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Steel Rule on Saw and Tape Measure Not Matching

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Blog entry by IantheTinker posted 02-16-2018 12:46 AM 696 reads 0 times favorited 10 comments Add to Favorites Watch

Hello all, I added a steel rule to my table saw fence rail today and noticed that it doesn’t match up with my tape measure. When I have it set to 32” both match.

However, the closer I get to “0”, the greater the difference becomes.


I first noticed when I made a cut at 20 1/2”, but when I double checked with my tape measure it said 20 9/16”. So I shifted the indicator line to the right by 1/16”. However, now when my fence is all the way to the blade this is what my indicator line shows.

I am a tad confused and am looking for any feedback folks can provide. I checked to make sure my steel tape is both straight and flat, and it is. I am unsure what else to do or where I may have goofed up.

-- “How you feeling, Roy?”... “a little unappreciated, Al...” - Die Hard



10 comments so far

View Woodknack's profile

Woodknack

12230 posts in 2464 days


#1 posted 02-16-2018 01:25 AM

Not uncommon for tapes not to match. Not much you can do except use one or the other or get two that match.

-- Rick M, http://thewoodknack.blogspot.com/

View IantheTinker's profile

IantheTinker

238 posts in 211 days


#2 posted 02-16-2018 01:37 AM



Not uncommon for tapes not to match. Not much you can do except use one or the other or get two that match.

- Rick_M

It just seemed odd to me that they matched at 32” and even at 16”, but so many others were about 1/16” off. I might be overthinking it, but I figured I would see if anyone else had experienced it.

-- “How you feeling, Roy?”... “a little unappreciated, Al...” - Die Hard

View CaptainKlutz's profile

CaptainKlutz

392 posts in 1578 days


#3 posted 02-16-2018 02:11 AM

Relative tape measure accuracy can be a real pain.
There are thousands of internet threads discussing precision .vs. accuracy.
Such as:” http://lumberjocks.com/topics/88986":http://lumberjocks.com/topics/88986

I believe off shelf Stanley is allowed to be +/- 1/16” anywhere along 12’ tape? Longer tapes are allowed more. If absolute accuracy matters then need to spend more $$ for Class 1 tapes. Fisk, Komelon, and of course Starett; all sell Class 1 tapes

In practical use the easiest thing to do is to check all your tapes against each other and find a set that agrees with each other most of time. Use the ones that agree, and throw the rest in trash, or label them for rough cuts only.

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View IantheTinker's profile

IantheTinker

238 posts in 211 days


#4 posted 02-16-2018 02:45 AM



Relative tape measure accuracy can be a real pain.
There are thousands of internet threads discussing precision .vs. accuracy.
Such as:” http://lumberjocks.com/topics/88986":http://lumberjocks.com/topics/88986

I believe off shelf Stanley is allowed to be +/- 1/16” anywhere along 12 tape? Longer tapes are allowed more. If absolute accuracy matters then need to spend more $$ for Class 1 tapes. Fisk, Komelon, and of course Starett; all sell Class 1 tapes

In practical use the easiest thing to do is to check all your tapes against each other and find a set that agrees with each other most of time. Use the ones that agree, and throw the rest in trash, or label them for rough cuts only.

Best Luck.

- CaptainKlutz

The steel rule I applied to my table saw rail is a Starret brand, if that is indeed a more reliable one then I will simply set to that and trust the cut to be what it states.

-- “How you feeling, Roy?”... “a little unappreciated, Al...” - Die Hard

View Woodknack's profile

Woodknack

12230 posts in 2464 days


#5 posted 02-16-2018 03:40 AM

Like Cap recommended above, good idea to check all your tapes against each other out to 10’ or more. Most of the time, it doesn’t matter if 3” is 3” or 3.005” as long as you are using the same rule for everything. For example, if I need a 3” wide apron, I set my saw at 3” and rip all at once. Close enough. When I need to cut a part to fit, I set up the saw directly using a sample piece, a story stick, or a caliper; so any inaccuracy in the saw ruler is irrelevant.

-- Rick M, http://thewoodknack.blogspot.com/

View Rich's profile

Rich

3342 posts in 673 days


#6 posted 02-16-2018 06:17 AM

Why not get a tape made for applying to a surface like that? Incra and others make peel and stick tapes that are very high quality. The fact that it’s adhered to the surface means no movement that could cause errors.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View IantheTinker's profile

IantheTinker

238 posts in 211 days


#7 posted 02-16-2018 11:15 PM



Why not get a tape made for applying to a surface like that? Incra and others make peel and stick tapes that are very high quality. The fact that it s adhered to the surface means no movement that could cause errors.

- Rich

I guess I wasn’t clear in my explanation, what I have been calling a “steel tape” is a Starret stick on steel tape measure. There is no movement and it sticks on great.

-- “How you feeling, Roy?”... “a little unappreciated, Al...” - Die Hard

View Rich's profile

Rich

3342 posts in 673 days


#8 posted 02-17-2018 01:37 AM

I guess I wasn’t clear in my explanation, what I have been calling a “steel tape” is a Starret stick on steel tape measure. There is no movement and it sticks on great.

- IantheTinker

I didn’t catch that. Like you, I’d put my trust in the Starrett. It’s a good brand. Instead of messing with different tape measures, which tells you nothing in the long run, make some test cuts. It’s the cut edge that matters anyway.

Set the fence to something like 5” or 6” according to the Starrett and rip a board. Measure it and see what it’s actual width is. This is where a golden standard is handy to have around. Something like a Starrett or PEC steel ruler, or some other rigid, fixed tool that you trust. I use a set of dial calipers, since you can’t get much more accurate than that. If the cut is off by a hair, move your cursor hairline window to compensate for it and cut again. Repeat until the cut is on the money. Odds are at that point all of your cuts will be exact, whether 3/4” or 20”, since that Starrett tape won’t be far enough off to matter over that distance.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View jbay's profile

jbay

2490 posts in 983 days


#9 posted 02-17-2018 01:44 AM

I would make all my checks by actually cutting each size piece, for comparison, and double check there sizes by pulling an inch. (not by measuring from the fence to the blade.)
Maybe your tape measure is off and the stick down tape is accurate? Try a different tape measure.

View Rich's profile

Rich

3342 posts in 673 days


#10 posted 02-17-2018 01:47 AM


I would make all my checks by actually cutting each size piece, for comparison, and double check there sizes by pulling an inch. (not by measuring from the fence to the blade.)
Maybe your tape measure is off and the stick down tape is accurate? Try a different tape measure.

- jbay

Yeah, it’s really hard to imagine a Starrett brand metal tape, stuck flat to a surface like that not being spot on. It’s not like it can flex or buckle or anything.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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