Fractional Calipers which are useful for woodworking!

[Alan DuBoff]

The thread RandyK posted on micrometers reminded me that a friend recently got a set of these fractional calipers from Harbor Freight, and it is actually very useful for working wood as it will convert between decimal, millimeters, and fractions. These are only $19.95, quite a reasonable price. The only caution is that most of the cheap imports tend to eat the batteries up pretty quick, he hasn't his long enough to tell yet. Pretty cool having the conversion though...:cool:

(linky pic to HF)

http://www.harborfreight.com/cpi/photos/97600-97699/97675.gif (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97675)

[Jim Becker]

I have had an analog version for a few years and they have indeed been very handy, both at the lathe and for general woodworking. "Hundreths" just don't work for me. Of course, I'm considering the move to metric at some point...LOL

[Michael Sobik]

I had a HF regular decimal style set of calipers. I got so frustrated with it I threw it out. It would work fine for a while, then the display with just start going crazy like I was sliding the head back and forth as fast as I could. Even removing the battery and replacing it didn't help. I never did trust it for anything.

As far as fractional stuff is concerned, it seems like you're missing out on a lot of accuracy. I mean if you have a piece of lumber that's some dimension that's not a fraction don't you "lose" that extra bit?

[George Sanders]

I bought a fractional caliper from Highland Woodworking. No more conversion charts! :D They really help when I'm using my planer.

[Jim Becker]

As far as fractional stuff is concerned, it seems like you're missing out on a lot of accuracy. I mean if you have a piece of lumber that's some dimension that's not a fraction don't you "lose" that extra bit?

You still have the ability to use "direct measurement" as you might with a story stick if you are using the caliper to match thickness. But you are correct that your accuracy is limited to the granularity of the measuring logic for the display plus your eye. It's the same with the DRO I have on the planer function of my J/P combo. I haven't found that to be a problem for the "function", but would not depend upon a digital scale for something that has to be "exact". For that, other methods are indicated.

[Mark Singer]

Digital calipers are one of my most used tools. From setting the height of blades to measuring thickness when planing, to layout of mortises and sizing tenons, they are the handiest tool!

[Mike K Wenzloff]

I do have DRO calipers...but I use them for metal. I cannot fathom why I would use them for wood--that applies to DROs for woodworking machinery. Sorry, Jim <g>.

I do have fractional calipers in the shop (non-dig versions). And we do use them for spot checking board thickness. When I actually made stuff, I did use them for checking furniture parts as they were being milled. Before that it was a simple thickness gauge.

Just how many people mill / thickness wood to the 1/64" (or tighter measurement)?

Take care, Mike

[Cliff Rohrabacher]

While I have no use for fractions preferring to think and work in decimals the conversion from Metric to English looks appealing.

I have been using my B&S conventional "rack and gear" calipers and a 12" Mitutoyo vernier scale rather a lot. Frequently I've considered a digital if for no other reason they are easier to read without my eye glasses and unaffected by the dust that can cripple a conventional "rack and gear" caliper.

I use close tolerances often enough especially when I am working on very small items.

Here is one example where tolerances as tight as 0.005" and angular tolerances of 0.005 radians and closer were critical:
http://www.sawmillcreek.org/showthread.php?t=55076

While working the hundreds of cuts comprising those individual little laminate pieces a tolerance stack would quickly become so great that the pieces would fail to fit together is say each cut was out by as little as 0.005" or if the angularity of the pieces was consistently out by some very small amount.
With 12 pieces making up any given ring segment if the parts were out by 0.050 of a degree radian I'd have huge gaps in the final assembly or even an entirely different over all geometry as a tiny error in angle would collectively work against every single joint.

So while I can agree (in principle) with folks who say that close tolerances are mostly pointless in wood as mere shifts in humidity can change the wood by substantial amounts, I still find myself relying on the more exacting measurements available from the precision tools I used in my work as a toolmaker.
I have micrometers up to 8" and I use 'em often enough.

As an aside: it is a known and proven fact that Metrics are an inherently dangerous system of measurement having been involved in dramatically more numerous and more serious work place accidents than the English system.

[Steve knight]

I use them all the time. but of course when they finally came out with fractional ones I had switched to decimals because of my cnc machine.
I often thickness to less then 1/64" on some parts.

