Ultimate digital caliper for modelers.


    [ ... ]

    Indeed -- and the only one which I know of which used old telephone company crossbar switches for running the scale time clock, as well as handling all the switching.
    I've sort of considered setting the "Followup-To: " header to restrict the cross posting somewhat. Yes -- I will. rec.crafts.metalworking and rec.models.railroad seem to work. Others can switch to there to follow the discussion if they care.
    Enjoy,         DoN.
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Salvι

Which is why here in Sweden they still use pre metric measurements equivalent to feet (fot) yards (Aln) and inches (Tum) and the local narrow guage railway 50 aln away from my flat has a gauge of three swedish feet.... oh yes lumber can also be bought in pre metric sizes. Beowulf
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Greg Procter wrote:

It DOES separate the MEN from the boys, doesn't it?
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Marc Heusser wrote:

Well, having been brought up with both, and having bought all kinds of things measured in both systems, and having lived through an incomplete conversion to metric here in Canada, my considered conclusion is that the old system is more consumer friendly. Why? Precisely because its measures are based on the human body.
And human drinking capacity. Have you noticed that "standard" metric drinks are sized very close to the old measures, with some rounding off here and there? Eg, a half pint is 227ml - the standard soft drink in Europe is now 250ml, which is about one tablespoon more.
There's also the convenience of estimating quantities that give us results within a half unit or so. For a carpet, for example, a centimetre is too small, and a metre too large, but a foot is just about right.
The usual argument in favour of the metric system is that it's "rational", because all its units are related to each other by powers of 10.*** Well, so what? The hard fact is that most people never convert units into each other -- they never need to do so. People need units that are easy to imagine in terms of use or consumption. It's no accident that in Austria when I were a lad sliced meat was bought by the "Deka", ie the 10gm unit. It's rather small, being less than half an ounce, but it's in the right range - a slice of ham weighed about a Deka, depending how the butcher set the slicing machine. On a recent trip to Austria I shopped at a farmer's market. I noticed that people asked for "about 1/8 kilo" of cheese, etc, not for 125gm. Interesting, eh?
I have nothing against the metric system, I use it a lot, actually. But I do get testy with people who believe that it's inherently superior to other systems of measurement. It isn't. It's just different. The same goes for the imperial system. Use either for what it's good for, and ignore it otherwise.
HTH
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wrote:

My old physics professor said: "There are two mensuration systems: the metric and the barbaric."
But to get back to the topic that started this amazingly long thread. Us modelers use a large variety of sources for our models: kits, plans, sometimes very old documentation (that may use the stone-furlong-fortnight mensuration system.). Kits and plans come in an amazing variety of scales: 1:4, 1:5, 1:6, 1:8, 1:12, 1:16, 1:24, 1:25, 1:32, 1:35, 1:48, 1:50, 1:75, 1:96, 1:100, ...1:720 ..and probably a whole bunch more that I've missed. The base may be either in feet and inches, or metric. Our materials, today, are usually either metric or English or both. So, let's say I have some small brass strips sized in inches, and I'm building a 1:75 scale model with metric plans. I want to know in an instant if that strip is the size I want...without dragging out a calculator, without having an RS-232 or other cable winding itself like a cobra around my delicate model, without a blue-tooth transmitter dragging my wrist down, and without having to go to the other room to look at the computer screen because my shop is not a healthy place for computers. I want to do that conversion in an instant. Apply my caliper to the material and instantly read the scale dimension in the proper units. The ultimate digital caliper for modelers would do just that.
Boris
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Imperial measure has roots probably back to Pharaohic Egypt as well as Babylon and ancient India. Many of these measures were designed mathematically to have a large number of even dividers. I'm not sure about measures like the cubit, but I'd imagine that in use it was divided and multiplied by values that gave a lot of even divisors also.
Certainly our clock, with its hours, minutes, and seconds, has these properties.
When ancient engineers worked on early gearing, they needed to be able to use evenly divided circles. In fact, they needed to use circles that could be divided using only the classical dividers and straightedge.
This, rather than a barleycorn, someone's foot, or someone's arm, were the justifications for the Imperial measurement systems.
On the other hand, 10 as a basis is obviously anthromorphic - and not very useful; try using a compass and straightedge and dividing a circle into ten equal parts. Now do the same thing for twelve parts.

