Any steel rules with graduations in 128ths?
- Thread starter ChuckM
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kevinculle
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I have never seen Imperial graduations finer than 1/64". I have an Incra 12" T-rule with 1/64" graduations at the bottom, and they are useable but I can't imagine reading 1/128" lines.
There sure wouldn't be much space between the lines. 1/128" is a little less than .008" I believe our laser graduation lines are about .004". That would leave less than .004" between lines and I'm not sure how many people could actually resolve that (without super-cheaters). If I'm looking for anything finer than 1/64th, I'm using calipers. Actually, that's a lie. If I'm looking for anything finer than 1/32nd, I'm probably using calipers.
I would have to say that a ruler is the wrong measuring instrument for that level of precision.
You are probably in the territory of a vernier caliper. Our QC Department had a 24” vernier (old style vernier, no dial, no digital readout). Even so, about $900.00.
But if you need that accuracy, you need the appropriate measuring instrument.
Note: I cannot think of any woodworking requirement for that level of accuracy.
https://www.tequipment.net/Mitutoyo...MI47HZvvrZ_gIV7yqzAB1A5QdZEAQYBCABEgKHlfD_BwE
You are probably in the territory of a vernier caliper. Our QC Department had a 24” vernier (old style vernier, no dial, no digital readout). Even so, about $900.00.
But if you need that accuracy, you need the appropriate measuring instrument.
Note: I cannot think of any woodworking requirement for that level of accuracy.
https://www.tequipment.net/Mitutoyo...MI47HZvvrZ_gIV7yqzAB1A5QdZEAQYBCABEgKHlfD_BwE
Cheese said:
100ths? It prompted me to look for a sample to see how it'd look like, and one of the results led me to a pdf at the littemachineshop site:https://www.google.com/url?sa=t&rct...eelrules.pdf&usg=AOvVaw0-qxuH5ORJ_LB3Fyix1dwM
I would note that large calipers do not use dials or digital readouts. Too much chance for accumulated error.
Instead they use a “vernier” scale (also called a “nonius” scale). That was the kind I was taught to use. It is easy enough to master.
The video is better than anything I could explain. It is based on the idea that humans are able to align things with great precision by eye.
The problem with those tight measurements is that they require tightening the calipers to the same tightness repeatedly. With soft woods, you run the risk of compressing the wood, rather than taking the measurement.
Micrometers attempted to increase repeatability by adding a knob at the end with a precision clutch that would repeat the pressure. But that is on metals. On pine or poplar, they would not be accurate.
Instead they use a “vernier” scale (also called a “nonius” scale). That was the kind I was taught to use. It is easy enough to master.
The video is better than anything I could explain. It is based on the idea that humans are able to align things with great precision by eye.
The problem with those tight measurements is that they require tightening the calipers to the same tightness repeatedly. With soft woods, you run the risk of compressing the wood, rather than taking the measurement.
Micrometers attempted to increase repeatability by adding a knob at the end with a precision clutch that would repeat the pressure. But that is on metals. On pine or poplar, they would not be accurate.
Vtshopdog said:
I bought my sister a Post slide rule. It used a genuine black widow spider’s web filament for the crosshair. I recall that it cost me about $70.00 back in 1966. That is about $660.00 in current dollars. She used it until the mid 1970s when she bought the first Texas Instrument scientific calculator.
In the mid 1970s, my brother-in-law wrote a book on how to use a slide ruler and it was accepted for publication. But the day TI announced their calculator, the publisher backed out of the agreement.
I believe I still have my 12” and 6” Pickett slide rulers. The 12” in high visibility yellow.
My old Machinery Handbook had trig and log tables. Newer editions dropped both.
It’s probably like riding a bike and put one in my hands and I could use it. But thinking now, I can’t remember how.
kevinculle
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I used a slipstick all through college (early '70s) and in my early years as an engineer. Once you become proficient you can work fast and precisely...no 10 significant figures but good enough for serious work. I still have mine down in the shop and every once in a while, I will take it out to see if I still can work it...so far, so good.
kevinculle said:
My sister was a research biologist (well-known in her narrowly defined field). She used the slide rule to prove to her satisfaction that her premise was correct. But for the research papers she needed exact numbers, which the slide rule does not provide. So the need for log and trig tables.
peacefulandpatriotically
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ChuckS said:
what is your intended use case for a ruler with 1/128" of an inch graduations?
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