Thread: Metrology

Thanks Roger for organising the tour. As the others said it was a great day out.

I think Ray and Josh with their purchases are going to give the NMI a run for their money.

Need some more Renishaw gear?
Renishaw ML10 XL80 Laser Interferometer Calibration Optics Machine Tools CMMS | eBay

Christian

Great day.... I could have spent a week hanging out in the dimensional lab. Some of their gear is simply stunning. Seeing the graph of the room temperature go up as we walked around the various work stations was quite interesting. The slings and arrows of the metrology lab; "you give too much body heat".
-J

some pictures here



cheers
Harty

Thanks for the pictures.... I can only imagine that building is sitting on a HUGE slab of concrete.... Or probably more to the point, many slabs of very very thick concrete all isolated from one another...

Hi RC

No i asked that question and the answer was the slab is what was already there which was an old warehouse all they did where vibration tests

cheers
Harty

Thank you for the wonderful photos Peter.

Bob.

Can't add a lot to the pictures
Someone like to explain this way to me? looks strange.
A nice idea to save you counting turns.
The sides of one of the main plates, I asked what they were for and I think he said you can tweak the plate, but maybe I missunderstood.
One of the large plates was 3 point, the other was four point. Well so Josh said I didnt look under the first one.
Shame none of the optics on this machine are used anymore.

Stuart

Originally Posted by Stustoys

Someone like to explain this way to me? looks strange.
A nice idea to save you counting turns.

Damn it Stuart! For the last year you guys have been saying I should get a DRO so I don't lose count of the turns. I finally lash out and buy one and now you post something simple and mechanical like this.

I imagine the drum with the spiral cut is on a shaft so it can be "zeroed" against the pointer. The spiral pitch would be the same as the leadscrew. 2 and a bit turns would be 2 lines of the spiral + the remanent on the dial.

Michael

Hi Michael,
Sorry cant really add much to the picture I dont even think we talked about what this machine did. There was a lot of "old stuff" around that didnt get used anymore.. like a metric Mit master height gage . Josh and I were just having a sticky. I cant say if or how it is adjusted(though it could be made the same as any other mill dial) there was a lot of texta marks on it. The only other thing I can think of ATM is that the pitch of the leadscrew doesnt matter. The pointer is free to slide at what ever pitch is on the dial. Look on the bright side, doesnt fix backlash errors.

Stuart

For those that are interested the BBC did a 3 part series called "Precision" which is about the history of National Standards.
The Silicon Ball was commissioned by the Yanks to a guy in Sydney to make. Apparently it took about 4 months of polishing to get it right. If you enlarged the ball to the diameter of the Earth, the highest hill would be about 2 metres.

Roger

Originally Posted by rogerbaker

For those that are interested the BBC did a 3 part series called "Precision" which is about the history of National Standards.
The Silicon Ball was commissioned by the Yanks to a guy in Sydney to make. Apparently it took about 4 months of polishing to get it right. If you enlarged the ball to the diameter of the Earth, the highest hill would be about 2 metres.

Roger

Thats pretty amazing...considering your average snooker ball, which seems awfully round, has mountains and valleys about twice as high as the earth does. (if it was that size of course)

So....how do they measure a sphere for round? With the talyrond on many different axis?

Good pics Harty. How big was that t slotted box square/table?

Cheers,
Ew

Originally Posted by Stustoys

I cant say if or how it is adjusted(though it could be made the same as any other mill dial) there was a lot of texta marks on it. The only other thing I can think of ATM is that the pitch of the leadscrew doesnt matter. The pointer is free to slide at what ever pitch is on the dial. Look on the bright side, doesnt fix backlash errors.

I think you have nailed it Stuart. The texta marks are to mark the starting point. While the pointer can slide, I think it would be pitched the same as the machine as it counts the turns. That way you know that when you are two lines away from the texta mark you have done two turns.
When I get back to a place with a scanner I'll do a sketch.

Michael

Originally Posted by Michael G

I think it would be pitched the same as the machine as it counts the turns. That way you know that when you are two lines away from the texta mark you have done two turns.

But a turn is a turn is a turn, regardless of pitch. So if you had say a 0.5mm pitch on the leadscrew you could still have a 5mm pitch on the dial so that you have room to write. Two turns will be 1mm even though the pointer has moved 10mm. We'll have to get back in there and have a better look

Originally Posted by rogerbaker

For those that are interested the BBC did a 3 part series called "Precision" which is about the history of National Standards.
The Silicon Ball was commissioned by the Yanks to a guy in Sydney to make. Apparently it took about 4 months of polishing to get it right. If you enlarged the ball to the diameter of the Earth, the highest hill would be about 2 metres.

Roger

Precision: The Measure of All Things, BBC Four | TV reviews, news & interviews | The Arts Desk