I actually have a pretty good eye doctor and requested something similar in that the upper lens was speced for read computer monitors. To be honest I haven't used the glasses much. The original idea was that they would be helpful at work. The problem is I'm not one to carry two pairs of glasses around and I have trouble finding the one pair I have.
David A Frantz
websterindustro4at4mac.com
Sent from my iPhone.
On Jan 26, 2011, at 4:54 AM, Matthew Tinker <mattinker@yahoo.com> wrote:
> I have bi-focal glasses that are specifically made so that the "reading" part is not made to read books, but to see further away when measuring. It is sometimes hard to convince opticans that you need to see at nearly arms length and that for reading I can have another pair of glasses!
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> Just a pssing thought!
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> regards, Matthew
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> Matthew TINKER
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> CNC conversion 1944 Colchester Lathe build-up log
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> http://www.cnczone.com/forums/showthread.php?t=35519
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> --- On Wed, 26/1/11, David Frantz <websterindustro@mac.com> wrote:
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> 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: Wednesday, 26 January, 2011, 0:22
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> In general do you find the digitals easier to use? Just the idea that you are freed from squinting or the contortions of using a magnifier and mic while manipulating the part in question does it for me.
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> David A Frantz
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> websterindustro4at4mac.com
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> Sent from my iPhone.
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> On Jan 25, 2011, at 6:13 PM, David Patterson <odd_kins@yahoo.com> wrote:
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>> 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.
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>> Dave Patterson
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>> odd_kins@yahoo.com
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>> http://home.comcast.net/~oddkins/foundry_home.html
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>> --- On Tue, 1/25/11, David Frantz <websterindustro@mac.com> wrote:
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>> From: David Frantz <websterindustro@mac.com>
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>> Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
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>> To: "gingery_machines@yahoogroups.com" <gingery_machines@yahoogroups.com>
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>> Cc: "gingery_machines@yahoogroups.com" <gingery_machines@yahoogroups.com>
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>> Date: Tuesday, January 25, 2011, 1:09 AM
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>> Dave;
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>> 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.
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>> I have a digital caliper now that is excellent at eliminating those vision related errors. Further it eliminates the constant search for that @$&"& magnifier.
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>> 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.
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>> The other great frustration of old age is "misplacing" things in plain sight.
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>> David A Frantz
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>> websterindustro4at4mac.com
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>> Sent from my iPhone.
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>> On Jan 24, 2011, at 11:54 PM, David Patterson <odd_kins@yahoo.com> wrote:
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>>> 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
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>>> 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".
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>>> Dave Patterson
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>>> odd_kins@yahoo.com
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>>> http://home.comcast.net/~oddkins/foundry_home.html
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>>> --- On Mon, 1/24/11, Rick Sparber <rgsparber@aol.com> wrote:
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>>> From: Rick Sparber <rgsparber@aol.com>
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>>> Subject: RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
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>>> To: gingery_machines@yahoogroups.com
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>>> Date: Monday, January 24, 2011, 7:57 PM
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>>> 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".
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>>> 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"
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>>> Rick
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>>>
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>>> -----Original Message-----
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>>> From: gingery_machines@yahoogroups.com [mailto:gingery_machines@yahoogroups.com] On Behalf Of David Patterson
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>>> Sent: Monday, January 24, 2011 7:17 PM
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>>> To: gingery_machines@yahoogroups.com
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>>> Subject: RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
>
>>>
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>>> 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.
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