[chet jamio]

I had some HF calipers and they're now in the trash. I've got a few new ones since then. The set from Rockler is nice because they read to the nearest 1/128 (about .008"). That places the measurement accuracy to with ±.004". Wixey makes a really nice set, but is more expensive. The best feature is that they display both decimal and fraction at the same time. They only display to 1/64, but they are actually more accurate than the 1/128 version, because they don't round up/down. For example, if a thickness is .497, the display only shows ".497", but if the thickness is .498, the display shows ".498 1/2". That places their accuracy at ±.002". That's probably overkill for most woodworkers, but I find it very useful.

[John Schreiber]

I can't think in any fractional unit smaller than a 16th. If I need a drill bit a little larger than a 5/16, I have to go over to the box of bits and grab the next one up rather than think of 21/64ths.

Decimal makes sense and metric makes even more sense. I saw a great description of woodworking in metric where all thickness measures were based on thinking of a 24 mm unit (a bit under one inch). You can easily compute a half, a third, a quarter, a sixth or an eighth of that measure and it's the same number of hours in a day so we are used to thinking that way.

It would be an adjustment, but I'll bet we would adapt quickly. When I've been overseas (or north), kilometers and Celsius become automatic.

[Eddie Darby]

While I have no use for fractions preferring to think and work in decimals the conversion from Metric to English looks appealing.

As an aside: it is a known and proven fact that Metrics are an inherently dangerous system of measurement having been involved in dramatically more numerous and more serious work place accidents than the English system.

Ever hear of the Gimli glider?

http://en.wikipedia.org/wiki/Gimli_Glider

The ground crew fueling the plane had to convert the fuel from volume into weight, and from one system into the other system. They made a mistake, and 'the game was a foot'.

It's not that metric is more dangerous to measure, it's having people working in two different systems that caused the problem in this case.

The world being what it is, has many different measuring systems. For example: In China an inch is not an Imperial inch in some cases, so rulers from China need to be checked for accuracy.

One problem that comes with any decimal point based measuring system, is the loss of a decimal during reproduction, such as in micro-filming, so the Europeans use commas, hoping that they will not get lost.

Also decimal points can easily be misplaced, and so you need to be sure they are all where they belong.
--------------------------------------------------
I go to the dollar store to get 6 replacement batteries for a buck, and the calipers seem to eat about a battery every couple months, so I figure it will take me more than a few decades of use to justify the more expensive, power conserving DRO's.

[Alan DuBoff]

I cannot fathom why I would use them for wood--that applies to DROs for woodworking machinery.
While it's not handy for you, I can tell you why it's handy for me. ;)

If you measure a board thickness for instance, it will give you a fractional number of that board. Let's say the board is not directly a usable fraction for the exact thickness of my wood? I can still open the calipers with my thumb to get the next usable fraction so I know how to dimension the rest of my lumber. This is very useful for hand planing, for instance.

I don't need the accuracy that they offer, I don't even want it for working wood. I do want the conversion. For that matter, I have a couple old vernier calipers I got from WaltQ on the cheap, few folks want those old style ones as they are not as useful for metal, but they work out well for wood and you can easily get a reading on wood, and convert it. I could probably be happy with a pair of vernier calipers that was marked in fractions, since I happen to work wood in fractions. And for that matter, I do know many of the conversions as I do that stuff, it just adds more thinking for me, and I like to think about conversions less. I also use a small Starrett 4" double square, in the same way, more often than the vernier calipers as it is marked in fractions already. But the vernier calipers are handy to measure and keep as a reference, I have 2 pair, I think I paid $1/each for them. Also I measure with the vernier and get the measurement against the rule.

I wouldn't use these in the same capacity I would use them for metal, and quite honestly having fractions is not useful to me in working metal, I do all of that in decimal and millimeter.

While I don't have a pair of these digital fractional calipers, I can see the use, and the conversion is worth the cost for me so I don't have to refer to a chart all the time. I currently use vernier calipers for that purpose, they are a crude way of accomplishing the same thing for me, without the electronics and/or fractions, as-is the small double square.

