Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Gear or disc micrometer for string measuring

Hi,

I am just in the process of buying my first tools.

While researching which micrometer to buy I came across a forum thread in which someone mentioned that they had yet to work out how to measure a string with a micrometer and so use calipers.

For those who aren't aware of the disc micrometers I thought I would post a mention of them here.

There are heaps on ebay but there is a picture of them in use on the jahn pianotiele website.

https://www.pianoteile.com/DesktopM...productid=1125&id=583&Lang=en-US

Ben

My choice is the 1" digital micrometer from Mitutoyo. Switches between inches and mm. I also have digital calipers from them. Great stuff!

I use a dial thickness gauge. After the original one quit, this is what I use now.

Good choice.

You need both, Ben. Digital may be a little higher price-wise, but well worth the difference.

Mitutoyo #317-351. It is digital and switches between Imperial and metric. It has a replaceable anvil and comes with both a round anvil and a relatively thin flat anvil that nicely fits between the strings for measuring wires still on the piano.

Pricey (most Mitutoyo tools are) but worth what they cost. They last forever -- I still have my first Mitutoyo mechanical/digital micrometer that also has a replaceable anvil. I bought that one in the early 1970s and it still works nicely. I only bought the electronic digital because...well, because I wanted a digital mic...and it can switch between Imperial and metric readings and I am getting lazy and have grown weary of converting.

ddf

While piano wire should definitely be measured with a micrometer as opposed to with calipers, I don't think every piano technician needs a disc micrometer. A regular one would do just fine, especially for someone such as yourself, starting out purchasing tools. Something like this:
micrometer

Sure you can't get decent measurements of all strings when at tension, but this is rarely needed anyway. Buy a utility micrometer and use the savings to buy regulating tools.

Don't use calipers -- they are not precise enough. Also . .

There is a difference between how many decimal places a digital device displays and its actual mechanical accuracy. On the cheap items, you can have a digital reading to 4 decimal places when the actual level of precision is only 1 decimal place. The rest of the numbers are simply bogus.

Good advice. (Still, I really like my Mitutoyo....)

One caution about disc micrometers -- their measuring surface is relatively large. You can end up with a really erroneous reading if the wire is at all corroded and/or rusty.

ddf

Hi

I already bought a mitutoyo mechanical micrometer. $60

Ben

I bought a Starrett like This back in 1969 and it still operates as smooth as silk. Ya git whutcha pay for.

Or the wire has a slight bend, or...
Besides, disc micrometers are not designed to measure small, point form objects such as wire (or anything round). They are designed to measure the thickness of of flat surfaces - sheet stock such as paper, metal, plastics etc. After 30 years of doing piano work without one, I finally got one to be able to more accurately measure bushing cloth and felt. I never use it for wire, tuning pins and such.

There are micrometers with a small plunge allowing to catch the wire while mounted.
For thicknesses of cloth, we usually use a spring loaded tool with disks.

Some corrections have to be done when measuring very soft felt.

When apprenticing we compared the thicknesses with a finger, and that seem to be as precise than using a micrometer.

For bushing cloth, 2 pieces side by side, the finger detect things that the micrometer does not, sometime.

Both checks are necessary in my opinion, and for cloth the spring mean you can only compare pieces of felt of the same surface size.