Author Topic: Digital caliper  (Read 237 times)

pep

Digital caliper
« on: November 12, 2018, 08:46:39 PM »
A different way to indicate and use a digital caliper, cutting to the chase.

Indicate a bore, 0.5, round bar 0.75
indicate the bore 0.5
Zero the caliper 0.000
Indicate the round bar 0.25
Machine too Zero... perfect fit
No math, calculator or note pad required

So what say you ?

While I'm at it got a new tool today, been wanting a set of these for a while.. Really nice piece..

Pep


RayH

Re: Digital caliper
« Reply #1 on: November 12, 2018, 11:04:42 PM »
I wouldn't use the described technique for a number of reasons.
Digital calipers are not the most accurate tool for precision work.
The jaws used for ID measuring have flat faces so they contact a bore on opposed cords, not at an exact diameter, which increases inaccuracy.

If the intended tolerance is loose enough the described technique could be OK, but not to my liking.
I have plenty of note paper and enjoy doing the math.

Sorry about that.
Ray

pep

Re: Digital caliper
« Reply #2 on: November 13, 2018, 12:04:01 AM »
No thin skin here, I posted it to see what kind of comments it will generate. Digital calipers not being accurate. Fat faces, if all reading are using the same flat faces, those become an accepted error, AKA tolerances .

 Pretty much going to be that way with any mechanical measuring device.

I not trying to convince anyone to change a thing. What I can vouch for is that I achieved and finished the task darn quick. 

The round bar measure + .0005, that keeps up I'll be doing it my way for sure.

Pep

4GSR

Re: Digital caliper
« Reply #3 on: November 13, 2018, 07:28:02 AM »
Me like many others have gotten spoil to using digital calipers for just about every measurement made in the shop.  I probably have at least ten sets of digital calipers including a left hand set.  At one time or another, when new, I've checked them against gage blocks and find them being dead on in any measurements to the full scale of the caliper.  Most of mine are the HF variety, too.  I do not use them for any precision measuring OD or ID, that's where my mics and telescoping gages come in the picture.

My most expensive pair I've bought over the years is a pair of Mititoyo 9" calipers, or is that 8"? I don't remember. Bought in 1997 from Enco.  They never saw any shop use, strictly used in the engineering office all the years of use.  I had to retire them about ten years ago because they started reading weird readings.  Would start loosing .002" per inch! So at 6" reading was about .012" off!  I've taken them apart many times, cleaned and put aback together and still no change in readings.  Just recently re-checked them again, dead on every 1" increment. But when you try to check at anything in between 1" with gage blocks, get weird readings.  As I said, they are retired.  Also, have my dad's Mitityo one's he bought before he passed away in 1995.  They still read fine the last time I checked them.  I don't use them because the display is small, sometimes hard to read. 

My Chinese knock offs are still kicking and holding after almost 20 years of use.  What can I say!

Ken
Ken

Carpenter84

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Re: Digital caliper
« Reply #4 on: November 13, 2018, 07:29:00 AM »
Actually. Not that bad of an idea. My digital mitutoyo mic has a zeroing button. With the telescoping gages, you can use the same method but with the accuracy of a mic...
I think I'd still confirm with a properly calibrated mic, tho.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

4GSR

Re: Digital caliper
« Reply #5 on: November 13, 2018, 07:31:10 AM »
When your splitting cunt hairs, better get the mics out! ???

woodchucker

Re: Digital caliper
« Reply #6 on: November 13, 2018, 08:45:19 AM »
I wouldn't use the described technique for a number of reasons.
Digital calipers are not the most accurate tool for precision work.
The jaws used for ID measuring have flat faces so they contact a bore on opposed cords, not at an exact diameter, which increases inaccuracy.

If the intended tolerance is loose enough the described technique could be OK, but not to my liking.
I have plenty of note paper and enjoy doing the math.

Sorry about that.


my calipers have knife edges for inside measurements, not flat.

Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://woodchucker.imgur.com

chips and more

Re: Digital caliper
« Reply #7 on: November 13, 2018, 09:29:29 AM »
I have many Starrett dial calipers around the shop. I like to have them read “0” when they are closed. This tells me nothing weird is going on with them. If I zeroed at some imaginary jaw opening it’s not that easy to get a reality check unless you note the reading when the jaws are closed and that to me is too much fiddling around. I understand your idea and if it works go for it, sounds good! And my calipers do have very narrow flats on the inside jaws but I have not had any problems. I'm not making NASA parts! I use the dial calipers for probably 99% of my metrology findings. I have a few first generation digital Starrett calipers that read in tenths but eat batteries, I like them. And have the newer Starrett digitals but don’t use them at all. I like the mechanical dial type. Be careful, I believe some of the Starrett calipers are made overseas now :(…I think using the caliper with proper finesse is the most important. To get a true repeatable reading with little or no error in uncertainty. If you nail that you might forget you have mikes laying around…Dave
« Last Edit: November 13, 2018, 12:06:30 PM by chips and more »

