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Accurate measurements?

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Forum topic by ynathans posted 03-26-2014 04:52 PM 1586 views 0 times favorited 25 replies Add to Favorites Watch
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ynathans

55 posts in 1474 days


03-26-2014 04:52 PM

Hey guys,

I’m relatively new to woodworking and have had a little bit of success so far. I was wondering something about accurate measuring.

I have found in projects that I have often been off by a ‘little bit’ with some things fitting together (but enough to matter) and over time I have been realizing that it is likely most related to accurate measuring than technique or tools. I am wondering about how others go about ensuring accurate measurements.

One thing I have noticed is that on a tape measure, the end of the tape (by the ‘1’) has a little nub on the end and looking closely at it, it seems like it adds a bit to the measurement, and that might be enough to knock off the measurement. I’ve read some things about ‘burning the 1’ does that refer to starting the measurement from 2 and then subtracting 1 to overcome the end of the tape problem? What about when measuring the inside of a box where that technique is not possible?

I was also wondering, if anyone has used a digital measuring kit to take measurements for a situation like inside a box or cabinet where the tape folds at the end and the hook at the end of the tape could create errors (or in other situations where precise measurements are necessary: bosch digital laser measure

For example, I had to hang something between two joists last night and this would have probably worked well.

If I could use something like that to eliminate little measuring issues I think my woodworking would improve alot.

Thanks,

Nathan


25 replies so far

View Rick.'s profile

Rick.

10093 posts in 2136 days


#1 posted 03-26-2014 05:00 PM

Roy Underhill says measuring is the enemy to precision, or something like that. The point being, use a story stick or mark a part directly based off other parts rather than using a ruler. I consider it the most important lesson I’ve learned watching The Woodwright’s Shop. It’s a different way of working than how I learned.

-- http://thewoodknack.blogspot.com/

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Monte Pittman

25897 posts in 2094 days


#2 posted 03-26-2014 05:15 PM

Another point, when using a tape measure on a project. Use the same tape measure for the entire project. No 2 tape measures are the same.

One of the reasons I don’t like having help on most projects, I know how I measure and mark my pieces. I know where to cut beside my line. It is essential to do it exactly the same every time. Make doing it right part of your routine.

Double check how square your tablesaw and mitre saw cut. Don’t assume anything is perfect today from the last timeit was used. Never assume that lumber from the store or lumber yard is cut square, IT’S NOT! OK, I think my rant is through.

-- Mother Nature created it, I just assemble it.

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waho6o9

7961 posts in 2333 days


#3 posted 03-26-2014 05:20 PM

Folding rulers with inside measurements rock

View lepelerin's profile

lepelerin

485 posts in 2081 days


#4 posted 03-26-2014 05:21 PM

I never use a pate measure except for rough dimension. I always use a ruler and stick with the same ruler for the entire project. Tape measure in my point of view (at least the tape measure I own) is not a precision tool. OK for carpentry but not for precision work. my .02 cents

View Gene Howe's profile

Gene Howe

9448 posts in 3185 days


#5 posted 03-26-2014 05:36 PM

I’d like to ban all tapes and rulers from my shop….well, the rulers are handy if I need a longer straight edge. But, the tapes are useless….almost.
Most of my inside measruring is done with little device like this:
Slide it in and lock it down, take it to the saw. No need for numbers.

Then, there’s a set of keyway stock that goes from 1/8” to 3/4” in 1/16” increments for smaller distances, and blade heights. With those and a set of 1,2,3 blocks, you can achieve a fair amount of precision.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View exelectrician's profile

exelectrician

2327 posts in 2184 days


#6 posted 03-26-2014 05:37 PM

I have a vernier caliper handy all the time, when I thickness material I target +/- 4 thou of the thickness I want.

-- Love thy neighbour as thyself

View Gene Howe's profile

Gene Howe

9448 posts in 3185 days


#7 posted 03-26-2014 08:32 PM

To gauge thickness out of the planer, a set of open end wrenches are pretty handy.

