Swiss AND Geared, Happy Michael?

[Anorak Bob]

I was chastised the other day for a lack of gearing in a contraption I made so when I chanced upon this I thought immediately of Michael. I like it and some others might like it too. :U

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More here - http://www.ebay.com/itm/391012001658?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D391012001658%26_rdc%3D1

[Michael G]

That's an interesting looking mechanism there, particularly the arm on the semi-circular scale. Those sort of mechanisms are always interesting as they have to come back to a starting point some how. A continuous dial must have been too easy for them...

Michael

[Stustoys]

Thanks BT,

Much head scratching with little result.

Anyone figured out how it works yet?

As a comparator its easy. As a mic its not so easy.
Undo the large thumb screw at the front.
Turn the mic to the 0.01mm you want it zeroed on.
Pull the vertical arm into mesh with the gear on the thimble.
Press down on the bar that connects the parallel arms(this moves the "large thumb screw holding thing" to 0 the scale)
Tighten thumb screw
Move vertical arm out of mesh.
Twiddle the post wrapped in string to open and close the mic(a whole .05mm) with measurement force taken care of but the weight.

Even if I believe all that, it still leaves one arm with nothing to do :(

I think you should buy it and lets us know BT ;)

Micheal, I dont recall having seen a 0.001mm direct reading mic(digital don't count :P)

Stuart

[Michael G]

Michael, I don't recall having seen a 0.001mm direct reading mic (digital don't count :p)

Actually, I think I can come close -
Bryan supplied me with a couple of Mahr xxx-mess DTI's. If I put them in the socket on the end of this -

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I can theoretically get down to micron level (in the temperature controlled tin roof shed...)
That's a Mahr 0 to 1" bench micrometer that in it's raw state goes to 10ths ( 2.5 micron)

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Then I can either put on the 1 micron gauge or the 0.00002" gauge (0.508 micron)
If I lock the barrel I could then use it as a comparator.

Michael

[simonl]

I think you should buy it and lets us know BT ;)


What! He hasn't even bought it yet? What are you waiting for Bob? This thread is misleading, I thought you were showing us your latest acquisition, not your latest dream! :cool:

Simon

[simonl]

I can theoretically get down to micron level (in the temperature controlled tin roof shed...)

Michael

So, just how far can you measure in the average tin shed? Is a tenth thou pushing the boundary?

Simon

[Michael G]

For comparative terms, it probably is insignificant.
However, the coefficient of linear expansion for steel is 12 microns per meter per degree C (http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html), so if you were measuring a piece of steel 100mm long on a 35 degree day with a micrometer just brought from your 20 degree house you would be 18 micron out - that's roughly 7 10ths.
I find that if I turn with carbide such that blue chips shower down I can be a thou or so out on diameter when things have cooled too.

Michael

[Stustoys]

Actually, I think I can come close -
That's a Mahr 0 to 1" bench micrometer that in it's raw state goes to 10ths ( 2.5 micron)

Close? thats like saying 1cm is close to 1" :p

Nice piece of kit none the less.



Then I can either put on the 1 micron gauge or the 0.00002" gauge (0.508 micron)

Once you add the gauge you have a comparator. As you cant really Zero the mic to the same level you are trying to read..........but thats what makes me wonder about the method I came up with above. how could that possibly get you to the nearest micron??


Stuart

[Michael G]

Close? that's like saying 1cm is close to 1" :p

On the contrary, it's exact if there is another 1.54cm in front of it.


Once you add the gauge you have a comparator. As you cant really Zero the mic to the same level you are trying to read how could that possibly get you to the nearest micron??

Using my method, the mic is locked, so whether the mic is in mm, inches or giraffes it doesn't matter. The comparison bit is done by the dial on the front.

As for the mic that Bob pointed out, I don't think that is a comparator mic in the normal sense. The way that the dial scale is set up, I think you lock the quadrant to the barrel and that provides the micron readings as well as being able to give a variation of plus/minus 50 micron on the base reading. I wonder whether you dial up the nearest division on the barrel, set the pointer to zero and then measure from there - so all the rest of it is doing is providing a better discrimination than the barrel scale. These days you are more likely to do that with a vernier scale on the barrel.

Michael

[eskimo]

more toys for the big boys :sad1:

I gotta find something none of you have got....

Where do you find this stuff...they're amazing

[DSEL74]

Tha's really purdy!!! Further than that I'm in way over my head..

[Michael G]

Where do you find this stuff...they're amazing

I can't afford this stuff at retail prices so for me it's mainly flicking through ebay (both here and OS) and taking a gamble on something that looks like a beater or that has been mis-labelled. There is also a bit of swapping and horse trading that goes on off-line. The indicators I got from Bryan were from a job lot he'd picked up and some were surplus to his needs. He felt he owed me a favour and so...

From memory that Mahr was from ebay and was so filthy that the badge was not readable. The indicator crystal was dusty enough that you couldn't see what it was. I was hoping to get something I could check dial indicators against, so bought it for the micrometer head. As sometimes happens with my plans the rest cleaned up alright so I've left the micrometer head where it is.

Michael