All of our mileage varies, and why we all work differently. :)

[Eddie Darby]

Pretty cool having the conversion though...:cool:
They also help to read what size those small tiny drill bits are.

[Jeff Bratt]

As an aside: it is a known and proven fact that Metrics are an inherently dangerous system of measurement having been involved in dramatically more numerous and more serious work place accidents than the English system.

Do you have even one shred of evidence to back up this outrageous claim?

Converting between different measurement systems, or working with an unfamiliar measurement system can be challenging. But the metric system is "inherently dangerous"? Balderdash...

[John Schreiber]

Do you have even one shred of evidence to back up this outrageous claim?
I think that is tongue in cheek. It's a true but meaningless statement. Most of the world works in metric. Therefore most of the accidents are related to metric measure. Kind of like pointing out all the damage caused by water and proposing to ban it.

[Cliff Rohrabacher]

Do you have even one shred of evidence to back up this outrageous claim?

Oh yes Absolutely~!!
It is a self proving fact.
The vast number of persons who suffer work place accidents are in nations that use the metric system.
This is cold hard proof that metrics are inherently dangerous.

I threw out all my metric rulers just to be on the safe side.

[/quote]Converting between different measurement systems, or working with an unfamiliar measurement system can be challenging. But the metric system is "inherently dangerous"? Balderdash...[/quote]

Well the numbers don't lie:
http://lamar.colostate.edu/~hillger/internat.htm
http://consolenomad.com/2007/06/19/nations-still-not-using-the-metric-system/
http://en.wikipedia.org/wiki/Metric_system

It would be somewhat hard to advance the thesis that the only three nations in the world not on the metric system have more workers let along more workplace accidents.

Look at China. they have such poor workplace safety standards as to be among the worst in the world And they use Metrics exclusively.
http://mybiggestcomplaint.com/100000-chinese-people-dying-in-workplace-accidents-in-china/881/

Metrics are just plain dangerous ~!!

[Doug Shepard]

I'm waiting on the HF that works in Bobs http://www.bobsrule.com/ and converts between decimal inches, mm, and Bobs. I've got a good inch/mm digital and an analog fraction/inch one. Between the 2 Ive got things covered. I never totally trust computer fraction approximations (and that's usually all they are). Try feeding a computer or calculator 1/3 + 1/3 + 1/3. You usually getback 0.9999... every time.

[Jeff Bratt]

Your data are unequivocal - but what about the lurking danger in our decimal monetary system? We must immediately switch back to pounds, florins, shillings, and pence before it's too late...

[Randy Klein]

I have a digital caliper that switches between metric, fraction, and decimal inches. At first I liked it, but now I long for an analog dial caliper fraction version.

The reason being, is that when measuring something, I'd get a reading of 21/64" or so, and I'm shooting for 1/4". I don't know right off the bat how close I am. Obviously I'm 5/64 away, but that takes a little thinking to get. And then I need to figure out that 5/64 is about 1/16", so I know I'm close.

But with the analog version, I can clearly see how the needle relates to the 1/4" tick that I'm aiming for without having to do any math.

[Roger Jensen]

I have a very nice one from Lee Valley, but I use my analog version more often.

The problem for me when using it with inch fractions is the denominator is always changing, from 4ths to 8ths to 16ths to 32nds to 128ths. I am always struggling to do the math to know how far I am from my desired length (e.g. I need 5/8ths but is 81/128ths a hair big or a hair small?). I know it sounds trivial, but by design none of the fractions displayed can be reduced.

I would LOVE a digital caliper that I could set the precision. That way I could force the tool to report everything in the precision I care about. If I only need to be within 1/16th I could set it and the tool would always round to the nearest 1/16th for me. Frankly, I can't imagine ever needing 128ths for wood measurements.

Sorry for the mini rant.

Roger

[Jeff Bratt]

I agree completely. I have two calipers a) the cheap, plastic dial style that reads in both 64ths and hundredths of a inch, and b) a more expensive digital, metal style that reads in thousandths of an inch or mm. The first I carry in my apron and use all the time. The second gets used only when I really need the extra precision. Plus I don't care as much if I drop the plastic one...