On topic though, what is needed is digital calipers and digital micrometers that allow more than just selection of metric or imperial. They also need to allow setting of scaling factors. This would allow the readout to be given in any arbitrary scaled units.
More apt to be both useful and achievable would be a set of gauges for thicknesses, widths, and diameters. Along with this would be gauges for screws and bolt heads, although they would be much harder to produce.
By the way, what is the 1:75 scale model a model of? If it is early 20th century motive power or rolling stock, it would most likely be a model of an American made unit. Which means that the original was built in Imperial units. So, all of the metric dimensions you have are a conversion to begin with. It's one thing if the manufacturer gives dimensions in 1:75th scale, but if they list the prototype dimensions in Metric, I'd say they have created a real problem. On the other hand, if they list only scale dimensions, all that is needed is a Metric reading caliper or micrometer.
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wrote:

If you order a wee dram or a gill of whisky in Scotland, you will be served correct measure.
Other curious discrepancies: "caliber" is generally understood to mean diameter of a bullet in hundredths of an inch, as .30 cal is about .30 inches dia which happens to be 7.62 mm. (Fancy that!) OK, but ".380" is really 9mm Kurz (short) which is .3543" dia. Further, ".38 special" ammo is routinely used for practice in ".357" handguns.
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"Bob Engelhardt" wrote: (clip) Do you know how it determines the denominator when it's not an exact

^^^^^^^^^^^^^^^^^ The most logical thing would be for it to read in the fractions that it is set up to resolve, and jump from one to the next, without trying to get exact matches to the other scales. If you are reading in 1/128's of an inch, for example, you are interested in the closest value to the actual diameter--not the closest value to a number in some other scale.
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Leo Lichtman wrote:

What I meant in my example was: If you measured something that was actually 15mm, but wanted it to read in fractions, how would it display?
I would hope that it wouldn't display in some fixed denominator, e.g., 128 ths. Because measuring something to be 96/128 is not nearly as useful as knowing it's 3/4. What about 80/128, now what is that? Let's see ... divide both by 16 gives 5/8. OK, 5/8 it is. I'd want one that would say 5/8, not 80/128. Can you imagine a list of material described this way: "2 pcs 80/128 brass, 4 72/128 long".
Bob
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Bob Engelhardt wrote:

Boy! That's even worse than Metric. :-) ...lew...
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Lumber comes to mind, an inch and a half board will be 6 quarter stock. Then you have sheet metal in gauge sizes which is neither fractional nor metric. Some how we all get by.
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Roger Shoaf
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Boris Beizer wrote:

I think I'll stick to my old manual type ones , I've had them for many years along with my micrometers and they served me well in my work ,now in my hobby. I have a few scale calculators that work well .
--
Kevin (Bluey)
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Kevin(Bluey) wrote:

I use mine for handloading. (to the tune of several thousand rounds a year avg.)
I cant see them being *that* necessary for plastic modeling.
;-)
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AM

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Good evening Boris;

And I suppose you would want it to print the data, too. What you request would be fine for single readings. Unless the instrument has a useful memory, you will have to write them down. Gee, just like the old days.
Cheers, John
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PRINT!!?? WiFi to a storage device.
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That's right. That's the intention. So if I'm working to say, 1:25 scale, and I pick up a piece of wood, I can immediately measure if it is the 5.4cm thickness I'm looking for.
Boris
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Low cost have a data port . But they need a 2nd memory so u can go back and forth ABS and REL .
Im doin ARM7 mcu , but software is Luddite , so no one is having fun . Ill give some free s/w soon , end all that . My s/w wont use English Text to program. Have you ever heard of anyone progarmming a computer at high level , with no text input ? I will be the first , Anyone , anywhere of any nationality will be able to program it in minutes , without a manual ..
BTW Stay away from VXB bearing . I got ripped . $500 of 6002 and 6003 , the cage was dragging ,
kinda like that HF mill-drill that used tapered rollers and lower roller cage was dragging on the housing !
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Boris Beizer spake thus:

So there are calipers with digital outputs? That gives me an idea: what if a guy were to connect such a caliper to a small custom-made unit, instead of a computer, that would display the size in whatever scale desired?
I probably have enough skills programming a little bitty CPU (like the Ubicom [formerly Scenix] SX-28) to make something like this. Sounds like a fun project. Could fit in a small box, easy to more around with you.
Anyone know the type of interface these calipers use? USB? Serial?
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David Nebenzahl wrote:

Serial of some sort, I should hope. Sounds like a good project for a programming excersize with a graphing calculator - like one of the advanced HPs...they have a serial interface.
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- Rufus

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me spake thus:

Looks like they use plain ol' RS-232. Now can anyone tell me the data format?
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