Engineering related instruments

I have read Stewart Hart's current thread on his Beam Compass (nice work Stewart) and I intended to post this on that thread as there are some similarities but although related, I think it might have smacked of highjack hence this new thread.>>

I "rescued" this fine example of British instrument making a few years back at a local boot sale - £2 if memory serves right. I'll never use it but it is such a lovely example of instrument making that I thought it might evoke some memories for chaps hereabouts if I posted photos of it.>>

Anyone who has used one will recognize it as a Planimeter and this one was made by ALLBRIT.>>

Rik

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Nice one Rick.

Mine is little newer and followed me through a couple of departmental moves, and eventually home after redundancy, despite being told to bin it about 1978.

I think I last used it in 1982 to rescue boss from a problem of his own making. Was he grateful. Nope! Got told off for not binning it! Considerable heat and light followed whist his position in the lower firmament was made clear.

Clive.

And Planimeters are used for measuring areas.
BobH

Not really an engineering instrument but something I hated the thought of it being destroyed so I rescued it from a skip. A Hilger & Watts theodolite.

Martin C

Yes! it is an Engineering instrument.

"Optical tooling" is a special branch of metrology

**LINK**

Hilger and Watts is one of the best makers.

Regards
John

We used theodolites and telescopes to make the wing and fuselage jigs for aircraft at BAC Weybridge. Also has 'stick' micrometers up to 12 feel long! They were made in 3', 1' and various other lengths with a 1" micrometer on the end. They were only about 5/8" diameter, so had to have several supports along their length.
http://www.sometcz.com/en/store/bore-gauges-and-instruments/stick-micrometers-sets
BobH

Edited By Speedy Builder5 on 24/11/2017 06:52:42

A friend of mine collected ships sextants, they made beautiful ornaments in his house. He passed away earlier this year so I do not know what became of them.

Hi All,

We had this nice stick Micrmeter set a while back from a car boot, it had absolutely zero interest on EBay starting at £4.99, listed 3 times and we finally let it go at a car boot for £3!

We have had a Moore & Wright one since which made £14.

Really nice things but not wanted it seems, even by collectors.

Cheers,

Martin

Martin Trouble today is a lot of people have no idea what thing like this are

Roy

John, the theodolite was made redundant by the switch to auto leveling "Dumpy" levels with a parallel plate micrometer head attached to them (reads to 0.1mm estimate to 0.01mm). We use these with Brunson (as in your link) scales or steel rules mounted in Brunson magnetic base scale holders for leveling large fabrications.

Reading 1mm over 1m between scales gives one milliradian (mrad or mils). With the micrometer head this becomes 0.1mm over 1m or 0.1mrad. Over 5m it is 0.02mrad. This is equivalent to 0.001146° or 0° 0" 4'. We stopped using precision levels for this type of work a long time ago!

Martin C

I used to use one of these over 40 years ago as part of working out the whirling speed of steam turbines. Don't ask me how, it's a long time ago.

Seeing those stick micrometers again, nearly bought them but ... , makes me wonder how on earth you can calibrate the set. Screw joints aren't precise at micrometer resolution and there could be 8 getting in on the act. Seems to me that its of no great use unless it can be reliably broken down and re-assembled to give consistent results.

Clive.

Rescued from a skip - you lucky dog, I had to pay money for mine! I have a late model marked 'Watts' but actually Rank Precision, which I think dates it to the 1970s. I bought it to indulge an interest in map making. Trouble was reading books doesn't prepare you for the weight of the equipment. The theodolite is about 9kg, the wooden tripod about 4kg, not sure about the staff and chains but it's no joke after a few hundred yards. Doing a survey really needs a small team. In addition to the surveyor, a fit bloke to carry the gear, and perhaps an assistant or two taking records, holding the staff etc. Taking readings without making mistakes is b***y hard work too.

For some reason my son was very reluctant to do the carrying or walk long distances with a staff while I triangulated in the rain. I used the theodolite in anger only once. Playing astronomy it's useful to align the telescope with true north. As I can't see Polaris from my back garden I used the theodolite to spot the star from the road, worked out my house's alignment relative to true north, and then aligned the telescope to the house.

Result - the neighbours think I'm mad.

The best way of mapping the village was to ride all the roads on a bike with a hikers GPS. Downloading the track allows you to produce a decent street map. Much easier than using a theodolite.  Not as easy as photocopying the one in the Parish Magazine.  Ho hum...

Dave

Edited By SillyOldDuffer on 24/11/2017 14:01:52

This Watts (before Hilger) was being thrown out from where I worked because no one could read it. I scrounged and took it home to dismantle. When it was in pieces, it was obvious why no one could read it, it had been used with coolant which had obscured the glass scale marked in degrees, and the eyepiece. When cleaned up it worked fine although not the easiest thing to use because to light needed to get in the back through a small frosted window.

It looks nice cleaned up though. I used to be an instrument calibrator and inspector so these things appeal.

Brian

Google 'plate solving' and 'astro tortilla'

Neil

Very interesting and new to me! More and more I realise I'm not keeping up. In theory I know how to use a theodolite and star sights to fix one's position on earth. The more stars used the better. It's hard work: you have to carefully record many observations and then use the results to do hard sums. In my hands the calculation is likely to go wrong. The idea of photographing a section of sky and pattern matching it against a star catalogue with a computer would never have occurred to me. That it's straightforward for amateurs with affordable kit is amazing.

I'm tempted to re-equip for astronomy. I gave up because I don't like the cold. Now it's affordable to control the telescope from indoors. I was very tempted last year but was put off by months of almost solid cloud cover. This morning I have clear blue sky. And I deserve expensive xmas presents from myself.

Dave

Edited By SillyOldDuffer on 25/11/2017 09:44:20