[Kevin Groenke]

I've got digital and analog, decimal and fractional. Starrett to HF. I find a dial much easier read than a digital, somehow context of what's on either side of the number makes things easier to visualize. I find I most frequently go for a 4" decimal dial. I suppose this is primarily because it's in an apron pocket, but then again it is in that apron pocket for a reason. Since it's in the apron pocket, it's a cheapo-Grizzly. Surprisingly tough, accurate and consistant, doesn't hurt the wallet too much if it gets dropped on the floor.

I spent some formative years in machine shops, so decimal equivalents to 32's are second nature. There is a big equivalence chart for the occasions I want to go finer. In much of my woodworking it's not the fraction that counts, but the .001"s: particularly in joinery. More than .010" is a sloppy M&T in my book, I aim for about .005" for a snug fit that doesn't require mallet blows or squeeze out all the glue. I cannot fathom how I would accurately measure a tenon cut w/ a tenoning jig on a tablesaw (or on a router table, or whatever) without a caliper: a ruler or square? NO WAY!

How often is plywood fractional? It's easier for me to find a .00X than a 64th whan setting up the dado blade. I find myself avoiding even fractions in solid wood pieces, I think it tends to make it look like sheet stock or factory made work. I sometimes use the digital w/metric and imperial to convert for whatever or when trying to determine if fasteners are mm or ".

Anyway, indispensible tools and the cheap ones are (mostly) perfectly functional for woodworking tasks. Everyone should have one (or more).

-kg

[Bill Houghton]

General Tools makes several models of fractional vernier calipers. I've picked up two or three at garage sales, but they're cheap enough at retail ($10 or so). Mine will measure down to 1/16" or 1/32", can't recall, directly; you can get down to 1/128" with the vernier measurements.

I have yet to need more precision for common woodworking. When I need more precision for measurements up to 1" (mostly for tooling), I turn to a micrometer.

One advantage of these calipers is that they are simple as can be, and unlikely ever to break down. The only pair I've had that failed did so because they got very very wet, and I didn't clean them off before they rusted solid (long story: my son and I discovered one January day that the pipe feeding our house water was about to fail - paper-thin, which is scary for galvanized pipe - and needed immediate replacement on a day when it was raining like Niagara, and the water rushing through the crawl space was imitating the Amazon. I was so wiped out at the end of a long day that I just tossed the tools in the shop and cleaned myself up. Found the calipers a week later, suitable for recycling but nought else).

See http://www.generaltools.com/Departments/Measuring-Tools/Calipers/Vernier-Calipers.aspx

[Alan DuBoff]

I didn't think this would be such a controversial topic, but several of you do use calipers.

Bill, I have a pair of the decimal vernier calipers that General makes, not sure where I got them even, but I use it and a couple others as kinda story sticks, in that I will get a measurement and set and use the vernier calipers for that mark, so with a few of the, I can set the thicknesses on several things, and they can be set quickly which is what I like about the vernier calipers.

Highland sells the same set as HF does, for $30, but I can save shipping at HF with a slight penalty for sales tax. I don't need them, to be honest, but if I am over there I might be tempted. I have enough tools to do as I need, at the moment. :o But I do think the conversion is useful for folks. :)

FWIW, my friend that showed them to me, is a luthier, and does a lot of guitar repairs, so the conversion comes in REALLY handy for him when doing fingerboards.

[Doug Shepard]

Your data are unequivocal - but what about the lurking danger in our decimal monetary system? We must immediately switch back to pounds, florins, shillings, and pence before it's too late...

What lurking danger? Are you referring to the rumored switch from the gold standard to the petroleum standard?:D

[John Schreiber]

What lurking danger? Are you referring to the rumored switch from the gold standard to the petroleum standard?:D
The petroleum standard may be a danger, but the danger of decimal monetary currency is clear. :eek: In the last 100 years, table saws have caused many injuries especially to the hands. 99.44% of those saws were purchased with decimal currency. Before 1762, before decimal currency was adopted, circular saws injured zero workers. :rolleyes: :D ;)

[Cliff Rohrabacher]

Your data are unequivocal - but what about the lurking danger in our decimal monetary system? We must immediately switch back to pounds, florins, shillings, and pence before it's too late...

Nothing could be more correct and the data prove it.

We need to get back to barter. I believe that at not time in history has there ever been a major recession among a people that used barter.