. Marking gauges, story sticks, and marking identical workpieces from the first one you get out. Put away the tapes and rules and quit measuring everything to a number the entire duration of a project.


Measure as little as possible using as few as possible rules.
The more you measure and mark, the more chances there are to introduce error.
Tapes and rules these days are much better than in the past but they aren't perfect and errors do occur. There usually isn't a problem switching between measuring devices but I try not to do it, it's just the method I use.
I'm also in the camp of using gauges, story sticks, templates and so on.

[Jim Koepke]

It's far more useful to have a gaggle of marking gauges than it is a gaggle of rules and tapes. Marking gauges, story sticks, and marking identical workpieces from the first one you get out. Put away the tapes and rules and quit measuring everything to a number the entire duration of a project.


Measure as little as possible using as few as possible rules.
The more you measure and mark, the more chances there are to introduce error.
Tapes and rules these days are much better than in the past but they aren't perfect and errors do occur. There usually isn't a problem switching between measuring devices but I try not to do it, it's just the method I use.
I'm also in the camp of using gauges, story sticks, templates and so on.

+2 on those!


I always wanted to like folding rules, but I never could. They were just more clumsy and time consuming compared to tape measures.

One of my favorite things about folding rules is two of the hinges lifts the rule off the work making it easy to slip a try square underneath for marking. As mentioned earlier, my oldest folding rule has well oiled hinges and can be picked up in the center and with a quick motion of the wrist be folded and set aside. Likewise, when needed, it can be picked up and with another motion of the wrist be fully open.

jtk

[Andrew Seemann]

It's far more useful to have a gaggle of marking gauges than it is a gaggle of rules and tapes. Marking gauges, story sticks, and marking identical workpieces from the first one you get out. Put away the tapes and rules and quit measuring everything to a number the entire duration of a project.

If it works for you, great; it might for me if I was doing small items by hand, but I tend to do largish pieces of furniture by machine, with hand tools here and there. I'm measuring and using the scales on the machines (all calibrated to each other). Marking and cutting everything by eye would kill my productivity. If I had the spare dough, I would put digital scales on everything just to eliminate misreading once and for all.

I do get the avoid measuring when you can thing, and I do avoid it when practical, but if/when measuring is faster and more accurate, I'm going to do it:)

[Kevin Jenness]

If it works for you, great; it might for me if I was doing small items by hand, but I tend to do largish pieces of furniture by machine, with hand tools here and there. I'm measuring and using the scales on the machines (all calibrated to each other). Marking and cutting everything by eye would kill my productivity. If I had the spare dough, I would put digital scales on everything just to eliminate misreading once and for all.

I do get the avoid measuring when you can thing, and I do avoid it when practical, but if/when measuring is faster and more accurate, I'm going to do it:)

That's how I work as well. I do set out story poles and sneak up on fits when it is required but I depend on various measuring devices that match up to one another including machine scales. Depending on one scale for a whole job wouldn't work for me, especially considering how often I mislay my tape measure. :) It is easy to misread a scale or rule, and for that I often make test cuts on scrap before committing to a cut.

[Charles Guest]

If it works for you, great; it might for me if I was doing small items by hand, but I tend to do largish pieces of furniture by machine, with hand tools here and there. I'm measuring and using the scales on the machines (all calibrated to each other). Marking and cutting everything by eye would kill my productivity. If I had the spare dough, I would put digital scales on everything just to eliminate misreading once and for all.

I do get the avoid measuring when you can thing, and I do avoid it when practical, but if/when measuring is faster and more accurate, I'm going to do it:)

Whatever works for you.

[James Pallas]

I usually do my layout work empiricaly so i only measure once. As an example. If building a dresser I make the top first. On the underside I do all of my layout work. I usually use my 6’ folding rule, squares, dividers, protractors, scribes, knife, etc. From that point I do all of my marking from that layout. I then use gauges and such to do joinery marking. I very seldom go back to a rule or tape for anything. I generally only use tape measures for rough carpentry or going to purchase materials or preliminary size measurements. Most machine layouts are done with squares, gauge blocks or calipers. I would say do what makes you comfortable. I did read at one time that the errors in measurement for tape measurements is 1.2 cm per meter in general, not confined to woodworking.
Jim

[Kevin Jenness]

If you swap between two or three things -- a tape, a bench rule, and a folding rule and you expect them to all be dead on by themselves and also in comparison to each other, then you have a fundamental misunderstanding of the process.

