14 replies to this topic

[Oregon-raybender]

A few forums ago I was asked about International Standards that are used for testing of optics (or any other objects or such)

I found Adam's video to be helpful in explaining why these are important. When ATMer's or any other tester goes about measuring their optic(s) There has to be an agreement between the test taken at lab and one done at home. The conditions and the tools (ie, interferometer, digital rail, software, etc... ) should be equal to or better than the conditions to which it was done. That is why ISO and ANSI and such standards are used to make sure there is an agreement between the two. I am not saying that such tests by ATMers or others are not valid and should at least get near to or read about the same. But you as the customer, supplier or user should understand the conditions they were tested in. That is why when I mention the battle of the ZYGOs (other such interferometers) is and can be an issue. The conditions should result with the same value(s).

 

If you are new to telescope making or need to understand the values to which your measuring your telescope mirror, secondary, lens, or any other optic. Adam gives a fair lesson on how precision measurements are made and why there are many factors to consider when such measurements are taken. The video is a simple explanation on why, how and use standards, in his case Gage Blocks, to measure in microns. For telescope makers, you are making surfaces to a fraction of that. If you are trying to learn machining of parts for you scope, it is helpful to understand how using gage blocks are helpful to gage tight precision while machining. That is why I having been in QA and understand the study of measure it's important to learn why sometimes the values maybe different and hard to repeat.

 

I hope this bit mentoring is helpful to you.

 

It's worth watching and fun to watch. There are times I was a bit nervous about the blocks falling on the floor. But in the

end he is aware he is a bull in the glass shop. Enjoy. If you are a fan of Adam, you will understand.

 

From the comment section: 

 

"Any measurement without the knowledge of uncertainty is meaningless" - Walter Lewin

 

"All measurement is a compromise of circumstance"

 

Starry Nights

 

https://www.youtube....h?v=qE7dYhpI_bI

 

https://www.mitutoyo...-Gage-Block.pdf

 

https://citeseerx.is...p=rep1&type=pdf

 

http://www.starrett-...r.com/gb46.html

Edited by Oregon-raybender, 05 January 2022 - 05:43 PM.

[skywolf856]

I spent my entire career as a mechanical machine designer, finishing as an automation systems robotics designer. Adam's video was an Epiphany for me to look at what I was trying to achive throuout my career and how everything is interrelated. This just blows my mind when I look at it thru Adam's eyes.  I love his basic enthusiasm for knowledge. I was used to working daily with machining tolerances measured in thousandth's, ten Thousandth's and Microns. How you dimensioned a part directly related to it's accuracy as the design was intended and how you could effect that outcome with a few key measurements. I guess this kind of mechanical insight is what drew me into this field in the first place and why I've always been facinated with it.

Edited by skywolf856, 05 January 2022 - 10:24 PM.

[MKV]

From the comment section: 

"Any measurement without the knowledge of uncertainty is meaningless" - Walter Lewin

"All measurement is a compromise of circumstance"

No matter how small, errors can add up.

Distinguish precision vs accuracy.

Foreknowledge of the resuls introduces bias.

Just because we can measure it, doesn;t mean it's significant.

Science is based on doubt, no faith.

 

And countless more...

[happylimpet]

Brilliant, but my goodness, what kind of civilization quotes a measurement as 3/4 inch, plus or minus 2.7 microns. Mars Polar Lander never stood a chance.

[Oberon]

Brilliant, but my goodness, what kind of civilization quotes a measurement as 3/4 inch, plus or minus 2.7 microns. Mars Polar Lander never stood a chance.

 

And yet we do. Ambidexterity at its finest!

[Xeroid]

Amazing video but I'll have whatever he's eating or drinking..or..

[TxStars]

It was funny when he thought editing would help the video..   LoL  

He needs to follow a script to keep his thoughts in check..

Edited by TxStars, 07 January 2022 - 04:30 AM.

[Starman47]

Actually his ad hoc approach is fun to watch. This is just the nature of his videos.

[Cordrazine]

Agree with him that he is not worthy of a $10,000 set of gauge blocks .  Check out the videos of someone who is worthy - Dan Gelbart. It is jokingly said that the foundation of Dan's house is a giant surface plate.

[duck]

he said the gauge blocks (ceramic) were within 20 nanometers of the specified height?

[Oregon-raybender]

I am not sure that they are that close, it maybe that the calibration height was measured to that height tolerance.

Adam's world is model making, like he said he was not worthy of such a set, but it was very nice gift for his work. (about $4K)

It is Mitutoyo's best material. It depends on what grade he was given. It is a set I would have in my lab for reference only for calibration of equipment. (the cost of quality) There are various grades, from shop to lab. Mitutoyo has some wonderful classes and information on their web site. The video is just a few steps down.

 

Starry Nights

 

https://www.mitutoyo.../?s=gage blocks

 

https://www.mitutoyo...e-gauge-blocks/

Edited by Oregon-raybender, 07 January 2022 - 03:41 PM.

[TxStars]

In the video he says the set is a grade 0 so that is about $4k for the set.

If you look at the spec sheet for the Grade 0 set the most variation is in the large 4" block which is roughly  +/-  0.000012"   

The 20 nanometer number comes from the space between two blocks when placed together.

 

Charles

[careysub]

The 20 nanometer number comes from the space between two blocks when placed together.

 

Charles

So that is "roughly" speaking, the flatness.

[TxStars]

So that is "roughly" speaking, the flatness.

Yes and No, it is a known distance value between the two "flat" surfaces.

Read this: 

http://starrett-webber.com/GB46.html

 

*btw always take the gage blocks apart asap .. LoL

 

Charles

Edited by TxStars, 07 January 2022 - 06:37 PM.

[Oregon-raybender]

I think he is talking about the oil thickness spacing of the blocks. Yes, never leave them together for long, a few hours at most, if that.

This is normally done for a set-up of equipment or calibration of equipment, like a 2" and 4" for 6 inch micrometer or caliper end of travel.

Remember, I give him a bit of leeway of understanding the measuring in values in nanometers, his world is in .001" or maybe .0005" 

The video is a really a simple understanding of what goes into measuring of parts and the equipment used. The attachments are from the

sources that explaining the fine points and requirements in the world of measurements, which is a science into it's self. 

 

Starry Nights