Quizical about Vernier Caliper Use

[ChrisN]

I'm lowering a saddle from the top. I need to take off very small amounts. I have a digital vernier caliper of good repute (EZ Cal by iGaging). It is zeroed.

I've measured the saddle's Original Height multiple times at each string point. Apparently, unless I perfectly replicate the lean/angle and/or pressure of how I'm measuring, the number adduced from the same spot on the bridge varies wildly. I measured each spot dozens of times until I got what I believed was a consensus number (the number I saw most often).

I reduced a spot on the saddle and remeasured - now, after removing only a slight amount of material, the number I get on the device sometimes exceeds my original consensus number, while other times it appears to confirm I've removed a small amount of material. We're dealing in thousandths of an inch, I understand, but this is annoying, I don't fee I can trust this process as I'm executing it, and I want to avoid ruining the saddle.

Also perplexing is the fact that I get a completely different number, depending on HOW I measure. If I rest the bottom of the caliper base on top of the saddle, then use the thumbwheel to extend the pin downward, I get one number, but I get a much different number (usually always higher than the other method) if I first over-extend the extension pin, put the pin to the bridge, then lower the caliper until it comes to rest on the saddle's top.

What's the proper technique for using this type of caliper to most accurately obtain this type of measurement and have it be consistent? Extend the pin after the caliper's resting on the saddle? Or extend the pin to the bridge first, then lower the caliper until it hits the saddle?

Any other tips (other than "get thee to a pro") appreciated.

[mirwa]

Its sense of touch, one of the hardest things to teach, we all apply different pressure when doing things.

When I was an apprentice (Jet Engine Mechanic), we spent weeks just measuring and filing things to learn sense of touch.

Steve

[murrmac123]

When lowering a saddle from the top, it is much easier (and more accurate) to use stacked feeler gauges in front of the saddle rather than trying to measure with a vernier caliper using the extension pin.

[John Arnold]

One of my pet peeves. Its not a vernier. Years ago, one of my friends said 'dial vernier' and I corrected him. Look it up.

https://en.wikipedia.org/wiki/Vernier_scale

[mirwa]

Originally Posted by John Arnold

One of my pet peeves. Its not a vernier. Years ago, one of my friends said 'dial vernier' and I corrected him. Look it up

Relevance?, no person above referred to it as a vernier, they have referred to the device as a digital vernier caliper, the industry descriptive standard for said device includes the words digital and vernier.

http://lmgtfy.com/?q=Digital+vernier+caliper

Steve

[frankhond]

I have the same gizmo (different brand). The problem is, while the reading shows an accurate looking result with some decimals, in reality the accuracy is limited. I.e. the device has inherent noise, and the digital readout is deceptively accurate. I find the old time analog version more reliable, because the design communicates to you what is possible.

For lowering the saddle, I would use a precision ruler (or a feeler gauge), err on the side of caution, string up and try, etc.

[ChrisN]

I like the ideas of using an analog caliper and using feeler gauges. The feeler gauges are in my toolbox, so that's what I'll use. Thanks for the tips - this was driving me crazy, especially as I did the same job on another guitar and don't recall running into this problem to this extent (and it came out perfect).

[redir]

The problem is probably that you are leaning the instrument one way or another changing the output. If you were measuring the depths of the saddle slot for example then the ruler part of the instrument would straddle the slot and be supported across it at two points. Then you measure the same every time.

IMHO that's way overkill for setting action at the saddle. You can just use a good steel ruler and eyeball it.

[Big Band Guitar]

I have spent 39 years in calibration and repair.

There are Vernier, Dial, and Digital.

Digital can be derived from rack and pinion, optical gradient. LVDT, or other means.

Dial is purely mechanical like a clock movement.

Vernier is a linear comparison.

There are no Vernier digital calipers. A search on that will yield results based on the words inputted. It is a misconception of terms not unlike a "ton of ideas".

[murrmac123]

Originally Posted by redir

IMHO that's way overkill for setting action at the saddle. You can just use a good steel ruler and eyeball it.

Now I am mystified.

Why would you want to use a steel rule, with all the parallax problems, when you can use a set of feeler gauges and get a perfect proportional decrement from, say, .090" to .070" with absolutely no necessity for squinting at a steel rule.

Any time you can eliminate the need for actually reading a measurement, and utilise your sense of touch instead, is a consummation devoutly to be wished.

IMO.

[arie]

use the step feature on the left side -if the igage has one. depth measurements freehand with the depth rod are tricky

[redir]

Originally Posted by murrmac123

Now I am mystified.

Why would you want to use a steel rule, with all the parallax problems, when you can use a set of feeler gauges and get a perfect proportional decrement from, say, .090" to .070" with absolutely no necessity for squinting at a steel rule.

Any time you can eliminate the need for actually reading a measurement, and utilise your sense of touch instead, is a consummation devoutly to be wished.

IMO.

I'm just saying that to reduce the action you measure at the 12th fret and then double that at the saddle to get the proper height. Do you use feeler gauges at the 12th fret? I just use a ruler. I admit I am no good with feeler gauges. I never seem to know if I am pushing to hard on it or not. But in the end though .001 inch is not really a valuable measurement at the saddle where action is concerned.

[ChrisN]

Originally Posted by redir

But in the end though .001 inch is not really a valuable measurement at the saddle where action is concerned.

I appreciate that position, and I confess to having simply sanded the bottoms of a few saddles to achieve 6/64 (E) and 4/64 (e), but I've recently come to know the joy of stepping the action down .004 (at the 12th) between strings (eg, start E at .80, then A at .76, D at 72, etc.), and doing that requires more precision than the ruler in /64ths. I've done the .004 step-down on another guitar and it feels the most natural/comfortable to play, for me.

But, I've learned here that I was using the wrong tool for the job.

[ChrisN]

Originally Posted by arie

use the step feature on the left side -if the igage has one. depth measurements freehand with the depth rod are tricky

I see nothing on the side that might be what you're talking about - just the screw-down thumb wheel to lock it in place.

I can confirm that depth measurements freehand with the depth rod are tricky, but I'd have to say for me they're worse than useless due to the wasted time trying to get it right.

I figured if the bottom of the depth rod was squared off and applied squarely against a squared-off bridge top, while the caliper's body (also squared off) was applied to the top of the saddle, then I should be able to achieve repeatable measurements, but it was not to be.

[mirwa]

Originally Posted by Big Band Guitar

There are no Vernier digital calipers. A search on that will yield results based on the words inputted. It is a misconception of terms not unlike a "ton of ideas".

Its nice when people come along and talk about nothing to do with the topic at hand, simply semantics about a descriptive.

Why do people do this?

We could argue such a mute point all day long, but it has nothing to do with the topic at hand, so why even raise said topic.

Maybe you should contact manufacturers who are selling new products and inform them of how incorrect they are and how they are corrupting society's way of thinking.

Steve