Now there is a problem with the measurment of parameters based upon the kilogram, The European one appears to have been on a diet for years and is losing weight. The American and European kilograms are different weights now, than they were when they were made. The process of re-definition is underway. See:
<http://www.bbc.co.uk/news/science-environment-12276822>
The kilogram is likely to be re-defined using the Watt balance, see:
<http://en.wikipedia.org/wiki/Watt_balance>
The first meeting to discuss the process begins in October.
For the sake of the dieters I hope they chose the lighter one!
Malcolm
I don't suffer from insanity I enjoy it!
--- On Wed, 1/26/11, Druid Noibn <druid_noibn@yahoo.com> wrote:
From: Druid Noibn <druid_noibn@yahoo.com>
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: gingery_machines@yahoogroups.com
Date: Wednesday, January 26, 2011, 2:52 AM
Hi Dave,
Understood - hobbyist here also.
Be well,
DBN
--- On Tue, 1/25/11, David Patterson <odd_kins@yahoo.com> wrote:
From: David Patterson <odd_kins@yahoo.com>
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: gingery_machines@yahoogroups.com
Date: Tuesday, January 25, 2011, 6:49 PM
If I still worked as a patternmaker you would be right and I would have the all. Now I just do it at home as a hobby. :-(
Dave Patterson
odd_kins@yahoo.com
http://home.comcast.net/~oddkins/foundry_home.html
--- On Tue, 1/25/11, Druid Noibn <druid_noibn@yahoo.com> wrote:
From: Druid Noibn <druid_noibn@yahoo.com>
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: gingery_machines@yahoogroups.com
Date: Tuesday, January 25, 2011, 3:39 PM
Hi Dave,
It would appear that the cost is already justified <smile>
Be well,
DBN
--- On Tue, 1/25/11, David Patterson <odd_kins@yahoo.com> wrote:
From: David Patterson <odd_kins@yahoo.com>
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: gingery_machines@yahoogroups.com
Date: Tuesday, January 25, 2011, 6:13 PM
I got 3 digital calipers, a digital depth gage and a digital angle finder. But I also have in vernier a height gage, depth gage, calipers and micrometer. For some reason I just keep collecting tools. I only need height gage and micrometer to go completely digital, just haven't justified the cost yet.
Dave Patterson
odd_kins@yahoo.com
http://home.comcast.net/~oddkins/foundry_home.html
--- On Tue, 1/25/11, David Frantz <websterindustro@mac.com> wrote:
From: David Frantz <websterindustro@mac.com>
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: "gingery_machines@yahoogroups.com" <gingery_machines@yahoogroups.com>
Cc: "gingery_machines@yahoogroups.com" <gingery_machines@yahoogroups.com>
Date: Tuesday, January 25, 2011, 1:09 AM
Dave;
Go digital when you can! It makes for a huge difference for old eyes. I have a bunch of old calipers and mics but I truly doubt I will buy another with vernier scales.
I have a digital caliper now that is excellent at eliminating those vision related errors. Further it eliminates the constant search for that @$&"& magnifier.
My goal is to get a digital mic in one and two inches before retirement. Yeah they are expensive, but they quickly become gotta haves as you get older. The other option is to hang magnifiers on every machine you own.
The other great frustration of old age is "misplacing" things in plain sight.
David A Frantz
websterindustro4at4mac.com
Sent from my iPhone.
On Jan 24, 2011, at 11:54 PM, David Patterson <odd_kins@yahoo.com> wrote:
> Lets assume,I know bad me to assume,you have to stack 6 blocks to reach 6". At +/- .0001 for each block, that would be +.0005" if all the were +.0001. Your micrometer has a tolerance of +/- .0001. if that runs to the full side your now at .0006. Don't know about your eyes but I can loose sight by +/- 2 to 3 marks by looking too long at the vernier scale, if I'm lucky I can get to +/- 1 mark. So now I have a possible error of about .0008 to .0009. That's assuming everything is to the plus side, it could also be the same to the low side, meaning tolerance band of .0016 to .0018, that is just for measuring the part. To get to +/- .002 for making a part is even harder. Because to hit an actual dimension of say 6.0000" +/- .0002 is near impossible for the home shop, because you can't measure that close to an actual dimension, nor can your machine cut a part that close, the graduations are .001 and the slop in the machine is probably .002"+, if you have
> a good machine. so yeah I'm more than happy to work to .002 or +/-.001". Guaranteed you pass your part, that you measured, to someone else to measure with a different micrometer the will get a different dimension than you, if you try to measure to .0001".
>
>
> Dave Patterson
> odd_kins@yahoo.com
> http://home.comcast.net/~oddkins/foundry_home.html
>
> --- On Mon, 1/24/11, Rick Sparber <rgsparber@aol.com> wrote:
>
>
> From: Rick Sparber <rgsparber@aol.com>
> Subject: RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
> To: gingery_machines@yahoogroups.com
> Date: Monday, January 24, 2011, 7:57 PM
>
>
>
>
>
>
> Dave,
>
> I think you are talking about how the error on each block combine to give the total error. My spacers are +/-0.0001" each. If I stack two of them up, then the worst case error is +/-0.0002". A more reasonable error would be the RMS error (root means squared error) which I figure is +/-0.00014". For 3 blocks the RMS error would be +/-0.00017".
>
> My shop is around 60 to 90 degrees but am not sure what the temperature coefficient is for these spacer blocks. I would be surprised if it ended up anywhere need 0.002"
>
> Rick
>
> -----Original Message-----
> From: gingery_machines@yahoogroups.com [mailto:gingery_machines@yahoogroups.com] On Behalf Of David Patterson
> Sent: Monday, January 24, 2011 7:17 PM
> To: gingery_machines@yahoogroups.com
> Subject: RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
>
> Rick, when it comes to stacking gage blocks at 1" I won't make any measurable difference. If you stack blocks to get 6" you may not end up with exactly 6", as opposed to using a single 6" block. The reason is tolerance stack up.The error could be 6 microns per block for clean blocks through a little dust or cleaning solution film between them and the error would be greater. The blocks are accurate at 68 degF colder or hotter they change size. If you have a need to calibrate your micrometer, take it out and have it certified, then use it in a controlled enviroment. other than that if you can work to .002" your still splitting hairs. I'm happy with that.
>
> Dave Patterson
>
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