And no, socket wrenches won’t work.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View dbmguy's profile

dbmguy

33 posts in 1333 days


#8 posted 03-26-2014 08:41 PM

Accuracy in getting project pieces to fit together properly is more a matter of technique than anything.

View Hammerthumb's profile

Hammerthumb

2742 posts in 1732 days


#9 posted 03-26-2014 08:53 PM

Have to agree with all of the above with the additional note about using pencils for marking. When a measurement is critical, use a marking knife to mark the measurement. I sometimes use a mechanical pencil with the .5 lead, but even this will give a wide line as compared to a marking knife. Rick’s comment about story sticks is one of the best tips to use. I seldom have to do measures, but use a steel rule when I do. I mostly just mark dimensions off of other work. It is rare when I use a tape, and then it is only for rough measuring.

-- Paul, Las Vegas

View Todd's profile

Todd

398 posts in 1433 days


#10 posted 03-26-2014 08:59 PM

Rulers and tapes are only for starting projects. Everything else is gauged. If I need to cut a part to fit, then I cut it a little large and “sneak” up on the size. Any duplicates are gauged after that part. My crosscut sled with a stop block serves that purpose well.

-- Todd, Huntsville, AL

View SCOTSMAN's profile

SCOTSMAN

5845 posts in 3342 days


#11 posted 03-26-2014 09:22 PM

I am afraid Monty is correct ,as I too find discrepencies with tape measures.That is unless you buy the very expensive ones. The chinese ones just aint 100% accurate. most of mine are very cheap as I buy about twenty and lay them all around, as I hate searching for one when I am tired. Alistair

-- excuse my typing as I have a form of parkinsons disease

View DrDirt's profile

DrDirt

4383 posts in 3499 days


#12 posted 03-26-2014 09:48 PM

Typically I don’t use a tape measure for projects or layout.

Most woodworking (like the Underhill quote) is not about accuracy but Precision.

From joinery like dovetailing, you cut pins first then use the PINS to mark the tails. I hence cut one piece to fit into the other, rather than doing layout and measurement of both, and then hoping it all comes together OK.

I scribe the drawer front to fit the opening… I don’t get a tape measure out and write down numbers for width and height, and adjust for an even gap…etc.

For most measuring tools – I find I need to just stick with one…. if I am changing from tapes, to rulers, to a different tape because i cant find the first one (again!) then I start to magnify errors.

Even if your tape tab is bent. If you measure 37” on all four legs…. it could be that you are really only at 36 7/8. But if all four legs are identical, the project comes out OK.

-- 'Political correctness is fascism pretending to be manners' ~George Carlin

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Dallas

3599 posts in 2244 days


#13 posted 03-26-2014 10:02 PM

No one has mentioned it yet but the sliding tab on the end of your tape is to allow for inside and outside measurements. Otherwise the act of hooking the tab or not hooking the tab on any two like pieces will come out being off by the thickness of the tab.

-- Improvise.... Adapt...... Overcome!

View JayT's profile

JayT

5404 posts in 1967 days


#14 posted 03-26-2014 10:12 PM

And the choir says “amen” to the above.

For me:

  • Tape measure and carpenters pencil for rough dimensions
  • Steel ruler and fine mechanical pencil for exact dimensions
  • Marking to fit and knife for accuracy and precision when fit really counts and measurements don’t

Learning to mark instead of measure allowed my woodworking to take a giant leap forward. That means more use of marking gauges, story sticks and dividers. Bonus—it’s also faster to mark instead of measure.

-- In matters of style, swim with the current; in matters of principle, stand like a rock. Thomas Jefferson

View longgone's profile

longgone

5688 posts in 3065 days


#15 posted 03-26-2014 11:28 PM

I use a group of Incra measuring tools and rulers and have found them to be absolutely perfect for my needs.

Tape measures are only good for roughing it out but not for any precision work
A good dial caliper is also extremely valuable in my shop

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