Some Metrology Gear

**RayG** · 4th December 2014, 10:11 PM

There was a heap of metrology stuff went at a Grays Auction recently.. I picked up a few bits and pieces..

I got a Tesa electronic gage, and probes, Out of 5 probes ( spread over 2 lots) 2 of the probes were crook, and 3 are good, one was brand new.
I also got a battery powered Tesa Inductive probe meter, but I don't have a picture of it, I'll put it up later. This is the mains powered one.

The most sensitive range is 3 microns full scale, and you can switch to 300 microns full scale. The probe is an inductive type, and is basically an LVDT. The case is heavy cast aluminium.

If you like things in imperial, then switch to 0.1 range on the lower right switch, then the red scale reads from 0 to 100 millionths.

The other thing I picked up was a monochromatic light source and some optical flats, and a set of gage blocks

The Light source is pretty much the standard sodium vapour light source, which is 575 nano meters, and so the 1/4 wave fringes are 144 nano meters. (0.144 microns)

The monochromatic light source, and the set of gage blocks, they look like a well kept set of inspection grade gage blocks. None missing, and first inspection I think they are in good nick.

The optical flats cam in a box of 4, and I think they are micrometer flats. Used to check micrometer anvils?

1.. Two wear slips 2. flats together

3. One wear slip 4. two wear slips

I'm still working out the subtlety of measuring the fringes, but first thing to know is that if the fringes are parallel, (and evenly spaced) then the object is flat.. albeit not parallel, the fringes are 0.144 microns apart.

The spacing between the fringes tells you how close to parallel the two surfaces are.

So... there's two new ( to me anyway ) ways of measuring very accurately.. Tesa inductive probes, and optical flats.

Ray

**.RC.** · 4th December 2014, 10:35 PM

Looks good Ray, when is the temperature controlled clean room coming online?

**Stustoys** · 4th December 2014, 10:39 PM

Nice haul Ray,
Lucky I didnt see that auction...... we would have been bidding on the same things it seems lol
though the optical protractor would have been nice... and if I could have thought of an excuse a 600mm raiser block for $19 lol

Originally Posted by RayG

The optical flats cam in a box of 4, and I think they are micrometer flats. Used to check micrometer anvils?

I assume they have a thickness on them?
Are the all the same or something like XX.000, XX.125, XX.250 and XX.375?(assuming metric)

Stuart

**simonl** · 4th December 2014, 10:44 PM

Hi Ray,

geezz you buy some neat stuff! That fringe pattern looks beautiful BTW.

Simon

**RayG** · 4th December 2014, 11:00 PM

Originally Posted by RC

Looks good Ray, when is the temperature controlled clean room coming online?

About 2-3 am most calm clear nights...

Originally Posted by Stustoys

Nice haul Ray,
Lucky I didnt see that auction...... we would have been bidding on the same things it seems lol
though the optical protractor would have been nice... and if I could have thought of an excuse a 600mm raiser block for $19 lol

I assume they have a thickness on them?
Are the all the same or something like XX.000, XX.125, XX.250 and XX.375?(assuming metric)

Stuart

Hi Stuart,

I had to go and measure them.. they are labelled 1A, 2A, 3A, 4A and measure 0.4994, 0.5057, 0.5126, 0.5187 ( just a quick check) respectively...

So, yes they are different thicknesses, There isn't any optical grade information, that I can see, and the label that would have shown the brand, and maybe a bit more info is missing

Ray

EDIT: I found a set on ebay http://www.ebay.com/itm/MITUTOYO-157...item1c49e0ddee
And the thicknesses on the Mitutoyo set are 0.5000, 0.5062, 0.5125, 0.5187 which is pretty close to what I got with a quick check.. So now I can go looking for instructions on Mitutoyo 157-901 optical parallels.

**Stustoys** · 4th December 2014, 11:19 PM

They are for checking the faces are square to the axis.
So you're checking the faces of the mic for parallel as near as damn it 90degs apart.

Stuart

**RayG** · 4th December 2014, 11:33 PM

Originally Posted by Stustoys

They are for checking the faces are square to the axis.
So you're checking the faces of the mic for parallel as near as damn it 90degs apart.

Stuart

I get it... the pitch of the micrometer thread is 40 tpi, which is 0.025 per turn

So starting with 1/2" 0.5000 is the first one
add 1/4 turn = 0.0625 gives 0.50625 for the second
add 1/2 turn = 0.0125 gives 0.5125 for the third
add 3/4 turn = 0.01875 gives 0.5187 for the fourth..

So as you say, the micrometer faces are checked for square and parallel every 1/4 turn.. simple.

Meantime, they can also check anything else for flatness...

Ray

**jhovel** · 5th December 2014, 02:45 AM

I'm glad the gauge blocks went to a good home. If they hadn't gone to you they might well have come here

**Hunch** · 5th December 2014, 07:14 AM

Next stop faro arm or two?

http://cal.cagp.com/event/marussia/

Looks like you can even buy a chow hobby lathe, blocks or granite do look nice though!

**RayG** · 5th December 2014, 10:46 AM

Originally Posted by Hunch

Next stop faro arm or two?

http://cal.cagp.com/event/marussia/

Looks like you can even buy a chow hobby lathe, blocks or granite do look nice though!

Thanks for that link...

No wonder F1 is so expensive... they have everything that opens and shuts for testing and measuring, but almost no in-house manufacturing? So I guess they design it and simulate in CAD send it out to be manufactured, then test it when it comes back to refine the mathematical models, and performance.

What I want to know is when did someone sneak into BT's workshop for this picture...

Ray

**Stustoys** · 5th December 2014, 11:18 AM

What I find funny about those flats. Parallelism: 0.8uin, Flatness 0.1uin, Thickness......lets call it 1/2 tho
Now you just need a metric set.

Originally Posted by RayG

What I want to know is when did someone sneak into BT's workshop for this picture...

Looks kinda like mine hey BT?

Stuart

**Anorak Bob** · 5th December 2014, 11:38 AM

Originally Posted by Stustoys

Looks kinda like mine hey BT?

Stuart

I'll answer on both our behalf's, "if only!!"

**RayG** · 5th December 2014, 08:04 PM

Same Auction, I picked up a Mitutoyo 3052 dial gage, this is a large 3" dial and long travel 30mm with 0.01 resolution. My aging eyes like the large dial, and my slipshod setup's like the long travel..

When I got it, it didn't return, so I thought .. the return spring must be broken... so I opened it up.. and the return spring is missing.. so I figure it's been used in an application where the spring pressure applied to the
part being measured is a problem, so they took the spring out... My problem is where should it go.. I scavenged a spring from a non functioning Mahr and installed it as shown in picture 3..

Is that where it's supposed to be? Seems to work ok, bit less pressure than normal I think...

Ray

**simonl** · 5th December 2014, 08:54 PM

Hi Ray,

without the spring, would backlash then be a problem?

Did you happen to see my 0.002mm DI there?

Simon

**RayG** · 5th December 2014, 09:00 PM

Originally Posted by simonl

Hi Ray,

without the spring, would backlash then be a problem?

Did you happen to see my 0.002mm DI there?

Simon

Don't know, I imagine they had an external weight of some sort? I didn't see your 0.002 DI, but I'm sure it was there, the pickup place in National Drive South Dandenong is actually a temporary GraysOnline depot of some sort, not the sellers premises. So there was all kinds of stuff stacked on pallets everywhere.

Ray

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