When is 1/16th of an inch not 1/16th?

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Forum topic by dalec posted 08-28-2009 07:22 PM 1644 views 0 times favorited 13 replies Add to Favorites Watch
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612 posts in 3910 days

08-28-2009 07:22 PM

Topic tags/keywords: question

I have a low end digital caliper that I have been using with the thought that it is a whole lot more precise, then again maybe not, than using a tape measure, especially with my vision not being nearly as good as it use to be. The digital caliper displays in mm, in fractional (64th) and digits.

I found that opening the caliper when it initially displays 1/16” and to the point the display changes to 5/64” is pretty noticable. The digital reading for 1/16” ranges between 0.0560” and 0.0705” a range of 0.0135”. It seems to be a lot of difference. I don’t want to be obsessive about my measurements, but ….

How many of you use digital calipers and do you use the mm, fractional or digits? Seems using digits rather than fractions is more accurate. How accurate is accurate enough for measurements under 6”? or that matter what level of accuracy do you expect over 6”?


13 replies so far

View PurpLev's profile


8536 posts in 3670 days

#1 posted 08-28-2009 07:28 PM

do what you’re more comfortable reading and calculating your work with.

and don’t forget – we work with wood, and wood moves. so even if you cut a part with a machinist dial caliper to within 0.001” accuracy – that part can shrink/expand tomorrow.

I think too many people are getting a bit too obsessive about measurements in woodworking.

even a M&T joint can’t be too perfect and tight – or it won’t take the glue, or wont close properly. you can only go so accurate, sometimes you just have to breath and work WITH the wood.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Rob Drown's profile

Rob Drown

789 posts in 3854 days

#2 posted 08-28-2009 07:29 PM

I use English digits. A good friend makes a strong case for doing all measuring in metric. It wouldtake some adjustment .

-- The expectations of life depend upon diligence; the mechanic that would perfect his work must first sharpen his tools. Confucius, 经过艰苦的努力的梦想可以成真

View Tim Marko's profile

Tim Marko

41 posts in 3810 days

#3 posted 08-28-2009 07:46 PM


I agree with PurpLev. I did the same thing you’re doing when I first got mine, and found the difference wasn’t enough to fret over. The caliper has helped me be more accurate, but I don’t worry about the tiny difference. 1/16=1/16 and I just leave it at that.

-- Tim, trying to come up with something cool to say here!

View Innovator's profile


3584 posts in 3435 days

#4 posted 08-28-2009 08:13 PM

I use dial calipers (digital works fine as well) for everything I do. I was trained as a tool and die maker so it was a natural transition to use it in woodworking.

In tool and die work you work within 0.0005 (and sometimes less) but for woodworking it doesn’t need to be as accurate. When I cut on the table saw for example I like to be within .010. I realize that the wood may move later but if I am off less up front the movement should be less noticeable later (at least in my simple mind).

Great tool, but don’t try to get tooooooooo close of a tolerance.

-- Whether You Think You Can or You Think You Can't, YOU ARE RIGHT!!!

View dalec's profile


612 posts in 3910 days

#5 posted 08-28-2009 08:21 PM

Thanks PurpLev, Rob and Tim.

I guess it gets down to getting the tight fitting joints with precision that is good enough to get that result. I hope that comes with experience.


View dalec's profile


612 posts in 3910 days

#6 posted 08-28-2009 08:35 PM


Thanks for you perspective on this topic. It is reassuring to hear what others have have learned and know.


View Karson's profile


35125 posts in 4422 days

#7 posted 08-28-2009 08:40 PM

I’ve got these things all over the shop. They are a plastic caliper that I get from harbor freight. I pay $1.99 for them and they are great.

You can measure up to 1/128 th of an inch with them. They are so handy. I’ve got them on my workbench, saw, jointer and probably the floor.

I also keep about 3 in a drawer for when I can’t find one of the others.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware soon moving to Virginia †

View dalec's profile


612 posts in 3910 days

#8 posted 08-28-2009 08:58 PM


I have not been real active on LJ as of late. Good to hear from you.

If I move around at all while in working in the shop, small items can be left just about anywhere. So with enough of them, I will eventually stumble across one of them, reasonably close to the moment I need it.


View Mike Gager's profile

Mike Gager

665 posts in 3288 days

#9 posted 08-28-2009 09:16 PM

karson, thats the same caliper i use as well. i would like to get a fancy digital model some day though

View PurpLev's profile


8536 posts in 3670 days

#10 posted 08-28-2009 09:17 PM

Karson, I’ve been thinking about that type of caliper since my digital one from the local WW store is finicky (loses it’s zeroing while using it, and battery doesnt last long).

lee valley sells a pack of 6 for $8.50 and they also have a more precise metal version for ~20 I think I’m gonna go with those, as I just can’t rely on the digital one I have anymore.

I think that’s as precise as I need to get. Thanks for the link!

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View dalec's profile


612 posts in 3910 days

#11 posted 08-28-2009 09:46 PM


You are right, as long as the calipers are identical, I should get the same results which is close enough for woodworking purposes. HF plastic ones are certainly the right price and no batteries needed.


View papadan's profile


3584 posts in 3390 days

#12 posted 08-29-2009 01:49 AM

I get the email coupons from HF. Bought 5 of those for .99 a couple weeks ago.

View Bill White's profile

Bill White

4947 posts in 3982 days

#13 posted 08-29-2009 07:22 PM

Betcha that NONE of the fine neander furniture makers used digital anything. Dividers, scribes, folding rules, and talent created the classic pieces we all enjoy. I’m with PurpLev. These folks who measure to the closest 10/1000 are obsessive, and could never build a house (they’d never finish measuring).
Bill (who’s TS top is as flat as I can tell)


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