I expect my measuring tools to match up because I have checked them. Engraved steel rules rarely vary in scale, occasionally the end is not at zero and that rule goes in the scrap bucket. Tapes can be compared to the steel rules in use and to each other, and are generally used for gross measurements. When the sliding end hook starts to show wear, that tape goes in the scrap bucket. Digital calipers, digital height gauge and dial indicator I do assume to be sufficiently accurate for my purposes.

Many of my projects are large enough that a story pole is too long to bring to the work- a wall of cabinets for instance- in which case the story pole sits on a shelf and is used for reference. I may use a tape or a test-cut stick to confirm part and assembly sizes. For cutting out parts on the dimension saw, the scales are constantly used in conjunction with test cuts, card stock shims and a magnetic back dial indicator for fine adjustments. As Andrew said, digital scales on all the machinery would be nice.

I approach measuring with scales with the attitude, "Trust, but verify." I have made many a miscut by misreading a rule so I rely a lot on test cuts and marking directly from the work in progress. I avoid measurements when I can, but using one rule for everything just doesn't seem practical for me.

When assembling a face frame I ensure the openings are exact size and parallel by using spacer sticks cut to the opening dimensions. When fitting a door to an opening or zeroing out the z-axis on my cnc I will use a taper gauge. When checking diagonals a bar gauge or trammel points often come into play.

This is not to say that mine is the right method, just that there are more ways to the woods than one.

[chris carter]

Well, I picked up a Stanley 36 ½ which is a 12 inch folding rule with a caliper on it (folded length is 6”). It is everything I could have hoped for. I checked it against my digital calipers and two steel rules that agree with said calipers. The result is that it was dead-on accurate along it’s scale and it’s calipers were also dead on accurate.

I mainly measure by eye, by putting boards against other boards, a story stick, etc. But I always need at least one or two measurements as a starting point. For bigger things I will often do a simple model Google sketchup so I can see things in a three dimensional model so then I’ll have a little more measuring to do so I don’t wind up with something different than what I planned on. This is also often required to get a sign-off from the wife! I also make a lot of things that need to fit other things. Like a table with a drawer that needs to fit certain predetermined objects, or I need to make sure I have clearance for knees (I’m crazy tall so there’s no margin for error). Or a toolbox that needs to fit certain tools, etc. There are always plenty of projects that require a lot of measurements while there are always plenty of projects that require next to none.

[Jim Koepke]

There is an article about a woman who makes leather goods in the NY Times > https://www.nytimes.com/2021/10/29/fashion/craftsmanship-sonia-ahmimou-handbags-paris.html

Her solution to always having to look for her tape measure was to have a ruler tattooed on her left forefinger.

jtk

[Kevin Jenness]

There is an article about a woman who makes leather goods in the NY Times > https://www.nytimes.com/2021/10/29/fashion/craftsmanship-sonia-ahmimou-handbags-paris.html

Her solution to always having to look for her tape measure was to have a ruler tattooed on her left forefinger.

jtk

I'm afraid the 64ths grads would disappear in the wrinkles

[chris carter]

There is an article about a woman who makes leather goods in the NY Times > https://www.nytimes.com/2021/10/29/fashion/craftsmanship-sonia-ahmimou-handbags-paris.html

Her solution to always having to look for her tape measure was to have a ruler tattooed on her left forefinger.

jtk

My mother could measure just about anything with her hands. Both distances (up to about 4ft) and volumes (up to about 2Tbl). I learned to cook from her and I didn't use measuring spoons; I just used my hands. And then I met my wife, who is a scientist - well, that didn't go over well. "What are you doing?!?! That's NOT measuring!!" Suffice to say, she has converted me. Turns out measuring spoons are slightly more accurate - go figure!