How to properly use a digital caliper? 2

[BreadboardPerson]

Hi, I zero the caliper at the beginning of each use. I noticed that depending on where I use it and even at the same location, depending on how much force I use to close the caliper, I get different values. So I get different readings all the time. What is the proper way to get the measurements? How much force should I use to close the jaws? Even lightly closing the jaws led to different values.

 

[kjoiner]

Hello,

This topic reminds me of a situation I ran into many years ago at a sheet metal vendor. I was pretty new and was sent to the vendor to perform some quality inspection before the parts were sent to our facility. The part in question was spec'd as 14ga steel. When I checked the part, I noticed it was 16ga steel. I brought it up to the fabricator and was told it was 14ga. I asked them to put calipers on the part and it measured around .062. They said that was correct. I said 14ga was .075. They pulled a piece of 14ga stock and I watched their guy measure the sample which measured .075. I pointed that out and then watched him squeeze the calipers so hard the measurement dropped to .062 and he said "see, it's .062". I told them to correct the part and left. Needless to say, we stopped using them and they were out of business in a short time afterward.

Kyle

 

[mfgenggear]

inspection and proper handling of inspection tools takes a few years of actual experience, I had 5 years as an apprentice, just in inspection handling and use.
and there is always a better method as the industry evolves. stay within the capability of the measuring tool as it was designed for. and use the right tool for the precision & method required.
calipers are for wide open tolerance.

 

[DAVIDSTECKER]

Some thing that happened to me years ago while using my digital calipers at my wood lathe with VFD was that the un-shielded high frequency was causing my caliper to give me all sorts of strange reading when I was near the lathe.
When I walked away for the second time to change the batteries I finally figured it out.

 

[MacGyverS2000]

The typical digital caliper uses capacitive sensing... how much EMI could that VFD have possible been throwing out?!!!

Dan - Owner

http://www.Hi-TecDesigns.com

 

[drawoh]

DAVIDSTECKER,

This is one more reason to stick with Vernier calipres.

--
JHG

 

[Compositepro]

They don't have to be Verniers. Dial type are also not affected by EMI . I don't know many people who know how to read a Vernier scale anymore.

 

[mfgenggear]

I have my original 44 years

 

[drawoh]

I have my original 44 years

Mine is not that old, but it is up there somewhere. The digital ones grow legs and wander around somehow.

--
JHG

 

[Compositepro]

I've grown tired of changing batteries on digital calipers, and do not buy them any longer.

I also had a guy ruin a part because he accidentally hit the "hold" button. After a while he started to wonder why the diameter of the part was not changing after taking a cut on the lathe.

 

[DAVIDSTECKER]

MacGyverS2000
The VFD is in a plastic box running an early 1900,s Allis Chalmers 3 ph motor.
No shielding any where.
The calipers are $8.00 Harbor Freight specials.

drawoh
I have a very good set of Starrett dial calipers but for wood turning the $8.00 HF unit is fine, or it least it should have been.

 

[CWB1]

I don't know many people who know how to read a Vernier scale anymore

Half of the reason I keep verniers at work is to discourage their being borrowed. The other half is bc I no longer have an in-house gagemaker to replace worn racks and damaged bezels so want a bulletproof tool in case of a careless borrower.

 

[MacGyverS2000]

I have 3 sets of HF digital calipers sitting at my wood lathe... when the batteries run out, they magically DON'T get replaced. I've found I use the calipers more often to transfer/check dimensions from one piece to another more often than I need an absolute measurement... like a rich man's story stick, I suppose.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Tmoose]

Compositepro said - "I've grown tired of changing batteries on digital calipers,"

Some guy on the internet did a test of various digital calipers' voltage requirements, different batteries' voltage/time curves, and various calipers' actual "of" state.
As I recall -
Cheaper calipers don't really turn "off."
Most DCs won't tolerate much voltage drop.
Battery manufacturers base their "equivalence" on dimensions some limited performance characterists.
LR44 ( Zinc + Manganese Dioxide) does not equal SR44 (Zinc + Silver Oxide . SR44 is MUCH better.

http://www.davehylands.com/Machinist/Caliper-Batteries/

I have taken to leaving the battery cover off my General $30 DC. When I want to use it, I just pop the battery back in.

 

[mfgenggear]

dial calipers don't require batteries

 

[drawoh]

mfgenggear,

Vernier calipres do inches and millimetres.

--
JHG

 

[EdStainless]

Anyone using non-electronic micrometers knows how to read verniers.
I have a old (way older than me) 0-1" mic that has two stages of vernier, intended to read to 0.00005".

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

Drawoh

Mine does, I have an old venier and dial calipers
0-1. 1-2, and 2-3 micrometer, now moth balled.
only use at home projects

 

[CWB1]

Anyone using non-electronic micrometers knows how to read verniers.

Not necessarily. A few years ago I picked up an old Slocomb mic set at auction that has rolling analog numbers like pre-1990 gas pumps. Its another example of the mechanical genius that predated modern IC electrickery.

 

[drawoh]

EdStainless,

I have 0-1" and 0-25mm micrometres. Yes, they have vernier scales.

--
JHG