4GSR

Re: Digital caliper
« Reply #8 on: November 13, 2018, 10:57:39 AM »
Talking about Starrett digitals made overseas, I believe they are all made over there.  They just bring the parts over here and fit them together with the Starrett touch! ;) The recent pair of Starrett's I bought a couple months back seem to have that touch of those you buy at HF.  :-\

Carpenter84

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Re: Digital caliper
« Reply #9 on: November 13, 2018, 11:12:21 AM »
As with everything...

It's just not profitable for companies to manufacture things locally. Can't compete with China's employment wages.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

Carpenter84

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Re: Digital caliper
« Reply #10 on: November 13, 2018, 11:17:38 AM »
Actually, in many cases now, things made locally are actually worse than products made in China.

We used to buy our windows and doors from a local Canadian manufacturer. The custom stuff is extremely expensive and not very good. Requires a lot of work on my end in order to make them fit and function properly. Just very quickly manufactured with no real quality control.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

woodchucker

Re: Digital caliper
« Reply #11 on: November 13, 2018, 11:31:51 AM »
Actually, in many cases now, things made locally are actually worse than products made in China.

We used to buy our windows and doors from a local Canadian manufacturer. The custom stuff is extremely expensive and not very good. Requires a lot of work on my end in order to make them fit and function properly. Just very quickly manufactured with no real quality control.


I'm seeing the same here in the USA. Many of the made in the USA items are horrible. Either the bean counter has hurt the company, or the low quality worker who couldn't care less.  Case in point the Maytag professional washer and dryer I bought. The dryer's 220 volt wire was sticking out of the back, caught between 2 pieces of sharp metal. The build person couldn't give 2 shits, the qc person didn't care, the packaging person didn't care... when I got it, it was so obvious sticking out when it belonged inside the unit.  3 lines of failure.. who's fault is that... but it had a sticker that it was proudly made in the USA... I was not so proud.
I have more examples, but it's a long list.. and its real sad to think that we produce more garbage than quality goods.
The Chinese are hungry, and we are fat and happy. just like any major league team, the hungry guys will do a better job than the fat and happy guys who are already making the money.
Jeff
Clausing 8520   SB Model 9a - power hacksaw, Milwaukee band saw in a table.  Delta Rockwell Surface Grinder (not online yet .. being rebuilt where am I going to stick this)
For pics: https://woodchucker.imgur.com

pep

Re: Digital caliper
« Reply #12 on: November 18, 2018, 07:31:29 AM »
 What else can we expect, companies paying folks to just show up. Cannot fire freeloaders and the clueless, incompetent dead weight.
 
It's the system, employee's and a company unable to require results from the hired help.

Pep

Actually, in many cases now, things made locally are actually worse than products made in China.

We used to buy our windows and doors from a local Canadian manufacturer. The custom stuff is extremely expensive and not very good. Requires a lot of work on my end in order to make them fit and function properly. Just very quickly manufactured with no real quality control.


I'm seeing the same here in the USA. Many of the made in the USA items are horrible. Either the bean counter has hurt the company, or the low quality worker who couldn't care less.  Case in point the Maytag professional washer and dryer I bought. The dryer's 220 volt wire was sticking out of the back, caught between 2 pieces of sharp metal. The build person couldn't give 2 shits, the qc person didn't care, the packaging person didn't care... when I got it, it was so obvious sticking out when it belonged inside the unit.  3 lines of failure.. who's fault is that... but it had a sticker that it was proudly made in the USA... I was not so proud.
I have more examples, but it's a long list.. and its real sad to think that we produce more garbage than quality goods.
The Chinese are hungry, and we are fat and happy. just like any major league team, the hungry guys will do a better job than the fat and happy guys who are already making the money.

pep

Re: Digital caliper
« Reply #13 on: December 06, 2018, 06:53:27 PM »
Kind of a fun PDF ......

Pep

chips and more

Re: Digital caliper
« Reply #14 on: December 07, 2018, 08:41:41 AM »
In that PDF, it comments on using the step measurement. It should be noted that not all calipers have that feature. On some calipers the moveable jaw is not flat in the area of question. All aside, this feature is very handy if your caliper has the capability. I use it a lot when doing lay out work and I mean a lot. I have not used the surface gauge scribe thing with surface plate since I was born. I do it all with my caliper and razor blade…Dave